METHOD TO FUNCTIONALIZE CELLS IN HUMAN BLOOD, OTHER FLUIDS AND TISSUES USING NANOPARTICLES
Compositions and methods for inhibiting metastatic cancer cells. The compositions comprise nanoparticles which have incorporated therein leukocyte adhesion molecules and therapeutic molecules exposed on their surface. The nanoparticles may be provided attached to leukocytes. Introduction of these compositions in to the circulation of individuals results in inhibition and reduction of metastatic cancer cells.
This application is a continuation of U.S. patent application Ser. No. 14/909,523, filed on Feb. 2, 2016, which is a National Phase entry of International Patent Application No. PCT/US2014/049602, filed on Aug. 4, 2014, which claims priority to U.S. Provisional Patent Application No. 61/861,487, filed on Aug. 2, 2013, the disclosures of each of which are incorporated herein by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENTThis invention was made with government support under grant number CA143876 awarded by the National Institutes of Health. The government has certain rights in the invention.
BACKGROUND OF THE INVENTIONCancer metastasis is responsible for over 90% of cancer related deaths. The metastatic spread of cancer is due to the shedding of cancer cells from a primary tumor, which enters blood and lymphatic vessels as circulating tumor cells, which can then travel to anatomically distant organs to form new tumors.
Currently, there are no methods to target circulating tumor cells in the bloodstream to prevent metastasis. There are related technologies that isolate circulating tumor cells (CTC) from patient blood, which can be used to track the severity of the cancer. However, there are no related technologies that can both capture and kill rare CTC in blood and lymphatic vessels.
SUMMARY OF THE INVENTIONThis disclosure provides a method to functionalize cells directly within the bloodstream using nanoparticles. In one embodiment, white blood cells are functionalized with nanoparticles which can then kill circulating tumor cells (CTC) in blood and lymphatic vessels to prevent cancer metastasis. In one embodiment, white blood cells are functionalized with nanoparticles which then adhere to various forms of cancer cells, immune cells and/or sites of inflammation.
The nanoparticle may be liposomes, silica nanoparticles, such as Cornell dots, quantum dots or any other nanoparticle that can be functionalized on its surface.
The nanoparticles functionalization can comprise functionalization with ligands, small molecules, protein, peptide, antibodies, aptamers, nucleic acids and/or chemotherapeutics or any other moiety that can be functionally attached to a nanoparticle. For example, the functionalization can comprise a moiety or molecule that recognizes white blood cells, such as selectin such that the nanoparticle functionalized with selectin binds to the selectin binding partner on the white blood cell. Another example is anti-CD57 which can bind to CD-57 which is found on NK cells. The nanoparticle can be further functionalized with another moiety or molecule that recognizes the target of interest, such as a CTC, other immune cells, sites of inflammation or cancer cells located in bone marrow or lymph nodes (such cells may be called disseminated tumor cells or DTCs).
It would be advantageous to select a moiety or molecule that recognizes a moiety or molecule specific to the target of interest. The nanoparticle can be functionalized with a molecule or moiety which induces an action specific for the target. One embodiment would be functionalization of the nanoparticle with apoptosis inducing ligands, such as TNF-related apoptosis-inducing ligand (TRAIL), which specifically binds DR4 or DR5 which are found on tumor cells and upon binding of TRAIL to the DR receptor induces apoptosis. In another embodiment, the nanoparticles are functionalized with chemotherapeutic molecules.
One example of use is to introduce a nanoparticle functionalized with selectin and TRAIL into the blood stream. The nanoparticle interacts with the white blood cell via interaction with selectin. The CTC further interacts with remaining free selectin molecules on the nanoparticle:white blood cell complex and due to close of TRAIL on the nanoparticle to the DR receptors on the CTC, the CTC receptor binds to TRAIL, inducing apoptosis/cell death of the CTC.
This invention can be used to treat highly metastatic cancers that travel through blood and lymphatic vessels, such breast, prostate, colorectal cancer, gastrointestinal tract cancers, pancreatic cancer, lung cancer and the like.
Another example of use is to introduce a nanoparticle functionalized with Selectin and an inflammation marker into the blood stream. The nanoparticle interacts with the white blood cell via Selectin. This functionalized nanoparticle:white blood cell complex further interacts with an inflammation site via moieties which bind to inflammation specific markers. The nanoparticle can then have a third functionalized moiety attached to it, or contained within it, which relieves or reduces the inflammation.
The present disclosure provides a new approach to functionalize cells in the blood using nanoparticles functionalized with different moieties and/or molecules. One moiety or molecule comprises selectin or another molecule which recognizes a host cell, such as blood cell, such as, for example, a white blood cell. An optional second moiety or molecule targets a second type of cell, such as circulating tumor cell. A last moiety or molecule binds to the second type of cell causing an action, such as cell death. In one embodiment, the cancer cells in the blood are killed by causing circulating white blood cells to present the cancer-specific apoptosis ligand TRAIL on their surface (via nanoparticles) along with E-selectin adhesion receptor. This approach occurs by using a nanoparticle functionalized with E-selectin and TRAIL. The E-selectin molecule binds to its receptor on the white blood cell. The tumor cell binds to other free E-selectin on the nanoparticle and then due to proximity, TRAIL binds to the TR receptor on the tumor cell surface.
This approach, demonstrated in vitro with human blood and also in vivo in mice, mimics both the cytotoxic activity of natural killer cells and also the chemical engineering concept of a fluidized bed reactor, which increases surface area for surface-catalyzed reactions. The resulting “unnatural killer cells” are an effective means to neutralize circulating tumor cells that enter blood with the potential to form new metastases.
The patent application contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
The present disclosure provides a new approach to targeting metastatic cancer cells, including circulating cancer cells and cancer cells that have spread to lymph nodes. The method of the present disclosure comprises providing tools for functionalizing host cells that naturally seek out cancer cells in vivo. Examples of such host cells include white blood cells and hematopoietic stem and progenitor cells. The host cells are functionalized via providing functionalized nanoparticles such that the functionalized host cells deliver the functionalized nanoparticles to cancer cells, and inhibit or destroy the cancer cells.
A feature of the present disclosure is that the functionalized nanoparticles do not target cancer cells directly. Rather, they use host cells (also referred to herein as intermediate cells) like leukocytes to find cancer cells. Thus, the approach makes use of intermediate cells (which normally seek out cancer cells), to facilitate delivery of the nanoparticles to them. Another feature of the disclosure is that the intermediate cells only have receptors (or complementary ligands) for the adhesion molecules and preferably do not have receptors for the therapeutic molecules. The target cells have receptors for therapeutic molecules and may have receptors for adhesion molecules. The intermediate cells seek out target cells and when armed with the nanoparticles, are able to deliver the therapeutic molecules to the target cells. In this manner, the intermediate cells can become “unnatural” killer cells.
In one embodiment, the intermediate cells are leukocytes and the adhesion molecule is selectin. In one embodiment, the intermediate cells are NK cells and the adhesion molecule is an antibody to CD57. In one embodiment, the intermediate cells are CD34+ hematopoietic stem and progenitor cells and the adhesion molecules is an antibody to CD34.
In one embodiment, this disclosure provides nanoparticles comprising both an adhesion molecule and a therapeutic molecule. In one embodiment, the adhesion molecule is one by which the nanoparticles can attach to leukocytes. The therapeutic molecule is one which will attach and/or inhibit or kill target cells—such as cancer cells. In one embodiment, when the nanoparticle is a liposome, the adhesion molecule and the therapeutic molecules are incorporated into the bilayer of the liposome such that they are exposed to the exterior and are available for interaction with other cells. For example, the selectin or the anti-CD57 molecules on liposomes are available for attachment to their corresponding ligands on leukocytes, and the TRAIL molecules are available for inhibiting or killing cancer cells.
In one embodiment, the present disclosure provides nanoparticles on to whose surface is incorporated i) an adhesion molecule which will attach the nanoparticles to intermediate cells; and ii) a therapeutic molecule which causes apoptosis of cells upon binding to cells displaying receptors for the therapeutic molecules.
Examples of nanoparticles are liposomal particles, silica nanoparticles, such as Cornell dots, quantum dots or any other nanoparticle that can be functionalized on its surface including PLGA or nanotubes, including carbon nanotubes and halloysite nanotubes. The nanoparticles may be liposomal which may be unilamellar or multilamellar or micelles. In one embodiment, the nanoparticles are unilamellar liposomes. In one embodiments, the nanoparticles are PLGA or nanotubes. The phospholipids making up the liposomes may be neutral or charged. For example, the phospholipids may be phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl serine or any other phospholipid. In one embodiment, the liposomes may comprise phosphatidylcholine, phosphoethanolamine, and cholesterol.
The size of the nanoparticles should be such that they are easily deliverable via the circulation. In one embodiment, the size of a majority of the nanoparticles is from 50-250 microns and all integers therebetween and all ranges therebetween. In one embodiment, the size of majority of the nanoparticles is from 100-150 microns. In one embodiment, the size of 60, 70, 80, 90, 95, 96, 97, 98, 99, or 100% of the particles is from 50-250 microns or 100-150 microns.
The number of adhesion molecules and therapeutic molecules on the nanoparticles (such as liposomes) may vary so long as attachment to host cells and then to cancer cells is achieved. For example, adhesion molecules may be more, less, or the same number as therapeutic molecules on a nanoparticle. In one embodiment, the therapeutic molecules are more than adhesion molecules. In one embodiment, the therapeutic molecules are 1×, 2×, 3×, 4×, 5×, 6×, 7×, 8×, 9× or 10× times the number of adhesion molecules on a nanoparticle. In one embodiment, the adhesion molecules are 2×, 3×, 4×, 5×, 6×, 7×, 8×, 9× or 10× times the therapeutic molecules on a nanoparticle. In one embodiment, the ratio of TRAIL molecules to selectin molecules is 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1 on a nanoparticle (such as a liposome).
Adhesion molecules useful in the present disclosure are those by which the nanoparticles can attach to leukocytes under the shear stress that is experienced in the circulation into which they are introduced, such as, for example, the blood stream. Examples of such adhesion molecules include selectins such as P-selectin and E-selectin, wherein the complementary ligand on the leukocytes is selectin-binding carbohydrate ligand. Other examples of selectins include L-selectin as well as recombinant selectin molecules such as P-selectin-IgG chimera and E-selectin-IgG chimera. In one embodiment, the adhesion molecules bind only to leukocytes and cancer cells and not to non-cancer cells (other than leukocytes). The shear flow typically encountered in vivo is in the range of 50-2500 l/s. Thus, the adhesion molecules on the nanoparticles and the complimentary ligands on leukocytes should be able to provide attachment under shear stress in the range of 50-2500 s−1 (0.5 to 25 dynes/cm2 and all integers and values to the tenth decimal place therebetween) and all integers therebetween. In one embodiment, the adhesion molecules are able to provide adhesion under shear stress encountered in post-capillary venules. The range of such shear stress is 0.5-5 dynes/cm2.
Examples of other cell adhesion molecules include selectins, cadherins, integrins, ICAM and VCAM1 or antibodies. An advantage of using selectins is that in contrast to nanoparticles functionalized with antibodies directed to ligands on tumor cells, nanoparticles functionalized with adhesion molecules, such as selectins, form bonds that break under shear flow encountered in the circulation so that the nanoparticles do not aggregate in the circulation. Even though weak, the binding of selectin to its ligand on leukocytes appears to be accentuated by shear flow as little or no binding was observed under static conditions. This was a surprising finding.
In one embodiment, the adhesion molecule is an antibody that binds to a ligand expressed on the surface of a cancer cell. For example, the adhesion molecule may be an antibody directed to CD57. Another example of a useful antibody is an antibody directed to CD34. Other useful antibodies may be against surface markers expressed by subpopulations of blood cells, lymphocyte markers, platelet markers, monocyte markers etc. The antibodies may be monoclonal or polyclonal or may be antigen (ligand) binding fragments of the antibodies. Additionally, the antibodies may be chimeric or humanized antibodies. Such antibodies can be made by methods known in the art or are commercially available.
Examples of therapeutic molecules are those which effect apoptosis in target cells such as cancer cells. In one embodiment, the therapeutic molecule are apoptosis inducing ligands. For example, the therapeutic molecule may be tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL), which binds to death receptors 4 and 5 on the surface of cancer cells to induce apoptosis through the intrinsic and extrinsic pathways. In one embodiment, the therapeutic molecules are Fas ligand, TNF-alpha, or fragments of these ligands or fragments of TRAIL protein and its variants, and antibodies to these ligands, such as Fas antibody.
The liposomes may be conjugated to selectin and TRAIL by routine conjugation methods. The proteins may be attached covalently or non-covalently. In one embodiment, Ni chelating lipids like DOGS-Ni-NTA or other chemistries like avidin/biotin can be used. Other nanoparticles, such as silica nanoparticles and C-dots, may be functionalized in methods known in the art for such nanoparticles. In one embodiment, DOGS-Ni-NTA is utilized to conjugate ES and TRAIL to the liposome surface. In one embodiment, 8-12% weight percent of DOGS-Ni-NTA may be used to conjugate ES and TRAIL to the liposome surface. In one embodiment, PC, SM, cholesterol and DOGS NTA-Ni is used. In one embodiment, the amounts of each component may vary from 45-65, 25-35, 5-15 and 0.5 to 10 wt % respectively, and all values to the tenth decimal place between these values and all ranges between these values.
In one embodiment, this disclosure provides leukocytes which have been functionalized by attachment to nanoparticles, which nanoparticles are attached to the leukocytes at least via the adhesion molecules and also display therapeutic molecules (such as TRAIL) on their surface. The leukocytes may be obtained from the blood of an individual and functionalized by incubation with the nanoparticles. The leukocytes may be of one or more types. For example, the leukocytes may be natural killer cells (NK cells). In one embodiment, the leukocytes express CD3, CD14, CD16, CD19, and/or CD56
In one aspect, the present disclosure provides compositions comprising functionalized nanoparticles, leukocytes, or both in pharmaceutically acceptable carrier suitable for administration to an individual. Such carriers are known in the art and may include, for example, normal saline, water, buffered water, isotonic aqueous solutions, glycine solutions and the like. The pharmaceutical carriers may include glycoproteins for enhanced stability, including albumin, lipoprotein and globulin. These compositions are generally sterilized by conventional means. For example, unilamellar liposomes may be sterilized using sterile filtration techniques.
In one aspect, this disclosure provides methods for targeting and killing metastatic cells, including circulating cancer cells. The method comprises introducing into the circulation of an individual who has been diagnosed with cancer or who is in need of treatment, a composition comprising the functionalized nanoparticles and/or functionalized leukocytes as described herein. The compositions may be introduced into the blood circulation and/or into the lymph circulation. The compositions may also be introduced into localized areas (at or near tumors) such that the functionalized nanoparticles or leukocytes will find their way to surrounding lymph nodes such as the draining lymph nodes.
In one embodiment, the disclosure provides a method for inhibiting metastatic cancer cells comprising introducing into the circulation of an individual a composition comprising nanoparticles which have incorporated therein or thereon leukocyte attachment molecules and cancer therapeutic molecules such that the molecules are exposed on the surface and available for interaction with leukocytes and cancer cells, wherein introduction of the nanoparticles into the circulation of an individual results in reduction in the number of metastatic cancer cells.
In one embodiment, the present disclosure provides a method of killing metastatic cancer cells that are residing in a lymph node comprising a) providing nanoparticles (such as liposomes) which are functionalized with adhesion molecules (such as selectins or anti-CD-57) and therapeutic molecules (such as TRAIL), and b) introducing the nanoparticles into the lymph circulation near the lymph node of an individual. The adhesion molecules attach the nanoparticles to intermediate host cells (such as NK cells) in circulation near the lymph node. The intermediate cells do not have receptors for therapeutic molecules. The nanoparticles attach to the intermediate cells and the intermediate cells seek out cancer cells thereby causing the nanoparticles to attach to the cancer cells residing in the lymph node via the therapeutic molecules causing cell death of the cancer cells in the lymph node.
In one embodiment, the method comprises isolating leukocytes from an individual, optionally, fractionating those to select one or more types of leukocytes, functionalize the leukocytes by incubating with nanoparticles that have incorporated therein adhesion molecules and therapeutic molecules, and then administering the functionalized leukocytes back to the individual. The source of the leukocyte and the recipient of functionalized leukocytes may be the same individual or may be different individuals. If different individuals, they may be matched for compatibility for transfer of blood cells.
In one embodiment, this disclosure provides a method for inhibiting metastatic cancer cells comprising: a) obtaining leukocyte from in individual; b) contacting said leukocytes with liposomes having a leukocyte attachment molecules, such as selectin molecules, and TRAIL molecules incorporated into their bilayers or onto their surface such that the liposomes attach to the leukocytes via the leukocyte attachment molecules resulting in functionalized leukocytes; and c) introducing the functionalized leukocytes into an individual. This results in a reduction in the number of metastatic cancer cells.
While the compositions of the present disclosure may be administered any time during treatment, to optimize the effect, the compositions may be administered when the CTCs are considered to be in greater numbers in the circulation. For example, the compositions may be administered 20-30 minutes after surgical removal of a tumor. The compositions may also be given prophylactically, such as 20-30 minutes before a surgical procedure to remove a tumor. In other embodiments, the compositions may be administered multiple times in a day or on a daily basis or as needed.
In one embodiment, we provide a therapeutic approach to target and kill circulating cancer cells in the bloodstream by administration of nanoparticles functionalized with the apoptosis-inducing ligand TRAIL and the adhesion receptor selectin. The nanoparticles then functionalize leukocytes directly within blood under shear flow. The functionalization of leukocytes under flow, effectively creating a form of “unnatural killer cells” within the bloodstream, is shown to be highly effective at treating circulating cancer cells in flowing human blood in vitro, and in the peripheral circulation of mice in vivo. By the method of the present disclosure, leukocytes are used to treat CTCs directly within the bloodstream.
In one aspect, this disclosure provides a method for inhibiting circulating cancer cells comprising introducing into the circulation of an individual a composition comprising nanoparticles which have leukocyte adhesion molecules and therapeutic molecules attached thereto, wherein introduction of the nanoparticles into the individual results in targeting and reduction in the number of circulating cancer cells in the bloodstream of the individual.
The method of the present disclosure provides an approach in which, it is considered that leukocytes are functionalized via interaction with the adhesion molecules on nanoparticles and can be used to target and kill circulating cancer cells. Thus, the functionalized leukocytes act as mimics of the cytotoxic activity of natural killer (NK) cells. The resulting “unnatural killer cells” provide an effective means to neutralize circulating tumor cells that enter blood with the potential to form new metastases.
In one embodiment, the method comprises targeting and killing cancer cells in the bloodstream, in which the extensive surface area of circulating leukocytes is used to display the cancer-specific apoptosis ligand TRAIL and selectin adhesion receptor to the surrounding fluid. The approach is inspired by the cytotoxic activity of natural killer cells, and is effective at killing cancer cells both in in vitro human blood samples and in mouse blood circulation. The mechanism is surprising and unexpected in that this repurposing of leukocytes in flowing blood is more effective than directly targeting the cancer cells with liposomes or soluble protein.
The compositions and methods of the present disclosure are useful for any indication where specific targeting of cells is helpful. For example, the compositions and methods are useful in any type of cancer. In one embodiment, the cancer often results in dissemination of cancer cells from its primary site, and such cells may appear as circulating cancer cells. Or the cells may lodge themselves in lymph nodes near the primary site or in some cases far from it. Examples of cancer include breast, prostate, lung cancer, melanoma, pancreatic, colorectal, GI tract, retinoblastoma, bladder and any other type of cancer.
The present method may be combined with the administration of agents known to sensitize cancer cells to TRAIL-mediated apoptosis, including conventional chemotherapeutics (camptothecin, cisplatin, doxorubicin, 5-fluorouracil, irinotecan, paclitaxel, gemcitabine), proteasome inhibitors, Bcl-2 inhibitors, IAP antagonists, HDAC inhibitors, CD20 antibodies, irradiation, synthetic triterpenolds, Sorafenib, aspirin, and natural products such as curcumin and piperlongumine. Thus, in one embodiment, the method comprises administration of the nanoparticles disclosed herein to an individual in need of treatment (such as in individual who is considered to be at risk of having circulating cancer cells) and administration of an agent that sensitizes cancer cells to apoptosis inducer (such as TRAIL). The agent sensitizing cancer cells to apoptosis inducers may be given before, after, or at the same time as the nanoparticles.
In the following description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments which may be practiced. These embodiments are described in detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural and logical changes may be made without departing from the scope of the present invention. The following description of example embodiments is, therefore, not to be taken in a limited sense, and the scope of the present invention is defined by the appended claims.
The Abstract is provided to comply with 37 C.F.R. § 1.72(b) to allow the reader to quickly ascertain the nature and gist of the technical disclosure. The Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.
Example 1This example describes the use of nanoparticles functionalized with cancer-specific apoptosis ligand TRAIL and selectin molecules to target and kill colon and prostate cancer cells in the blood. This approach, is demonstrated in vitro with human blood and also in mice.
Materials and Methods
Reagents and antibodies. Human serum albumin (HSA), bovine serum albumin (BSA), Accutase™, HEPES, DMSO, NaCl, MgCl2, CaCO3 and chloroform (ACS grade with 0.5-1% ethanol added as stabilizer) were all obtained from Sigma-Aldrich (St Louis, Mo.). RPMI 1640 cell culture media, fetal bovine serum (FBS), Hank's balanced salt solution (HBSS), penicillin-streptomycin (PenStrep) and Dulbecco's phosphate buffered saline (DPBS) were all obtained from Invitrogen (Grand Island, N.Y.). His-tagged recombinant human tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), his-tagged recombinant human E-selectin-IgG chimera (ES) and Annexin-V FITC Apoptosis Detection Kit were purchased from R&D Systems (Minneapolis, Minn.). BCECF AM solution and trypsin-EDTA solution were obtained from Invitrogen (Carlsbad, Calif.). PBS-based enzyme-free cell dissociation media was purchased from Millipore (Billerica, Mass.). L-α-lysophosphatidylcholine from egg (Egg PC), sphingomyelin from egg (Egg SM), ovine wool cholesterol (Chol), 1,2-dioleoyl-sn-glycero-3-[(N-(5-amino-1-carboxypentyl) iminodiacetic acid) succinyl] (nickel salt) (DOGS NTA-Ni) and 23-(dipyrrometheneboron difluoride)-24-norcholesterol (Bdp-Chol, Ex/Em 490 nm/504 nm) either dissolved in chloroform (Egg PC, Egg SM, Chol, DOGS NTA-Ni) or in powder form (Bdp-Chol) were purchased from Avanti Polar Lipids (Alabaster, Ala.). Rat anti-human CD62E (E-selectin) antibody was purchased from Abcam (Cambridge, Mass.). Anti human CD3, CD14, CD16, CD19 and CD56 conjugated with Pacific Blue™, APC Cy7™, PERCP-Cy5.5, APC, and PE respectively along with corresponding isotypes were all purchased from BD Biosciences (San Jose, Calif.).
Cell lines and cell culture. Colon cancer cell line COLO 205 (ATCC number CCL-222) was obtained from ATCC (Manassas, Va.) and cultured in RPMI 1640 supplemented with 2 mM L-Glutamine, 25 mM HEPES, 10% v/v FBS and 100 U/mL PenStrep (complete media) under humidified conditions at 37° C. and 5% CO2. Prostate cancer cell line PC-3 (ATCC number CRL-1435) was obtained from ATCC and cultured in F-12K medium supplemented with 10% v/v FBS and 100 U/mL PenStrep. Human umbilical vein endothelial cells (HUVEC) were purchased from Cascade Biologics (Portland, Oreg.) and maintained in Medium 200 (Cascade Biologics) supplemented with low-serum growth supplement (Cascade Biologics) and 5% fetal bovine serum (Invitrogen). HUVECs were utilized from passages 2-5 for experiments. For all experiments, >95% viability was assessed by trypan blue exclusion dye.
Preparation of liposomes. Multilamellar liposomes, composed of egg L-α-lysophosphatidylcholine (Egg PC), egg sphingomyelin (Egg SM), ovine wool cholesterol (Chol), 1,2-dioleoyl-sn-glycero-3-[(N-(5-amino-1-carboxypentyl) iminodiacetic acid) succinyl] (nickel salt) (DOGS NTA-Ni) at weight ratios 60-50%:30%:10%:0-10% (Egg PC/Egg SM/Chol/DOGS NTA-Ni), were prepared by a thin lipid film method. DOGS-NTA-Ni is a lipid conjugated to nickel-nitrilotriacetic acid (Ni-NTA) that allows for attachment to his-tagged proteins. Briefly, stock solutions of all lipids were prepared by dissolving powdered lipids in chloroform to produce a final concentration of 5 mg/mL Egg PC, 20 mg/mL Egg SM, 5 mg/mL Chol and 20 mg/mL DOGS-NTA-Ni in glass containers and stored at −20° C. Appropriate volumes of the lipids were taken from the stock solution to make lipids with varying concentrations of DOGS NTA-Ni in a glass tube and gently dried under nitrogen. To ensure complete removal of chloroform, the lipids were left under vacuum for an additional 12 h. With increasing amounts of DOGS NTA-Ni, the corresponding amount of Egg PC was decreased (Table S1). The lipid film was hydrated with a liposome buffer composed of 150 mM NaCl, 10 mM HEPES and 1 mM MgCl2 dissolved in nuclease-free water to create multilamellar liposomes. The resulting multilamellar liposomes were sized by repeated thawing and freezing, and then subjected to 15 extrusion cycles at 60° C. through two different pore size (200 and 100 nm) polycarbonate membranes (Nucleopore, Whatman, N.J., USA) to produce unilamellar nanoscale liposomes. Recombinant human ES and TRAIL were dissolved in nuclease-free sterile water to a final concentration of 1 mg/mL and 100 μg/mL. Aliquots of stock solutions were stored at −20° C. and used as needed within 60 days. Freshly prepared nanoscale liposomes were then incubated with ES (final concentration 71.43 nM) and TRAIL (250 nM final concentration) for 30 min at 37° C. and then overnight at 4° C., to ensure maximum protein binding via the interaction between his-tag and Ni-NTA. Based on approximations for ligand density on liposomes suggested in previous work by Huang and Mason (1), there were approximately 65 TRAIL and 19 E-selectin proteins present on the surface of each liposome, assuming a unilamellar liposome diameter of 100 nm. To remove unbound TRAIL and ES, liposomes were diluted 1:6 with liposome buffer and subjected to ultracentrifugation at 100000 g for 3 h at 4° C. The supernatant with unbound TRAIL and ES was carefully removed and collected for further evaluation, and the remaining liposomes were gently resuspended in buffer. A similar procedure was used to create fluorescent conjugated liposomes by replacing ovine wool cholesterol with 23-(dipyrrometheneboron difluoride)-24-norcholesterol. Freshly prepared nanoscale liposomes were diluted in buffer, and the mean particle diameter and surface charge (zeta potential) were measured by dynamic light scattering using a Malvern Zetasizer nano ZS (Malvern Instruments Ltd., Worcestershire, UK), according to the manufacturer's protocols. Conjugated liposomes were measured to be 117.8±10.3 nm in diameter, with a zeta potential of −5.7±4.6 mV.
Static experiments. COLO 205 cells were seeded in multiwell plates at a seeding density of 300,000 cells/mL, 1 day prior to experimentation to ensure that the cells were in the linear phase of the growth cycle. Media was changed prior to experimentation. Cells were incubated with either the supernatant from ultracentrifugation or 10 μL of conjugated and purified liposomes. The cells were maintained in culture conditions with the supernatant or nanoscale lipids for 24 h and later analyzed by an Annexin-V assay to quantify the proportion of viable cells.
Uniform shear flow experiments. To simulate the shear stress conditions of blood flow, cancer cells were subjected to uniform shear in a cone-and-plate viscometer. Cancer cells seeded one day prior to the experiment were gently detached from the surface using PBS-based enzyme-free cell detachment solution or accutase. Cells were then washed twice in 1×DPBS and resuspended in buffer at a concentration of 1×106 cells/mL. 10 μL of lipids was added to 490 μL of cell suspension (at 106 cells/mL) and immediately added to the cone-and-plate viscometer. Shear rate was set to 188 s−1 for 2 h. All samples were exposed to shear flow at RT, to prevent potential sample evaporation and/or drying in the cone-and-plate viscometer over prolonged periods of shear. After 2 h, the cells were removed and washed twice in resuspension buffer at 200 g for 5 min. Cells were resuspended in complete media and cultured for 24 h. In the case of fluorescent lipids, an aliquot was taken for visual inspection on an inverted microscope (Olympus America Inc, Melville, N.Y.) equipped with fluorescence and an intensified CCD digital camera (Cooke Corporation, Romulus, Mich.) to record images. For spiking experiments, peripheral blood was collected into Vacutainer tubes containing heparin and allowed to equilibrate to RT before use. 1×106 COLO 205 or PC-3 cells were tagged fluorescently with 3 μM BCECF AM solution for 15 min at 37° C., washed twice and collected via centrifugation at 200 g for 5 min. The supernatant was discarded, and the collected cells were resuspended in 1 mL of whole blood. 10 μL of lipid was then added to 490 μL of spiked blood and immediately added to a cone-and-plate viscometer previously coated with 5% BSA. Spiked blood was subjected to a uniform shear rate of 188 s1 for 2 h. As an additional comparison for spiking experiments, identical experiments were performed in buffer instead of whole blood. In leukocyte functionalization experiments, 10 μL of lipid was added to 490 μL human blood, sheared in a cone-and-plate viscometer at a uniform shear rate of 188 s−1 for 2 h, and subsequently centrifuged to remove the plasma containing unbound liposomes. The removed plasma was replaced with freshly isolated plasma, and the blood samples were used for identical spiking experiments mentioned above. After shearing, the blood sample was collected from the device and carefully layered over 1.5 mL of Ficoll and centrifuged at 480 g for 50 min at RT. The buffy coat containing MNCs and cancer cells was recovered and washed twice in resuspension buffer, collected, cultured for 24 h, and analyzed for viable fluorescent cancer cells using flow cytometry. To evaluate the effect of hematocrit, the number of RBCs was varied by removal via centrifugation. Volumes of RBCs were replaced with excess plasma from the same blood donor. Cancer cells were spiked into blood samples as mentioned earlier, at a concentration of 1×106 cells/mL. 10 μL of liposome solution was added to 490 μL of blood and sheared for 2 h at 188 s−1. Samples were collected, incubated, and analyzed for viability on a flow cytometer as described above. In some experiments, 490 μL of whole blood was sheared with 10 μL of liposome solution, and the plasma and any remaining unbound liposomes and/or liposome fragments were separated by centrifugation. To determine the effects of remaining unbound liposomes and/or liposome fragments on cancer cell viability, the recovered plasma was incubated with 500,000 COLO 205 cells for 24 h at 37° C. and analyzed for cell viability using flow cytometry.
Polymorphonuclear (PMN) and mononuclear cell (MNC) isolation. All human subject protocols were approved by the Institutional Review Board for Human Participants of Cornell University. Peripheral blood was collected from healthy, willing donors after informed consent into Vacutainer tubes containing heparin and allowed to equilibrate at room temperature (RT) before use. 3 mL of blood diluted with resuspension buffer was carefully layered over 3 mL of 1-Step™ Polymorphs (Accurate Chemical & Scientific Corporation, Westbury, N.Y.) and centrifuged at 480 g for 50 min at RT. Two separate layers of MNCs and PMNs were collected and washed twice with resuspension buffer.
Leukocyte functionalization with ES/TRAIL liposomes in whole blood. To assess the adhesion of ES/TRAIL liposomes to leukocytes in whole blood under flow, 490 μL of whole blood was sheared with 10 μL of fluorescent ES/TRAIL liposome solution for 30 min in a cone-and-plate viscometer at a shear rate of 188 s−1. Leukocytes were then separated using 1-Step™ Polymorphs and assessed for adherent ES/TRAIL liposomes using confocal microscopy. To assess the fraction of leukocyte subpopulations that adhere to ES/TRAIL liposomes, leukocytes were labeled with anti-human CD3, CD14, CD16, CD19 and CD56, along with corresponding isotype controls, and analyzed for adherent ES/TRAIL liposomes using flow cytometry. To assess the specificity of the ES interaction with leukocytes, liposomes were incubated with a functional blocking anti-human E-selectin antibody prior to shearing in whole blood. To assess the fraction of leukocytes in blood adhered to ES/TRAIL liposomes before shear, fluorescent ES/TRAIL liposomes were added to whole blood and then separated using 1-Step™ Polymorphs.
Endothelial cell viability assay. 40 mm diameter circular glass coverslips (Thermo Scientific, Waltham, Mass.) were plasma treated (Harrick Plasma Cleaner, Ossining, N.Y.) for 2 min and subsequently incubated in 1% polyethylenemine (PEI) at room temperature for 10 min. Coverslips were then washed in water 3 times and treated with 0.1% glutaraldehyde (Sigma-Aldrich, St. Louis, Mo.) in PBS at room temperature for 30 min. Coverslips were washed in water 3 times, dried, and treated with 0.1 mg/mL of type I rat-tail collagen (Becton Dickinson, Franklin Lakes, N.J.) in HEPES (pH 8.0, Sigma-Aldrich, St. Louis, Mo.) for 2 h at 4° C. Coverslips were placed in petri dishes (60 mm×15 mm; Sigma-Aldrich), washed 3 times in PBS, and briefly sterilized via UV exposure for 15 min. HUVECs were plated on coverslips, at a density of 500,000 cells per coverslip, in Medium 200 supplemented with low-serum growth supplement (Cascade Biologics), 5% fetal bovine serum (Invitrogen), and 100 U/mL PenStrep. HUVECs were cultured for 4 days on coverslips prior to experiments, and then adhered to the plate of a cone-and-plate viscometer using vacuum grease. HUVECs were then treated with 2.94 mL of human blood and 60 μL of PBS, ES/TRAIL (TRAIL final concentration: 0.3 μg/mL), or soluble TRAIL in PBS (TRAIL final concentration: 0.3 μg/mL) for 4 h at 37° C. in a humidified cone-and-plate viscometer at a shear rate of 188 s1. As a positive control, HUVECs were treated with a high concentration of soluble TRAIL (15 μg/mL). Coverslips were removed from the viscometer, gently washed in PBS, and placed in Medium 200 supplemented with low-serum growth supplement, 5% fetal bovine serum (Invitrogen), and 100 U/mL PenStrep. HUVEC morphology was assessed using brightfield and phase contrast microscopy. HUVECs were immediately placed into culture for 8 h, maintained at 37° C. and 5% CO2. HUVECs were then treated with 0.25% Trypsin-EDTA solution (Gibco) for 2 min at 37° C., followed by treatment with an equal volume of trypsin neutralizer solution (Gibco). HUVECs were collected from coverslips, washed twice in PBS, and assessed for viability using an Annexin-V assay.
Liposome and COLO 205 cell injection in mice. C57BL/6J mice aged 16-20 weeks (both sexes), weighing 25-32 g, were obtained from The Jackson Laboratory. Mice were anesthetized using isoflurane (5%) for all procedures. Either 120 μL of saline, sTRAIL (15 μg/mL; TRAIL plasma concentration ˜1.0 μg/mL), ES/TRAIL (TRAIL injection concentration: 15 μg/mL; TRAIL plasma concentration ˜1.0 μg/mL) liposomes or ES liposomes suspended in saline were injected retro-orbitally using a 30-G needle and animals were removed from anesthesia. Three mice were used in each group. Thirty minutes later, animals were re-anesthetized and 2×106 COLO 205 cells, labeled by 2 μg/mL Hoescht (#H1399, Invitrogen) or 3 μM BCECF AM suspended in saline were injected into the tail vein. Animals were removed from anesthesia and the cancer cells were allowed to circulate for 2 h. All animal procedures were approved by the Cornell University Institutional Animal Care and Use Committee.
Analysis of circulating COLO 205 cells. Animals were euthanized with a lethal dose of pentobarbital. Blood was removed from the heart via cardiac puncture and collected into sodium heparin-coated tubes. Leukocytes and circulating COLO 205 cells were separated using Ficoll-Paque PLUS™. After centrifugation, the MNC buffy coat was collected, washed in buffer containing Ca2+ and cultured for 2-3 h in multiwell plates. Cell viability was assessed using flow cytometry.
Two-photon imaging of lung tissue. Animals were anesthetized and received injections of saline, sTRAIL, ES/TRAIL liposomes or ES liposomes, followed by an injection of Hoescht-labeled cancer cells, as described above. After two hours of cancer cell circulation, an Alexa Fluor 568 labeled Annexin-V probe (#A13202, Invitrogen) was injected retro-orbitally and allowed to circulate for 2 h to ensure maximum detection of apoptotic cells. Animals were then given a lethal dose of pentobarbital. After euthanasia, intact lungs were resected and immediately imaged via two-photon excited fluorescence microscopy. Two-photon imaging was conducted on a locally-designed microscope using a train of 800-nm, 87-MHz, 100-fs pulses from a Ti:sapphire laser oscillator (MIRA HP, pumped by a Verdi-V18, Coherent) for excitation. Laser scanning and data acquisition were controlled by ScanImage software. For high-resolution imaging of COLO 205 Hoechst-labeled nuclei and Annexin V labeling a 20× (numerical aperture: 0.95) water-immersion objective (Olympus) was used. Fluorescence was detected using emission filters with 460-nm and 645-nm center wavelength with 65-nm bandwidth to image Hoescht and Alexa Fluor 568 (Invitrogen), respectively. Spectrally-broad autofluorescence from the lung tissue was visible in both channels.
Counting and viability scoring of COLO 205 cells in lung. Hoechst-labeled COLO 205 cells were manually counted from ˜10 representative two-photon image stacks taken from the lung in each mouse using Image J (NIH) cell counting software. The Hoechst signal was of similar magnitude to the background lung autofluorescence in the 460-nm channel. To aid in identifying nuclei, the Hoechst channel was compared with the 645-nm channel, where autofluorescence was also visible, but Hoescht was not and Alexa Fluor 568 signal was significantly brighter than autofluorescence. In addition, attributes such as size and shape to distinguish the labeled COLO 205 cells were used. Each imaged volume was about 0.022 mm3. The total number of cells in the lung was estimated by scaling the imaged volumes to the total lung volume, which was measured via a volume displacement method. Counts were recorded by two different observers, each blinded to the treatment received, and averaged. To determine which COLO 205 cells were apoptotic, we determined whether Alexa Fluor 568 Annexin V labeling was present at each of the COLO 205 cell nuclei we identified.
Flow cytometry. Mode of cell death was analyzed using an Annexin-V apoptosis assay on an Accuri C6 flow cytometer. Samples were prepared for as per the manufacturer's instructions. Briefly, cells were classified into four categories based on dye uptake: viable cells (negative for Annexin-V and propidium iodide (PI)), early apoptotic cells (positive for Annexin-V only), late apoptotic cells (positive for Annexin-V and PI) and necrotic cells (positive for PI only). For blood spiking experiments, fluorescent untreated cancer cells and liposome treated samples were assessed for viability using a flow cytometer. A gate was set based on a viable, untreated cancer cell control. Equal volumes from all samples were used for analysis. Cell viability was determined by measuring the amount of cells positive for fluorescent BCECF staining. For in vivo animal experiments, 100 μL of each sample was processed. A gate denoting viable, BCECF AM-labeled cancer cells was established by processing a viable, fluorescent sample of COLO 205 cells in buffer. COLO 205 cells recovered from mouse blood were differentiated based on size and fluorescence using flow cytometry. The number of cancer cells per milliliter of mouse blood was determined based on the amount of mouse blood recovered from each animal.
Statistical analysis. Where appropriate, student's t-test and one-way ANOVA with Tukey post test comparing all means were employed at a significance level of α=0.05. All statistical analyses were performed using GraphPad Prism 5.0c for Mac OS X GraphPad software (San Diego, Calif. USA) and Kaleidagraph (Synergy) software.
Results
ES/TRAIL liposomes adhesively interact and induce apoptotic cancer cell death under shear flow. Many types of circulating tumor cells (CTC), and cancer cell lines derived from colon, breast, prostate, and pancreas are known to display glycosylated ligands that allow them to adhesively interact with E-selectin (ES) under physiological shear flow. This has been proposed to explain why some cancers home to tissue specific capillary beds such as the bone marrow and liver. To target and kill cancer cells of this form, we used nanoscale liposomes conjugated with a mixture of recombinant human E-selectin (ES) protein and tumor necrosis factor (TNF)-related apoptosis inducing ligand were developed (TRAIL;
In the post-capillary venules where selectin-mediated adhesion and cell extravasation into tissues typically occur, moderate shear rates can initiate flowing cell interactions with the endothelial cell wall. To recreate these physical forces in vitro, a cone-and-plate shear assay was developed to probe the interactions of cancer cells and ES/TRAIL liposomes under venular shear rates. After exposure to shear flow (shear rate: 188 s1) for 2 h, COLO 205 cells exposed to ES liposomes displayed their normal morphology, while substantial membrane blebbing was observed in those exposed to ES/TRAIL liposomes, characteristic of cells undergoing apoptosis (
To investigate the adhesive characteristics of ES/TRAIL liposomes to cancer cells under flow, COLO 205 cells were exposed to ES/TRAIL liposomes consisting of fluorescent cholesterol and exposed to shear flow as in previous in vitro shear assays. Flow cytometry revealed that >99.9% of the COLO 205 cell population was adhered to ES/TRAIL liposomes after exposure to shear flow (
ES/TRAIL liposomes functionalize leukocytes in whole blood under shear flow in vitro. In addition to CTCs, circulating leukocytes also possess ligands for E-selectin, which are necessary in the inflammatory response and lymphocyte homing to lymphatic tissues. To assess the potential to functionalize leukocytes with ES/TRAIL to target and kill CTC, we treated whole human blood with fluorescent ES/TRAIL liposomes under shear flow in a cone-and-plate viscometer. Upon exposure to shear (shear rate: 188 s1), ES/TRAIL liposomes readily bind to leukocytes via selectin ligands on the leukocyte surface (
To quantify leukocyte subpopulations that adhere to ES/TRAIL liposomes under flow, leukocytes were separated from whole blood and analyzed for both leukocyte marker expression and adherent ES/TRAIL liposomes using flow cytometry. Functionalized leukocytes were labeled with CD3, CD14, CD16, CD19, and CD56 antibodies, as such markers are commonly expressed on most T-lymphocytes, monocytes, neutrophils, B-lymphocytes, and natural killer (NK) cells, respectively. Minimal adhesion of ES/TRAIL liposomes to leukocytes in blood was observed in the presence of a functional blocking ES antibody (
ES/TRAIL functionalization does not induce significant leukocyte or endothelial cell death. To assess the effects of ES/TRAIL functionalization on leukocyte viability, mononuclear leukocytes isolated from human blood were treated with ES/TRAIL liposomes under both static and shear flow conditions. Annexin-V assays revealed no significant differences in leukocyte viability when leukocytes were incubated with ES (
To assess the effects of ES/TRAIL functionalization on endothelial cell viability, human umbilical vein endothelial cells (HUVEC) were treated with ES/TRAIL liposomes in human blood under shear flow conditions in vitro. Treatment with ES/TRAIL liposomes or an equivalent concentration of soluble TRAIL in human blood under shear flow for 4 h induced no significant differences in HUVEC viability, compared to untreated HUVEC exposed to shear in human blood (
Apoptotic effects of ES/TRAIL therapy are enhanced in human blood under flow. Clinically, CTCs are sparsely distributed in the complex milieu of whole blood, at concentrations as low as 1-100 cells/mL. To examine whether ES/TRAIL liposomes would effectively target cancer cells in the presence of blood cells and serum under flow conditions, we fluorescently labeled colorectal COLO 205 and prostate PC-3 cancer cell lines and spiked them into human peripheral blood. Surprisingly, under identical shear flow conditions ES/TRAIL therapy was even more effective at killing cancer cells in the presence of human blood (
To evaluate the impact of blood cells on the efficacy of ES/TRAIL treatment, fluorescent COLO 205 and PC-3 cells were spiked in human blood of varying hematocrit percentages. All additional blood cell components were maintained, while the volume of removed erythrocytes was replaced with plasma from the same blood donor. Interestingly, the apoptotic effects were hematocrit-dependent, as higher hematocrit significantly decreased the number of viable COLO 205 and PC-3 cells after ES/TRAIL treatment (
To assess the mechanism by which leukocytes act as a pervading carrier surface for functional TRAIL, blood was pretreated with ES/TRAIL liposomes under shear flow, with blood cells subsequently separated from unbound ES/TRAIL via centrifugation and replaced with fresh blood plasma. ES/TRAIL therapeutic effects under shear flow remained nearly identical, as COLO 205 and PC-3 cells spiked into a suspension of blood with washed, pretreated blood cells were killed at roughly the same rate as unwashed blood (
ES/TRAIL functionalized leukocytes reduce number of viable cancer cells in mouse circulation in vivo. To assess the cytotoxic effects in vivo, ES/TRAIL liposomes were also tested for their ability to kill cancer cells flowing in the peripheral circulation of mice. Two million fluorescently labeled COLO 205 cells were injected into the tail vein of immunocompetent C57BL/6J mice, 30 min after injection of 120 μL of either ES/TRAIL liposomes, ES liposomes, or soluble TRAIL (
Using flow cytometry, we measured ˜130,000 cancer cells/mL blood for mice injected with control ES liposomes, compared to <2,000 cancer cells/mL blood surviving from ES/TRAIL treated mice (
ES/TRAIL treatment reduces number and increases apoptosis of remaining circulating COLO 205 cells lodged in vivo in mouse lung. Previous studies have shown that more than 90% of tumor cells that enter the vasculature via tail vein injection lodge into lung vasculature within the first two hours. To assess the viability of the remaining circulating cancer cells lodged within mice, fluorescent COLO 205 cells lodged within the lungs of mice were identified using two-photon excited fluorescence microscopy (
We then evaluated the apoptotic effects of ES/TRAIL liposomes on cancer cells that have already lodged into the lungs of mice. After the injections of liposomes and COLO 205 at previously used time points (
Natural killer cells, activated by interleukin-2 or other factors, are induced to present TRAIL protein on their surface. These cells participate in immunosurveillance against micrometastases in the body, and comprise 10-20% of peripheral blood mononuclear cells. While the liposome-coated leukocytes described here are not specifically programmed to actively invade tissues and seek out solid tumors, they do have frequent opportunities for incidental contact with CTCs in the bloodstream and there may be some degree of homing of normally-functioning leukocytes to solid tumors. We find that TRAIL is most potent when it is tethered to the surface of leukocytes in shear flow—rather than freely soluble or on untethered liposomes in the absence of blood. Tethering nanoscale liposomes to the surface of peripheral blood leukocytes is also beneficial for increasing liposome circulation time, by avoiding renal clearance mechanisms.
While not intending to be bound by any particular theory, it is believed that the much higher cytotoxic activity in shear flow of leukocytes coated with ES/TRAIL liposomes have, compared to isolated ES/TRAIL liposomes or soluble TRAIL protein may be due to compressive force between surfaces. Two spherical particles colliding in linear shear flow will experience a compressive force between them which scales as Fc˜μ*G*a*b, where L is the fluid viscosity, G is the shear rate, and a and b are the radii of the smaller and larger sphere, respectively. Thus, a 10 Lm diameter leukocyte colliding with a cancer cell may experience 100 times the compressive force of a 100 nm liposome colliding with a cancer cell. Compressive forces could flatten down any cell surface glycocalyx composed of biologically inert macromolecules, thus allowing TRAIL to come within a reactive distance to the cancer cell death receptors and form bonds.
Recombinant human TRAIL/Apo2L, also known as PRO1762 developed by Amgen/Genentech, has been the subject of numerous Phase 1, la, 2, and 3 clinical trials over the past decade, with minimal adverse effects reported. There are many intracellular proteins, such the inhibitors of apoptosis protein (IAPs) family members that also confer TRAIL resistance to normal cells. Additionally, the dosages of TRAIL used in this current study ranged from 0.06-0.08 mg/kg, two orders of magnitude lower than the clinical dosages of 1-30 mg/kg used in human clinical trials. While different types of cancer cells show different levels of sensitivity to TRAIL-induced apoptosis, it has been well documented that there is a wide range of agents known to sensitize cancer cells to TRAIL-mediated apoptosis, including conventional chemotherapeutics (camptothecin, cisplatin, doxorubicin, 5-fluorouracil, irinotecan, paclitaxel, gemcitabine), proteasome inhibitors, Bcl-2 inhibitors, IAP antagonists, HDAC inhibitors, CD20 antibodies, irradiation, synthetic triterpenolds, Sorafenib, aspirin, and natural products such as curcumin and piperlongumine.
Example 2This example describes the use of nanoparticles functionalized with an cancer-specific apoptosis ligand TRAIL and an antibody to CD57. These nanoparticles were used in a model for lymph node micrometastases.
Materials and Methods
Microfabrication of silicon wafers and microbubble formation. A lithography mask was designed with using AutoCAD LT 2008 (Autodesk, Inc., USA). The mask included three different types arrays of rectangular trenches with 60 μm, 100 μm and 200 μm circular openings. Depth of the trenches was 150 μm. Silicon wafers were produced from this mask (MEMS and Nanotechnology Exchange, Virginia USA) using the Bosch deep reactive ion etching (DRIE) process. The hydrophobic coating produced during the Bosch process was left intact. The DRIE silicon wafers were used to produce microbubble in PDMS. Dow Corning's Sylgard® 184 silicone elastomer kit in a 10:1 base to curing agent ratio (w/w) was manually mixed in a 50 mL tube for 2 min and poured onto silicon wafers. The mixture was allowed to spread out on the wafer for 30 min at room temperature and cured at 100° C. for 2 hr. The PDMS was then peeled off from the wafers and the arrays were cut in small chips to be used in cell culture experiments. The experiments described in this work were all performed on microbubbles formed from the 100 μm circular openings on the wafer.
Cell lines and culture conditions. Three lymph node seeking metastatic cell lines from different types of cancers were used in this study. LNCaP (prostate cancer), COLO 205 (colorectal cancer) and MDA-MB-231 (breast cancer) were purchased from American Type Culture Collection (ATCC) and maintained in culture at 37° C. with 5% CO2 in humidified incubator. LNCaP and COL0205 cells were cultured in RPMI-1640 (Cellgro, 10-040-CV) supplemented with 10% fetal bovine serum (FBS) (Atlanta Biologicals, S11050H), and 1% penicillin/streptomycin (PS) (Gibco®, 15140-122). MDA-MB-231 cells were cultured in high glucose DMEM (Gibco®, 11965-092) supplemented with 10% FBS and 1% PS. HNK-1, a hybridoma cell line (ATCC® TIB-200™) was cultured in RPMI-1640 (ATCC®30-2001™) supplemented with 0.02 mM 2-mercaptoethanol (Gibco®, 21985-023) and 20% ultra low IgG FBS (Gibco®, 16250-078). The hybridoma line secretes anti-CD57 (IgM isotype), a monoclonal antibody against human natural killer cells.
Preparation of TRAIL and anti-CD57 functionalized liposomes. Hydro Soy PC L-α-phosphatidylcholine (HSPC), cholesterol, 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy (polyethylene glycol)-2000] (DSPE-mPEG2000) and 1,2 distearoyl-sn-glycero-3-phosphoethanolamine-N-[maleimide (polyethylene glycol)-2000](DSPE-Mal-mPEG2000) were purchased from Avanti Polar Lipids (Alabaster, Ala., USA). Liposomes were composed of HSPC: cholesterol: DSPE-mPEG200: DSPE-Mal-mPEG2000 at a molar ratio of 2:1:0.08:0.02. Lipids were mixed to produce a total of 10 mM lipid in 1 mL and kept in a glass vial covered with parafilm inside a vacuum glass chamber over night to remove residual organic solvent. The lipid cake was then hydrated in 1 mL of buffer composed of 20 mM 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) and 150 mM sodium chloride in phosphate buffered saline (PBS) at pH 7.5. The hydrated lipids formed multi-lamellar vesicles and they were then disrupted by 10-15 freeze (2 min)/thaw (3 min) cycle before extrusion. The lipid suspension was then forced through a polycarbonate filter with successively smaller pore size (400 nm, 200 nm and 100 nm) mounted on a holder in a heating block (Avanti® mini-extruder). The temperature was maintained at 60° C. above the phase transition temperature of the lipids.
Anti-CD57 was isolated from hybridoma supernatant using a protein-L agarose column (Thermoscientific, 20510) following a protocol supplied by the manufacturer for gravity-flow based isolation of proteins. Recombinant human TRAIL (Peprotech 310-04) and anti-CD57 were thiolated using 1 mM Traut's reagent (Thermoscientific, 26101) added in 6-fold molar excess to the proteins in solution. Excess Traut's reagent was removed using a desalting column (Thermoscientific, 89889) by spinning the reaction mixture three times for 2 min at 1000×g. Thiolated proteins were then functionalized on the surface of liposomes overnight at 4° C. via maleimide-thiol chemistry by adding an appropriate amount of protein to set the concentration of maleimide in liposomes at 6-fold molar excess to the concentration of thiol groups in proteins. The protein-functionalized liposome was stored at 4° C. for up to a week and was prepared fresh whenever required. Successful functionalization of proteins to liposomes was determined by measuring the average particle size by dynamic light scattering using a Malvern Zetasizer nano ZS (Malvern Instruments Ltd., UK).
To produce fluorescent liposomes used in this study, cholesterol in the lipid composition was replaced with TopFluor cholesterol (Avanti polar lipids, 810225). The same protocol was used to make fluorescent liposomes by minimizing the exposure to light.
Conjugation of liposomes to natural killer cells. Natural killer cells were isolated from whole blood of healthy volunteers using the RosetteSep™ human NK cell enrichment cocktail (Stemcell technologies, 15065) following the protocol supplied by the manufacturer. NK cells were maintained in culture using Myelocult™ (Stemcell technologies, H5100) supplemented with 1 mM hydrocortisone and 100 U/mL of human recombinant interleukin-2 (IL-2) (Millipore, IL002).
For conjugating CD57-expressing NK cells to anti-CD57 and TRAIL functionalized liposomes, NK cells were pelleted and resuspended in 200 μL of 2% bovine serum albumin (BSA). They were then incubated with a specific volume of protein-functionalized liposomes at 4° C. for 1 hr. The volume of liposomes to be added to 1×106 NK cells was determined by incubating 1×106NK cells with 5, 10, 25 and 50 μL of fluorescent liposomes. The NK cells were then washed twice with PBS to remove any unbound liposomes by centrifuging them at 1000 rpm for 10 min. The fluorescent intensity histograms from flow cytometric analysis (BD Accuri™ C6 flow cytometer) were used to determine the optimum volume of liposomes to be added to 1×106NK cells. Successful conjugation of liposomes to NK cells was verified using flow cytometry and fluorescent microscopy with appropriate filters on an Olympus IX81 microscope. NK cells conjugated to TRAIL-functionalized liposomes are referred to herein as “super NK cells”. To ensure that there were no deleterious effects of conjugating TRAIL-functionalized liposomes to NK cells, conjugated cells were cultured in vitro for 24 hr and stained for live cell marker Calcein-AM (Molecular Probes®, C3100MP).
Characterization of cell lines for death receptor expression. Cancer cells were analyzed for the expression of death receptors (DR4 and DR5) using flow cytometry (Guava Easycyte™ flow cytometer). LNCaP, COLO 205 and MDA-MB-231 cells grown to confluence in 6-well plates were washed with PBS and cells were harvested using enzyme-free cell dissociation buffer (Gibco®, 13151-014). Approximately 0.5×106 cells were resuspended in 100 μL 2% BSA. Cells were then incubated with 10 μL of PE-conjugated monoclonal antibody against DR4 (R&D Systems, FAB347P) and DR5 (R&D Systems, FAB6311PS) and 10 μL of corresponding isotype control (R&D Systems, IC0041P) at 4° C. for 45 min. Following incubation, unreacted antibodies were removed by washing with PBS twice by centrifugation at 1000 rpm for 5 min. Cells were resuspended in 400-600 μL of 1% BSA for flow cytometric analysis.
Cell culture experiments in MB arrays. Super NK cells were co-cultured with cancer cells in MB arrays at 37° C. for 24 hr. For co-culturing super NK cells and cancer cells in MB arrays, we followed the protocol described in detail previously. Briefly, small chips (1 cm×0.5 cm) containing arrays of MB were rinsed in 70% ethanol and distilled water and dried with nitrogen gas. The backside of the chips was rendered hydrophilic by etching them in a plasma chamber with atmospheric air for 10 min to keep the chips submerged in cell culture media. The chips were then blocked and subjected to negative pressure in a vacuum chamber to remove the air trapped inside the microbubbles during the curing process. NK cells were conjugated to TRAIL-functionalized liposomes as described in Section 2.4 and about 0.1×106 super NK cells were resuspended in 200 μL cell culture media composed of RPMI-1640 supplemented with 10% FBS and 1% PS. Approximately 100 μL of the cell stock solution was applied to top of the chip and incubated for 30 min at room temperature (25° C.) under sterile conditions. After incubation, the cell solution was removed and the chip was rinsed twice to remove any cells that may have deposited on the surface outside the spherical cavities. After seeding super NK cells, about 0.1×106 cancer cells (LNCaP, COLO205 and MDA-MB-231) in 200 μL of cell culture media was applied to the top of the chip and incubated for 10-15 min. The chips were rinsed twice and then placed inside a single well of a 24-well plate filled with 1 mL of cell culture media. The 24-well plate containing the MB chips was placed inside a humidified cell culture chamber maintained at 37° C. with 5% CO2.
The following control conditions were used in the cell culture experiments. Before seeding MB arrays with cancer cells, MB arrays were incubated with liposome buffer, naked liposomes (liposome without TRAIL), TRAIL-functionalized liposomes, unmodified NK cells.
In situ detection of apoptotic cancer cells. To determine the therapeutic efficacy of the proposed approach, cells cultured in MB arrays were stained in situ using an apoptosis detection kit (Trevigen®, 4840-01-K). The kit is based on Annexin V-FITC to label early apoptotic cells and propidium iodide (PI) to label late apoptotic/necrotic cells. Incubation reagent was prepared using a protocol provided by the manufacturer. The reagent was further diluted 1:10 times in 2% BSA. The MB chips were removed from 24-well plates and 100 μL of diluted reagent was applied on top of the MB chips. The chips were incubated for 30 min at room temperature in the dark. After incubation, the chips were washed gently 5-10 times by immersing them in a well containing PBS. The chips were then imaged using an Olympus IX81 microscope with appropriate filters for FITC and PI. Images were taken at 12 hr and 24 hr after culture to label apoptotic cancer cells.
Digital images from fluorescence microscopy were processed using ImageJ after normalizing for background intensity (NIH, USA). A region of interest was defined around each microbubble for analysis of Annexin V-FITC and PI staining. Areas were analyzed for the mean intensity and the values are reported as bar graphs for a quantitative measure of apoptotic cancer cells in MB arrays. The mean pixel intensity between different treatment groups was compared for statistical significance using unpaired student t-test.
Confocal microscopy. NK cells were labelled with CellTracker green (Molecular Probes®, C7025) and LNCaP cells were labelled with CellTracker red (Molecular Probes®, C34552) and seeded on MB arrays following the protocol mentioned in Section 2.6. The chips were then transferred into a glass bottomed 24-well plate and imaged using a Zeiss 710 laser scanning confocal microscope.
Results
Microbubbles geometry closely recapitulates the anatomy of deep cortical unit of a lymph node. In this work we were interested in developing a unique application of MB arrays as a model for mimicking lymph node micrometastases. Their semi-rounded geometry with a single circular opening on the top closely resembles the semi-rounded anatomy of a deep cortical unit of a lymph node centered on the top of an afferent lymphatic. PDMS is a commonly used polymer for cell culture applications. Apart from mimicking the deep cortical unit of a lymph node in terms of anatomy, PDMS provides a realistic mechanical loading to cells. The elastic modulus of PDMS is 50-200 kPa, which is very close to the modulus of several soft tissues including lymph nodes. The top view and side view of MB formed from 100 μm circular openings are shown in
Characterization of TRAIL and anti-CD57 functionalized liposome. Successful functionalization of TRAIL and anti-CD57 on the liposome surface is mediated by maleimide-thiol conjugation as indicated in
Anti-CD57 on the liposome surface mediates conjugation of liposome to NK cells. Conjugation of TRAIL-functionalized liposomes to NK cells is mediated by CD57 expressed on the surface of NK cells and anti-CD57 functionalized on the liposome surface (
Cancer cell lines cultured in microbubbles form small micrometastasis-like spheroids. Micrometastases are small aggregates of cancer cells less than 2 mm in diameter and they can remain dormant for many years before forming overt metastases. Microfabrication has led to the development of 3D cell culture systems which have taken cancer cell lines a step closer to in vivo tumors. A model for micrometastasis should be able to recapitulate the in vivo microenvironment. Microenvironment plays an important role in driving cells in micrometastasis progressively towards becoming an established metastatic lesion ultimately leading to secondary metastases5. We have shown that MB arrays can concentrate soluble factors secreted by cells to create a microenvironmental niche for cells cultured in them47. Cancer cells seeded in MB arrays form micrometastasis-like aggregates 24 hr after culture (
Cancer cells progressively become apoptotic when cultured with super NK cells in MB. To determine the effectiveness of super NK cells in targeting cancer cells, super NK cells were seeded prior to seeding cancer cells first in MB arrays. Confocal micrographs of LNCaP cells labelled with CellTracker red and super NK cells labelled with CellTracker green cultured in a single MB are shown in
Identification of disseminated tumor cells (DTCs) in lymph nodes has served as a prognosticator of poor survival in several types of cancers. The results from several clinical studies suggest that DTCs can remain inactive for several years before a patient is diagnosed with overt metastasis. This has led to the development of several targeted therapies to target micrometastases within a relatively short span of time. However, to date, an adaptive immune therapy based approach to amplify the therapeutic potential of endogenous NK cells has not been proposed. In this work we used microbubble arrays formed on PDMS as an in vitro model for mimicking lymph node micrometastases. We showed that lymph node-seeking cancer cells cultured with NK cells conjugated to TRAIL-functionalized liposomes in MB arrays begin to undergo apoptosis after 24 hr in culture. Our data indicates the usefulness of the present method for targeted therapies for cancer cells metastasizing to lymph nodes.
Example 3This example provides another illustration of this disclosure where the intermediate cells are CD34+ hematopoietic stem and progenitor cells (HSPCs). The nanoparticles can be coated with (i.e., functionalized) anti-CD34 antibody and TRAIL. A composition comprising such nanoparticles can be administered as described herein. In the circulation, the liposomes will quickly attach to the surface of CD34+ HSPC, causing the HSPC to be coated with the therapeutic protein TRAIL. The TRAIL-coated HSPC will then “home” back to the bone marrow through the natural stem cell homing process. This phenomenon is well known and forms the basis for bone marrow transplant, in which HSPC are introduced intravenously to a bone marrow recipient, and then the HSPC find their way back to the bone marrow and engraft there. It may be advantageous to repeat with one additional liposome dose 24 hours after the first dose, as the stem cell homing process is gradual and is promoted by the reestablishment of the natural GCSF chemotactic gradient into the marrow (after exogenous GCSF is cleared from the system). Once in the bone marrow microenvironment, TRAIL-coated HSPC will come into close contact with dormant tumor cells residing in the bone marrow, and will induce apoptosis, programmed cell death, in the tumor cells. It is expected that the effects of the TRAIL protein will be transient: sufficient to induce apoptosis in bone-marrow-residing dormant tumor cells, but without any lasting effects on erythropoiesis.
To mobilize the HSPCs, the patient may be treated for several (such as up to 5, from 5-10 or more) days with granulocyte colony stimulating factor (GCSF), which is known to “mobilize” the HSPCs from the bone marrow into the peripheral circulation. GCSF is a natural peptide and a clinically approved drug, which is used to mobilize HSPC to the peripheral circulation. When the HSPCs are in the peripheral circulation, they can be harvested for directed functionalization, or the individual can be administered the nanoparticle composition.
The therapeutic molecule placed on the liposomes which becomes attached to the surface of HSPC does not have to be TRAIL, and can be any type of molecule that causes cancer cell death via surface contact interactions. The therapeutic molecule need not be attached to the HSPC via nanoscale liposomes functionalized with antibody, and could be attached via some other type of nano particle, or even a composite molecule with a therapeutic domain conjugated to an adhesion/attachment end. A feature of this embodiment is the sequential process of: (1) causing HSPC to leave the BM and enter into the peripheral circulation, (2) attachment of therapeutic molecule carrying nanoparticles to the HSPC surface while the HSPC are in the peripheral circulation, and (3) exploiting the natural tendency of HSPC to home back to the bone marrow, to carry the therapeutic molecule to the bone marrow and neutralize (dormant) tumor cells that are residing in the bone marrow.
Although the present invention has been described for the purpose of illustration, it is understood that such detail is solely for that purpose and variations can be made by those skilled in the art without departing from the spirit and scope of the invention which is defined by the following claims.
Claims
1. A method of killing metastatic cancer cells comprising:
- a) providing nanoparticles which are functionalized with selectin and therapeutic molecules selected from the group consisting of tumor necrosis factor-related apoptosis inducing ligand (TRAIL) and Fas ligand, wherein the selectin on the nanoparticles binds to selectin binding ligands on leukocytes in circulation, and wherein TRAIL interacts with DR4 and DR5 receptors, and Fas ligand interacts with Fas on cancer cells causing apoptosis of the cancer cells; and
- b) introducing the nanoparticles into the circulation of an individual in need of treatment thereby allowing the nanoparticles to bind to the leukocytes and the leukocytes to seek out cancer cells thereby causing the nanoparticles to interact with the cancer cells via the therapeutic molecules causing cell death of the cancer cells.
2. The method of claim 1, wherein the nanoparticles are liposomes.
3. The method of claim 2, wherein the liposomes are unilamellar liposomes, wherein majority of the liposomes have a size from 50 to 250 microns.
4. The method of claim 1, wherein the nanoparticles are introduced into the circulation of an individual by intravenous administration.
5. The method of claim 1, wherein the nanoparticles are introduced into the lymphatic circulation of the individual.
6. The method of claim 1, wherein the nanoparticles are introduced into the circulation of an individual prior to, after, or at the same time as surgical removal of a tumor.
7. The method of claim 1, comprising an additional step of administering an agent which enhances the killing effect of the therapeutic molecules on cancer cells.
8. A method of killing metastatic cancer cells that are residing in a lymph node comprising:
- a) providing nanoparticles which are functionalized with selectin and therapeutic molecules selected from the group consisting of tumor necrosis factor-related apoptosis inducing ligand (TRAIL) and Fas ligand, wherein the selectin on the nanoparticles binds selectin binding ligand on leukocytes in circulation, and wherein the TRAIL interacts with DR4 and DR5 receptors, and Fas ligand interacts with Fas on cancer cells causing apoptosis of the cancer cells; and
- b) introducing the nanoparticles into the lymph circulation near the lymph node of an individual thereby allowing the nanoparticles to bind to the leukocytes and the leukocytes to seek out cancer cells thereby causing the nanoparticles to interact with the cancer cells residing in the lymph node and causing cell death of the cancer cells in the lymph node.
9. The method of claim 8, wherein the nanoparticles are liposomes.
10. The method of claim 9, wherein the liposomes are unilamellar liposomes, wherein majority of the liposomes have a size from 50 to 250 microns.
11. The method of claim 8, wherein the nanoparticles are introduced into the lymph circulation of the individual prior to, after, or at the same time as surgical removal of a tumor.
12. The method of claim 8, comprising an additional step of administering an agent which enhances the killing effect of the therapeutic molecules on cancer cells.
Type: Application
Filed: Aug 23, 2019
Publication Date: Jan 9, 2020
Inventors: Michael R. King (Ithaca, NY), Michael J. Mitchell (Ithaca, NY), Kuldeepsinh Rana (Lakewood, CO), Elizabeth C. Wayne (Ithaca, NY), Chris B. Schaffer (Ithaca, NY), Siddarth Chandrasekaran (Ithaca, NY)
Application Number: 16/549,549
