Abstract: The invention provides a method for both the positive and negative selection of at least one mammalian cell population from a mixture of cell populations utilizing a magnetically stabilized fluidized bed. One desirable application of this method is the separation and purification of hematopoietic cells. Target cell populations include human stem cells.

Abstract: Human hematopoietic stem cells are provided by separation of the stem cells from dedicated cells. The stem cells may than be maintained by regeneration in an appropriate growth medium. Means are provided for assaying for the stem cells as to their capability for producing members of each of the hematopoietic lineages.

Abstract: Boron compound complexing reagents, boron compound complexes, and methods of synthesizing these reagents and complexes are disclosed. These reagents and complexes include those shown in General Formula III, General Formula IV, and General Formula VI. In one embodiment, the reagents of General Formula III may be used to produce, after condensation with a bioactive species (BAS), the reagent of General Formula IV. The reagent of General Formula IV may be used to form a complex with a boron compound, such as a complex shown in General Formula VI.

Abstract: The present invention provides methods and bioreactors for expanding stem cells in a population of cells substantially enriched in hematopoietic stem cells and substantially free of stromal cells. The method comprising the steps of inoculating the population of cells in an expansion container in a volume of suitable medium such that the cell density is at least about 5,000 cells/1 mL and at an initial oxygen concentration of less than 8%; adding an effective amount of at least one cytokine to cause stem cell expansion; culturing the cells under suitable conditions such that the cells condition the medium; increasing the oxygen concentration to about 20%; exchanging the medium at a rate which allows expansion of the stem cells; and culturing the cells under conditions such that the stem cells are expanded. The present invention also provides a bioreactor constructed to accomodate the operational requirements for stroma-free stem cell expansion.

Abstract: Human hematopoietic stem cells are provided by separation of the stem cells from dedicated cells. The stem cells may than be maintained by regeneration in an appropriate growth medium. Means are provided for assaying for the stem cells as to their capability for producing members of each of the hematopoietic lineages.

Abstract: The present invention provides a simple and reliable means for isolating populations of hematopoietic cells enriched for stem cell activity on the basis of possession of high CD34 cell surface antigen density ("CD34hi"). CD34.sup.hi cell preparations are useful, for example, for drug discovery efforts, for reconstituting hematopoiesis in an animal lacking a functioning hematopoietic system, and for gene therapies.

Abstract: A method for obtaining human hematopoietic stem cells is provided by enrichment for stem cells using a novel stem cell marker. Compositions enriched for stem cells are obtained using novel antibody HCC-1 which is specific for a CD59 epitope highly accessible on stem cells, and less accessible or absent on mature cells. The enriched population of cells derived from these methods are also provided.

Abstract: A fluorescence spectral overlap electronic compensation circuit for high speed flow cytometry systems is provided. In high-speed flow cytometry systems, such as systems with a pulse rise time up to 2 .mu.s, baseline restoration circuits may not adequately eliminate the DC offset of input signals, in which case, DC offset will result in errors after overlap compensation. In addition, analog spectral overlap compensation operations may result in signal distortions that are unacceptable when using a log amp whose output signal depends on the absolute value of its input signal. The disclosed fluorescence spectral overlap compensation circuit includes an adjustable DC offset compensation circuit to more accurately reduce the DC offset components of signals, and a half-wave rectifier for eliminating the signal distortions caused by spectral overlap compensation operations.

Abstract: The invention relates to methods of obtaining compositions enriched in hematopoietic stem cells by separating out an enriched fraction of cells expressing the marker CDw109. Methods of obtaining compositions enriched in hematopoietic megakaryocyte progenitor cells are also provided. Compositions enriched for stem cells and populations of cells obtained therefrom are also provided by the invention. Methods of use of the cells are also included.

Abstract: Methods and DNA cloning vectors are provided for obtaining genes encoding secreted proteins and cell surface proteins.

Abstract: A class of sulforhodamine labeling reagents capable of binding with a biomolecular species to produce a conjugate with fluorescent properties. The sulforhodamine labeling reagents have the structure: ##STR1## The group X is selected from an alkyl, an olefin, a monocyclic aliphatic saturated hydrocarbon, an aryl, or nothing at all. The group Y is selected from an amide, a substituted amide, or nothing at all. The group Z is selected from a monocyclic aliphatic hydrocarbon, an aryl, or an alkyl, as defined with respect to group X, a polyethylene glycol chain of the general form (CH.sub.2 CH.sub.2 O).sub.n, or nothing at all. The alkyl or polyethylene glycol chain may further have inert intermediate amide, ether, or disulfide functionalities. The group X, group Y, and group Z cannot all be nothing at all or non-existent. The group R is an electrophilic moiety suitable for conjugation of the fluorescent labeling reagent with a biomolecular species. Also disclosed is a method of making the reagents.

Abstract: The invention provides methods for screening agents for potential anti-viral effects by assessing the ability of the agents to suppress viral replication and/or pathology in thymic cells grown in thymic organ culture in vitro. Also provided are methods to study viral pathology and infectivity.

Abstract: A method for initiating metastasis of human tumor cells under experimental conditions is provided. Immunocompromised non-human mammals having a viable, xenogeneic organ or tissue are used as a host for human tumor cells. The cells are introduced into the chimeric animal after the solid tissue is implanted and are then able to grow and metastasize as they would in situ. Therapeutic regimens may be evaluated in this system to determine efficacy against metastatic processes.

Abstract: Human hematopoietic stem cells are identified according to expression of specific cell surface markers. Substantially homogenous stem cell compositions are obtained by selective isolation of cells free of markers associated with differentiated cells, while displaying epitopic characteristics associated with the stem cells. The stem cells may then be maintained by regeneration in an appropriate growth medium. Means are provided for assaying for the stem cells as to their capability for producing members of each of the hematopoietic lineages.

Abstract: An apparatus and process for measuring particles that prevents the particles from being contaminated during the measuring and optional sorting process wherein a flow chamber or region is mechanically isolated from a sterile enclosure which surrounds the flow chamber. The present invention in one embodiment provides an apparatus comprising of a droplet generator, a charging system, a deflecting system, a sterilization system, a light source, a detector, a cooling system and a vacuum system. The droplet generator and the charging system and the flow chamber associated with the droplet generator operate within an illumination frame where the particles (e.g. biological cells) are actually measured.

Abstract: Chimeric immunocompromised hosts are provided, comprising human bone marrow of at least 4 weeks from the time of implantation. The bone marrow is found to assume the normal population of bone marrow except for erythrocytes. The bone marrow may be used to study the effect of various agents on the proliferation and differentiation of hematopoietic cells.

Abstract: A human hematopoietic system is provided in an immunocompromised mammalian host, where the hematopoietic system is functional for extended periods of time. Particularly, human fetal liver tissue and human fetal thymus is introduced into an appropriate site of a young immunocompromised mouse at a site supplied with a vascular system, whereby the fetal tissue results in novel formation of functional human bone marrow tissue.

Abstract: A method is provided for screening compounds for the ability to supress thymocyte depletion in thymuses of HIV-infected individuals, particularly enhancing the CD4.sup.+ -expressing population as compared to an untreated individual. Particularly, drugs are provided which allow for this result, cyclosporine A being exemplary.

Abstract: The invention provides methods for screening agents for potential anti-viral effects by assessing the ability of the agents to suppress viral replication and/or pathology in thymic cells grown in thymic organ culture in vitro. Also provided are methods to study viral pathology and infectivity.

Abstract: Primordial tissue is introduced into immunodeficient hosts, where the primordial tissue develops and differentiates. The chimeric host allows for investigation of the processes and development of the xenogeneic tissue, testing for the effects of various agents on the growth and differentiation of the tissue, as well as identification of agents involved with the growth and differentiation.