Purpose: The present study evaluated the long-term fate of transplanted autologous fat using a novel facial augmentation model we have developed in the rabbit.

Materials & Methods: Eleven adult New Zealand White rabbits underwent fat harvest from the groin region using standard Coleman techniques. One milliliter of aspirate was transplanted to the left upper lip of each rabbit. Tissue specimens were harvested at post-op day 0, and 1 month, 3 months and 6 months following surgery. The right upper lip served as an internal control in each case.

Results: Aspirates of adipose tissue yielded between 1.2 and 2.4 cc of injectable fat from each rabbit. Transplanted fat is easily seen on histology as the normal rabbit lip in this area is relatively free of native fat. Histologic evaluation of the transplanted fat from postoperative time points showed a significant inflammatory response present at one month post-op with diffuse areas of necrosis. At three months postop, the transplanted tissue was more structured with collagen ingrowth and sequestration of fat necrosis. At six months postop, the transplanted fat was well-organized with nearly all non-viable tissue absent and presumably resorbed. There was also evidence of neovascularization of the transplanted fat. Overall survivability was variable with approximately 50% remaining in two of three animals at six months; the third animal demonstrated approximately 30% fat survival.

Conclusion: We have established a novel, reproducible model with an internal control for long-term evaluation of transplanted fat. Histology suggests an early inflammatory response to the injected fat followed by sequestration of non-viable tissue. Our transplanted fat remained viable at six months with good overall survivability and minimal fibrosis.