Effectiveness of Allogeneic Platelet-Rich Fibrin on Second-Intention Wound Healing of Experimental Skin Defect in Distal Limb in Donkeys (Equus asinus)

Second-intention wound healing may be impaired by wound or host factors and thus more advanced therapies are required for a fast and satisfactory outcome. Platelet-rich fibrin (PRF), rich in growth factors that are essential for tissue repair, could improve wound healing. Twelve apparently healthy male donkeys were divided into two groups. Four full-thickness excisional skin wounds (2 × 2 cm) were created on lateral surfaces of the right metacarpal and left metatarsal of all donkeys (two wounds on each limb). Control wounds were left without treatment. Meanwhile, the wounds were treated topically with PRF. Wound healing was evaluated clinically, histologically, and through gene expression. The times required for complete wound closure were significantly shorter in PRF-treated wound compared with untreated wounds (36.00 ± 1.26 vs. 48.50 ± 1.87). All wounds of PRF groups healed faster than untreated wounds. Epithelization and wound contraction were observed earlier in PRF-treated wound compared with the control group (at second and third week, respectively). In PRF group, granulation tissue was regular, smooth, and observed earlier than in the control group. Histological and molecular evaluation confirmed the gross findings via early granulation tissue formation, higher epithelialization, collagen deposition, fibroblast proliferation, and angiogenic and myofibroplastic genes (collagen type 3α1, vascular endothelial growth factor, fibroblast growth factor 7, and transform growth factor β1) revealed significant overexpression in PRF-treated group when compared with the control at 15 and 30 days after wounding. Allogeneic PRF is considered a step forward in improving cutaneous wound healing in lower limb in donkeys via higher epithelialization, wound contraction, and could accelerate wound closure with smooth and regular granulation tissue.