Balkrishna Jahagirdar

This study demonstrates that a CD34(-), vascular endothelial cadherin(-) (VE-cadherin(-)), AC133(+), and fetal liver kinase(+) (Flk1(+)) multipotent adult progenitor cell (MAPC) that copurifies with mesenchymal stem cells from postnatal human bone marrow (BM) is a progenitor for angioblasts. In vitro, MAPCs cultured with VEGF differentiate into CD34(+), VE-cadherin(+), Flk1(+) cells - a phenotype that would be expected for angioblasts. They subsequently differentiate into cells that express endothelial markers, function in vitro as mature endothelial cells, and contribute to neoangiogenesis in vivo during tumor angiogenesis and wound healing. This in vitro model of preangioblast-to-endothelium differentiation should prove very useful in studying commitment to the angioblast and beyond. In vivo, MAPCs can differentiate in response to local cues into endothelial cells that contribute to neoangiogenesis in tumors. Because MAPCs can be expanded in culture without obvious senescence for more than 80 population doublings, they may be an important source of endothelial cells for cellular pro- or anti-angiogenic therapies.

MethodsMAPC cultures.BM was obtained from 55 healthy volunteer donors (2-45 years of age) after obtaining informed consent per the guidelines of the University of Minnesota Committee on the Use of Human Subjects in Research.MAPCs were generated as previously described (3).Briefly, BM mononuclear cells were depleted of CD45 + and glycophorin A + cells using micromagnetic beads (Miltenyi Biotec, Sunnyvale, California, USA).Cells (5 10 3 ) that were negative for CD45 and glycophorin A were diluted in 200 l expansion medium consisting of 58% low-glucose DMEM (Invitrogen Corp., Grand Island, New York, USA) and 40% MCDB-201 (Sigma Chemical Co., St. Louis, Missouri, USA), supplemented with 1 insulin-transferrinselenium, 1 linoleic acid-BSA, 10 -8 M dexamethasone, 10 -4 M ascorbic acid 2-phosphate (all from Sigma Chemical Co.), 100 U penicillin, and 1,000 U streptomycin (Invitrogen Corp.); along with 0-10% FCS (HyClone Laboratories, Logan, Utah, USA), 10 ng/ml EGF (Sigma Chemical Co.), and 10 ng/ml PDGF-BB

This study demonstrates that a CD34(-), vascular endothelial cadherin(-) (VE-cadherin(-)), AC133(+), and fetal liver kinase(+) (Flk1(+)) multipotent adult progenitor cell (MAPC) that copurifies with mesenchymal stem cells from postnatal human bone marrow (BM) is a progenitor for angioblasts. In vitro, MAPCs cultured with VEGF differentiate into CD34(+), VE-cadherin(+), Flk1(+) cells - a phenotype that would be expected for angioblasts. They subsequently differentiate into cells that express endothelial markers, function in vitro as mature endothelial cells, and contribute to neoangiogenesis in vivo during tumor angiogenesis and wound healing. This in vitro model of preangioblast-to-endothelium differentiation should prove very useful in studying commitment to the angioblast and beyond. In vivo, MAPCs can differentiate in response to local cues into endothelial cells that contribute to neoangiogenesis in tumors. Because MAPCs can be expanded in culture without obvious senescence for more than 80 population doublings, they may be an important source of endothelial cells for cellular pro- or anti-angiogenic therapies.