Ahluwalia A, Jones M K, Brzozowska I, Tarnawski A S
Medical and Research Services, Veterans Affairs Medical Center, Long Beach, CA, USA.
Department of Medicine, University of California, Irvine, CA, USA.
J Physiol Pharmacol. 2017 Dec;68(6):841-846.
Regeneration of blood vessels (neovascularization) is critical for tissue injury healing. The contribution of bone marrow-derived endothelial progenitor cells (BMD-EPCs) to neovascularization during tissue injury healing is not fully elucidated and it is not clear whether BMD-EPCs can form new capillary blood vessels independently or jointly with fully differentiated endothelial cells (ECs). The aim of this study was to establish an in vitro model of vasculogenesis/angiogenesis by co-culture of BMD-EPCs and gastric endothelial cells (GECs) on Matrigel, examine direct interactions of these cells; and, identify the mechanisms involved. We isolated BMD-EPCs and GECs from bone marrow and stomach of rats, respectively. In these cells, we examined the expression of CD34, CD133, CD31, VEGF-R2, stromal derived factor 1 (SDF-1) and CXCR4, and, their ability to form capillary-like tubes when cultured separately or when co-cultured (1:5 ratio) on growth factor-reduced Matrigel. Fluorescence-labeled BMD-EPCs seeded alone on Matrigel formed capillary-like tubes reflecting in vitro vasculogenesis, and when co-cultured with GECs on Matrigel, formed 'hybrid' tubes containing BMD-EPCs nested between GECs thus reflecting in vitro angio-vasculogenesis. These 'hybrid' tubes were 1.5-fold wider (P < 0.001) and had more extensive (5.1-fold increase) loops (P < 0.01) at the junctions of BMD-EPCs and GECs versus tubes formed by GECs alone. GECs expressed SDF-1 that likely mediated homing of BMD-EPCs (which expressed the SDF-1 receptor, CXCR4) and their incorporation during neovascularization. BMD-EPCs can independently form capillary-like tubes on Matrigel, and when co-cultured with fully differentiated ECs on Matrigel, form capillary-like 'hybrid' tubes comprised of both cell types. Both BMD-EPCs and GECs express SDF-1 and CXCR4, which indicate direct paracrine interactions between these cells during neovascularization.
血管再生（新生血管形成）对于组织损伤愈合至关重要。骨髓来源的内皮祖细胞（BMD-EPCs）在组织损伤愈合过程中对新生血管形成的作用尚未完全阐明，并且尚不清楚BMD-EPCs能否独立形成新的毛细血管，还是与完全分化的内皮细胞（ECs）共同形成。本研究的目的是通过在基质胶上共培养BMD-EPCs和胃内皮细胞（GECs）建立血管发生/血管生成的体外模型，研究这些细胞的直接相互作用，并确定其中涉及的机制。我们分别从大鼠的骨髓和胃中分离出BMD-EPCs和GECs。在这些细胞中，我们检测了CD34、CD133、CD31、VEGF-R2、基质细胞衍生因子1（SDF-1）和CXCR4的表达，以及它们在单独培养或在生长因子减少的基质胶上共培养（1:5比例）时形成毛细血管样管的能力。单独接种在基质胶上的荧光标记BMD-EPCs形成反映体外血管发生的毛细血管样管，当与GECs在基质胶上共培养时，形成包含嵌套在GECs之间的BMD-EPCs的“混合”管，从而反映体外血管血管生成。与单独由GECs形成的管相比，这些“混合”管在BMD-EPCs和GECs的连接处宽1.5倍（P < 0.001），环更广泛（增加5.1倍）（P < 0.01）。GECs表达可能介导BMD-EPCs归巢（其表达SDF-1受体CXCR4）及其在新生血管形成过程中掺入的SDF-1。BMD-EPCs可以在基质胶上独立形成毛细血管样管，并且当与完全分化的ECs在基质胶上共培养时，形成由两种细胞类型组成的毛细血管样“混合”管。BMD-EPCs和GECs均表达SDF-1和CXCR4，这表明这些细胞在新生血管形成过程中存在直接的旁分泌相互作用。
