Study on the effect and mechanism of different doses of platelet-rich gel combined with platelet-rich plasma on rat skin flap transplantation

Background: Investigating the Effects and Mechanisms of Platelet-Rich Gel (PRG) Combined with Platelet-Rich Plasma (PRP) on the Transplantation of Dorsal Skin Flaps in SD Rats. Method: A rat dorsal pedicle skin flap model was established, and 84 SD rats were randomly divided into 14 groups: the control group, the PRG topical treatment group, and the PRG+PRP combined treatment group. The control group received no intervention. The PRG group was treated with PRG at doses of 50 μl/cm² and 100 μl/cm² applied to the base. The combined group received PRG application followed by PRP injection at the base, with treatments including 50 μl/cm² PRG + 50 μl/cm² PRP, 100 μl/cm² PRG + 50 μl/cm² PRP, 50 μl/cm² PRG + 100 μl/cm² PRP, and 100 μl/cm² PRG + 100 μl/cm² PRP. On postoperative days 3 and 5, the necrosis ratio of the skin flap, the defect length measured by ultrasound contrast, and the degree of edema were recorded. On postoperative day 3, skin flap tissues from each group were collected for VEGF and CD34 immunohistochemical staining. The expression levels were scored, and the number of microvessels was counted based on CD34 staining. Result: On postoperative days 3 and 5, the 50 μl/cm² PRG + 50 μl/cm² PRP group exhibited the lowest skin flap necrosis ratio and the shortest defect length measured by ultrasound contrast, both of which were significantly lower than those in the control group (P < 0.05). On postoperative day 3, the expression levels of VEGF and CD34, as well as the number of microvessels in this group, were significantly higher than those in the control group (P < 0.05). Conclusion: The 50 μl/cm² PRG + 50 μl/cm² PRP group can achieve the optimal improvement in the post-transplantation condition of skin flaps by enhancing the expression of VEGF and CD34 in the flap tissue and promoting angiogenesis.