Enhancement of endothelial differentiation of adipose derived mesenchymal stem cells by a three-dimensional culture system of microwell

Adipose derived mesenchymal stem cells (AdMSCs) have been demonstrated to have ability to differentiate into several cell lineages, including endothelial cells. The low endothelial differentiation efficiency, however, limits further clinical application of AdMSCs for therapeutic angiogenesis. This study was designed to investigate the feasibility to promote endothelial differentiation efficacy of AdMSCs using microwell array as a 3-D culture system. AdMSCs aggregates were prepared using photocrosslinkable polyethylene glycol dimethacrylate (PEGDM) derived microwell. AdMSCs aggregated and formed well defined 3-D aggregates following seeding. The microwell was effective in regulating the size of AdMSCs aggregates with low variation. AdMSCs within the 3-D aggregates maintained the cell surface epitopes of AdMSCs with high viability. Endothelial growth medium was used to induce the in vitro endothelial differentiation of AdMSCs. Both gene expression results from real time PCR and protein expression data from immunofluorescent staining revealed that 3-D cultured aggregates significantly promote the endothelial differentiation efficacy of AdMSCs. AdMSCs or AdMSCs aggregates were injected into the subcutaneous space of nu/nu mice to investigate the endothelial differentiation in vivo. The immunofluorescent staining data indicated promoted endothelial differentiation of 3-D aggregates compared with 2-D AdMSCs. Aggregates dissociated cells were obtained by transferring 3-D aggregates onto the adherent surfaces. Cells dissociated from induced aggregates were still positive for endothelial specific markers and were able to form endothelial-like tube structures on matrigel, indicating the endothelial properties. We conclude that microwell is an ideal 3-D culture system for promoting endothelial differentiation efficacy of AdMSCs.