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WO1996000778A1 - Cellules endotheliales de moelle osseuse humaine - Google Patents

Cellules endotheliales de moelle osseuse humaine Download PDF

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Publication number
WO1996000778A1
WO1996000778A1 PCT/US1995/007989 US9507989W WO9600778A1 WO 1996000778 A1 WO1996000778 A1 WO 1996000778A1 US 9507989 W US9507989 W US 9507989W WO 9600778 A1 WO9600778 A1 WO 9600778A1
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bone marrow
cells
endothelial cells
marrow endothelial
isolated
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PCT/US1995/007989
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English (en)
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Adam S. Asch
Shahin Rafii
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Cornell Research Foundation, Inc.
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Publication of WO1996000778A1 publication Critical patent/WO1996000778A1/fr

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    • C—CHEMISTRY; METALLURGY
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    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N5/00—Undifferentiated human, animal or plant cells, e.g. cell lines; Tissues; Cultivation or maintenance thereof; Culture media therefor
    • C12N5/06—Animal cells or tissues; Human cells or tissues
    • C12N5/0602—Vertebrate cells
    • C12N5/0652—Cells of skeletal and connective tissues; Mesenchyme
    • C12N5/0669—Bone marrow stromal cells; Whole bone marrow
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N5/00—Undifferentiated human, animal or plant cells, e.g. cell lines; Tissues; Cultivation or maintenance thereof; Culture media therefor
    • C12N5/06—Animal cells or tissues; Human cells or tissues
    • C12N5/0602—Vertebrate cells
    • C12N5/0634—Cells from the blood or the immune system
    • C12N5/0644—Platelets; Megakaryocytes
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
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    • C12N5/00—Undifferentiated human, animal or plant cells, e.g. cell lines; Tissues; Cultivation or maintenance thereof; Culture media therefor
    • C12N5/06—Animal cells or tissues; Human cells or tissues
    • C12N5/0602—Vertebrate cells
    • C12N5/0634—Cells from the blood or the immune system
    • C12N5/0647—Haematopoietic stem cells; Uncommitted or multipotent progenitors
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N5/00—Undifferentiated human, animal or plant cells, e.g. cell lines; Tissues; Cultivation or maintenance thereof; Culture media therefor
    • C12N5/06—Animal cells or tissues; Human cells or tissues
    • C12N5/0602—Vertebrate cells
    • C12N5/069—Vascular Endothelial cells
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N2502/00—Coculture with; Conditioned medium produced by
    • C12N2502/28—Vascular endothelial cells
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N2509/00—Methods for the dissociation of cells, e.g. specific use of enzymes

Definitions

  • the present invention relates to human bone marrow endothelial cells.
  • the bone marrow microenvironment is a complex, three dimensional structure where hematopoietic elements proliferate, differentiate, mature, and ultimately migrate into the circulation as mature erythrocytes, lymphocytes, granulocytes, monocytes, and platelets.
  • Stromal cells which form the backbone of the bone marrow microenvironment, consist of fibroblasts, endothelial cells, adipocytes, osteoclasts, and monocytes. They secrete cytokines, produce extracellular matrix, and mediate direct cellular contact which regulates hematopoiesis.
  • the fibroblasts of the bone marrow adventitia are composed of adventitial reticular cells ("ARC") (Aizawa, S., et al.
  • BMEC bone marrow derived microvascular endothelial cells
  • Tavassoli M. , et al . , "Homing Receptors for Hemopoietic Stem Cells are Lectins with Galacyosyl and Mannosys Specificities, " Trans. Assoc. Am. Phys. , 100:294 (1994); Tavassoli, M. , “Localization of Megakaryocytes in the Bone Marrow,” Blood Cells, 15:3 (1989) ; and Springer, T.A.
  • endothelial cell types particularly human umbilical endothelial cells (“HUVEC”).
  • HAVEC human umbilical endothelial cells
  • IL-l ⁇ interleukin-1 / ⁇
  • Tavassoli, M. et al., "Molecular Basis of Homing Intravenously Transplanted Cells to the Marrow," Blood, 76:1059 (1990) , which is hereby incorporated by reference.
  • the specific expression of unique adhesion molecules on the surface of bone marrow microvascular endothelium may regulate the trafficking of hematopoietic elements, particularly pluripotent stem cells in and out of the bone marrow microenvironment.
  • BMEC reside in close association with other cell types such as fibroblasts, adipocytes, mature megakaryocytes, plasma cells, and hematopoietic cells, and form an interface between the circulation and the hematopoietic compartment.
  • fibroblasts adipocytes, mature megakaryocytes, plasma cells, and hematopoietic cells
  • hematopoietic cells form an interface between the circulation and the hematopoietic compartment.
  • Aizawa, S., et al. "Molecular Basis of the Recognition of Intravenously Transplanted Hemopoietic Cells by Bone Marrow," Proc. Natl. Acad. Sci. USA, 85:3180 (1988) ; Tavassoli, M. , et al. , "Homing Receptors for Hemopoietic Stem Cells are Lectins with Galacyosyl and Mannosys
  • CD34+CD38- Progenitor Cells are More Primitive than CD34+ LFA1+
  • the present invention relates to isolated (i.e. separated from the bone marrow environment) bone marrow endothelial cells which can be characterized in a number of ways.
  • One characteristic of these cells is that they support the adhesion of megakaryocytes and bone marrow mononuclear cells.
  • These cells can also be characterized as a source of one or more cytokines supporting either progenitor cell proliferation, differentiation of pluripotent progenitor cells to megakaryocytes, or supporting platelet formation by megakaryocytes.
  • Another characteristic of the bone marrow endothelial cells is that they support proliferation of hematopoietic cells generally.
  • the present invention also relates to a process of isolating bone marrow endothelial cells from bone marrow.
  • bone marrow spicules are recovered from bone marrow and digested with one or more proteolytic enzymes.
  • Microvessel fragments are recovered from the digested bone marrow spicules, and these fragments are grown to form bone marrow endothelial cells.
  • Figure 1A is an immunofluorescence from an intact bone marrow spicule stained with monoclonal antibody to factor VIII/vWF demonstrating selective staining of endothelial cells and megakaryocytes (arrows) . Note the complex vascular network, crisscrossing the spicule. Large polyploid megakaryocytes can be seen in association with endothelial cells (100X) .
  • Figure IB is a photograph of partially collagenase
  • FIG. 1 is a phase contrast micrograph (lOOx) of a typical microvessel isolated from bone marrow aspirate.
  • FIG. 2B is an immunohistochemistry showing factor VIII/vWF staining of a microvessel using monoclonal anti-factor VIII/vWF antibody and immunoperoxidase detection (10OX) . Note the spindle shaped endothelial cell lining the microvessel. Red stain is peroxidase substrate, amino-ethyl carbazole.
  • Figure 2C shows colonies of BMEC emerging from attached microvessels after five days of incubation in ECGM (50X) .
  • Figure 2D shows monoclonal anti-CD34 (HPCA-1, BD) staining with immunoperoxidase detection of a typical microvessel, demonstrating the strong expression of this antigen throughout the microvessel. Red stain is alkaline phosphatase substrate, fast red (100X) .
  • Figure 3A is a phase contrast microscopy of a monolayer of BMEC grown from a microvessel explant and purified after Ulex selection. Note the spindle-like and cobblestone morphology of these endothelial cells (50X) .
  • Figure 3B is an epifluorescence of similar monolayer demonstrating that greater than 98% of cells show fluorescence, characteristic of acetylated-LDL uptake (50X) .
  • Figure 3C is an immunoperoxidase staining with monoclonal antibody to factor VIII/vWF of BMEC monolayers (50X) .
  • Figure 3D is an immunoperoxidase staining with monoclonal antibody to CD34 antigen (HPCA-1) . Only early passage cells express this antigen (12OX) .
  • Figure 3E is an immunoperoxidase stain with monoclonal antibody to PECAM, demonstrating the expression of this antigen specifically at cellular junctions (50X) .
  • Figure 3F is a negative control, immunoperoxidase stain with monoclonal mouse IgG. Red stain is peroxidase substrate amino-ethyl carbazole (5OX) .
  • Figure 4A is an electron microscopic analysis of a BMEC monolayer showing a typical endothelial cell with numerous mitochondria and Weibel-Palade bodies.
  • Figure 4B is a higher magnification of the same BMEC demonstrating the presence of cigar shaped Weibel palade bodies (arrows) which is characteristic of vascular endothelium.
  • Figure 5 shows CD34+ progenitor cell adhesion to BMEC.
  • Bone marrow derived CD34+ cells isolated by immunoadsorption technique, were incubated with BMEC monolayers at 37°C, in the presence or absence of blocking antibodies for one hour and adherent cells were quantified by phase contrast microscopy.
  • FIG. 6 shows CD34+ progenitor cell adhesion to IL-lS stimulated BMEC monolayers.
  • BMEC monolayers were incubated with IL-l/S (10 ng/ml) for 16 hours, then incubated with bone marrow derived CD34+ cells isolated by an avidin- biotin column for one hour in the presence of antibody to CD34 (HPCA-1 or 11.1), or 1 mM EDTA, and adherent cells were quantified by phase contrast microscopy.
  • Figures 7A and 7B show the proliferation of CD34+ progenitors on BMEC monolayers.
  • the capacity of BMEC to function as a feeder layer supporting the expansion of pluripotent stem cells was compared with human umbilical vein endothelial cells and with K36EG (media supplemented with kit-ligand, IL-3, IL-6, erythropoietin, and G-CSF) .
  • K36EG media supplemented with kit-ligand, IL-3, IL-6, erythropoietin, and G-CSF.
  • CFU were determined in 0.36% agarose supplemented with K36EG.
  • K36EG supported expansion to 35 days, HUVEC did to 49 days and BMEC to 56 days.
  • BMEC-derived cytokines support proliferation.
  • CD34+ progenitor cells incubated in wells separated from BMEC and CFU, were determined as described above.
  • Figures 8A and 8B show the characterization of proliferating cells in BMEC-CD34+ progenitor coculture experiment.
  • this is an immunoperoxidase stain with monoclonal antibody to GPIIb/IIIa ("10E5") of a typical cytospin sample obtained from an aliquot of day 21 proliferating peripheral CD34+ progenitor cells plated in the upper chamber of the transwell plate with BMEC monolayer grown as a stromal layer in the lower chamber, demonstrating the relative high frequency of GPIIb/IIIa positive cells.
  • Red stain is peroxidase substrate amino-ethyl carbazole.
  • Figure 8B shows an electron microscopic analysis demonstrating the presence of cells measuring 17 to 25 micron, with organelles resembling alpha granules ("AG”) , open calalicular system (“OC”) , demarcation membrane system (“DMS”) , glycogen stores (“GC”), unilobed nucleus (“N”), and other features and that are characteristic of early megakarocytes.
  • AG alpha granules
  • O open calalicular system
  • DMS demarcation membrane system
  • GC glycogen stores
  • N unilobed nucleus
  • Figure 9 shows the quantification of GPIIb/IIIa positive cells in BMEC-CD34+ progenitor coculture experiment.
  • the number of immunoperoxidase positive cells was quantified by counting 500 cells on each cytospin slide.
  • Figures 10A-C show lectin UEAl binding to platelets and megakaryocytes.
  • Figure 10A is a plot of cell count versus log fluorescent intensity, showing a flow cytometric analysis of Ulex-labeled platelets. Platelets were washed in Tyrodes buffer containing, ImM EDTA, and 2.8 X10" 6 M PGE1, and then incubated with FITC-labeled control antibody (mouse IgG) or lng/ml of FITC-labeled UEAl (Sigma, st. Louis, Mo.), for one hour at 4°C. Flow cytometric analysis was performed on a Coulter flow cytometer, EPICS Profile II.
  • FIG. 10B is a plot of flow cytometric analysis of Ulex-selected megakaryocytes: Megakaryocytes were isolated by incubation of plastic nonadherent whole bone marrow mononuclear cells with UEAl coated plastic dishes, for one hour at 4 C. The megakaryocytes were detached by competitive binding with L-fucose, or trituration, and were incubated with 10 ⁇ g/ml of monoclonal antibody to GPIIb/IIIa (10E5) for 30 minutes, washed thrice, and then incubated with FITC-labeled goat antimouse IgG for 30 minutes.
  • GPIIb/IIIa monoclonal antibody to GPIIb/IIIa
  • FIG. 10C is a plot of cell count v. DNA content, showing ploidy determination of Ulex selected megakaryocytes. Megakaryocytes were washed in HBSS and permeabilized with Triton X-100 (Sigma) containing RNase. After 30 minutes staining with 50 ⁇ g/ml of propidium iodide and monoclonal antibody to 10E5, the cells were analyzed with a EPICS profile II flow cytometer. Flow cytometry show that 38 ⁇ 4% cells were 2N, 32 ⁇ 6% were 4N, 9 ⁇ 3% were 8N, 8 ⁇ 2% were 16N. 32N, and 64N population comprised a very small population GPIIb/IIIa positive cells. The 2N control signal is derived from human peripheral blood lymphocytes.
  • Figures 11A-F show the role of BMEC in regulation of platelet formation.
  • Figure 11A-C shows a time course of megakaryocyte, BMEC coculture experiment. UEAl selected megakarocytes were incubated with resting BMEC in the presence of ATP medium at 37 C.
  • Figure 11A is a phase contrast photograph representing day 1 of coculture experiment where a single retractile megakaryocyte (arrow) is attached to BMEC. (75X) .
  • Figure 11B after 7 days in coculture the megakaryocyte (arrow) produces a single pseudopod (P) which extends along other endothelial cells (75X) .
  • FIG. 11C shows a single long pseudopod (P) is formed, which disintegrated into platelet-like particles (75X) .
  • Figure 11D shows BMEC conditioned medium induces platelet formation.
  • Figures HE and F show electron microscopic analysis of platelet-like particles.
  • an electron micrograph of platelet-like particles obtained from supernatant of coculture medium (ATP medium) each measuring between, 2 to 2.5 microns, demonstrates morphological features such as dense granules ("DG”) , mitochondria (“MT”) , glycogen stores (“GS”) , surface connected canalicular system (“SCCS”), and other features identical to normal human platelets.
  • DG dense granules
  • MT mitochondria
  • GS glycogen stores
  • SCCS surface connected canalicular system
  • Figures 12A-C show the flow cytometric analysis of platelet-like particles from coculture experiment.
  • the two panels represents the light scattering pattern of platelet-like particles derived from coculture medium, before and after stimulation with ionophore A23187 (lOng/ml) , demonstrating the change in scattering pattern of these particles upon activation with ionophore, consistent with shape and size change.
  • Figure 12B is a histogram demonstrating expression of GMP140 by ionophore activated platelet-like particles. Platelet-like particles were incubated for five minutes with ionophore A23187, and then incubated with a monoclonal antibody to GMP140 ("AMAC”) or control antibody for 30 minutes at 4 C.
  • AMAC monoclonal antibody to GMP140
  • Figure 12C is a flow cytometric analysis of the platelet-like particles obtained from BMEC conditioned medium.
  • platelet-like particles obtained from BMEC conditioned medium express GMP140 upon stimulation with ionophore.
  • the present invention is directed to isolated bone marrow endothelial cells which can be characterized in a number of different ways. These cells have ATCC Accession No. CRL11666, submitted June 20, 1994.
  • a cell line can be produced by transforming the bone marrow endothelial cells using conventional procedures.
  • B. Schwartz, et al . "Mammalian Cell Lines Can Be Efficiently Established In Vi tro Upon Expression of the SV40 Large T Antigen Driven By A Promoter Sequence Derived From the Human Vimentin Gene, " Biol. Cell, 73:7-14 (1991), which is hereby incorporated by reference.
  • the isolated bone marrow endothelial cells of the present invention support the adhesion of megakaryocytes and bone marrow mononuclear cells.
  • the bone marrow mononuclear cells can be CD34+progenitor cells, plasma cells, erythroid cells, and myeloid cells.
  • the megakaryocytes and CD34+progenitor cells bind to the isolated bone marrow endothelial cells of the present invention at a level of 20 to 30 times greater than the amount of megakaryocytes and CD34+progenitor cells in bone marrow in the presence of divalent cations.
  • Binding the CD34+progenitor cells to the isolated bone marrow endothelial cells is inhibited by CD34 antibodies and ethylenediaminetetraacetic acid. Binding of the CD34+progenitor cells to the isolated bone marrow endothelial cells is enhanced by treatment of these cells with interleukin-1 / S with such binding being divalent cation independent and not inhibited by ethylenediaminetetraacetic acid or CD34 antibodies.
  • the isolated bone marrow endothelial cells show selective adhesion of CD34+HLA-DR " CD38 " phenotype cells.
  • the isolated bone marrow endothelial cells can also be characterized as a source for one or more cytokines supporting progenitor cell proliferation.
  • the isolated bone marrow endothelial cells of the present invention have an enhanced ability to cause progenitor cell proliferation compared to bone marrow fibroblasts and human umbilical cord vein endothelial cells.
  • Such one or more cytokines support CD34+ pluripotent progenitor cell self-renewal.
  • the isolated bone marrow endothelial cells of the present invention are a source for one or more cytokines supporting differentiation of pluripotent progenitor cells to megakaryocytes.
  • pluripotent cells differentiate ultimately to form a number of different mature blood cells. When this occurs, such progenitor cells must be replenished to continue the production of new mature blood cells.
  • the isolated bone marrow endothelial cells produce one or more cytokines which support the renewal of such pluripotent cells.
  • the results obtained demonstrate that the normal depletion of stem cells as measured by the ability to form colonies in semi-solid agar assays is markedly delayed by post-culture supernatant from bone marrow endothelial cells.
  • No known combination of cytokines produces similar activity.
  • the present invention can also be characterized in terms of being a source of one or more cytokines supporting platelet formation by megakaryocytes.
  • the initial stage of megakaryocyte development involves sequential proliferation of CD34+pluripotent stem cells into megakaryocyte blast forming units ("BFU-MK”) , and colony forming units (“CFU- MK”) , which eventually mature into megakaryoblast (“MK- blast”) .
  • Cytokines such as interleukin-3 (“IL-3”) and granulocyte macrophage- colony stimulating factor (“GM-CSF”) are believed to regulate the proliferation of these early megakaryocytic precursors.
  • IL-3 interleukin-3
  • GM-CSF granulocyte macrophage- colony stimulating factor
  • MSF megakaryocytic maturation
  • CD34+progenitor cells to a megakaryocytic lineage has been hypothesized. Later megakaryocytic development is characterized by nuclear endoreplication of precursors with a recognizable megakaryocytic phenotype and the acquisition of additional phenotypic characteristics of mature megakaryocytes. As demonstrated infra in the examples, the isolated bone marrow endothelial cells of the present invention produce one or more cytokines which support the differentiation of pluripotent progenitor cells to megakaryocytes.
  • cytokines can support megakaryocyte differentiation from pluripotent stem cells (IL3, IL6, GM-CSF) , none alone or in combination result in the percentage of megakaryocytic lineage commitment observed with bone marrow endothelial cells or bone marrow endothelial cells post culture supernatant.
  • pluripotent stem cells IL3, IL6, GM-CSF
  • the close association of megakaryocytes and bone marrow endothelial cells has been noted and is responsible for the daily production of 2 x 10 11 platelets.
  • the platelets are formed within the megakaryocytes and then released into circulation through the bone marrow endothelial cells. This is achieved as a result of the megakaryocytes extending pseudopodia through the bone marrow endothelial walls which are cut off to release the platelets.
  • the isolated bone marrow endothelial cells produce one or more cytokines which support platelet formation from mature megakaryocytes.
  • cytokines can be obtained from a cDNA expression library prepared from poly(A) + RNA derived from early passage bone marrow endothelial cell monolayers. This is described in more detail in the examples.
  • the isolated bone marrow endothelial cells produce a number of known cytokines, including interleukin-3, interleukin-6, granulocyte-colony stimulating factor, kit ligand, and granulocyte macrophage colony stimulating factor. As demonstrated in the examples, these cytokines are elaborated by the bone marrow endothelial cells at the following levels: 32 + . 11 pg/ml for interleukin-3, 292 ⁇ 21 pg/ml for interleukin-6, 3000 ⁇ 478 pg/ml for kit ligand, 345 + . 32 pg/ml for granulocyte-colony stimulating factor, and 373 ⁇ 36 pg/ml for granulocyte macrophage colony stimulating factor.
  • these cytokines are elaborated by the bone marrow endothelial cells at the following levels: 32 + . 11 pg/ml for interleukin-3, 292 ⁇ 21 pg/m
  • the isolated bone marrow endothelial cells of the present invention are capable of supporting hematopoietic cells in much the same fashion as endothelial cells in bone marrow do. It is at the medullary marrow spaces where the endothelial cells line microvessels and sinusoids that post-embryonic hematopoiesis is localized. During this process, progenitor cells traffick to and from this site where they bind and begin proliferating and differentiating into various mature hematopoietic cells.
  • the present invention also relates to a process of isolating the bone marrow endothelial cells.
  • This process involves providing bone marrow, usually by an aspiration process, as described, for example, in M.M. Wintrobe, et al . , Clinical Hematology, pp. 59-61 (8th ed. 1981) , which is hereby incorporated by reference.
  • This aspirate must be a vigorously-obtained, deep bone marrow aspirate in order to obtain a high yield of spicules containing vessel fragments.
  • Such a product is obtained by vigorously repositioning the bone marrow needle during aspiration from deep within the bone marrow cavity.
  • Bone marrow spicules are then recovered from the bone marrow and digested with proteolytic enzymes. Microvessel fragments from the digested spicules are then recovered, and these fragments are grown as explants to form the bone marrow endothelial cells of the present invention.
  • Filters can be used in both the steps of recovering the bone marrow spicules from bone marrow and of recovering microvessel fragments from the digested spicules. In both cases, the desired material (i.e., the spicules or the microvessel fragments) are retained on the filter.
  • the spicules and the microvessel fragments can be recovered with a filter made from stainless steel or polypropylene which has a 40-200 micron mesh.
  • Suitable buffers include saline-type buffers with ethylenediaminetetraacetic acid ("EDTA”) added, such as Hanks Buffered Saline with EDTA.
  • EDTA ethylenediaminetetraacetic acid
  • Digestion of spicules with one or more proteolytic enzymes is carried out at about 30-40°C.
  • the proteolytic enzyme is used in a concentration of 0.05 to 0.5% and, preferably, is collagenase. Trpysin is another potentially useful proteolytic enzyme.
  • Microvessel fragments recovered from the digested spicules are grown as explants in endothelial cell growth medium. To do this, the microvessels are washed and then collected by gentle vortexing or trituration. The material collected is plated on fibronectin or gelatin coated plastic dishes. After 5-7 days of growth, a mixed population of BMEC and other adventitial cells are present.
  • bone marrow endothelial cells are grown from the microvessel fragments, these cells should be separated from contaminating fibroblasts and adipocytes.
  • One technique of achieving such separation involves binding the bone marrow endothelial cells to magnetic particles coated with a material to which these cells bind, and separating magnetically the magnetic particles with surface bound bone marrow endothelial cells from other materials.
  • the bone marrow endothelial cells have a number of important uses. As noted above, these cells are a source for one or more cytokines supporting progenitor cell proliferation, supporting differentiation of pluripotent progenitor cells to megakaryocytes, and supporting platelet formation by megakaryocytes.
  • the bone marrow endothelial cells of the present invention can be used to isolate and recover each of these cytokines for pharmaceutical uses.
  • the clinical utility of the cytokines described would be in support of hematopoiesis in patients with cancer or leukemia undergoing chemotherapy where such cytokine support would be expected to diminish the hematologic toxicity that often limits therapy and its effectiveness.
  • the cytokines described would be of use in the support of patients undergoing marrow transplantation by shortening the period of cytopenia pre-engraftment and diminishing the toxicity of this form of therapy.
  • the cytokines described would be of use for the ex vivo expansion of hematopoietic progenitor cells prior to transplantation.
  • bone marrow endothelial cells of the present invention is in a process of ex-vivo expansion of bone marrow.
  • many cancer patients are treated by having a small amount of their bone marrow removed and then undergoing chemotherapy.
  • the initial removal of bone marrow is needed to replace the bone marrow in the patient which is destroyed by chemotherapy.
  • the initially removed bone marrow is then transplanted back into the patient.
  • the transplanted amount of bone marrow is relatively small, it takes several weeks for the patient's body to regenerate his bone marrow to normal levels.
  • the isolated bone marrow endothelial cells of the present invention can be used to grow the removed bone marrow to permit greater amounts of it to be transplanted back into the patient.
  • extracted bone marrow is placed on a layer of bone marrow endothelial cells of the present invention and allowed to grow.
  • Such growth of the bone marrow cells is supported by the bone marrow endothelial cells in much the same manner as bone marrow cell growth is supported in vivo .
  • Bone marrow aspirates were obtained with a standard Jamshidi needle in preservative free heparin (50 units/ml) from posterior or anterior iliac crests of normal volunteer donors undergoing bone marrow harvest at Memorial Sloan-Kettering Cancer Center (MSKCC) .
  • MSKCC Memorial Sloan-Kettering Cancer Center
  • Each 3 ml of bone marrow aspirate obtained from a single bone marrow puncture resulted in removal of approximately 150 to 300 floating spicules with sizes ranging from 250 to 500. All steps of isolation were performed at room temperature. If the bone marrow aspirate was stored at 4°C, it was allowed to warm up to room temperature before processing to avoid solidification of fatty components which interfered with filtration steps.
  • bovine serum albumin BSA
  • the bone marrow aspirate consisting of floating fat laden spicules, was immediately diluted 1:1 in Hanks balanced salt solution (“HBSS”) with ImM EDTA (i.e., buffer A) , and passed through a 40 micron stainless steel filter to remove the loosely attached hematopoietic cells.
  • HBSS Hanks balanced salt solution
  • ImM EDTA i.e., buffer A
  • the retained stromal elements which consisted mostly of fat laden spicules, were washed with 50 ml of buffer A to remove loosely attached cells and plasma.
  • the filter was then placed in a 50 ml conical tube and the retained spicules were resuspended in 5 ml of buffer A, followed by the addition of 5 ml of 0.2% collagenase (final concentration of 0.1%) for 20 to 30 minutes at 37°C. Occasionally, a sample of the material undergoing collagenase digestion was removed and examined by phase contrast microscopy to assess the adequacy of digestion.
  • the digested material was passed gently through a 20 or 21 gauge needle, and then refiltered through another 40 micron filter to obtain microvessel fragments
  • the retained microvessels were washed with 30 ml of buffer A, and then collected by gentle vortexing or trituration of the filters in a 50 ml conical tube and plated on fibronectin or gelatin coated 12 or 6 well cluster plastic dishes. Centrifugation of the microvessels for two minutes at 150g accelerated their attachment to the plastic dish.
  • endothelial cell growth medium containing M199 medium (MA, Bioproducts) , heparin 90 ⁇ g/ml (Sigma, St. Louis), endothelial cell growth factor 20 ⁇ g/ml (Organon Teknika Corp.), L-glutamine 2mM (Sigma, St. Louis), penicillin (80 units/ml) , and streptomycin (80 ⁇ g/ml) , a mixed population of endothelial cell colonies and other adventitial cells were present.
  • ECGM endothelial cell growth medium
  • endothelial cells originating from the microvessel explants were washed free of hematopoietic cells, but areas of fibroblast growth were occasionally noted.
  • selective metabolic labeling of endothelial cells with Dil-acetylated LDL was used to estimate the purity of endothelial cells within each well.
  • Endothelial cells were further purified from wells with smallest amount of fibroblast contamination (endothelial cell to fibroblast ratio: greater than 1:1) by positive selection using Ulex europaeus 1 ("UEAl”) .
  • UEAl lectin Sigma was covalently bound to Tosyl activated DYNABEADS ⁇ S M- 450 (Dynal, Great Neck, NY) , by the method of Sternberg, E.P., "Mechanisms of Platelet Production," Blood Cells, 15:23-47 (1989) and Radely, J.M. , "Megakaryocyte Maturation in Long-term Culture,” Exp. Hematol. , 19:1075 (1991), which are hereby incorporated by reference.
  • the mixed population of cells was treated with 1 mM EDTA, and 0.05% collagenase, washed twice in HBSS, and then resuspended in HBSS + 5% FCS at a cell density of 5 x 10 5 cells/ml.
  • the cells were incubated for 10 minutes at room temperature with Ulex coated beads (50 beads/endothelial cell) .
  • Ulex coated beads 50 beads/endothelial cell
  • the BMEC bound to UEAl-coated beads were washed five times by resuspending them in 10 ml of HBSS + 5% FCS and mixing by end-over-end rotation for one minute, followed by separation using a magnetic particle concentrator ("MPC") (Dynal, Great Neck, NY) .
  • MPC magnetic particle concentrator
  • the contaminating cells in the washes were plated for further identification.
  • the endothelial cells were detached from the UEAl beads by incubation in HBSS + 5% FCS containing 0.01M fucose (L-isomer) (Sigma) for 10 minutes at 4°C and the beads were removed with MPC.
  • the pure BMEC collected in each wash were pooled, centrifuged, resuspended in ECGM and plated on gelatin coated tissue culture dishes. BMEC monolayers isolated in this fashion can be passaged for 8-10 times.
  • Early passage cells (Aizawa, S., et al. , "Molecular Basis of the Recognition of Intravenously Transplanted Hemopoietic Cells by Bone Marrow," Proc. Natl. Acad. Sci . USA, 85:3180 (1988) ;
  • Tavassoli, M. , et al. "Homing Receptors for Hemopoietic Stem Cells are Lectins with Galacyosyl and Mannosys Specificities," Trans. Assoc. Am. Phys., 100:294 (1994) ; Tavassoli, M. , “Localization of Megakaryocytes in the Bone Marrow,” Blood Cells, 15:3 (1989) and Springer, T.A., "Adhesion Receptors of the Immune System," Nature, 346:425 (1990) , which are hereby incorporated by reference) were used for experiments described below.
  • the flow through from the digested material can be washed and then treated with Ulex coated DYNABEADS' 5 to remove endothelial cells, or, alternatively, digested material can be plated on gelatin coated plastic dishes. This allows for the attachment of endothelial cells and removal of nonadherent hematopoietic cells.
  • contaminating cells can be weeded out or Ulex coated DYNABEADS'" can be used to isolate endothelial cells from contaminating stromal cells which are predominantly adventitial fibroblasts, adipocytes, and attached megakaryocytes, and monocytes.
  • fibroblasts reside in close association with the subluminal surface of microvessels, contamination with fibroblasts is the major impediment to the isolation of pure endothelial cell monolayers.
  • the degree of fibroblast contamination varies for each isolation, and depends on the size of microvessels, the extent of collagenase digestion, and success of UEAl affinity separation. Bulky, branched microvessels do not attach to gelatin or fibronectin coated plastic dishes, as easily as small, fragmented microvessels. Monitoring of spicules during collagenase digestion ensures optimal digestion of microvessels.
  • the ratio of endothelial cells to fibroblasts (optimal ratio of BMEC to fibroblasts of greater than 1:1) is critical for successful Ulex selection. Sternberg, E.P., "Mechanisms of Platelet
  • fibroblasts attach to plastic dishes far more avidly than endothelial cells, are insensitive to brief EDTA (0.5mM) treatment, and require longer collagenase digestion (greater than five minutes with 0.1% collagenase) to detach from plastic dishes.
  • endothelial cell colonies grown from microvessel explants can selectively be detached from monolayers containing contaminating fibroblasts by incubation in 0.5 mM EDTA, and brief exposure (2-3 minutes) to 0.05% collagenase.
  • Bone marrow aspirates were obtained from normal subjects undergoing bone marrow harvest at MSKCC. Ten ml of bone marrow aspirate was drawn into syringes containing 50 units/ml of preservative free heparin, and passed through an 80 micron filter to remove stromal elements. The bone marrow was diluted with buffer A, layered over ficoll- hypaque (density 1.077) , and centrifuged at 400xg for 20 minutes, and the mononuclear cells at the interface were collected, washed in buffer A, and counted.
  • Plastic adherent cells were removed by incubating ficoll purified marrow cells (5 x 10 5 cells/ml) on costar plastic dishes at 37°C for 2 hours. The nonadherent cells were passed again through a 80 micron mesh to remove any cell clumps, and resuspended in IMDM medium (Sigma) , 20% fetal calf serum, and monothioglycerol (10 ng/ml) at a density of 5 x 10 5 cells/ml. For adhesion studies with BMEC, the cells were resuspended in HBSS supplemented with calcium (2mM) and magnesium (2mM) .
  • Low-density bone marrow mononuclear cells (less than 1.077 g/ml) were separated over Ficoll-Paque (Pharmacia; Upsala, Sweden) .
  • CD34+ cells were enriched using a commercially available cell separation system kit from Cell Pro, Inc. (Debili, N. , et al.
  • Monoclonal antibodies to factor VIII/vWF (Dako) , PECAM (Becton Dickinson), thrombospondin (11.4, Oncogene Science, Manhasset, NY) , ICAMl (IOL54, AMAC), VCAM (1G11, AMAC) , ⁇ -actin (Dako), BPIb (SZ2, AMAC), GPIIb/IIIa (10E5, a gift from Dr. B. Coller, Stony Brook Medical Center), LFA1 (I0T16, AMAC) , L-Selectin (Dreg-56, a gift from E.
  • Plastic nonadherent bone marrow mononuclear cells (5 x 10 5 cells/ml) were incubated with HUVEC (Bruno, B., et al . , "Further Examination of the Effects of Recombinant Cytokines on the Proliferation of Human Megakaryocyte Progenitor Cells," Blood, 77:2339 (1991) , which is hereby incorporated by reference) or BMEC monolayers in HBSS with calcium and magnesium in 6 well cluster plates at 37°C for one hour with gentle shaking.
  • the nonadherent cells were removed and adherent cells were characterized by light microscopy (Wright/Giemsa staining) and immunohistochemistry using monoclonal antibodies against CD34 (HPCA-1) , GPlb (SZ2) , and GPIIb/IIIa (10E5) .
  • GPlb or GPIIb/IIIa positive cells were counted in the entire two six well cluster plates and scored as megakaryocytes, and small round CD34+ but Factor VIII/vWF negative cells were scored as CD34+ progenitor cells. Erythroid and myeloid progenitors were identified morphologically by standard Wright/Giemsa staining.
  • CD34+ progenitor cells purified by avidin-biotin immunoadsorption column (Cell Pro) (Debili, N., et al. , "Expression of CD34 and Platelet Glycoproteins During Human Megakaryocytic Differentiation," Blood, 80:3022 (1992) , which is hereby incorporated by reference) , (10 ⁇ l of 10 6 cells/ml) , were added to washed resting or stimulated BMEC monolayers cultured on Terasaki (Nunc, Illinois) or 96 wells.
  • Cell Pro avidin-biotin immunoadsorption column
  • Adhesion assays were performed for 30 minutes at 37°C in HBSS supplemented with magnesium (2mM) and calcium (2mM) , and unbound cells were removed by three washes with HBSS/Ca/Mg. Adherent cells on endothelial surfaces were counted manually using an inverted phase-contrast microscope.
  • monoclonal antibodies (10 ⁇ g/ml) to CD34 (HPCA-1 BD, or 11.1 Oncogene Science) , VCAM (IGll) , LFAl (IOT16) were incubated with BMEC on ice for 20 minutes prior to the study.
  • CD34 inhibition assays the antibody to CD34 (10 ⁇ g/ml) was also added to the fluid phase during the adhesion study.
  • BMEC monolayers and microvessel explants were fixed in 3% formalin in PBS for 30 minutes then quenched with 0.1 M glycine in PBS pH 7.4 for 10 to 15 minutes with Histochoice (Amresco, Solon, Ohio), and blocked with 1.5% horse serum.
  • Monoclonal antibodies to Factor VIII/vWF, CD34 (HPCA-1) , PECAM, thrombospondin, ICAMl, VCAM, ⁇ -actin, GPlb, GPIIb/IIIa, or L-Selectin, at different dilutions were incubated with fixed cells, for one hour.
  • biotylinated anti-mouse or anti-rabbit immunoglobulin diluted 1:200 in PBS containing 1.5% horse serum was incubated with cells for 30 minutes at room temperature. Endogenous peroxidase was quenched with 0.3% hydrogen peroxide in PBS for 30 minutes. Endogenous alkaline phosphatase was quenched with levamisole 1.25 mM for 20 minutes. After 30 minutes of incubation with avidin labeled peroxidase or alkaline phosphatase, slides were rinsed and incubated with peroxidase substrate, amino-ethyl carbazole (red stain) , or alkaline phophatase substrate fast red (red stain) for 10-20 minutes. After a final rinse, the cells were counter-stained with 1% hematoxylin.
  • Dil-Ac-LDL acetylated low- density lipoprotein labeled with dioctadecyl 1,3,3,3,- tetramethyl-indocarbocyanine perchlorate
  • BMEC adherent and nonadherent CD34+ cells washed twice in PBS, resuspended in HBSS with 1% BSA, were incubated with saturating doses of monoclonal antibodies to CD34, CD38, HLA-DR, LFAl, for 30 minutes at 4°C. After washing, cells were stained with saturating amounts of FITC or rhodamine-conjugated goat anti-mouse IgG F(ab) 2 (Coulter) . Controls were isotype matched non-immune Ig's and FITC conjugated anti-mouse IgG F(ab) 2 (AMAC) . Cell associated immunofluorescence was assayed by quantitative flow cytometry using a Coulter Profile II.
  • Example 7 Electron Microscopy
  • BMEC monolayers were washed three times with HBSS containing Ca/Mg, then fixed in 2% paraformaldehyde, 0.5% gluteraldehyde, followed by 1% osmium tetroxide. After dehydration, the samples were embedded for electron microscopy. 60-70 nm (silver-grade) sections were cut using a diamond knife (Diatome, Ft. Washington Pa) on a Sorvall MT-5000 microtome (DuPont) . Sections were stained with 0.1% lead citrate and examined using a JEOL-100CXII electron microscope at an accelerating voltage of 80 KV.
  • BMEC were obtained from explants of microvessels and were characterized with respect to morphology, expression of factor VIII/vWF, thrombospondin, PECAM, CD34, and acetylated LDL uptake.
  • Figure 1A is a photomicrograph of an intact bone marrow spicule stained with FITC-labeled monoclonal antibody to factor VIII/vWF, demonstrating the relative frequency of endothelial cells in the bone marrow and their close association with other hematopoietic elements, particularly mature megakaryocytes.
  • Figure IB is a photomicrograph of a partially collagenase digested bone marrow spicule demonstrating the complex vascular network of a typical spicule with a central microvessel branching into single layered sinusoidal endothelial cells.
  • Figure 2A shows a typical microvessel fragment retained on a 40 micron mesh after 30 minutes of collagenase digestion. Immunohistochemical staining of these microvessel fragments with factor VIII/vWF monoclonal antibody ( Figure 2B) demonstrated the spindle shaped endothelial cells lining the microvessel, and relative absence of other adventitial elements such as fibroblasts, and adipocytes.
  • Figure 2C shows the proliferation of BMEC colonies from microvessel within an intact bone marrow spicule with monoclonal antibody to CD34.
  • CD34 was significantly expressed only by the monolayers in the first passage. The degree of CD34 expression was diminished and barely detectable by the second passage.
  • BMEC monolayers did not stain with monoclonal antibodies to GPlb, GPIIb/IIIa, ⁇ -actin, ICAM, L-Selectin or VCAM (data not shown) .
  • Electron microscopic analysis of BMEC monolayers demonstrates the presence of Weibel Palades bodies which is characteristic of vascular endothelium ( Figure 4) .
  • Bone marrow mononuclear cells obtained from normal donors were isolated on a Ficoll gradient and depleted of monocytes and other plastic adherent cells. The non-adherent hematopoietic cells were incubated with BMEC and HUVEC monolayers for 1 hour at 37°C in PBS supplemented with calcium (2mM) and magnesium (2mM) . Attached cells were characterized by light microscopy, Wright/Giemsa staining and immunohistochemistry using monoclonal antibodies against CD34 (HPCA-1) , GPlb (SZ2) , GPIIb/IIIa (10E5) .
  • GPlb or GPIIb/IIIa positive cells were counted in two six well cluster plates and scored as megakaryocytes, and small round CD34 positive but factor VIII/vWF negative cells were scored as CD34+ progenitor cells.
  • Erythroid, or myeloid progenitors or plasma cells were identified morphologically by standard Wright/Giemsa staining. Megakaryocytes and CD34+ progenitor cells adhered less well to HUVEC monolayers. The binding of plasma cells, mature myeloid precursors and ly ⁇ nphoid appearing cells comprised the remainder of the adherent cells .
  • megakaryocytes and CD34+ progenitor cells comprise only 0.05 to 1% of bone marrow mononuclear cells, they represent 22 ⁇ 4, and 15 ⁇ 2 percent of the cells adherent to BMEC resting monolayers respectively. This represents a twenty to thirty fold enrichment and suggests adhesion mechanisms specific to these cell types. Megakaryocytes and CD34+ progenitor cells adhered less well to HUVEC monolayers . The remainder of the adherent cells were comprised of plasma cells, mature myeloid precursors, and lymphoid-appearing cells (Table 1) .
  • bone marrow CD34+ progenitor cells isolated by an avidin-biotin column were incubated with BMEC monolayers at 37°C for one hour. Ten percent of the added CD34+ cells were adherent to resting BMEC monolayers . This adhesion was partially blocked by antibodies to CD34 (HPCA-1, 11.1) , and was blocked with EDTA (ImM) ; antibodies to VCAM, ICAM, or LFAl did not block binding (see Figure 5) .
  • the phenotype of the adherent CD34+ progenitor cells that were detached from endothelial cells by brief treatment (one minute) with 0.5 mM EDTA was examined by flow cytometry.
  • CD34+ progenitor cells Purified by biotin- avidin immunoadsorption column from bone marrow mononuclear cells, were incubated with resting BMEC monolayers at 37°C for one hour, and the adherent population of CD34+ cells were detached from BMEC monolayers by brief (1 minute) EDTA (0.5mM) treatment. The adherent and the nonadherent population of CD34+ cells were incubated with 10 ⁇ g/ml of FITC-labeled monoclonal antibodies to CD34 (HPCA-1) , HLA-DR, CD38, and LFAl and the percentage of positive cells were determined by flow cytometry. The values in the table represent the percent positive cells. As shown in this table, the adherent population of CD34+ progenitor cells are enriched for the more pluripotent phenotype CD34+HLA-DR-CD38 ' .
  • CSVTCG Thrombospondin Sequence Motif
  • BMEC is a unique type of endothelium that may regulate hematopoiesis by direct cellular contact and/or expression and secretion of specific cytokines.
  • BMEC are morphologically similar to other types of endothelial cells, such as HUVEC, bovine aortic, and brain microvascular endothelial cells. Although BMEC grow in a cobblestone manner, they are more spindle shaped. They stain positively for factor VIII/vWF, PECAM, CD34 (early passages) , and thrombospondin, but do not stain with antibodies to ⁇ -actin, GPIIb/IIIa, GPlb, L-selectin, VCAM or ICAM. BMEC monolayers express higher levels of PECAM at areas of cell-cell contact.
  • PECAM which is a 140-Kd glycoprotein, is also expressed on monocytes, neutrophils, megakaryocytes, and a subset of CD4 cells and may function as a transmigratory bridge permitting the exit of mature cells such as neutrophils, lymphocytes, and monocytes out of bone marrow.
  • CD34 antigen is a 110 kd glycosylated protein, which is expressed on pluripotent hematopoietic progenitor cells, as well as on other vascular endothelial cells such as HUVEC, capillaries of different tissues (Heidenriech, R. , et al. , "Organization of the Gene for Platelet Glycoprotein lib,” Biochemistry, 29:1232 (1990) and Gordon, M.Y. , et al .
  • GM-CSF Hematopoietic Growth Factor
  • neoplastic tissues such as angiosarcomas, Kaposi's sarcomas, and hepatic hemangioendotheliomas. Roberts, R. , et al.
  • Heparan Sulphate Bound Growth Factors A Mechanism for Stromal Cell Mediated Haemopoises, " Nature, 332:376 (1988) and Jaffe, E.A., "Culture of Human Endothelial Cells Derived from Umbilical Veins: Identification by Morphologic and Immunologic Criteria,” J. Clin. Invest. , 52:2745 (1973) , which are hereby incorporated by reference.
  • endothelium from large veins, arteries, placental and lymphatics are CD34 negative. Heidenriech, R. , et al .
  • CD34 may function as an adhesion molecule that mediates the transit of peripheral progenitor cells to the bone marrow.
  • Our immunohistochemical studies indicate that only first passage BMEC monolayers are positive for CD34 but do not express this glycoprotein with subsequent passages.
  • Adhesion studies demonstrate that CD34+ progenitor cells display affinity for resting BMEC (passages 2-4) monolayers that is divalent cation dependent and is partially inhibited by anti-CD34 antibody.
  • vascular CD34 has been identified as a counter receptor for leukocyte L-selectin (S. Baumhueter, et al. , "Binding of L Selectin to the Vascular Sialomucin CD34," Science 262:15 (1993), which is hereby incorporated by reference) , raising the possibility that a similar interaction might mediate progenitor cell adhesion to L-selectin expressed by endothelium.
  • the CD34+ cells that are adherent to BMEC monolayers are enriched for the CD34 + HLA-DR ⁇ CD38 ⁇ phenotype, which is reported to be a more pluripotent cell type within the CD34+ progenitor cell population.
  • Tayrien, G. , et al "Purification and Properties of a Megakaryocyte Stimulatory Factor Present in Both Serum Free Conditioned Medium of Human Embryonic Kidney Cells and in Thrombocytopenic Plasma," J. Biol . Chem. , 262:3263 (1987) ; Jackson, C.J., et al .
  • IL-l / ⁇ The role of inflammatory mediators such as IL-l / ⁇ in regulating hematopoiesis is incompletely understood.
  • IL- l / ⁇ is known to regulate adhesion mechanisms that govern the transit of inflammatory cells from the circulation by increasing the expression of ICAM and VCAM on the luminal surface of the endothelium, resulting in upregulation of monocyte and poly ⁇ norphonuclear cell adhesion.
  • Hynes, R.O. "Integrins: Versatility, Modulation, and Signaling in Cell Adhesion," Cell, 69:11 (1992) and Tavassoli, M. , et al .
  • Self renewing potential is characteristic of true stem cells and ex vivo expansion of CD34+ progenitors as measured by expansion assays are a measure of the proliferative potential of the cells as well as the in vi tro environment. Over time in culture, the capacity of a starting population of CD34+ progenitors to form CFU's diminishes as an inverse function of differentiation and correlates positively with self renewal of a pluripotent component.
  • BMEC support ex vivo CD34+ proliferation as well as do bone marrow- derived fibroblasts and better than HUVEC or medium along ( Figures 7A and 7B) .
  • cytokines produced by BMEC post culture supernatant of BMEC and HUVEC monolayers was examined for its content of IL-3 IL-6, SCF, G-CSF, and GM- CSF (Table 3) .
  • the addition of conditioned medium obtained from BMEC increased progenitor cell expansion in agarose assays beyond that obtained with K36EG, raising the possibility that a novel cytokine or cytokines may be responsible for these effects.
  • Control Medium HUVEC BMEC (pg/ml) (pg/ml) (pg/ml)
  • CD34+ progenitor cells can proliferate into megakaryocytes in the presence of optimal megakaryocytic growth conditions.
  • CD34+ progenitor cells were plated in the upper chamber of a 24-well transwell plate (Costar) separated from direct contact with either BMEC, or HUVEC, or bone marrow fibroblasts, grown as monolayers on the lower chamber of the transwell plates.
  • CD34+ progenitor cells were obtained by an avidin-biotin column from peripheral blood mononuclear cells (Cell Pro) .
  • Culture supernatants from COS-1 cells will be harvested 48 and 72 hours after transfection and assayed for an increase in activity in the culture systems described over that observed in the presence of kit-ligand (20ng/ml) , IL-3 (50ng/ml) , IL-1 (20ng/ml) , EPO (8u/ml) , GM-CSF (lOOng/ml) , and possibly IL-11 (20ng/ml) .
  • kit-ligand (20ng/ml)
  • IL-3 50ng/ml
  • IL-1 20ng/ml
  • EPO 8u/ml
  • GM-CSF GM-CSF
  • IL-11 possibly IL-11 (20ng/ml) .
  • Very recent data shows that IL-11 is expressed by IL 1-beta treated cells and not only by resting BMEC.
  • Hirt plasmid DNA preparation followed by additional transfection cycles will be performed further to subdivide positive pools and assayed to isolate a single
  • CD34+ progenitor cells 1000/well
  • an increase in CD34 and GPIIb/IIIa expression over time can be followed.
  • the culture conditions will be as previously described in our preliminary data except that kit-ligand, IL3, IL6, ILll, and GCSF will be present throughout to permit screening for only those pools that synergize with the known active cytokines elaborated by these cells.
  • the results of these microassays will be confirmed using flow cytometric analysis, immunohistochemistry, and electron microscopy as needed.
  • Rapid screening may also be facilitiated by a lib promotor-growth hormone construct.
  • a promotor-growth hormone construct Heidenriech, R.R. , et al. , "Organization of the Gene for Platelet Glycoprotein lib," Biochemistry, 29:1232 (1990), which is hereby incorporated by reference.
  • This construct will be used to transfect the starting CD34+ progenitor population and assay for GH in the microtiter wells by ELISA. In this fashion, a non-destructive assay on well supernatants can be performed and the cells can continue to be cultured over time.
  • the conditioned medium from the BMEC will be fractionated to isolate and purify the putative cytokine (s) to homogeneity.
  • assays will be performed in the presence of kit--ligand (20ng/ml) , IL-3 (50ng/ml) , IL-1 (20ng/ml), EPO (8u/ml) , GM-CSF (lOOng/ml) , and IL-11 (20ng/ml) so that novel rather than known BMEC-derived cytokines can be identified.
  • Antibodies will be raised to the purified active material; also, direct amino acid sequencing will be performed by the Harvard microchemistry facility.
  • a cDNA library derived from early passage BMEC will be screened with monospecific affinity purified antibody or with deduced oligonucleotides derived from direct amino acid sequence analysis. Strategies for these approaches are described briefly below.
  • the bone marrow matrix is a rich source of cytokines that are bound reversibly by specific glycosaminoglycans.
  • Gordon, M.Y., et al . "Compartmentalization of a Hematopoietic Growth Factor (GM- CSF) by Glycosaminoglycans in the Bone Marrow
  • heparin, fucoidin, chondroitin sulfate or heparin sulfate will allow us to identify specific polyanions that influence the activity of post culture supernatants and thus may be useful in establishing a separation method.
  • Both the eluate from heparin or other polyanion sepharose as well as the flow through will be added separately or in combination of Ulex-selected or GPIIb/IIIa selected megakaryocyte cultures, and the number of functional platelet-like particles produced will be quantified by flow cytometry.
  • the fraction(s) with the highest amount of Meg-CSF or CD34+-sustaining activity will be fractionated by size and affinity chromatography using anion (Mono-Q) and cation (Mono-S) exchange resins. Fractions from each procedure or combinations of fractions will be bioassayed as described above and in Methods leading ultimately to purification.
  • Post-culture supernatants will be separated into 0-20, 20-40, 40-60, and 60-100% fractions and dialyzed against phosphate buffered saline, pH 7.4. Active fractions will be further separated by anion exchange chromatography using Mono-Q and/or Mono-S FPLC and analyzed as described above. Antibodies to the purified material will be raised and affinity purified and a BMEC cDNA prokaryotic expression library will be screened in order to clone and sequence the molecule. Alternatively, amino acid sequencing may provide an opportunity to use an oligonucleotide probe to screen the BMEC library.
  • Example 11 Megakaryocyte maturation and platelet formation are mediated by BMEC derived humoral factors.
  • Ulex or GPIIb/IIIa selected megakaryocytes were cultured in the presence of BMEC conditioned medium. Exposure to BMEC conditioned medium but not control medium derived from bone marrow fibroblasts or HUVEC monolayers, resulted in enlargement of megakaryocytes and the formation of randon pseudopods or proplatelets which formed functional platelet-like particles identical to those produced by contact between BMEC and megakaryocytes ( Figure 11D) . These platelet-like structures also have light scattering identical to normal human platelets, baseline staining with GPIIb/IIIa, GPlb, and agonist induced GMP140 expression ( Figures 12C and D) .
  • cytokine (s) elaborated by BMEC are responsible for platelet production by megakaryocytes. Cell contact appears to guide the directional formation of the proplatelet along and between endothelial cells.

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Abstract

Cellules endothéliales de moelle osseuse humaine caractérisée par leur capacité à contribuer à l'adhésion de mégacaryocytes et de cellules mononucléaires de moelle osseuse, ainsi que par le fait qu'elles constituent une source pour une ou plusieurs cytokines soutenant la prolifération de cellules parentes, la différenciation de cellules parentes pluripotentes en mégacaryocytes ou la formation de plaquettes par des mégacaryocytes. On isole les cellules endothéliales de moelle osseuse de la présente invention en prélevant des spicules dans de la moelle osseuse, en faisant digérer les spicules de moelle osseuse par une ou plusieurs enzymes protéolytiques, en récupérant des fragments de microvaisseaux des spicules de moelle osseuse digérée et en mettant en culture lesdits fragments de microvaisseaux pour former des cellules endothéliales de moelle osseuse.
PCT/US1995/007989 1994-06-28 1995-06-26 Cellules endotheliales de moelle osseuse humaine WO1996000778A1 (fr)

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Non-Patent Citations (6)

* Cited by examiner, † Cited by third party
Title
BLOOD, Vol. 82, No. 10, issued 1994, RAFII et al., "Human Bone Marrow Microvascular Endothelial Cells Support Adhesion of Hematopoietic Progenitor Cells", page 22a, Abstract #76. *
BLOOD, Vol. 82, No. 10, issued 1994, SCHWEITZER et al., "Isolation of Human Bone Marrow Endothelial Cells", page 22a, Abstract #77. *
EXP. HEMATOL., Vol. 18, issued 1990, FEI et al., "A Method to Establish Pure Fibroblast and Endothelial Cell Colony Cultures from Murine Bone Marrow", pages 953-957. *
EXP. HEMATOL., Vol. 20, issued 1992, MASEK et al., "Isolation of Human Bone Marrow Sinusoidal Endothelial Cells - A Method Based on Density Gradient Centrifugation and Lectin Affinity", page 724, Abstract #74. *
J. CELLULAR BIOCHEMISTRY, S18A, issued 1994, SCHWEITZER, "Isolation and Immunophenotyping of Human Bone Marrow Endothelial Cells", page 334, Abstract # EZ415. *
SCANNING ELECTRON MICROSCOPY, Vol. 2, issued 1986, IRIE et al., "Structural Features of Isolated, Fractionated Bone Marrow Endothelium Compared to Sinus Endothelium in Situ", pages 615-619. *

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