Stromal vascular fraction (SVF) cells enhance long-term survival of autologous fat grafting through the facilitation of M2 macrophages.

Optimum perfusion may be the key to the endurance, and hence survival, of autologous adipose tissue transportation. Stromal vascular fraction (SVF) cell therapy can greatly improve the survival of fat grafts by enhancing angiogenesis. However, SVF cells are poorly retained in later stages of SVF-assisted adipose tissue transplant. Therefore, it hardly defines the angiogenic effect through long-term transportation. Adipose tissue suffers from acute hypoxia in the early stage of transportation, leading to the recruitment of macrophages. M2 macrophages enhance angiogenesis in adipose transplantation by acting as an angiogenic signal source, promoting tip cell migration and assisting tip cell fusion. Furthermore, the angiogenic and anti-inflammatory micro-environment in the graft created by M2 macrophages may stimulate the transformation of infiltrating macrophages to M2 macrophages. These M2 macrophages may enhance the long-term retention of graft through angiogenesis. Based on these observations, we postulate that the long-term angiogenic effect of SVF cells may be achieved through the facilitation of the M2 macrophages.