Adipose-derived stem cells (ASCs) are a potential adult mesenchymal stem cell source for restoring endothelial function in patients with critical limb ischemia. Fibroblast growth factor 2 (FGF2) and vascular endothelial growth factor (VEGF) play a major role in angiogenesis and wound healing. This study evaluated the effects of FGF and VEGF on the proliferation, migration, and potential endothelial differentiation of human ASCs with regards to their use as endothelial cell substitutes.Methods:
ASCs were isolated from clinical lipoaspirates and cultured in M199 medium with fetal bovine serum (10%), FGF2 (10 ng/mL), VEGF (50 ng/mL), or combinations of FGF2 and VEGF. Cell proliferation rates, viability, and migration were measured by growth curves, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), and scratch assays. For cell attachment determinations, ASCs were seeded onto a scaffold of small intestinal submucosa for 5 days. Endothelial differentiation capabilities of ASCs were confirmed by expression of endothelial cell-specific markers using quantitative polymerase chain reaction, immunofluorescence staining, and cord formation on Matrigel (BD Biosciences, San Jose, Calif). PD173074, a selective inhibitor of FGF receptor, was used to confirm the importance of FGF signaling.Results:
ASCs treated with FGF or combinations of FGF and VEGF showed increased proliferation rates and consistent differentiation toward an endothelial cell lineage increase in platelet endothelial cell adhesion molecule (CD31), von Willebrand factor, endothelial nitric oxide synthase, and vascular endothelial cadherin message, and in protein and cord formation on Matrigel. FGF and VEGF stimulated ASC migration and increased the attachment and retention after seeding onto a matrix graft of small intestinal submucosa. Blockade of FGF signaling with PD173074 abrogated ASC endothelial cell differentiation potential.Conclusions:
These results indicate that FGF and VEGF are ASC promoters for proliferation, migration, attachment, and endothelial differentiation. FGF and VEGF have a costimulatory effect on ASC endotheliogenesis. These results further suggest that ASCs with enhanced FGF signaling may potentially be used for tissue engineering and cell-based therapies in patients with critical limb ischemia.Clinical Relevance:
Endothelial dysfunction is a primary mediator of vascular disease and critical limb ischemia. Treatment of this disease state is limited by available conduit and the inherent thrombogenicity of bypass grafts. Development of phenotypically and functionally similar endothelial cells from adipose-derived stem cells may allow for the creation of vascular conduits that are readily available and provide increased patency rates. Our study differentiated a cell line from human adipose that could be manipulated into endothelial cells that exhibit characteristics of endothelial cells, providing further information to already existing literature.