Thoughts on the Long-Term Effects of Platelet-Rich Fibrin on Fat Graft Survival

We read with great interest the article by Yu et al entitled “Long-Term Effects of Platelet-Rich Fibrin on Fat Graft Survival and Their Optimal Mixing Ratio.” ¹ The authors demonstrated the role of platelet-rich fibrin (PRF) in promoting a successful fat graft outcome by providing histologic evidence and measuring protein levels, and showed that the optimal concentration of PRF was a 1:10 PRF/fat ratio. This study provided additional evidence for the advantages of using PRF and suggested clear standards for its clinical application.

The preparation of PRF—the second generation of platelet concentrates—does not require exogenous stimulants, which may make it safer than platelet-rich plasma (PRP) for clinical applications. In terms of effectiveness, a comparative animal study showed that PRF is more effective than PRP at promoting volume retention and neovascularization in fat grafting.² However, the lack of relevant high-quality clinical studies on the efficacy and safety of PRF has limited further clinical applications.

The differences in the anatomy, metabolism, and immune system between humans and rodents present challenges when interpreting data from animal experiments. Mice, as well as other rodents such as rats and rabbits, have panniculus carnosus, which is completely different from the subcutaneous fat structure in humans. This makes them unsuitable as animal models for fat grafting, in spite of their availability, low cost, and ease of handling.

To prepair animals for fat grafting, Yu et al made two 1-cm-diameter circles in the backs of mice. The fat was then injected into the circle, giving a graft of limited mobility. We have found that in practice the loose panniculus carnosus in rodents makes the transplanted fat slide easily, and we believe that the modified animal model the authors proposed can help solve this problem. However, we would like to know why Yu et al performed the fat grafting 1 week after preparing the animals, and whether and when the suture was removed. We suggest that the authors could usefully have provided figures showing general observations and histologic staining at 4 to 12 weeks to demonstrate that adhesion produced by the suture can still limit the graft mobility in the long term. Furthermore, further studies should be performed on whether the authors’ animal model affects the graft outcome, compared with the conventional animal model (without sutures). There are 2 circles on the hindquarters of each mouse, and we would like to know if the 2 circles were injected with grafts from different groups or from the same group.

In Yu et al’s study, liposuction was performed with a standard 3-mm liposuction needle. We suggest that the authors provide more specific information about the cannula, such as the size, quantity, and shape of the side holes, as these parameters are closely related to the size of the lipoaspirates and the outcomes achieved with them. In addition, we would like to know why the lipoaspirates were cut into 1-mm³ granules, as the further cutting of lipoaspirates is seldom performed in practice.

There were 5 groups in the study, including 1 control group (solely fat) and 4 PRF groups (fat + PRF). All the groups were injected with 0.2 mL of fat or 0.2 mL of fat and different concentrations of PRF. The total injection volume of the graft differed among the groups due to the different concentrations of PRF. We fear that the volume effect may have lead to a bias in the results.

Disclosures

The authors declared no potential conflicts of interest with respect to the research, authorship, and publication of this article.

Funding

The authors received no financial support for the research, authorship, and publication of this article.

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