Effect of chitosan nanospheres loaded with VEGF on adipose tissue transplantation: a preliminary report.

Neovascularization plays an important role in adipose tissue transplantation, because survival of implanted cells strongly relies on sufficient oxygen and nutrient supply. Vascular endothelial growth factor (VEGF) is known as the master regulator of angiogenesis. It is capable of starting the complex cascade of events leading to endothelial cell activation, assembly of new vascular structures, mural cell recruitment, and vessel stabilization. However, consensus is lacking regarding safe and efficient methods for applying VEGF in free fat transplantation in the clinical setting. We investigated whether chitosan nanospheres, a biocompatible high-molecular-weight material, safely improve the efficiency of VEGF application in free fat transplantation. Immunologically compromised nude mice were used as adipose tissue transplantation receptors. Nanospheres loaded with VEGF were mixed with adipocytes and injected subcutaneously to the dorsa of mice. Grafts were harvested at weeks 3, 6, and 12. We found that treated-graft weight and vascularization were significantly higher than controls in a time-dependent manner. We demonstrated that chitosan nanospheres loaded with VEGF significantly promote the fat graft neovascularization and improve adipocyte survival.