Effect of local, long-term delivery of plateletderived growth factor (PDGF) on injected fatgraft survival in severe combined immunodeficient (SCID) mice

Background: Autogenous fat injection is widely used for the correction of acquired and congenital soft tissue defects. However, the high absorption rate results in the need for over-correction of the defect and repeat procedures. We hypothesised that platelet-derived growth factor (PDGF), a potent mitogen and known stimulant for murine preadipocytes, would improve fat graft survival when concentrations were sustained with a gelatine microsphere delivery system. Methods: Abdominal fat was harvested from an otherwise healthy 43-year-old woman during a breast reconstruction. Prior to subdermal injection into severe combined immunodeficient (SCID) mice, the fat grafts were divided into 1-ml aliquots, mixed with microspheres bound to PDGF, free PDGF, or nothing depending on its experimental group, and weighed. The following experimental groups were thus created (minimum n = 8 per group): (1) fat graft control, (2) fat graft with free PDGF, (3) fat graft with blank microspheres, and (4) fat graft with microspheres bound to PDGF. After 12 weeks, the fat xenografts were harvested for analysis of weight maintenance and histological and morphometric evaluation. Results: The addition of PDGF bound to gelatine microspheres was effective in improving xenograft weight maintenance (P = 0.018) and preservation of adipose tissue architecture (P < 0.0005) compared to controls at 3 months. The microspheres were completely absorbed at 12 weeks. Conclusions: Sustained, local delivery of PDGF via a gelatine microsphere delivery system resulted in improved weight maintenance of the xenografts with greater preservation of adipose tissue architecture at 3 months compared to controls.