Long-term Clinical Outcomes of Autologous Non-activated Platelet-rich Plasma (A-PRP) Delivered Through Mechanical and Controlled Infiltration in Male and Female Androgenetic Alopecia: A 10-year Prospective Randomized Evaluator-blinded Study

Abstract

BACKGROUND: Androgenetic alopecia (AGA) is the most common cause of progressive hair loss in men and women and is associated with significant psychosocial distress. Platelet-rich plasma (PRP) is a regenerative therapy that stimulates follicular activity, angiogenesis, and dermal papilla activation through growth factor release. OBJECTIVES: This prospective randomized evaluator-blinded clinical trial evaluated the long-term efficacy and safety of autologous non-activated PRP (A-PRP) delivered through a standardized mechanical and controlled infiltration protocol. METHODS: Between January 2015 and January 2025, 234 patients with AGA were enrolled, including 135 men (Norwood-Hamilton I-IV) and 99 women (Ludwig I-II); 25 patients had previous confirmed COVID-19 infection. Patients received three A-PRP sessions at 30-day intervals with intradermal administration of 0.2 mL/cm2. Hair density (HD), hair thickness (HT), and total hair count (HC) were assessed by computerized trichoscopy and phototrichogram analysis at baseline, 12, 36, 60, and 120 months. RESULTS: At 12 months, HD increased by 31.4%, HT by 26.8%, and HC by 29.7% compared with baseline (p < 0.001). HD remained above baseline at 36 months (+24.1%) and 60 months (+17.3%). At 120 months, patients receiving maintenance treatment showed an 11.2% improvement. Female patients demonstrated greater preservation of hair shaft diameter. No significant differences were observed according to previous COVID-19 infection, and no severe adverse events occurred. CONCLUSIONS: Standardized A-PRP infiltration provides a safe and effective regenerative approach for AGA, with maintained clinical improvement during long-term follow-up. These findings support the role of standardized delivery protocols in improving reproducibility and therapeutic consistency in regenerative hair restoration.