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The Effect of Platelet-Rich Plasma in Hair Regrowth: A Randomized Placebo-Controlled Trial

Keywords: Autologous, Platelet-rich Plasma, PRP, Ageing, Clinical translations, Clinical trials


Platelet-rich plasma (PRP) has emerged as a new treatment modality in regenerative plastic surgery, and preliminary evidence suggests that it might have a beneficial role in hair regrowth. Here, we report the results of a randomized, evaluator-blinded, placebo-controlled, half-head group study to compare, with the aid of computerized trichograms, hair regrowth with PRP versus placebo. The safety and clinical efficacy of autologous PRP injections for pattern hair loss were investigated. PRP, prepared from a small volume of blood, was injected on half of the selected patients’ scalps with pattern hair loss.

Study Overview

This was a randomized, placebo-controlled, half-head group study conducted by plastic surgeons, biologists, pathologists of the University of Rome “Tor Vergata,” and a dermatologist of the Catholic University of the Sacred Heart of Rome. Evaluators of computerized trichograms were blinded to treatment. A follow-up period of 2 years was chosen because a reduction in the effect of PRP by 14 months after the last treatment has been observed.


For each patient, the scalp affected by hair loss was divided into four areas (frontal, parietal, vertex, and occipital) and cleansed with 70% alcohol; local anesthesia was not injected in the treated areas. PRP (0.1 ml/cm2) was injected in selected areas of the scalp. PRP injections were performed with a 30-gauge, 1-ml Luer-lock syringe (Fig. 4). Interfollicular injection of PRP was performed 3 times in each patient at intervals of 30 days. Patients with hair loss localized to the frontal and parietal areas were injected with the PRP only on the frontal areas; the parietal area was treated with placebo (injection of physiological solution). Patients with hair loss in the parietal and vertex parts were injected with the PRP only in the parietal part of the scalp; the vertex area was treated with placebo (injection of physiological solution). The same number of injections was repeated in the scalp half treated with PRP and in the half treated with placebo.


In this study, a mean of 1,484,555.6 platelets per microliter in the PRP preparation could effectively stimulate follicular and perifollicular angiogenesis, which is suggested to be one of the major factors in active hair growth. Our data and data published by us and other authors since 2011 suggest that the injection of PRP preparations has a positive therapeutic effect on male androgenic alopecia without major side effects.

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