Anti-inflammatory effect of stromal vascular fraction cells in fat transplantation

In previous studies, it has been demonstrated that the stromal vascular fraction (SVF) promoted the retention rate of grafts following fat transplantation through its angiogenic properties. However, the effect of SVF on inflammatory response subsequent to fat transplantation remains unclear. Fat from C57 mice were mixed with green fluorescent protein (GFP) SVF cells or phosphate-buffered saline and transplanted into C57BL/6 mice. The graft was harvested and immunofluorescent staining was performed on 1, 7, 14 and 30 days. The numbers of vessels and macrophages, as well as the inflammation level, in the two groups were evaluated. Although the GFP fluorescence indicated that most SVF cells were dead following transplantation, there was a higher graft retention rate in the SVF-assisted group compared with the control group. The SVF-assisted group also presented higher expression levels of interleukin (IL)-6 and tumor necrosis factor-α, and lower levels of IL-10, as well as increased M2 macrophages in comparison with the control group. Therefore, the results indicated that SVF promoted the retention rate of grafts following fat transplantation through the well-known pro-angiogenic mechanism (paracrine function and involvement in the formation of new vessels), as well as through the anti-inflammatory property of SVF (expression and suppression of various cytokines and conversion of the macrophage phenotype).