Optimizing Fat Grafting in an In-Vivo Rat Tissue Engineering Chamber Model

Abstract

INTRODUCTION: One of the main concerns of fat grafting is resorption over time, raising questions of sustainability. This study aims to gain insights into fat grafting and improve long term outcomes by adding a novel acellular adipose derived matrix (Adipogel). MethodS: A rat tissue engineering model was used for this study. An arteriovenous loop, created from the femoral vessels, was positioned inside a 2ml perforated chamber in the groin. In the control group, the chamber was filled with 1mL of minced autologous fat centrifuged at 3000 RPM (1286g) for 3minutes. In a second group 1mL of Adipogel was added to the 1ml fat graft while a third group contained Adipogel (2mL) alone. 6 additional 1mL fat graft samples were centrifuged and immediately fixed for histological assessment. The constructs were morphologically and histologically examined at 6 (n=3) and 12weeks (n=6). An antibody for Perilipin was used to label viable adipocytes. The volume of viable adipocytes was assessed using point counting (CAST System, Olympus, Denmark). RESULTS: At 6weeks the volume of grafted fat tissue in the control group remained stable, but the majority of the inserted fat cells appeared dead. Similar results were observed in the Fat + Adipogel group. At 12weeks tissue growth and neo-adipogenesis was observed in all groups (Figure 1), however the group where Adipogel was combined with the fat graft, demonstrated significantly higher levels of viable fat (35.32% ±12.43) compared to chambers containing fat alone (13.83% ±9.98) or Adipogel alone (12.64% ±5.93) (Figure 2). No significant differences in construct volume were found.Figure 1: Viable adipocyte volume in the construct at 6 and 12 weeks.Figure 2: Viable adipocyte volume percentage in the construct at 12 weeks.CONCLUSION: These results suggest that the mechanisms behind fat graft success appear to be based on regeneration of fat, probably from adipose derived stem cells, rather than on fat graft survival. At 12weeks, excellent adipogenesis was seen with the addition of a novel adipose derived matrix (Adipogel) to the fat graft. We believe that the use of Adipogel has a great potential in fat grafting. Furthermore, we showed that a pedicled adipose fat flap can be generated in vivo, offering perspectives for larger reconstructive flap surgery as well.