Postnatal bone marrow stromal cells elicit a potent VEGF-dependent neoangiogenic response in vivo

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Abstract
Bone marrow stromal cells (MSCs) are pluripotent cells capable of differentiation into several tissue types. This present study was performed to determine their functional neoangiogenic potential in vivo. Whole bone marrow was harvested from C57Bl/6 mice, and the adherent cellular fraction was culture expanded for 14 doublings. These MSCs were resuspended in Matrigel and their angiogenic effect assessed in isogenic recipients. At 2 weeks postimplantation, the mean vascular density in Matrigel plugs containing 2 × 106 MSCs/ml was 41±5.0 blood vessels (BVs)/mm2 compared to 0.5±0.7 for empty Matrigel (P2, respectively. Arteriogenesis was observed only in the MSC-containing implants. With the use of LacZ retroviral labeling of ex vivo expanded MSCs, we show that ∼ 10% of LacZ+MSCs differentiated into CD31+ and VEGF+ endothelial cells. More than 99% of the neoangiogenic phenomena arose from recruitment of host-derived LacZnull vascular structures. Neutralizing anti-VEGF antibodies inhibited the MSC-initiated angiogenic response in vivo by 85% (Pde novo and VEGF plays a central role in the observed host-derived angiogenic response. We propose that ex vivo expanded autologous MSCs may serve as cell therapy to promote therapeutic angiogenesis.