SKIN FREEZING SYSTEMS FOR TREATING ACNE AND SKIN CONDITIONS
A method and system in accordance with a particular embodiments of the technology includes applying a substance onto skin of a human subject. An applicator is then applied to the subject to cool a region of the subject. After cooling the tissue, a nucleation initiator is used to initiate a freeze event in the tissue. The nucleation initiator can be an ice crystal that inoculates the skin upon contact to create a predictable freeze event therein. The time of contact between the ice crystal and the skin can be controlled to achieve desired effects.
The present application claims the benefit of and priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 62/334,213, filed May 10, 2016, which is incorporated herein by reference in its entirety.
INCORPORATION BY REFERENCEThe following U.S. Patent Applications and U.S. Patents are incorporated herein by reference in their entireties:
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TECHNICAL FIELDThe present disclosure relates generally to systems for cooling tissue. In particular, several embodiments are directed to treatment systems, methods, and substances for controllably cooling tissue to treat acne or other conditions.
BACKGROUNDExocrine glands found in the skin have a role in maintaining skin health, including lubricating, waterproofing, cleansing and/or cooling the skin or hair follicles of the body by excreting water-based, oily and/or waxy substances through skin pores or hair follicles. Overproduction and/or oversecretion of these substances by certain exocrine glands, such as sebaceous glands and sudoriparous glands (e.g., sweat glands), can cause unappealing skin disorders that have proved difficult to treat. For example, overproduction of sebum, a waxy substance produced and secreted by sebaceous glands, can lead to the formation of comedones (e.g., blackheads, whiteheads, etc.) and other inflammatory conditions of the skin associated with acne (e.g., inflamed papules, pustules, nodules, etc.), which can potentially lead to scarring of the skin. Overproducing sebaceous glands associated with hair follicles are mostly found in highly visible regions of the body, such as along the face, neck, upper chest, shoulders and back.
Hyperhidrosis is a condition associated with excessive sweating caused by the overproduction and secretion of sweat from sweat glands in the skin of mammals. Excessive sweating from eccrine sweat glands, which are distributed almost all over the body, can cause discomfort and embarrassment. For example, focal hyperhidrosis can occur on the palms of the hands, soles of the feet, face and scalp. Apocrine sweat glands, particularly in the axilla (i.e., armpits), have oil-producing cells that can contribute to undesirable odor.
Treatments for these and other skin and tissue conditions are often ineffective, non-lasting, and/or have undesirable side-effects.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawings will be provided by the Office upon request and payment of the necessary fee.
Many aspects of the present invention can be better understood with reference to the following drawings. Identical reference numbers identify similar elements or acts. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale.
The present disclosure describes treatment systems for improving the appearance, function and health of tissue and for performing other treatments. Several of the details set forth below are provided to describe the following examples and methods in a manner sufficient to enable a person skilled in the relevant art to practice, make and use them. Several of the details and advantages described below, however, may not be necessary to practice certain examples and methods of the technology. Additionally, the technology may include other examples and methods that are within the scope of the technology but are not described in detail.
Various aspects of the technology are directed to cooling a surface of a patient's skin to produce a cooling event (e.g., a partial freeze event, a total freeze event, etc.) that affects tissue, cells, structures, appendages, or targeted features. Systems disclosed herein can target glands (e.g., exocrine glands, sebaceous glands, sweat glands, sudoriparous glands, etc.), structures in the skin (e.g., hair follicles, superficial nerves, etc.), and/or layer(s) of tissue (e.g., dermal layer, epidermal layer, subcutaneous layer, sub-layer(s) of the epidermis, dermis, subcutaneous, etc.). In some embodiments, the cooling event reduces or limits overproduction and/or oversecretion of exocrine glands to treat comedones and/or other inflammatory conditions of the skin associated with acne, such as inflamed papules, pustules, nodules, etc. For example, the cooling event can cause an effective amount of thermal injury to glands to reduce or limit overproduction and/or oversecretion by those glands to reduce or eliminate acne or other skin conditions. The cooling event can include freezing a region of the dermal layer containing the targeted exocrine glands without affecting non-targeted tissue. Treatment applicators can be configured for use along the face, neck, upper chest, shoulders, back, and other treatment sites and can target specific layers in the skin, subcutaneous tissue, specific structures, particular cells, etc.
In certain embodiments, a method for predictably freezing a subject's skin at a desired predictable time includes lowering a temperature of the skin below a freezing point of fluid in the skin so that the skin is at a first temperature. An ice crystal contacts the skin to inoculate the skin and to create a predictable freeze event therein. A time of contact between the ice crystal and the skin is controlled so that the predictable freeze occurs at a desired time. In some procedures, the method can be performed using an applicator that is applied to the subject's skin.
In some embodiments, a method for freezing dermal tissue more than once while freezing epidermal tissue only once includes applying a coupling media to an applicator. The coupling media has a medium therein capable of forming ice crystals. A temperature of the applicator is lowered below a freezing point of the medium to at least partially freeze the medium. The coupling media, which is carried by the applicator, is placed on a subject's skin surface. The temperature of the applicator can be adjusted to a treatment temperature for freezing at least a portion of the medium in contact with the skin surface to freeze dermal and epidermal tissue. In some procedures, the applicator is warmed an amount sufficient to allow the dermal tissue to thaw but not enough to allow the epidermal tissue to thaw. After the dermal tissue at least partially thaws, the temperature of the applicator is adjusted to a second treatment temperature such that the at least some of the thawed dermal tissue refreezes and the epidermal tissue remains frozen.
In further embodiments, a method for freezing dermal tissue more than once while freezing epidermal tissue only once includes at least partially freezing the dermal tissue and epidermal tissue using an applicator configured to cool a skin surface of a subject. While the epidermal tissue remains frozen, the applicator is warmed an amount sufficient to allow at least some of the dermal tissue to thaw, and after thawing at least some of the dermal tissue, cooling the applicator to re-freeze at least some of the dermal tissue.
In one embodiment, a method for predictably freezing skin comprises supercooling a subject's skin using a coupling media and an applicator at a first applicator temperature. The first applicator temperature is higher than a freezing point of the coupling media. The coupling media includes a freezing point depressant which inhibits freezing of the coupling media and the skin. The skin is inoculated to freeze the skin without lowering a temperature of the applicator below the first applicator temperature.
In some further embodiments, a method for treating skin includes lowering a temperature of a subject's skin below a freezing point of target tissue of the skin. Cooling of the skin is monitored so that freezing therein does not occur. An amount of non-freezing cooling treatment delivered to the skin is controlled so that the target tissue reaches a predetermined first level of cooling. After the target tissue reaches the predetermined first level, the skin is frozen. An amount of freezing cooling treatment delivered to the skin is controlled so that the target tissue reaches a predetermined second level of cooling
A system for treating a subject includes an applicator configured to cool a subject's skin surface when the applicator is applied to the subject and a controller. The controller can be programmed to cause the applicator to, for example, create or maintain at least one ice crystal and/or induce a freeze event in the subject's skin via the at least one ice crystal.
At least some of the embodiments disclosed herein can be for cosmetically beneficial treatments. As such, some treatment procedures may be for the sole purpose of altering a treatment site to conform to a cosmetically desirable look, feel, size, shape or other desirable cosmetic characteristic or feature. Accordingly, cosmetic procedures can be performed without providing any or minimal therapeutic effect. For example, some treatment procedures may be directed to goals, such as the reduction of acne, that do not include restoration of health, physical integrity, or the physical well-being of a subject. In some embodiments, methods can target skin irregularities, wrinkles, and sebaceous glands to treat acne; sweat glands to treat hyperhidrosis; hair follicles to injure and remove hair; or other targeted cells to change a subject's appearance or address a condition. Treatments may have therapeutic outcomes (whether intended or not), such as, psychological benefits, alteration of body hormone levels (by the reduction of adipose tissue), etc. Various aspects of the methods disclosed herein can include cosmetic treatment methods for achieving a cosmetically beneficial alteration of a portion of tissue within the target region. Such cosmetic methods can be administered by a non-medically trained person. The methods disclosed herein can also be used to (a) improve the appearance of skin by tightening the skin, improving skin tone and texture, eliminating or reducing wrinkles, increasing skin smoothness, thickening the skin, (b) improve the appearance of cellulite, and/or (c) treat sebaceous glands, hair follicles, and/or sweat glands.
At least some embodiments of the technology include producing one or more controlled freeze events. The location and extent of freezing can be controlled to produce a therapeutic or cosmetic effect. Nucleation initiators, nucleation inhibitors, and/or treatment substances can be used before, during, and/or after the freeze event. The nucleation initiators can include, without limitation, ice nucleation agents, injectable substances (e.g., saline, ice slurries, etc.), energy that promotes ice nucleation, or other initiators that affect freezing. Nucleation inhibitors can include, without limitation, cryoprotectant solutions, freeze temperature depressants, and/or heaters.
According to one aspect of the technology, a subject's skin is lowered to below its melting/freezing point (“melting point”). The skin temperature is monitored to control an amount of non-freezing effects. An ice crystal contacts skin to cause a freeze event in the skin. The skin can be monitored to control an amount of freeze treatment. The skin can also be monitored to detect any further non-freeze effects, freeze effects, or thaw effects to precisely and predictably control an overall level of treatment. Skin preparation techniques can be utilized to enhance absorption of the substance into the skin by abrading and/or scrapping of the epidermis. Example substances include thermal coupling gels, cryoprotectant solutions, and/or ice nucleating agents that may be incorporated into or part of a hydrogel material, a liposome, an emulsion, a nano-emulsion, nanoparticle mixture or solution, and/or combinations thereof. Nano-emulsions and nanoparticles may be desirable since their small size makes them suitable to being absorbed into the epidermis and dermis by traveling along hair follicle apertures and/or skin pore apertures. A cryoprotectant can be used to enhance the amount of non-freezing treatment to be delivered prior to any freeze event because the cryoprotectant can allow significant supercooling of the skin prior to initiating a freeze event. In one embodiment, an ice nucleating agent is utilized to reliably and predictably form ice crystals.
An applicator can predictably freeze targeted tissue or structures by producing a freeze event that occurs in an expected way. For example, tissue can be cooled to start a freeze event at an anticipated time (e.g., at a particular time or within an expected period of time), propagate the freeze at a desired rate, achieve a desired extent of freezing, or the like. Treatment parameters can be selected based on the desired predictability of the freeze event. For example, the skin surface can be cooled to produce a freeze event at least 80%, 85%, 90%, or 95% of the time in a typical patient. This provides a predictable freeze. If a freeze event does not occur, the skin can be warmed and cooled again to produce a freeze event.
One advantage of freezing is that for a given amount of desired tissue damage, a procedure that produces freezing can take considerably less time than a procedure which does not involve freezing. This is because with freezing, cell walls are damaged.
Damage to tissue due to freezing and cooling is mainly dependent on, for example, cooling rate, end temperature, holding time (unfrozen and/or frozen), and thawing rate. These variables can be controlled to achieve the desired cryoinjury to target tissue.
Tissue damage at the cellular scale is known to occur due to intracellular (IIF) and extracellular ice (EIF) formation. Cryoinjury due to IIF can be accomplished by inducing irreversible damage to the tissues and by necrosis destroying cell organelles and membranes from the inside. Cryoinjury due to extracellular ice formation is mainly due to hyperosmolarity in extracellular space and dehydration of the cells because of the extracellular ice. These processes provoke direct cell death or programmed cell death (e.g., apoptosis of the cells).
In order to accomplish tissue injury, a sufficient end low temperature can be reached. Individual tissues and cells may have different susceptibility to cold. Consequently, lethal temperatures can vary among different components of the skin. Multiple cycles of a treatment temperature protocol should increase efficacy as well.
Holding time in a frozen state enhances cryogenic tissue injury mechanisms. As ice crystals grow in size during a holding time period, the more they will enhance injury due to IIF and/or EIF.
Thawing is a destructive factor facilitating recrystallization (ice crystal restructuring), namely, crystals growing bigger, and rehydration of cells causing membrane disruption and cell death.
For skin, cold can affect the blood microcirculation which can induce reversible or irreversible vascular changes. During cooling there is vasoconstriction of blood vessels which in some temperature treatment protocols may provoke the occurrence of stasis and tissue ischaemia. During freezing, there may be damage to the endothelium of blood vessels and other cellular injury due to EIF and IIF. Vasoconstriction facilitates hypoxia, a state in which cells release vasodilatation cytokines which after thawing enhance refractory vasodilatation and reperfusion injury. Reperfusion also facilitates inflammatory and perivascular oedema of tissues.
Additionally, partially or totally frozen tissue has a higher thermal conductivity and a lower specific heat than unfrozen tissue. The thermal conductivity continues to increase and the specific heat continues to decrease as additional tissue is frozen. This change in thermal properties can result in enhanced efficiency (e.g., a factor of four to eight improvement in cooling efficiency) as compared to a treatment which does not involve freezing, even when the treatment temperatures of the non-freezing treatment with supercooling are similar to the freezing treatment temperature. Accordingly, with freezing, the depth of penetration of cooling into the skin and surrounding tissue can be significantly faster than without freezing.
Some embodiments are directed to treating tissue below the skin or sublayers or sub-thicknesses of the skin, such as the epidermis, dermis, subdermis, subcutaneous, and sub-layers thereof to treat wrinkles, fine lines, pores, moles, freckles, port wine stains, and other vascular issues, acne, or the like. Additionally or alternatively, treatments can be performed to rejuvenate skin, resurface skin, address skin coloration issues, block pain, etc., and to affect targets, such as appendages, cellular elements, or combinations thereof. Appendages that can be treated include, without limitation, hair follicles, sebaceous glands, sweat glands, arrector pili, nerves, blood vessels, etc. Cellular elements that can be treated include, without limitation, corneocytes, keratinocytes, melanocytes, sebocytes, fibroblasts, blood cells, collagen, elastin fibers, etc. The systems and methods disclosed herein are useful for treating the targets and conditions disclosed herein.
References throughout this specification to “one example,” “an example,” “one embodiment,” or “an embodiment” mean that a particular feature, structure, or characteristic described in connection with the example is included in at least one example of the present technology. Thus, the occurrences of the phrases “in one example,” “in an example,” “one embodiment,” or “an embodiment” in various places throughout this specification are not necessarily all referring to the same example. The headings provided herein are for convenience only and are not intended to limit or interpret the scope or meaning of the technology.
B. TREATMENT SITESAnother skin condition is hyperhidrosis. Hyperhidrosis is characterized by abnormal sweating due to high secretion levels of sweat glands 26. Eccrine sweat glands are controlled by the sympathetic nervous system and regulate body temperature. When an individual's body temperature rises, eccrine sweat glands secrete sweat (i.e., water and other solutes) that flows through a gland tubule 28. The sweat can evaporate from the skin surface to cool the body. Apocrine sweat glands (not shown) secrete an oil-containing sweat into hair follicles 20. The axilla (e.g., armpit) and genital regions often have a high concentration of apocrine sweat glands. Hyperhidrosis occurs when sweat glands produce and secrete sweat at levels above that required for regulation of body temperature, and the condition can be generalized or localized (i.e., focal hyperhidrosis) to specific body parts (e.g., palms of hands, soles of feet, brow, scalp, face, underarms, etc.).
The applicator 104 can accurately target tissue while minimizing or limiting effects on non-targeted tissue. It has been discovered that when an ice crystal contacts skin 10 of the subject at a temperature which is below its phase transition temperature (e.g., melting/freezing temperature) and in a supercooled state, a freeze event can be immediately triggered in the skin. The ice crystal can thus be used to predictably control initiation of the freeze event. Once the freeze event is triggered, it can rapidly propagate through the volume of supercooled tissue. The heat of fusion released during freezing may take the bulk tissue out of its supercooled state, and thereafter the partially frozen skin may prevent non-frozen tissue from reentering a supercooled state. Additionally, the heat of fusion in some procedures, the period of time from the beginning of a freeze event in supercooled tissue to the point where the tissue is largely no longer in a supercooled state may be 1 second, 2 seconds, 3 seconds, 5 seconds, 10 seconds, or another suitable period of time. The time period for supercooling can depend on the target location, volume of targeted tissue, supercooled tissue volume, temperature profile, tissue characteristics (e.g., water content of tissue), and/or additives (e.g., compositions, energy, etc.) that may be used as part of the procedure. Because freeze propagation rates may be strongly dependent on the supercool temperature, the temperature of the supercooled tissue can be decreased or increased to increase or decrease, respectively, freeze propagation rates.
The applicator 104 can be used to precisely control a start time of the freeze event, an amount of damage caused by an initial freeze event (e.g., by controlling an amount of supercooling created prior to initiating the freeze event), a duration of the freeze event (e.g., by controlling a temperature of an applicator), and thawing rate (e.g., start of thaw cycle, etc.). The timing of freeze events can be precisely controlled by controlling the generation of the ice crystal and when the ice crystal comes in contact with supercooled skin so that freeze events can be produced “on command,” and this control allows for specialized treatment methods to be implemented to controllably and effectively treat a range of tissue while controlling and/or limiting damage to tissue. In addition, additives can be used to manage freeze events at varying optimum temperatures to target tissue at varying skin depths while controlling tissue damage, extent of injury to non-targeted tissue, etc. By controlling when and how to freeze, treatment procedures can target certain tissue without targeting other tissue while also controlling a level of treatment of targeted tissue and effects to non-targeted tissue.
In some embodiments, a temperature-controlled surface 111 of the applicator 104 can be cooled to affect target structures, such as glands, hair follicles, nerves (e.g., superficial nerves), or one or more layers of tissue (e.g., dermal layer, epidermal layer, subcutaneous layer, sub-layer(s) of the epidermis, dermis, and/or subcutaneous layer, etc.). To treat acne, the surface of the subject's skin can be cooled to produce a temperature at or below −15° C., −10° C., −5° C., 0° C., 5° C., 10° C., 15° C., or 20° C. and to produce either a cooling non-freeze event or a freeze event in a targeted portion of the skin. Localized freeze events can be generated to affect targeted structures while minimizing, limiting, or substantially preventing thermal injuries to non-targeted tissue, structures, etc. Substances used with the applicator 104 can include cryoprotectants, nucleating agents, liposomes, emulsions, hydrogels, combinations thereof, or the like. Mechanical energy (e.g., massaging), ultrasound energy, radiofrequency (RF) energy, and/or freeze initiators can control a freeze event by, for example, initiating, promoting, and/or inhibiting freezing. In some procedures, ultrasound energy is delivered to supercooled tissue to trigger freezing in the tissue. Radiofrequency energy can be used to warm tissue to isolate freezing to a target region. Freeze initiators can be used to initiate a freeze event in the tissue or freeze event in another substance that ultimately causes freezing in the tissue. Example freeze initiators include, but are not limited to, one or more water ice crystals, cryoprobes, or substances that rapidly freeze to produce freeze events. Freeze events can include partially or completely freezing liquids or lipids proximate to or within cells, and/or structures, to destroy, reduce, disrupt, modify, or affect targeted features. The characteristics of the cooling event or freeze event can be controlled to manage thermal injury. Such characteristics include, without limitation, the amount of cooling or freezing, density and distribution of ice crystals, freezing rate, or the like.
Cryotherapy can affect, without limitation, glandular function, structures of glands (e.g., gland portions, duct portions, etc.), number of glands, sizes of glands, and/or number and/or sizes of cells. The freeze event can be maintained for a period of time long enough to elicit a desired result. In some embodiments, for treating exocrine glands, a subject's skin can be cooled to produce a partial freeze event that destroys, reduces, disrupts, modifies, or affects cells or structures of exocrine glands or the supporting anatomical features (e.g., ducts, pores, hair follicles, etc.). The level of freezing can be controlled to limit unwanted tissue damage, such as damage to non-targeted tissue, excess damage to targeted tissue (e.g., to avoid excess damage to targeted tissue), and so forth. The skin surface can be continuously or periodically cooled or heated to increase or decrease, respectively, the number and/or sizes of ice crystals at the target region. In one procedure, the tissue can be kept in a supercooled state for longer than, for example, about 1 second, 5 seconds, 10 seconds, 20 seconds, 30 seconds, 1 minute, several minutes, or other time period selected to allow the tissue to reach a steady state temperature and desired width, length, and depth of a tissue volume which is in a supercooled state. Once tissue is frozen, it can be kept in a partially or totally frozen state for longer than about, for example, about 1 second, 5 seconds, 10 seconds, 20 seconds, 30 seconds, 1 minute, several minutes, or other time period selected to achieve desired effects, while reducing or limiting undesired effects, such as frostbite or necrosis.
The applicator 104 can include one or more elements 167 for detecting cooling events, freezing events, supercooling, and so forth. The thermal device 109 can be controlled based on the output from the element 167 to cool a temperature-controlled surface 111, which, in turn, cools the patient's skin. The element 167 can include one or more temperature sensors, pressure sensors, detectors, combinations thereof, or the like. Alternatively, separate sensors can be used to monitor the treatment site.
C. TREATMENT SYSTEMSThe connector 103 can be a cord that provides energy, fluid, and/or suction from the base unit 106 to the applicator 104. The base unit 106 can include a fluid chamber or reservoir 105 (illustrated in phantom line) and a controller 114 carried by a housing 125 with wheels 126. The base unit 106 can include a refrigeration unit, a cooling tower, a thermoelectric chiller, heaters, or any other devices capable of controlling the temperature of coolant in the fluid chamber 105 and can be connectable to an external power source and/or include an internal power supply 110 (shown in phantom line). The power supply 110 can provide electrical energy (e.g., a direct current voltage) for powering electrical elements of the applicator 104. A municipal water supply (e.g., tap water) can be used in place of or in conjunction with the fluid chamber 105. In some embodiments, the system 100 can include a pressurization device 117 that can provide suction and can include one or more pumps, valves, and/or regulators. Air pressure can be controlled by a regulator located between the pressurization device 117 and the applicator 104. If the vacuum level is too low, tissue may not be adequately (or at all) held against the applicator 104, and the applicator 104 may tend to move along the patient's skin. If the vacuum level is too high, undesirable patient discomfort and/or tissue damage could occur. A vacuum level can be selected based on the characteristics of the tissue and desired level of comfort. In other embodiments, the applicator 104 does not use a vacuum.
An operator can control operation of the treatment system 100 using an input/output device 118 of the controller 114. The input/output device 118 can display the state of operation of the applicator 104 and treatment information. In some embodiments, the controller 114 can be communicatively coupled to and exchange data with the applicator 104 via a wired connection or a wireless or an optical communication link and can monitor and adjust treatment based on, without limitation, one or more treatment profiles and/or patient-specific treatment plans, such as those described, for example, in commonly assigned U.S. Pat. No. 8,275,442, which is incorporated by reference in its entirety. In some embodiments, the controller 114 can be incorporated into the applicator 104 or another component of the system 100.
Upon receiving input to start a treatment protocol, the controller 114 can cycle through each segment of a prescribed treatment plan. Segments may be designed to supercool tissue, to nucleate supercooled tissue, to freeze tissue, to thaw tissue, to warm tissue, and so on. In so doing, the power supply 110 and the fluid chamber 105 can provide power and coolant to one or more functional components of the applicator 104, such as thermoelectric coolers (e.g., TEC “zones”), to begin a cooling cycle and, in some embodiments, to activate features or modes, such as vibration, massage, vacuum, etc.
The controller 114 can receive temperature readings from temperature sensors, which can be part of the applicator 104 or proximate to the applicator 104, the patient's skin, a patient protection device, etc. It will be appreciated that while a target region of the body has been cooled or heated to the target temperature, in actuality that region of the body may be close, but not equal to, the target temperature, e.g., because of the body's natural heating and cooling variations. Thus, although the system 100 may attempt to heat or to cool tissue to the target temperature or to provide a target heat flux, a sensor may measure a sufficiently close temperature or heat flux. If the target temperature or the flux has not been reached, power can be increased or decreased to change heat flux to maintain the target temperature or “set-point” selectively to affect targeted tissue. The treatment site can be continuously or intermittently evaluated by monitoring various parameters. The skin can be continuously monitored to detect its temperature to determine whether it is in a frozen state, an unfrozen state, or other state.
In some procedures, the applicator 104 can achieve a level or amount of supercooling at a suitable temperature below, for example, −15° C., −10° C., −5° C., or 0° C. After achieving a predetermined level of supercooling, the applicator 104 can automatically start a freeze event. The freeze event can be detected and/or monitored using the applicator 104 or separate device. A level of treatment can be controlled following initiation and/or completion of the freeze event. One or more post freeze protocols can be performed to thaw or otherwise thermally affect tissue to allow treatment to be specifically tailored to effectively treat certain targets, and to not treat or minimize treatment of non-targeted tissue. For example, post-freeze protocols can be used to inhibit, limit, or substantially minimize permanent thermal injuries. In some embodiments, post-freeze protocols can include gradually or rapidly warming non-targeted and targeted tissue.
At block 142, the skin can be cooled to lower the temperature of the skin below a freezing temperature of fluid in the skin. For example, the temperature of the skin can be lowered to a first temperature that is more than 3° C., 5° C., 7° C., 9° C., 10° C., or 11° C. below the melting/freezing temperature of fluid in the skin and can be maintained for a first period of time. After the first period of time expires, the skin temperature can be lowered to a second temperature that is lower than the first temperature so as to create an ice crystal. In other embodiments, the first temperature can be maintained at a constant temperature while creating an ice crystal by, for example, altering the composition of a coupling media. The coupling media can freeze and cause ice nucleation in the tissue.
At block 144 of
At block 146, a time of contact between the ice crystal and the skin can be controlled. A user can hold the applicator against the skin surface while the ice crystal contacts the skin surface. Upon completion of a contact period, the system can notify the subject or operator to remove the applicator from the subject. The applicator can be pulled off the subject to stop the crystal contact. Alternatively, the applicator can be warmed to melt the ice crystal at the completion of the desired contact period. The temperature of the applicator can be controlled to set the length of ice crystal/tissue contact, as well as the length of the freeze event by detecting the freeze event and further controlling when the temperature of the skin is raised to a temperature above the ice crystal's melting point to stop the freeze event.
In some treatments, the method 140 can include lowering a temperature of a subject's skin below a melting/freezing point or temperature of target tissue of the skin. The applicator 104 can monitor cooling of the skin using the sensor so that freezing therein does not occur. The amount of non-freezing cooling treatment delivered to the skin can be controlled so that targeted tissue of the skin reaches a predetermined first level at block 142. After the targeted tissue reaches the predetermined first level, the skin is frozen (block 144). The sensor can be used to identify and monitor the freeze event. An ice crystal can come into intimate contact with the supercooled skin during the supercooling period and prior to the time when the beginning of a freeze event is desired to occur, without adverse effects. After the supercooling period has elapsed to create a predetermined first level of supercooling, the ice crystal(s) can be brought into contact with the skin to initiate the freeze event, and damage associated with the initial freeze event can be largely proportional to the level or extent of supercooling. The freeze event can be maintained for any desired period of time, and after the freeze event, additional freeze events can further affect the tissue. The amount of freezing/cooling treatment delivered to the skin can be controlled so that it reaches a predetermined second level. In some treatments, the ice crystal is used to cause freezing of skin in the first level of the supercooled state. The predetermined second level, when combined with the first level, can be selected to provide a therapeutically effective amount of thermal injury.
A shallow skin treatment can include contacting the subject's skin with ice crystals while the skin has a bulk temperature just slightly below its melting/freezing point, such as by 0.2° C., 0.5° C., 1° C., 2° C., or 3° C. There may be minimal to no significant skin supercooling, so that the initial freeze event is small (e.g., a fraction of the tissue initially frozen will be small) and relatively small tissue can be frozen when the initial freeze event occurs. Accordingly, initial tissue damage can be predominately located in the epidermis and upper layer of the dermis, with deeper layers, such as subdermal, fat and muscle tissue, being largely unaffected. As such, treatments can be performed on acne-prone regions where damage to subcutaneous tissue may be problematic and undesired. Once the freeze event occurs, additional tissue in the skin will not enter a supercooled state because ice crystals in the skin can inhibit or prevent further supercooling. Further additional incremental cooling can result in predictable incremental freezing, and if minimal depth of treatment is desired, a tissue thaw protocol can be started immediately or very soon following the freeze event.
The system 100 can also perform deeper treatments, including aggressive and deeper skin treatments, by supercooling targeted tissue and then contacting the targeted tissue with an ice crystal to trigger a freeze event. The supercooled tissue can include epidermal tissue, dermal tissue, subcutaneous tissue and can be cooled as much as by 4° C., 5° C., 6° C., 7° C., 8° C., 9° C., 10° C., 12° C., 15° C., 17° C., 20° C., 25° C., 30° C., or 35° C. and for a significant period of time, such as 30 seconds or 1, 2, 3, 4, 5, 7, 10, 12, 15, 20, 25 or more minutes. The temperature and treatment period can allow for variable and controlled levels of skin supercooling prior to initiating a freeze event. An overall level of treatment can also include multiple treatments, each of which individually delivers a dose which is less than a total dose of treatment to ultimately be delivered. For example, after an initial skin supercooling and freeze event has been performed at a given treatment site, device software can be programmed to repeat the supercooling and freeze event cycle a second time, optionally after a tissue rewarming/thaw step between cycles. Temperatures and the treatment period for the second cycle can be the same as those of the first cycle or different. Additional treatment cycles could also be delivered. In this example, it would not be necessary to move the applicator between cycles, and the cycles could optionally be separated by a tissue rewarming/thaw step. As another alternative, an additional treatment at any given site could be performed later in the patient procedure after an applicator has treated other tissue sites. Still another alternative is that an additional treatment could be delivered during a separate patient procedure performed either later the same day as the first treatment, or the next day or several days or a week later, and the procedure could be repeated on a regular basis if desired (e.g., every day, every other day, every week, every month, etc.). Any number of desired follow-on treatments can be performed to achieve sufficient and desired overall levels of tissue treatment to create a desired tissue response.
The method 140 can be used to perform the treatments disclosed herein, such as the treatments discussed in connection with
Ice crystals can be formed along an applicator, using temperature programming. Water (e.g., droplets of water, a layer containing water, etc.) can be disposed on the applicator surface (e.g., surface 111 in
Tissue can be slowly or rapidly rewarmed as soon as practicable after a freeze event has occurred to limit, reduce, or prevent damage and adverse side effects associated with the freeze event. After freezing begins, the skin can be slowly or rapidly warmed as soon as possible to minimize or limit damage to the epidermis. In other procedures, the skin is partially or completely frozen for a predetermined period of time and then warmed. According to one embodiment, the applicator 104 of
Absorption enhancers, cryoprotectant agents, INAs, and coupling media can be delivered via liposomes, hydrogels, emulsions, or the like. Absorption enhancers can increase permeation to affect uptake of, for example, water, INAs, cryoprotectants, etc. Skin can be warmed before or during exposure to applied substances to increase uptake into the epidermis, with minimal or limited increased uptake into the dermis due to the dermal-epidermal junction barrier. The characteristics of the tissue can be affected by mechanically altering the subject's skin. These characteristics can include absorption characteristics, thermal characteristics, or the like. For a treatment which does not include freezing and only cooling or supercooling, it is desirable to increase an uptake of a cryoprotectant into the skin to provide maximum protection against the possibility of a non-intended freeze occurring. For a treatment which is to include freezing, it is desirable to increase an uptake of an INA and/or water to increase the possibility of a freeze event being initiated and being initiated at a desired time, and to increase a level of cryoinjury.
The applicator can be kept in thermal contact with the skin surface for a first treatment period (e.g., 2 minutes, 2.5 minutes, 3 minutes, etc., with 2.5 minutes being shown in
After completion of the freeze period, the applicator and skin temperature can be rapidly raised to a normal temperature, such as room temperature or above. In some procedures, the applicator can be warmed at a rate of about 1° C./s, 2° C./s, 2.5° C./s, 3° C./s, or other rate selected to thaw frozen tissue.
A substance can be applied to either the skin, the applicator, or both, and can be used to generate ice crystals. The substance can be a coupling media with one or more cryoprotectant agents and can be applied when it is initially at a temperature above its melting point, which can be several degrees below 0° C. and lower than a melting/freezing point of fluid in the skin tissue. The melting/freezing point of the applied substance can be in a therapeutic skin supercool treatment temperature range or other suitable temperature range. After a predetermined amount of skin supercooling has occurred, the temperature of the applied substance can be lowered to a value below its melting point or temperature to create ice crystals therein to initiate the freeze event in the skin.
Cryoprotectant agents can comprise propylene glycol, glycerol, polyethylene glycol, combinations thereof, or other biocompatible agents. In some embodiments, the substance is a cryoprotectant solution with a cryoprotectant agent mixed with water to provide a desired melting/freezing point. The concentration of the cryoprotectant agent can be increased to lower the melting/freezing point of the substance. By controlling a concentration of the cryoprotectant, characteristics of the substance (e.g., melting point, spontaneous freezing point, etc.) can be controlled, thus enabling ice crystal generation at/below any desired temperatures while inhibiting or preventing ice crystal generation at/above certain temperatures. INAs can be incorporated into the substance to, for example, provide predictable initiation of freeze events once the temperature of the substance is lowered below the melting/freezing point of the INA.
Ice crystals can be generated by diluting a precooled coupling media to raise its melting/freezing point. The applied substance can be a 25% by volume PG cryoprotectant solution with a melting temperature of −11° C. Tissue can be supercooled to a desired temperature (e.g., −8° C., −10° C., −12° C., etc.). After the desired amount of supercooling has occurred, the freeze event can be initiated by further lowering the temperature of the applied substance (e.g., “diving” the temperature) to a temperature of about −18° C. so as to freeze the substance. Instead of further lowering the temperature, or “diving,” a freeze event can be initiated at a target freeze temperature (e.g., −10° C.) or at a higher temperature by injecting cold water or another substance into the applied substance at a predetermined location to locally dilute the cryoprotectant concentration to a level whereat the melting point of the coupling media is higher than the target freeze temperature. The melting/freezing point of the coupling media can be, for example, close to −1° C., −0.5° C., or 0° C. so that ice crystals form in the diluted substance and initiate a freeze event in the skin. Dilution can be with 100% water, water doped with an INA, or another substance, thereby providing consistent and predictable freezes at temperatures as warm as, for example, −1° C., −2° C., or −3° C. Alternatively, a water and ice mixture or a water, ice, and INA mixture can be injected to provide freezes at about a desired temperature (e.g., −1° C., −0.5° C., etc.). This method can be used in conjunction with substantial skin supercooling to initiate a freeze event at relatively warm temperatures, for example −1° C., −2° C., −3° C., −4° C., or −5° C., by pre-warming the skin after the supercooling period at a lower temperature (e.g., −8° C., −10° C., or −12° C). has elapsed, which can significantly reduce or prevent harm to non-targeted tissue, such as the epidermis, as compared to a treatment where the freeze event is started at a lower temperature, such as −10° C. or even lower (e.g., −18° C. when “diving” is utilized to initiate the freeze event).
EXAMPLE 3Energy can be used to manage ice crystal formation. When aqueous coupling medias are lowered below their melting/freezing points and are in a supercooled state, ultrasound can induce ice crystal formation in the skin and/or a freeze event in the coupling media whether or not the coupling media is only slightly or significantly supercooled. Although delivering ultrasound can obviate INAs, ultrasound and INAs can be used together. Ultrasound has been used to form ice crystal in aqueous coupling agents. For example, a dental cleaning ultrasound probe operated at about 20 kHz and about 25 W forms ice crystals in coupling agents. In another example, a non-dental ultrasound probe operated at about 20 kHz and 1 W forms ice crystals. Ultrasound with other parameters can be selected based on desired ice crystal formation and/or growth.
EXAMPLE 4After tissue is in a supercooled state, a freeze event triggering or promoting substance can be injected into or near the target region. The substance can be partially frozen ice or a water slurry solution that generates an immediate freeze event. In some embodiments, the epidermis can be rewarmed to a temperature close to 0° C. prior to the freeze event, and an injection of saline ice water slurry into the dermis can initiate the controlled freeze under the epidermis. Needles, catheters, or injection devices can be introduced into the subject to inject the substance.
Various combinations of steps in examples 1-4 can be combined. To enhance or maximize freeze injury in the dermis while limiting or minimizing side effects associated with freezing in the epidermis, contact between an ice crystal and the tissue can be delayed until a desired level of skin supercooling is achieved. A volume of target skin can be substantially supercooled and then contacted by ice crystals to maximize freeze injury to the skin while minimizing side effects. A large amount of prior supercooling can maximize an amount of tissue damage that occurs during the initial freeze event, and can allow non-targeted tissue to be rewarmed to inhibit, limit, or substantially prevent thermal injury to that non-targeted tissue. The epidermis can be non-targeted tissue that can be immediately or quickly re-warmed after the freeze event in the targeted tissue, such as the dermis. Warming can limit or minimize an amount of time the epidermis is in a frozen state. This is in contrast to a treatment method whereby little or no supercooling is employed. In this latter case, to obtain a therapeutic level of treatment equivalent to the former case (which utilizes substantial supercooling and substantial fractional freezing during the initial freeze event, since cooling is delivered “top down,” via the surface of the skin), the epidermal tissue needs to be maintained in a frozen state longer after the freeze event is initiated, which can exacerbate damage to non-targeted epidermal tissue.
To restrict freezing injury to mostly upper skin layers while significantly sparing deeper tissue from significant injury, ice crystals can contact the skin immediately or very soon after the skin temperature is lowered below the skin's melting/freezing point. Limited superficial epidermal freezes can be achieved with minimal injury to dermal, fat and muscle layers, especially when the duration of the freeze event is kept relatively short. In some facial procedures, the freeze injury can be limited to the skin to avoid any appreciable reduction of subcutaneous tissue or underlying muscle which form a support structure for the skin.
At block 152, the treatment site can be prepared by, for example, mechanically, chemically, or otherwise altering the skin. Mechanical alteration can be achieved by brushing or scraping the skin surface intermittently or continuously for a period of time, such as about 30 seconds, 1 minute, 2 minutes, 3 minutes, or a suitable length of time selected based on the desired amount of surface cleaning, permeation, and/or exfoliation (e.g., exfoliation of the stratum corneum). In other embodiments, permeability of the skin can be adjusted by clearing pores in the stratum corneum, producing and/growing vacuoles (e.g., vacuoles in the epidermis below the stratum corneum), combinations thereof, or the like. In some treatments, an adhesive strip can be applied to and removed from the skin to remove uppermost layers of the epidermis, clean the treatment site, increase permeability of the skin, or otherwise prepare the treatment site. The uppermost layers of the epidermis are dryer than lower layers, so when the uppermost layers are removed, the exposed lower layers have greater water content so they are more susceptive to being frozen during a procedure designed to freeze tissue, especially when an INA is used to facilitate the freeze. Permeability of the skin can also be increased by using microneedling whereby a plurality of microscopic holes are formed in the skin to create pathways for absorption of a coupling media. Alternatively, sonophoresis can be used whereby ultrasound waves are used to stimulate micro-vibrations within the skin to increase the overall kinetic energy of molecules making up the coupling media or topical agent to be delivered into the skin to increase absorption. Some preferred frequencies are 20-40 kHz, or more than 1 MHz. Other frequencies could be used. Alternatively, increased absorption can be achieved using iontophoresis techniques for increasing absorption using, for example, electric fields to push topical agents into the skin. A permeability coefficient of coupling media for passing through tissue (e.g., epidermal tissue) can be increased at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 95% to achieve desired absorption rates using any one or more of the above described techniques. Other techniques can be used to facilitate delivery of coupling media or substances. Different testing techniques (e.g., static cell techniques, flow-through diffusion techniques, etc.), algorithms, and modeling can be used to determine the permeability coefficient and can be used to determine flux, including a steady state flux.
At block 154, coupling media can be applied to the skin. The coupling media can include, without limitation, water, hydrogels, cryoprotectants, emulsions, combinations thereof, or the like before preparing the treatment. Applying the coupling media may include placing, spraying, coating, or rubbing a liquid, gel, or sheet coupling media onto the skin using an instrument including, for example, a brush, a spatula, a spray bottle or a syringe, or by hand (e.g., an operator's gloved hand).
The coupling media can include one or more temperature depressants, INAs, etc. The temperature depressants can include, without limitation, polypropylene glycol (PPG), polyethylene glycol (PEG), propylene glycol, ethylene glycol, glycerol, dimethyl sulfoxide (DMSO), or other glycols. The temperature depressants may also include ethanol, propanol, isopropanol, butanol, and/or other suitable alcohol compounds that may lower the freezing point of a solution (e.g., body fluid) to about 0° C. to −40° C., and more preferably to about −10° C. to −16° C. Certain temperature depressants (e.g., PPG, PEG, etc.) may also be used to improve smoothness and to provide lubrication. Additionally or alternatively, the coupling media can include one or more thickening agents, pH buffers, humectants, surfactants, and/or additives.
At block 156, the subject's skin can be cooled. An applicator can be applied to the treatment site to place the applicator in thermal contact with target tissue. Tissue can be supercooled and then frozen, to limit or prevent unwanted side effects. The surface of a human subject's skin can be cooled to a temperature no lower than −40° C. to avoid unwanted skin damage. The surface of the skin can be heated to bring shallow non-targeted tissue out of the supercooled state while the deeper targeted region remains in the supercooled state.
At block 158, the supercooled targeted region can be nucleated to produce freezing that can destroy or damage targeted cells, for example, due to crystallization of intracellular and/or extracellular fluids. A catalyst for nucleation (e.g., mechanical perturbations, RF energy, alternating electric fields, etc.) can be provided following a protective increase of a temperature of non-targeted epidermal layers. The mechanical perturbations can be vibrations, ultrasound pulses, and/or changes in pressure. Non-targeted layers of tissue can be warmed enough to avoid freezing upon nucleation of targeted tissue. The treatment systems disclosed herein can utilize applicators disclosed herein to perform such supercooling methods.
Some treatments include freezing dermal tissue more times than adjacent epidermal tissue. At block 156, dermal and epidermal tissue can be cooled and frozen (block 158). The skin can be warmed by an applicator (which is at a temperature slightly below 0° C.) an amount sufficient to allow the dermal tissue to thaw due to internal body heat but not the epidermal tissue which is further removed from blood flow than is dermal tissue. After thawing the dermal tissue, block 158 can be repeated by chilling, for example, the skin to refreeze the dermal tissue while the epidermal tissue remains frozen. A desired level of damage to the dermal tissue can be achieved by repeatedly freezing and thawing the dermal layer, because the primary mechanism of damage during freezing is caused by ice crystal nucleation and growth.
Some treatments include a warm/thaw step 159 following the freeze event(s) whereby the frozen and cooled tissue is rewarmed either passively or actively by the applicator. After the warm/thaw step 159, the cooling 156 and freezing 158 steps can immediately be repeated, as shown by arrow 153, any number of times, such as 1, 2, 3, 4 or more times, preferably during the same patient treatment and optionally without moving the applicator. Alternatively, the cooling 156 and freezing 158 steps can be repeated during the same patient treatment but after the applicator has been moved to another treatment site and then brought back to the original treatment site, or during a separate patient treatment session either later in the day of the first treatment or the next day or several days later. Any number of repeat sessions can be employed to achieve an overall desired level of treatment. Arrows 157 and 155 show possibilities for the retreatment which can include a repeat of the skin preparation step 152 and/or a repeat of the applying coupling media step 154, as desired.
Skin can be mechanically stimulated before, during, and/or after any steps in the method 140 (
Different techniques can be used to evaluate the permeability of the skin before and/or after performing the stripping process. In one procedure, the coupling agent can be applied to the treatment site and then cells at the treatment site can be progressively removed by repeatedly applying the stripping element or by applying a series of stripping elements. The stripping elements and treatment site can be evaluated to determine the volume of the coupling media absorbed by the skin.
D. SUBSTANCES FOR TREATMENTSBecause ice crystals can be reliably generated to trigger on-command freeze events, a substance can be used to improve thermal coupling between a skin surface and a cooling applicator. In some embodiments, the substance is an aqueous solution coupling agent, which contains a cryoprotectant agent. Further substances can contain water and a medium for promoting an on-demand reliable creation of an ice crystal when initiation of freezing in the treatment is desired. Liquid water has clusters of molecules that are undergoing constant collisions with other molecules and clusters, sometimes breaking apart and sometimes forming new clusters. When water is being cooled, as the temperature drops and the thermal movement of water molecules decreases, the tendency of water molecules to aggregate becomes stronger and the likelihood that a critically large cluster of molecules will form increases rapidly. Ice nucleation is catalyzed upon formation of a critically large cluster of molecules. Consequently, initiation of freeze or ice nucleation in a sample of water (or a coupling agent) takes place from a nucleus with an ice-like structure. The nucleus can promote the organization of water molecules into an ice crystal lattice.
Water and aqueous coupling agents have a natural tendency to cool to a temperature significantly below their equilibrium freezing point before ice nucleation; that is, they have a tendency to supercool. There are two modes of ice nucleation of water: homogenous and heterogeneous. When a critically large nucleus is formed by spontaneous aggregation of the water molecules themselves, the nucleation is referred to as “homogeneous.” For a macroscopic quantity of water, the size of a cluster needed for ice nucleation is often about 25 molecules. The radius of the cluster can be about 3 molecules. The critical radius that coincides with this size gives a temperature of −41° C., which is called the homogeneous nucleation temperature for water. Accordingly, the homogeneous nucleation temperature for water is the minimum temperature that pure water can be cooled to before freezing occurs spontaneously.
When aggregation of water molecules is catalyzed by an external source, the nucleation is referred to as “heterogeneous.” The cause of external nucleation can be the introduction of ice crystals or another external substance into the supercooled sample. For example, crystallization can be triggered by the physical introduction of a nucleation initiator (e.g., a seed crystal or nucleus) around which a crystal structure can form to create a solid.
The substances can be hydrogels, liposomes, or emulsions, such as oil-in-water (O/W) emulsions, water-in-oil (W/O) emulsions, oil-in-oil (O/O) emulsions, or nano-emulsions, and can provide homogeneous or heterogeneous nucleation.
1. Nucleation Initiators
An INA can be a substance that promotes the formation of a seed crystal (or initial cluster), thus catalyzing a heterogeneous ice nucleation. When INAs are used, water freezing takes place at a temperature higher than would be required in the case of a homogeneous nucleation, and the largest biological ice nucleators may trigger freezing at −1° C. to −5° C. or other lower temperatures, long before a spontaneous water freeze would normally otherwise occur. Spontaneous water freezes can variably occur at −10° C., −15° C., −20° C., or −25° C. or lower, and the timing of the spontaneous freezes is very unpredictable. Example INAs include biogenic-derived proteins, materials derived from a Gram-negative epiphytic bacteria, and/or materials belonging to the genus Pseudomonas, Erwinia, or Xanthomonas. For example, INAs may be inorganic- or organic-derived substances that promote heterogeneous ice nucleation. Embodiments of the present technology can include methods of producing controlled and predictable freezes of the skin and subcutaneous tissue using INAs.
In general, INAs can promote the formation of ice crystals in water-like substances at a specific temperature, such as generally a few degrees below 0° C. INAs can be used synergistically with a selected temperature treatment protocol to control the onset and extent of a freeze event during cryotherapy and can be used to promote in-vivo freezing at higher temperatures than a natural homogeneous nucleation freezing point of skin tissue. An aspect of some embodiments of the present technology relates to methods of producing a controlled freeze of the skin and subcutaneous tissue using INAs. Cooling methods using INAs permit the triggering of ice nucleation at specific temperatures, such as temperatures close to 0° C. Thus, INAs may provide an advantage in therapies that require freezing and variable treatment temperatures with desired therapeutic treatment/safe temperature ranges and that create a precise and controllable extent of skin and tissue damage from a freeze event.
Various Gram-negative epiphytic bacteria have been known to produce INAs. These belong to the genera Pseudomonas, Erwinia and Xanthomonas, among others. One of the highest level of ice nucleation activators is an ice nucleation protein (INP) from some ice-nucleating bacteria. Protein molecules and materials located on the outer membrane of these bacteria are responsible for the ice nucleation. Cells can also be lysed or otherwise produce pieces of cellular material (e.g., membranes) in which such INAs are found or trapped, for example, Pseudomonas syringae.
One commercially accessible INA is SNOMAX® available from Snomax LLC, Englewood, Colo., which is derived from the bacterium Pseudomonas syringae (freeze-dried protein powder). This protein initiates a freezing process by serving as an ice nucleator and raises the predictable freezing temperature of water to about −3° C. SNOMAX® is used widely for snowmaking and is safe for human use and non-pathogenic. SNOMAX® can be a powder that exhibits 1012 to 1013 ice nuclei per gram at temperatures less than about −4° C. Coupling agents prepared with SNOMAX® or other substances derived from the bacterium Pseudomonas syringae can have enough INAs to produce reliable ice nucleation at desired temperatures. Bacteria/cell concentration has a direct effect on the nucleation temperature of water. INAs can be used in standard powder form, and can be used as ice nucleators with or without added water. In some embodiments, INAs can be fractionally delivered to skin, such as by microneedles (e.g., an array of microneedles). Biocompatible INAs can be invasively delivered using needles, such as intradermal needles. Additionally or alternatively, INAs can also be used with non-contact cooling devices, such as cooling/freezing sprays.
INAs can be used in cooling protocols to cause ice nucleation at temperatures about −2° C., −3° C., or −4° C. At these temperatures, damage to epidermal tissue can be significantly less than damage typically produced at lower freezing temperatures. The temperature for ice nucleation can be selected to be high enough to avoid significant skin pigmentation changes associated with freeze events.
A non-invasive applicator (e.g., applicator 104 of
2. Hydrogel Materials
An aspect of the present technology relates to methods of using hydrogel substances with freezing point depressants (cryoprotectants) and/or INAs for creating a controlled “on command” predictable freeze. Hydrogel substances are a class of crosslinked polymers that, due to their hydrophilic nature, can absorb large quantities of water. Hydrogel substances can have a suitable water content for controlling freezing, including controlling ice nucleation, ice crystallization, freeze propagation, or the like. Integral parts of the hydrogel synthesis include a monomer, an initiator, and a crosslinker. Hydrogel properties can be modulated by varying their synthetic factors, such as reaction temperature, monomer type, monomer crosslinker, crosslinker-to-monomer ratio, monomer concentration, and type and amount of initiator. The composition of hydrogels can be selected for a specific application by selecting proper starting materials and processing techniques.
Hydrogels can be mixed with one or more freezing point depressants and can be engineered to have desired melting/freezing temperatures (e.g., optimum melting temperatures). The freezing point depressants can inoculate tissue. Additionally or alternatively, hydrogels can be combined with INAs that have a set activation temperature to make the hydrogels able to freeze consistently at predetermined temperature ranges (or a specific temperature) different from those associated with hydrogels without ice nucleating agents. The combination of hydrogels, freezing point depressants, and/or INAs can result in a controllable freeze at desired temperatures, such as −3° C., −2° C., −1° C., or other temperatures. Temperatures close to 0° C. can be less damaging to epidermal tissue and are well suited for less aggressive temperature freezing protocols, so temperatures can be selected to protect one or more upper layers of the skin to eliminate or minimize any substantial discoloration side effects associated with freezing skin treatments and to eliminate any permanent adverse events.
The water accommodated by the hydrogel structure can be classified in four types: free, interstitial, bound, and semi-bound water. Free water is located in the outermost layer and can be easily removed from hydrogels under mild conditions. Interstitial water is not attached to the hydrogel network but is physically trapped between the hydrated polymer chains. Bound water is directly attached to the polymer chain through hydration of the functional groups or ions. The bound water remains as an integral part of the hydrogel structure and can be separated only at very high temperatures. Semi-bound water has intermediate properties of bound water and free water. The free and interstitial water can be removed from the hydrogels by centrifugation and mechanical compression.
Controlled freeze techniques can take advantage of the water composition of hydrogels. Hydrogels can be designed to have a specific freezing point or specific freezing temperature range by having a specific ratio of water-monomer-crosslinker content. Cryoprotectant additives, such as glycols (e.g., PG) or other substances, can be used as well to lower their freezing point.
A hydrogel can act as an initiator of a predictable freeze event. As the hydrogel freezes, the hydrogel provides “initial seeds” or crystal sites to inoculate tissue and thus catalyze a controlled predictable freeze at a specific temperature in the skin. In some embodiments, a predictable freeze event can be freezing of tissue that occurs at least 90%, 95%, or 98% of the time when freezing is desired. A predictable controlled freeze event in a hydrogel can also be achieved by precooling the hydrogel to a temperature below its melting point. The freeze event can be initiated by injecting a nucleation initiator (e.g., ice/water slurry) into the hydrogel to create freezing that reaches the surface of the hydrogel adjacent the patient, which causes freezing of the subject's skin. In other procedures, ultrasound or other nucleation energy can be used to produce a freeze event in the hydrogel. According to one embodiment, additives (e.g., cryoprotectants and/or INAs) can be embedded in isolated layers within an interior of the hydrogel so that these substances are not on an exterior surface of the hydrogel sheet or hydrogel pad and hence do not come in direct contact with skin or other tissue being treated. Encapsulating these substances within the hydrogel obviates the need to choose INA substances that have been tested and validated to be safe when in contact with skin or tissue. Predictable hydrogel freezes can be enhanced by additives, such as INAs.
A further embodiment is a hydrogel that contains an INA placed uniformly throughout areas where it is desired to seed freeze propagation. Further, the INA can be dispersed exclusively within interior portions of a volume of hydrogel. For example, the INA can be within a hydrogel sheet so that the INA does not extend to a surface of the sheet, thereby preventing contact between the INA and the skin. The INA can seed a freeze event in an interior region of the hydrogel, and the freeze event can rapidly propagate to an outer surface of the hydrogel, which in turn contacts the skin and causes a freeze event in the skin.
The ice nucleating inhibiting regions can have a melting/freezing point lower than the ice nucleating region and can include volumes of temperature depressants, such as evenly or unevenly spaced apart volumes of PG. The pattern, number, and composition of freeze inhibiting features can be selected based on the desired nucleation inhibiting characteristics.
The hydrogel can be sticky on both a patient side and an applicator side. Sticky upper and lower surfaces can help maintain contact with the subject's skin and applicator and, in some embodiments, help to minimize or limit movement of the hydrogel during treatment. A liner can be used to prevent contamination of the hydrogel. A side of the hydrogel that contacts a liner can be sticky. In some embodiments, the hydrogel can be a sheet with a uniform or variable thickness with adhesive applied to one or more of its outer surfaces.
Hydrogels can be used in the methods discussed in connection with
At block 144 in
Referring to the method 150 in
3. Liposomes
Liposomal transport of substances into tissue can be used to deliver substances to specific tissue in a more effective manner than by just applying the substances to a surface of the skin. Because a liposome is lipophilic, it can be absorbed at least into the stratum corneum and can then release a substance within the liposome at a specific location or depth in the subject's tissue. Liposomes can trap water in significant “buckets” that enhance the water content of skin when the liposome breaks down, and make freeze protection more predictable when used with significant amounts of cryoprotectant in the water in the liposome. Liposome skin hydration can be more effective than directly applying water to a skin surface since the stratum corneum is normally hydrophobic.
A topically applied liposome can enhance thermal contact between the applicator/skin and can provide controlled delivery of agents (e.g., cryoprotectant, INAs, etc.), and the liposomes can penetrate the stratum corneum better than either water or water mixed with a cryoprotectant. Additionally, liposomes can deliver different agents to different locations, thus allowing direct transfer of agents to specific targeted cells. In one embodiment, the liposome contains a cryoprotectant (e.g., propylene glycol) and can break down to release the cryoprotectant. In another embodiment, the liposome selectively releases an INA to provide controlled freezing capability through specific tissue.
According to embodiments where freezing is desired, substances (e.g., INAs, cryoprotectant, etc.) can be incorporated into liposomes such that the liposomes can controllably release the substances into the skin. Specifically, liposomes can be formulated to maintain their structure when penetrating the skin to minimize, limit, or substantially prevent release of substances. When enough liposomes accumulate in a certain desired tissue or layer of the skin, an “on-command” breakdown of the liposomes can be initiated to trigger a burst release of the embedded agents. In some embodiments, the liposome can contain an INA for initiating freeze events. Triggering methods for breaking down liposomes include using temperature (e.g., temperature cycling), ultrasound, or a cleansing agent to disrupt or break lipid encapsulation of the liposomes. An applicator can include heaters for heating the treatment site to cause release of the agents, can include transducers for delivering mechanical energy in the form of ultrasound waves, or can include other elements for disrupting liposomes to perform the methods discussed in connection with
Liposomes can have compositions selected based on, for example, a rate of agent release, stability, and/or other desired characteristics. In some embodiments, the rate of agent release can be increased by applying energy, such as ultrasound, heat, or other energy suitable for breaking down lipids that entrap agents. For example, a media can include first liposomes for delivering cryoprotectants to the epidermis and second liposomes for delivering INAs to the dermis. Once the first liposomes are absorbed by the epidermis, they can release the cryoprotectant to protect the epidermis. After the second liposomes have passed through the epidermis and been absorbed by the dermis, they release the INA into the dermal tissue. Upon cooling the treatment site to a temperature below a melting/freezing point of the skin, the INA can cause a predictable freeze in the dermal tissue. Accordingly, each agent can be delivered to specific locations using liposomes. Liposomal medias can be used before, during, and/or after a treatment session. In some procedures, a topical media is applied to the skin surface to deliver cryoprotectant to shallow tissue before cooling. Another media (e.g., media with an INA) can be injected into deeper tissue once the tissue is cooled and is ready for freezing.
4. Emulsions
Emulsions are a class of disperse systems comprising two immiscible liquids and can contain liquid droplets, which comprise the disperse phase, dispersed in a liquid medium, which is the continuous phase. Emulsions can be oil-in-water (O/W) emulsions, water-in-oil (W/O) emulsions, oil-in-oil (O/O) emulsions, or nano-emulsions. Nano-emulsions are desirable since they can penetrate the epidermis and dermis along hair follicle apertures and skin pore apertures.
Ex-vivo bench tests with skin using treatment cycles show the unpredictability of supercooling skin and precise control freezing with INAs. In one test, a thermocouple was placed between a coupling layer (coupling media) and skin to detect freezing. A coupling layer of only water was tested to confirm there is no freezing of tissue without an INA. Thermocouple temperature data of five tests, including two water-only tests (where no freezes occurred) and three tests using an INA (where three separate freezes occurred), were conducted to show the effects of INAs and the feasibility of the controlled freeze concept.
A treatment cycle can be determined by selecting supercooling parameters, freeze parameters, and thaw parameters. The supercooling parameters can include cooling profiles, target temperatures, and/or time periods. A cooling profile can include a cooling rate for ramp-down to reach the supercool temperature. The target tissue can be kept at a subzero target supercool temperature for the supercool time period without phase change.
Freeze parameters can include cooling profiles for keeping the tissue in the frozen state and/or time periods for keeping the tissue frozen. The freeze parameters can be selected to increase or decrease thermal injury. After completion of the freeze time period, cooled tissue can be warmed using a thawing cycle.
Supercooling parameters, freeze parameters, and/or thaw parameters can be obtained experimentally ex-vivo and/or in-vivo. For example, in-vivo human tests have shown that skin can be supercooled to subzero temperatures, for example, as low as −20° C., without phase change. When the temperature is lowered far enough, the tissue will freeze. It has been experimentally established that human skin tissue will often spontaneously freeze at around −25° C. The temperature of spontaneous freezing depends on the characteristics of the tissue, such as water content of tissue, cellular structure, etc.
When a freeze event is initiated, the entire dermis and epidermis underlying the applicator may not be completely frozen. This is because even at steady state (e.g., when heat extraction by the applicator balances warming from subdermal tissue and blood flow) the bulk temperature of the tissue is not cold enough to absorb all the heat of fusion from the freeze event so as to achieve a 100% tissue freeze. As the heat of fusion is released during the freeze event, the bulk temperature of the tissue rises to a level close to, for example, 0° C. such that additional freezing ceases (absent additional significant heat extraction by the applicator) and the skin is only partially frozen when equilibrium is established. The temperature of the cooling plate can be adjusted to compensate for heat of fusion or other natural heating associated with the subject's body. Without being bound by theory, it is believed that the skin would need to be supercooled to a temperature around −70° C. for the skin to totally freeze and remain complete frozen during a freeze event, but such a low supercool temperature is highly undesirable because severe adverse events, particularly to the epidermis, would result.
The temperature of the temperature-controlled surface 211 can be increased to 18° C., 20° C., or 22° C. at a rate of 1° C./s, 2° C./s, or 3° C./s. This will quickly thaw the tissue to minimize or limit further damage to cells. For example, the skin can be cooled at a rate of 0.25° C./s, held at a target temperature of −8° C. for 2 minutes, and then thawed at a rate of 2° C./s. Other cooling rates, target temperatures, and thaw rates can be selected based on the desired level of freezing, thermal injury, etc.
Targeted tissue can be frozen more times than non-targeted tissue. Repetitive freeze-thaw cycles effectively damage or kill tissue because, aside from suffering multiple cycles of deleterious solution effect and mechanical ice crystal damage, cell membrane integrity will be compromised after the first freeze-thaw cycle, making it a less effective barrier for freeze propagation in subsequent freeze-thaw cycles, and cells are much more susceptible to lethal intracellular ice formation in the subsequent freeze-thaw cycles. In some embodiments, targeted tissue can be frozen multiple times in a single treatment session while freezing non-targeted tissue, such as the epidermis, only one time. Additionally, targeted tissue can be frozen multiple times without supercooling any tissue. In some procedures, the dermis is repeatedly frozen to injure or destroy target glands without repeatedly freezing the epidermis.
Because the epidermis is never thawed using this treatment protocol, a larger freezing rate will have a much less damaging effect on the epidermis. In second or subsequent freeze-thaw cycles, a much larger freezing rate can be used to transition from a thaw temperature (e.g., −1.5° C., −1° C., 0.5° C., etc.) to a refreeze temperature (e.g., −8° C., −10° C., −12° C.), and this may further increase the probability of intracellular ice formation in the dermis, as further explained below.
The repeated freezing approach allows for complete control over most or all or some of the variables that govern post-thaw tissue viability. These variables include, without limitation, skin freezing rate, target temperature, duration of freeze, and warming rate. The skin freezing rate is not as controllable using other approaches when skin is substantially supercooled because a macroscopic freeze event happens almost instantaneously (over a period of a few seconds) when skin is nucleated or inoculated with ice when the skin is in a supercooled state. Without being bound by theory, it is believed that the freezing rate is important because in a procedure in which extracellular space ice formation is triggered at −2° C., if the tissue is then slowly cooled to −10° C., there would be sufficient time for intracellular water to diffuse out and enter the extracellular space along a concentration gradient. This causes the intracellular solute concentration to rise and depress the intracellular melting/freezing temperature, thereby helping to reduce the probability of lethal intracellular ice formation at colder temperatures. However, if the skin is triggered to freeze at −10° C. (with a large supercooling window), there will not be enough time for cell dehydration, and thus no intracellular freezing point depression. Therefore, at a colder supercooling temperature (−10° C.), intracellular ice formation and associated increased cell damage is more likely. A large amount of supercooling has been demonstrated to correlate with greater risk of intracellular ice formation, which sometimes is desirable, but in other instances may be undesirable, depending on what tissue is and is not being targeted.
As discussed in connection with
Referring to
The applicator can continuously or intermittently extract heat to gradually increase the volume of frozen coupling media for a holding period.
The freeze event can be triggered by a temperature a few degrees colder than the supercooling temperature. In one procedure, skin can be cooled to a supercooling temperature of −13° C. while still being able to trigger a freeze at a temperature only slightly lower, such as −15° C. This “dive” temperature of 2 degrees is much smaller than those required by conventional techniques that do not use a coupling media containing ice crystals that contact the skin (which are of the order of about 10 degrees) and serves as a skin-ice inoculating agent for triggering a predictable freeze event. For any given maximum end temperature for the applicator, a smaller dive temperature can result in a larger supercooled volume, and at the time of the tissue freeze, the frozen volume will also be larger compared to a treatment with a larger dive temperature. After the tissue has been frozen for a desired length of time, the applicator can warm the tissue to inhibit or limit further disruption, injury, etc. Warming and cooling cycles can be repeated any number of times in any order to thermally affect the targeted tissue.
The skin can be cooled to a temperature above the freezing point of the coupling media in order to trigger a freeze event. When tissue is supercooled at −13° C. with a coupling media that has a slightly warmer freezing temperature (e.g., a freezing temperature of −11.5° C.), the skin will not be inoculated at temperatures significantly warmer than −13° C. In some procedures, it may be desirable to initiate a skin freeze at higher temperatures to minimize or limit injury to the epidermal tissue during the freeze event. To address this need, a higher temperature melting/freezing point can be achieved by dilution of the coupling media to a lower concentration of a freezing point depressant. The melting/freezing temperature of the coupling media can be raised a sufficient amount to trigger a freeze at a temperature well above the supercooling temperature. Briefly, supercooling at time t1 can be accomplished by choosing a coupling media that has a freezing temperature lower than that at time t1. After supercooling, the applicator temperature ramps up to a higher temperature at time t2. A volume of water can be delivered into the coupling media to dilute it, ensuring that the diluted coupling media has a freezing point warmer than the temperature at t2. This will trigger a freeze in the diluted coupling media to quickly trigger a skin freeze. A relatively warm on-command freeze in the supercooled diluted coupling media can be triggered using, for example, energy (e.g., ultrasound), low temperature probes (e.g., an extremely small cold finger probe), and/or an INA.
At the end of the supercool cycle, the temperature of the applicator can be raised to a higher temperature (e.g., −10° C.) suitable for ice inoculation. A substance, such as cold water at 1° C., can be infused through the applicator to dilute the coupling media. The temperature and flow rate of the water can be selected such that the diluted coupling media has a freezing point warmer than a predetermined value. For example, the diluted coupling media can have freezing point higher than about −10° C. for freeze inoculation at about −10° C.
Ultrasound can be used to initiate, promote, and/or control a freeze event. Referring now to
One or more INAs can be incorporated into the coupling media before, during, and/or after applying the coupling media to the patient. Dilution of the coupling media to a point where its diluted melting temperature is above its actual temperature will cause the diluted coupling media to freeze, which in turn will cause freezing of the skin.
Dilution also enables supercool cycling at relatively low temperatures (e.g., −10° C., −15° C., −20° C.) and tissue freezes at relatively high temperatures (e.g., −10° C., −5° C., −4° C., −3° C., or −2° C.) to enhance or maximize damage to targeted tissue and limit or minimize damage to non-targeted tissue. The targeted tissue can be tissue in the dermis and/or lower skin layers, and the non-targeted issue can be the epidermis or shallow tissue. Although enhancing or maximizing damage can be achieved by multiple consecutive treatments with different concentrations of coupling media, a single treatment can provide desired damage to reduce treatment time and costs.
Various techniques can be used to protect non-targeted tissue while affecting targeted tissue volumes and/or specific structures within, for example, the epidermis, dermis, subcutaneous tissue, etc. The targeted structures can include, without limitation, hair (e.g., hair follicles), skin appendages (e.g., sweat glands, sebaceous glands, etc.), nerves, and/or dermal components, such as collagen, elastin, or blood microvascularity. Targeted structures can be affected while inhibiting, preventing, or substantially eliminating unwanted side effects. Because appendages and other cells/structures may have different lethal temperatures, a multi-step temperature profile can be used to target specific tissue and/or structures. Moreover, preserving the non-targeted tissue, such as the epidermis, from undue injury or damage could be beneficial in to prevent, for example, pigment changes and/or scarring, as well as to promote healing. Freezing the epidermis at a different temperature than the underlying dermis can be achieved by using the characteristic activation temperature of the INA and by intentionally supercooling the dermis at lower temperatures before applying the INA. In some procedures, the epidermis can be at a higher temperature to inhibit, limit, or substantially prevent permanent thermal injuries to the epidermis.
Some embodiments of the technology include methods of using linked polymers containing water, a crosslinked polymer that contains water, optionally an INA, and/or optionally a freezing point depressant for controlled freeze of skin tissue. According to one preferred embodiment, the polymer can be a hydrogel for use for controlled freezing of skin tissue. The hydrogel can be an effective initiator of a freeze event. As hydrogel freezes, it can provide initial seeds or crystal sites to inoculate and freeze tissue, thus catalyzing a controlled predictable freeze at specific temperature(s) in skin.
Referring now to
The images were generated after a few minutes of supercooling the tissue. The temperature of the supercooled tissue was lowered to a trigger temperature to trigger a freeze (illustrated in lighter color) in the non-PG hydrogel, illustrated on the left side of
The hydrogel of
It may be advantageous to cool tissue and/or affect specific structures within the dermis and subcutaneous tissue, like hair, skin appendages, nerves, dermal components such as collagen, elastin, or blood microvascularity but at the same time to preserve the epidermis. Since appendages and other cells/structures may have a different lethal or injury temperature, a multi-step temperature profile may be needed. Moreover, preserving the epidermis could be beneficial in the prevention of skin pigment changes and skin scarring. Additionally, preserving the epidermis can result in more favorable healing and fewer side effects. Freezing the epidermis at a different temperature than the underlying dermis is possible by using the aforementioned techniques. Specifically, the skin bulk tissue can be supercooled at low temperatures and then the temperature of the epidermis can be raised before, for example, delivering the INA or activating nucleation. Epidermal sensitivity is reduced when the epidermis freezes at a temperature of around −5° C. or higher. If freezing below those temperatures occurs, melanocytes and/or their melanin production in the epidermis may get unduly altered causing pigmentation. So, according to some embodiments of the disclosed technology, temperature protocols can be used that cause freezing of the epidermis at or above −5° C.
The images show temperature distributions in tissue related to the temperature profile step change of the temperature-controlled surface from −10° C. to −4° C. An isotherm has been added (T=0° C.) at time=380 seconds, time=385 seconds, and time=400 seconds. The isotherm at T=0° C. is the boundary in which phase change to ice crystallization (freezing of skin) may extend the most (i.e., deeper tissue is warmer than 0° C. and will not freeze if ice nucleation were to occur since the fluid in the skin at this depth is above its freezing temperature).
The injected substance can include, without limitation, hydrogel, hydrogel/INA, partially frozen water, ice nucleators, combinations thereof, or the like. An advantage of injecting an ice crystal or substance (e.g., an INA) that will create an ice crystal is that a freeze event will occur at a specific region. The freeze event can be initiated in the dermis or other lower tissue layer and not in the epidermis. This limits or minimizes damage to the epidermis. Additionally, the epidermis can be warmed to a temperature close to or above its melting/freeze temperature. In some embodiments, a freeze event can be initiated in tissue below the dermis, such as in subcutaneous tissue. After producing the freeze event, the same or different needle can inject additional substances into the tissue. The additional substances can include cryoprotective agents, liquids (e.g., warm water or saline), or other substances that can effect therapy.
Multiple injections can be made to create multiple freeze events. A first substance can be delivered into tissue to create a first freeze event, and a second substance can be delivered into other tissue to produce a second freeze event. For example, the first substance can be adapted to completely freeze at a first target region, and the second substance can be adapted to produce a partial freeze event at a second target region spaced apart from the first target region. Different levels of freezing and severity of thermal injury can be achieved even though the first and second target regions are at the same temperature. In other treatments, the first and second target regions can be at different temperatures, and the first and second substances can be selected based on those temperatures. In this manner, different types of freeze events can be generated at different locations.
With continued reference to
In block 356, the surface of the human subject's skin is heated an amount sufficient to raise the skin surface temperature from the first temperature to a second temperature, which can be a non-supercooled temperature, while the targeted region remains in the supercooled state. For example, the epidermis can be heated to a temperature higher than about 0° C., higher than about 5° C., higher than about 10° C., higher than about 20° C., higher than about 30° C., or higher than about 35° C. There can be a temperature gradient between the targeted tissue and the skin surface such that most of the non-targeted shallow tissue is at a non-supercooled temperature.
In block 356, the device of
In block 358 of
Heat can be applied to warm epidermal cells to a temperature above freezing while glands in the dermis are at or near the supercooled temperature. The step of applying heat can include warming a portion of most of the epidermal layer under the treatment device to a temperature above about 0° C., about 5° C., about 10° C., about 20° C., about 25° C., or about 32° C. Warming can be accomplished before, during, or after the freeze event. The subject's body heat, warm blood, or other mechanisms can naturally heat the epidermis to avoid or limit freeze damage to those cells.
If deeper tissue is not targeted, such tissue could be warmed using focused electrical currents, such as focused ultrasound or RF energy. Applicators can include one or more electrodes, transducers, or other energy-emitting elements. For example, an applicator can cool the skin surface shown in
The methods disclosed herein are capable of supercooling tissue without initiating nucleation by cooling tissue at a relatively slow rate (e.g., the temperature profile can cause a slow cooling of the tissue at the target region). For example, the rate of cooling can be either equal to, slower or faster than about 0.5° C., 1° C., 2° C., 3° C., 4° C., 5° C., 6° C., 7° C., 8° C., 9° C. or 10° C. per minute. A preferred rate of cooling is about either 2° C., 4° C., or 6° C. per minute. Additionally or alternatively, a treatment device can apply a generally constant pressure during cooling to the supercooled temperature range to avoid pressure changes that would cause inadvertent nucleation. In a further embodiment, the targeted tissue can be cooled while the patient is held still (e.g., without movement of the treatment site) to avoid mechanically disturbing the supercooled tissue and unintentionally causing crystallization.
F. SUITABLE COMPUTING ENVIRONMENTSAs illustrated in
In operation, the input module 708 accepts an operator input 719 via the one or more input/output devices described above with respect to
In the illustrated example, the process module 712 can generate control variables based on sensor readings 718 from sensors (e.g., sensor 167 of
In various embodiments, the processor 701 can be a standard central processing unit or a secure processor. Secure processors can be special-purpose processors (e.g., reduced instruction set processor) that can withstand sophisticated attacks that attempt to extract data or programming logic. The secure processors may not have debugging pins that enable an external debugger to monitor the secure processor's execution or registers. In other embodiments, the system may employ a secure field programmable gate array, a smartcard, or other secure devices.
The memory 702 can be standard memory, secure memory, or a combination of both memory types. By employing a secure processor and/or secure memory, the system can ensure that data and instructions are both highly secure and sensitive operations such as decryption are shielded from observation. The memory 702 can contain executable instructions for cooling the surface of the subject's skin to a temperature and controlling treatment devices in response to, for example, detection of supercooling, a partial or complete freeze event, movement of the applicator (e.g., applicator pull off), or the like. In some embodiments, the memory 702 can include nucleation instructions that, when executed, cause the controller to command an applicator to alter the composition of a coupling media, inject nucleation initiator, etc. Additionally or alternatively, the memory 702 can include thawing instructions that, when executed, causes the controller to control the applicator to heat tissue. In some embodiments, the stored instructions can be executed to control the applicators to perform the methods disclosed herein without causing undesired effects, such as significantly lightening or darkening skin one of more days after the freeze event ends. The instructions can be modified based on patient information and treatments to be performed. Other instructions and algorithms (including feedback control algorithms) can be stored and executed to perform the methods disclosed herein.
In some embodiments, the controller 114 is programmed to cause the applicator to create or maintain at least one ice crystal and to induce a freeze event. The memory 702, for example, can contain instructions that when executed cause the applicator to operate to cause one or more ice crystals to contact the subject skin so as to induce a freeze event. In one embodiment, the memory 702 contains instructions that when executed by the processor 701 cause the applicator to be a suitable temperature for supercooling target tissue and for freezing the skin without lowering a temperature of the temperature-controlled surface below a particular level. The instructions can be used to control or communicate with components of applicators. These components can include, without limitation, one or more thermoelectric elements, fluid elements, energy-emitting elements, and sensors. The thermoelectric elements can be Peltier devices capable of selectively cooling or heating the tissue. The fluid elements can be cooling channels, conduits, or other fluid elements through which fluid can flow to heat and/or cool tissue. The energy emitting elements can be radiofrequency electrodes, ultrasound electrodes, or other elements capable of delivering energy to control freezing, warm tissue, or the like.
Suitable computing environments and other computing devices and user interfaces are described in commonly assigned U.S. Pat. No. 8,275,442, titled “TREATMENT PLANNING SYSTEMS AND METHODS FOR BODY CONTOURING APPLICATIONS,” which is incorporated herein in its entirety by reference.
G. CONCLUSIONThe treatment systems, applicators, and methods of treatment can be used to treat acne, hyperhidrosis, wrinkles, subcutaneous tissue, structures (e.g., structures in the epidermis, dermis, subcutaneous fat, muscle, nerve tissue, etc.), and so on. Methods for cooling tissue and related devices and systems in accordance with embodiments of the present invention can at least partially address one or more problems associated with conventional technologies as discussed above and/or other problems whether or not such problems are stated herein. Methods for affecting skin of a human subject's body include positioning an applicator of a cooling apparatus on the subject and removing heat from a treatment site to affect the appearance of the subject's skin with or without causing an appreciable reduction of subcutaneous adipose tissue. Acne along the face can be treated without causing any reduction of subcutaneous adipose tissue wherein acne along the back can be treated while reducing of subcutaneous adipose tissue. Systems, components, and techniques for reducing subcutaneous adipose tissue are disclosed in U.S. Pat. No. 7,367,341 titled “METHODS AND DEVICES FOR SELECTIVE DISRUPTION OF FATTY TISSUE BY CONTROLLED COOLING” to Anderson et al., U.S. Patent Publication No. US 2005/0251120 titled “METHODS AND DEVICES FOR DETECTION AND CONTROL OF SELECTIVE DISRUPTION OF FATTY TISSUE BY CONTROLLED COOLING” to Anderson et al., and U.S. Patent Publication No. 2007/0255362 titled “CRYOPROTECTANT FOR USE WITH A TREATMENT DEVICE FOR IMPROVED COOLING OF SUBCUTANEOUS LIPID-RICH CELLS,” the disclosures of which are incorporated herein by reference in their entireties. For example, sufficient amount of thermal energy can be removed from the site so as to reduce wrinkles by, for example, reducing the number of visible wrinkles and/or sizes of the wrinkles. In other embodiments, a sufficient amount of thermal energy is removed from the treatment site so as to tighten skin at the treatment site, or in further embodiments, to alter the tissue between a surface of the skin and subcutaneous lipid-rich cells of the subject's body. In a further embodiment, tissue is cooled to induce fibrosis that increases the firmness of tissue at the treatment site. Fibrosis can be induced in the epidermis, dermis, and/or subcutaneous tissue. Vacuum applicators can stretch, stress, and/or mechanically alter skin to increase damage and fibrosis in the skin, affect glands, control freeze events (including initiating freeze events), etc.
It will be appreciated that some well-known structures or functions may not be shown or described in detail so as to avoid unnecessarily obscuring the relevant description of the various embodiments. Although some embodiments may be within the scope of the technology, they may not be described in detail with respect to the figures. Furthermore, features, structures, or characteristics of various embodiments may be combined in any suitable manner. The technology disclosed herein can be used for improving skin and skin conditions and to perform the procedures disclosed in U.S. Provisional Application Ser. No. 61/943,250, filed Feb. 21, 2014, U.S. Pat. No. 7,367,341 entitled “METHODS AND DEVICES FOR SELECTIVE DISRUPTION OF FATTY TISSUE BY CONTROLLED COOLING” to Anderson et al., and U.S. Patent Publication No. US 2005/0251120 entitled “METHODS AND DEVICES FOR DETECTION AND CONTROL OF SELECTIVE DISRUPTION OF FATTY TISSUE BY CONTROLLED COOLING” to Anderson et al., the disclosures of which are incorporated herein by reference in their entireties. The technology disclosed herein can target tissue for tightening the skin, improving skin tone or texture, eliminating or reducing wrinkles, or increasing skin smoothness as disclosed in U.S. Provisional Application Ser. No. 61/943,250.
Unless the context clearly requires otherwise, throughout the description, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in a sense of “including, but not limited to.” Words using the singular or plural number also include the plural or singular number, respectively. Use of the word “or” in reference to a list of two or more items covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list. In those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense of the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense of the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.).
Any patents, applications and other references, including any that may be listed in accompanying filing papers, are incorporated herein by reference. Aspects of the described technology can be modified, if necessary, to employ the systems, functions, and concepts of the various references described above to provide yet further embodiments. While the above description details certain embodiments and describes the best mode contemplated, no matter how detailed, various changes can be made. Implementation details may vary considerably, while still being encompassed by the technology disclosed herein. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
Claims
1. A method for predictably freezing a subject's skin at a desired predictable time, comprising:
- lowering a temperature of the skin below a freezing point of fluid in the skin so that the skin is at a first temperature;
- causing an ice crystal to contact the skin to inoculate the skin and to create a predictable freeze event therein; and
- controlling a time of contact between the ice crystal and the skin so that the predictable freeze occurs at a desired time.
2. The method of claim 1, further comprising physically contacting a surface of the skin with the ice crystal.
3. The method of claim 1, further comprising introducing the ice crystal into the subject using a catheter so that the ice crystal contacts a dermal layer of the skin.
4. The method of claim 1, further comprising forming the ice crystal in a cryoprotectant solution located on the skin.
5. The method of claim 4, further comprising
- maintaining the temperature of the skin at the first temperature for a first treatment period, wherein the first temperature is more than 7 degrees C. below the freezing point of the fluid in the skin; and
- after the first treatment period, cooling the cryoprotectant solution from a temperature above a freezing point of the cryoprotectant solution to a temperature below the freezing point of the cryoprotectant solution to form the ice crystal therein.
6. The method of claim 4, further comprising diluting a cryoprotectant concentration on a skin surface so as to raise a freezing point of the diluted concentration to a value above a temperature of the cryoprotectant solution so that formation of the ice crystal does not require that the skin temperature be lowered below the first temperature.
7. The method of claim 1, further comprising using ultrasound energy to create the ice crystal either in the skin or in a substance in contact with the skin.
8. The method of claim 1, wherein the first temperature is at least 10 degrees C. below the freezing point of the fluid in the skin prior to inoculating the skin.
9. The method of claim 8, further comprising:
- maintaining the first temperature for a first treatment period;
- after the first treatment period has expired, lowering the skin temperature to a second temperature lower than the first temperature to create the ice crystal; and
- maintaining the second temperature for a second treatment period.
10. The method of claim 9, further comprising after the second treatment period has expired, rapidly warming a surface of the skin to a third temperature higher than the first or second temperature.
11. The method of claim 10, further comprising:
- maintaining the third temperature for a third treatment period, wherein the third temperature is a cold therapeutic temperature within 5 degrees C. of the freezing point which causes minimal damage to epidermal tissue; and
- allowing the surface of the skin to warm to room temperature or above room temperature.
12. The method of claim 1, wherein the first temperature is less than 3 degrees C. below the freezing point of the fluid prior to inoculating the skin.
13. The method of claim 1, further comprising maintaining the first temperature for a predetermined period of time to create a predetermined level of skin supercooling prior to causing the ice crystal to contact the skin.
14. The method of claim 1, further comprising
- detecting the freeze event; and
- controlling a length of time of the freeze event by controlling when the temperature of the skin is raised to a temperature above the freezing point of the fluid in the skin based on detection of the freeze event.
15. The method of claim 1, further comprising forming the ice crystal prior to lowering the temperature of the skin below the freezing temperature of the fluid.
16. The method of claim 15, further comprising forming the ice crystal after lowering the temperature of the skin below the freezing temperature of the fluid.
17. The method of claim 1, further comprising using a coupling media in contact with the skin to aid in removing heat from the skin, and wherein the coupling media includes an ice nucleating agent, a hydrogel, and/or a freezing point depressant.
18. The method of claim 1, further comprising:
- applying a coupling media to the skin, the coupling media having a medium therein capable of forming ice crystals; and
- establishing a temperature of an applicator in thermal contact with the coupling media to predictably freeze a portion of the medium in physical contact with a skin surface such that the frozen portion of the medium causes freezing of the skin.
19. The method of claim 18, wherein the coupling media comprises a crosslinked polymer which includes water, and wherein the coupling media has a specific ratio of water-monomer-crosslinker content so as to have a predetermined freezing point higher than either −40, −25, −20, or −15 degrees C.
20. The method of claim 19, wherein the crosslinked polymer is a hydrogel.
21.-40. (canceled)
Type: Application
Filed: May 24, 2022
Publication Date: Feb 9, 2023
Inventors: Leonard C. DeBenedictis (Dublin, CA), Joel N. Jimenez Lozano (Dublin, CA), Like Zeng (North Chicago, IL), George Frangineas, JR. (Fremont, CA), Linda Pham (Pleasanton, CA)
Application Number: 17/752,703
