Effects of adipose-derived stromal cells and endothelial progenitor cells on adipose transplant survival and angiogenesis

Abstract Background: A paracrine mechanism is thought to mediate the proangiogenic capacity of adipose-derived stromal/stem cells (ASCs). However, the precise mechanism by which ASCs promote the formation of blood vessels by endothelial progenitor cells (EPCs) is unclear.Methods: We cocultured ASCs with EPCs at various concentrations to study the effects on angiogenesis. The supernatant from cultured ASCs was cocultured with EPCs to evaluate the effects on the expression of vascular endothelial markers in EPCs, as well as capacity for migration and invasion. We then mixed ASCs with EPCs and transplanted them with adipose tissue into New Zealand white rabbits to evaluate the effects on angiogenesis in adipose tissue grafts.Results: As the relative abundance of ASCs cocultured with EPCs increased, the rate of angiogenesis among EPCs decreased. The supernatant from ASC cultures increased the migration and invasion of EPCs and upregulated the expression of vascular endothelial markers in EPCs. In vivo, ASCs promoted the production of blood vessels by EPCs.Conclusions: ASCs are not recruited as structural components of blood vessels but do appear to regulate endothelial progenitor-mediated angiogenesis. The results obtained show that ASC paracrine signaling promotes the formation of blood vessels by EPCs. ASC paracrine signaling appears to promote angiogenesis by increasing the migration and invasion of EPCs and simultaneously upregulating the expression of vascular endothelial markers in EPCs. The results of in vivo experiments showed that ASCs promote the formation of blood vessels in EPC cultures.