The effect of host tissue and radiation on fat-graft survival: A comparative experimental study

Because lipofilling is often associated with various reconstructive procedures, especially breast reconstructions, improving fat-graft retention remains a major concern for plastic surgeons. We conducted an experimental protocol in a rat model simulating an autologous breast reconstruction method using the fat-augmented latissimus dorsi myocutaneous (LDM) flap. This study aimed to compare the survival rates of autologous adipocytes when injected subcutaneously and intramuscularly and to evaluate the role of recipient host tissue, volume of the injected fat, and postoperative radiation on fat-graft retention. Thirty rats were divided into five groups (A, B, C, D, and E), of six rats each. All animals underwent a pedicled LDM flap transfer to the anterior thoracic wall, and different volumes of autologous fat were injected into three recipient areas, namely, the pectoralis major and latissimus dorsi muscles and the subcutaneous tissue of the flap's skin island, as follows: 1 mL of fat was injected in total in group A, 2 mL in groups B and D, and 5 mL in group C. Group D animals received postoperative radiation (24 Gy), whereas group E animals (controls) did not undergo any fat grafting procedure. Eight weeks after surgery, adipocyte survival was assessed in all groups using histological and immunochemistry techniques. The results showed that the pectoralis major muscle was the substrate with the highest adipocyte survival rates, which were proportional to the amount of fat injected, followed by the latissimus dorsi muscle and the subcutaneous tissue. Increased volumes of transplanted fat into the subcutaneous tissue did not correspond to increased adipocyte survival. Irradiation of host tissues resulted in a statistically significant decrease in surviving adipocytes in all three recipient sites (p<0.001). Our study strongly suggests that muscle ensures optimal fat-graft retention, whereas postoperative radiation negatively affects adipocyte survival following fat transplantation.