Enhanced fat graft survival via sustained delivery of FGF-2 based on chitosan core-shell microspheres

Objective To construct a novel carrier with core-shell structure-inner core of pFGF2-EGFP-loaded TACS coated by hydroxybutyl chitosan (HBC), and to explore its effects on granular fat graft survival. Methods The core-structured particles (TACS-pFGF2-EGFP) and core-shell-structured particles (HBC@ TACS-pFGF2-EGFP) were prepared to explore the release pattern of pFGF2-EGFP of these particles. The expression of FGF2 protein was detected by Western-Blot in 293T cells transfected with the sustained - release microspheres in vitro. Cell proliferation assay demonstrated that 10μg/ml pFGF2 plasmid could promote 293T cells growth. Eighteen New Zealand white rabbits were used for adipose tissue transplantation experiment. Rabbit left ear was treated as experimental group, 2 ml fat granules and HBC@TACS-pFGF2-EGFP were implanted; rabbit right ear was used as control group, 2 ml fat granules and HBC@TACS-empty plasmids were transplanted. The specimens were harvested at 4, 8, 12 weeks separately after fat transplantation. Gross view, HE staining, and immunohistochemical staining were performed to observe graft survival, biological characteristics, and neovascular density. Results HBC@TACS-pFGF2-EGFP particles could sustained release Pfgf2 gene in vitro, and successfully express FGF2 protein after transfecting 293T cells. At different time points after transplantation, the volume of adipose tissues was gradually reduced with time. The fat volume and survival rate of adipose tissues in the experimental group were significantly higher than that in the control group (P<0.05). HE staining showed that the arrangement of new adipocytes in the experimental group was more regular than that in the control group. Immunohistochemistry staining showed that the micro vessel density and FGF2 protein expression level in the adipose tissue of the experimental group were higher than those in the control group (P< 0.05). Conclusions HBC@TACS-pFGF2-EGFP particles with sustained release of FGF2 can improve the survival of granule fat transplantation. Key words: Gene therapy; Fat granule grafting; Basic fibroblast growth factor