Observations on the Survival and Neovascularization of Fat Grafts Interchanged between C57BL/6-gfp and C57BL/6 Mice

Background: Autologous fat transplantation has become a prevalent option for soft-tissue augmentation throughout the body. However, there is still much controversy over whether the fat grafts have survived or have been replaced in the recipient sites and over how the vessels grow. Methods: After C57BL/6-gfp mice and C57BL/6 mice were paired randomly, the inguinal fat was excised and cut into pieces with scissors, and the adipose granules, approximately 0.2 ml (0.195 g), were transplanted subcutaneously with syringes to the dorsa of the paired mice. Samples were obtained at different time intervals: 3 days, 7 days, 2 weeks, 4 weeks, 2 months, 3 months, and 4 months after transplantation. Each fat sample was weighed to evaluate the graft volume. Histology, origin, and densities of neovascularization were examined by immunohistochemical staining. Results: At 4 months, there was no significant difference in either graft survival or histologic evaluation. Histologic evaluation manifested the normal physiologic process of inflammation, neovascularization, remodeling, and maturity at different time intervals. At the endpoint, the immunohistochemical staining of CD34 showed that the difference in capillary density of the fat graft—31.3 ± 3.9 capillaries/mm2 on the dorsa of the C57BL/6-gfp mice and 29.6 ± 3.2 capillaries/mm2 on the dorsa of the C57BL/6 mice—was not statistically significant. The α-smooth muscle actin staining indicated that there were neovascularized vessels in both C57BL/6-gfp and C57BL/6 fat grafts. Conclusions: Fat grafts can survive and neovascularized vessels can grow from the recipient sites. Fat transplantation is feasible and will be applied more widely if fat graft survival is improved.