Differential Therapeutic Efficacy of Autologous Platelet-Rich Plasma at Varying Concentrations in the Treatment of Deep Second-Degree Burn and Its Underlying Molecular Mechanisms.

BACKGROUND: Platelet-rich plasma (PRP) shows promise in burn management, yet optimal platelet concentrations, timing, and standardized protocols remain unclear, leading to inconsistent clinical outcomes. AIMS: To compare the therapeutic efficacy of PRP at different platelet concentrations in deep second-degree burns and to explore associated molecular mechanisms. PATIENTS/METHODS: Twenty-eight patients with small-area deep second-degree burns were randomly assigned to four groups: Group A (PRP 600-1000 × 109/L), Group B (normal saline control), Group C (PRP 1000-1400 × 109/L), and Group D (PRP 1400-1800 × 109/L). Outcomes included wound healing time, wound coverage rates at 2 and 3 weeks, bacterial culture positivity, and 3-month scar scores. Full-thickness biopsies were collected on days 5, 9, and 16 for histopathology, immunohistochemistry, and growth factor quantification. RESULTS: All PRP groups showed faster healing and lower infection rates compared with controls. Group C achieved the shortest healing time (p < 0.05). Growth factor concentrations rose with increasing platelet levels, but M2 macrophage polarization was highest in Group C. Elevated transforming growth factor-β (TGF-β) in Group D appeared to trigger negative feedback, limiting M2 accumulation and diminishing added benefit. Scar scores did not differ significantly among PRP groups. CONCLUSIONS: PRP accelerates wound healing and reduces infection risk in deep second-degree burns. A platelet concentration of 1000-1400 × 109/L provides the best therapeutic balance. Excessively high concentrations may impair repair through TGF-β-mediated inhibitory effects. Future research should explore controlled-release strategies to optimize PRP-derived growth factor activity.