FGF-2 enhances vascularization for adipose tissue engineering

BACKGROUND: Current therapies for soft-tissue reconstruction include autologous tissue flaps and alloplastic implants. Although autologous fat transplantation using a minimally invasive cannula harvest has less donor-site morbidity than tissue flaps, there is a variable degree of fat resorption over time. Preadipocytes isolated from harvested fat are better able to withstand the mechanical trauma from the suction cannula and subsequently may result in improved cell survival and generation of new fat tissue after transfer to another anatomic site. The authors hypothesized that particulate small intestinal submucosa could be useful as injectable cell delivery vehicles for preadipocytes, and that the release of fibroblast growth factor (FGF)-2 would enhance vascularization. METHODS: Preadipocytes were isolated from discarded human adipose tissue and cultured on small intestinal submucosa particles in a stirred bioreactor (spinner flask). Preadipocytes attached and proliferated on small intestinal submucosa microparticles and maintained high viability over several weeks of culture. FGF-2 was encapsulated in poly(lactic-co-glycolic acid) microspheres and injected in conjunction with the preadipocyte/small intestinal submucosa particles into a mouse subcutaneous model. RESULTS: Preadipocytes attached and proliferated on small intestinal submucosa particles in vitro. In vivo, vascularization was significantly enhanced with the incorporation of FGF-2-loaded poly(lactic-co-glycolic acid) microspheres. In addition, cell survival during the 14-day in vivo observation period was confirmed by fluorescent dye labeling. CONCLUSIONS: Small intestinal submucosa particles are a favorable scaffold for preadipocytes, allowing ex vivo proliferation on particles small enough to be injected. Delivery of FGF-2 from poly(lactic-co-glycolic acid) microspheres resulted in cell survival and enhanced vascularization.