Long-Term Effects of Platelet-Rich Fibrin on Fat Graft Survival and Their Optimal Mixing Ratio

Background: Platelet-rich fibrin (PRF) can promote fat graft survival, but the reported mixing ratio of PRF to fat ranges from 1:25 to 1:2, lacking a clear standard for clinical application. Objectives: The authors sought to explore the long-term effects of PRF on grafted fat and their optimal mixing ratio. Methods: Nude mice were randomly divided into a control group (receiving subcutaneous injection of fat granules) and 4 PRF groups (receiving subcutaneous injection of PRF and fat granules at volume ratios of 1:5, 1:10, 1:15, and 1:20, respectively). The graft samples (n = 12) were obtained in weeks 4, 8, and 12 to (1) calculate retention rates; (2) evaluate gene and protein expression of vascular endothelial growth factor A (VEGF-A), peroxisome proliferator-activated receptor-gamma (PPAR-gamma), type I collagen A1 (COL1-A1), and B-cell lymphoma-2 associated X protein (BAX); (3) perform hematoxylin and eosin, Masson's trichrome, alpha-smooth muscle action, and periplipin-1 stainings; and (4) count the microvessels and viable adipocytes. Results: Compared with the control group, PRF groups had higher retention rates, a higher gene/protein expression of VEGF-A, a lower gene/protein expression of COL1-A1 and BAX, less fibrosis, and more microvessels and viable adipocytes. Group 1:10 was superior to other groups in terms of retention rates and other evaluation indexes. The expression of PPAR-gamma did not significantly differ among groups. Conclusions: PRF may not play a long-term effect on adipogenesis, but it can still promote fat graft survival through facilitating vascularization, regulating collagen production, and inhibiting apoptosis. PRF can achieve the best promoting effect when the mixing ratio of PRF to fat is 1:10, which is recommended as the optimal ratio for clinical application.