Investigation of the effect of mobile and immobile region on fat graft viability in rats

Introduction and Purpose: In Plastic Surgery practice, fat grafts are frequently used for tissue augmentation, body contouring and face rejuvenation, and scar revisions. Ease of harvest, ease of use, and repeatability are the advantages of fat grafts. Foreign body reactions are not encountered due to its being an autologous tissue(1). Not being able to always acquire the desired volume and unpredictable resorptions are the major disadvantages. According to former studies, after applications of autologous fat graft, resorptions were observed at different rates (2,3) . Many studies have been done to increase the viability of adipocytes in autologous fat grafts(2). Nevertheless, no standard application is present in Plastic Surgery routine(4). No studies have focused on the effects of mobile and immobile areas on the viability of fat grafts. In this study, by creating a new rat model, the relation of fat graft with mobile and immobile areas of rats have been investigated. Materials and Method: In this study, 24 male Wistar albino rats were used. Rats were divided into two random groups. According to its mobility, a new recipient site model in rats is defined. In the first experiment group, the fat harvested from the right inguinal area, after measuring its weight and volume, is grafted en bloc to the pouch created under the scalp, which is chosen as the immobile area. In the second experiment group, the fat harvested from the same area as the first group, after measuring its weight and volume is grafted en bloc to the pouch created under the skin of the dorsal cervical area, which is chosen as the mobile area. After 6 weeks, all grafts from both groups were collected and their weight and volume were measured. The presence of adipocytes, fibrosis, inflammation, vascular density, necrosis, formation of cyst-vacuole were examined histopathologically. The comparison of weights and volumes, and histopathological data were evaluated statistically. Results:When the weights of the fat grafts harvested were compared, no significant difference were found between Group 1 and Group 2 (p> 0,05). Statistical analysis of the histopathological datas found no significant difference between group 1 and group 2 in terms of cyst-vacuole formation, inflammation, normal fat tissue, necrotic fat tissue and fibrosis (p>0,05). Vascular density were seen to be higher in group 1 and this was found to be statistically significant difference (p<0,05). xi Discussion and Conclusion:Fat grafting is widely used in Plastic Surgery practice. In our study, a new rat model was defined investigating the effect of mobile and immobile areas on fat graft viability. When the weights of the fat grafts obtained from the mobile and immobile areas at day 42 were compared no significant difference was found. Histopathological examination revealed vascular density in fat grafts at immobile regions to be higher. Numerous studies have been conducted investigating ways to increase fat graft survival. Some of these studies aimed to increase fat graft vascularity in order to increase survival. In some studies, antioxidant substances or neovascularization inducing agents have been used to increase vascularity(3). In some of these studies, increases in vascularity have been obtained with significant differences. However, these have not made into our routine practice yet. In our study, the vascular density in fat grafted at immobile areas has been found to be significantly higher. It is believed that with the increase in vascular density, fat graft survival rate can be improved. In our study, a new rat model for fat graft applications at mobile and immobile have defined and made its place in the literature.