Effect of exogenous adipose-derived stem cells in the early stages following free fat transplantation.

Cotransplantation of adipose-derived stem cells (ASCs) is an effective therapeutic approach for enhancing the survival of transplanted fat tissue; however, the role of ASCs in free fat transplantation remains unclear. In the present study, fat harvested from C57BL/6 mice expressing green fluorescent protein was injected subcutaneously into the back of C57BL/6 mice, who also received ASCs (group A) or received the fat tissue only (group B). The grafts were harvested at days 1, 4, 7, 14, 30 and 90 following the transplantation. Graft volume and histology were evaluated, and the secretion levels of vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) were quantified using enzyme-linked immunosorbent assays. No statistically significant difference was identified between groups A and B in the graft survival rate up to day 14 following the aspirated fat transplantation; however, the graft survival rate decreased during the following 14-90 days. Initially, group =A exhibited a higher graft survival rate and a greater degree of angiogenesis compared with group B. The ratio of dead cells was not significantly different between the two groups on day 1; however, group A had a greater number of living interstitial cells compared with group B at the later time points. The secretion of VEGF by the ASCs had an earlier peak time in group A (day 4) compared with group B (day 7). In addition, the secretion of HGF in group A was greater compared with group B. Therefore, the role of exogenous ASCs in free fat transplantation may not directly participate in angiogenesis and adipogenesis, but may promote the survival ratio of the graft-resident interstitial cells, which are involved in angiogenesis and adipogenesis, via a paracrine effect.