In Vivo Bioimaging Analysis Of Stromal Vascular Fraction Cells-assisted Fat Grafting: The Interaction And Mutualism Of Transplanted Stromal Vascular Fraction Cells And Grafted Fat
Shuangbai Zhou, M.D., Chengan Chiang, M.D., Kai Liu, M.D., Ph.D., Yun Xie, M.D., Qingfeng Li, M.D., Ph.D..
Shanghai Jiao Tong University, Shanghai Ninth People's Hospital, Shanghai, China.
PURPOSE: Fat graft transplantation are widely used in reconstructing soft tissue defect, but unpredictable survival rate of transplanted fat is a big obstacle in promoting the application of fat grafting. Recent researches have suggested that adipose-derived stromal vascular fraction could promote survival of grafted fat. There has been seldom reports tracing and revealing the dynamic change in survival of grafted fat in vivo and discussing the possible influence of fat graft to transplanted SVFs.
METHODS: In this study, fat tissue and SVF separated from luciferase (Luc)-transgenic rats were applied for continuous bioimaging analysis of fat graft survival. The luciferase rat fat (0.2ml) was subcutaneously injected into the back of nude mice with or without freshly isolated SVFs from 0.2 ml wild type rat fat. All fat grafts were in vivo tracing for 63 days for comparing survival rates in two groups. After 63 days, fat grafts were harvest for immunohistochemical staining to evaluate the structural integrity. Moreover, to evaluate the influence of surrounding fat tissue to transplanted SVFs, we transplanted Luc-SVFs separated from 0.2 ml luciferase fat to back of nude mice, either with wild type fat tissue or alone and dynamically observed them for 63 days by bioimaging. Also, differentiation of SVFs was analyzed by specific cell markers.
RESULTS: The bioimaging results of Luc-fat showed that fat tissues transplanted with SVF had higher survival ratio than those transplanted alone (49.99(5.38)% in SVF Group vs. 32.78(3.32)% in Control Group, p<0.001). SVF-assisted fat grafts had more integral structure and less necrosis cysts. The results of in vivo tracing transplanted SVFs demonstrated that, without fat graft micro-environment, injected SVFs were faded sharply within 21 days. While with the existence of fat graft tissue, transplanted SVF survived for a significantly longer time and could be found survived 63 days past injection. Survived
SVFs contributed to fat graft survival and regeneration by differentiating into adipocytes, preadipocytes and endothelial cells.
CONCLUSIONS: In this article, we showed that a novel technique of in vivo tracking and observing transplanted fat tissue. The results of bioimaging showed that SVF assisted fat graft had significant superiority that fat graft transplanted alone. Meanwhile, microenvironment of surrounded fat tissue had contribution in promoting SVFs living and differentiation. Our research also demonstrated that SVFs contribute to the survival and reconstruction of fat tissue by differentiating into multiple cell types.
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