Augmentation of postnatal neovascularization with autologous bone marrow transplantation

Background-Endothelial progenitor cells (EPCs) have been identified in adul t human peripheral blood. Because circulating EPCs should originate from bo ne marrow (BM), we examined whether BM mononuclear cells (BM-MNCs) can give rise to functional EPCs and whether transplantation of autologous BM-MNCs might augment angiogenesis and collateral vessel formation in a rabbit mode l of hindlimb ischemia. Methods and Results-Rabbit BM-MNCs were isolated by centrifugation through a Histopaque density gradient and cultured on fibronectin. EPCs developed f rom BM-MNCs in vitro, as assessed by acetylated LDL incorporation, nitric o xide (NO) release, and expression of von Willebrand factor and lectin bindi ng. Unilateral hindlimb ischemia was surgically induced in rabbits (n=8), a nd fluorescence-labeled autologous BM-MNCs were transplanted into the ische mic tissues. Two weeks after transplantation, fluorescence microscopy revea led that transplanted cells were incorporated into the capillary network am ong preserved skeletal myocytes. In contrast, transplanted autologous BM-fi broblasts did not participate in EC capillary network formation (n=5). Then , in an additional 27 rabbits, saline (control; n=8), autologous BM-MNCs (n =13; 6.9+/-2.2x10(6) cells/animal), or BM-fibroblasts (n=6; 6.5+/-1.5X10(6) cells/animal) were injected into the ischemic tissues at postoperative day 7. Four weeks after transplantation, the BM-MNC-transplanted group had mor e angiographically detectable collateral vessels (angiographic score: 1.5+/ -0.34 versus 0.94+/-0.26 and 1.1+/-0.14; P<0.05), a higher capillary densit y (23+/-5.8 versus 10+/-1.9 and 11+/-0.8 per field; P<0.001), and a greater laser Doppler blood perfusion index (505+/-155 versus 361+/-35 and 358+/-2 2 U; P<0.05) than the control and BM-fibroblast-transplanted groups. Conclusions-Direct local transplantation of autologous BM-MNCs seems to be a useful strategy for therapeutic neovascularization in ischemic tissues in adults, consistent with "therapeutic vasculogenesis."