Shapiro J, Ho A, Sukhdeo K, et al. - In this randomized placebo-controlled split-scalp study with patients (n = 35) with androgenetic alopecia, the impacts of platelet-rich plasma (PRP) on hair regrowth and thickness were evaluated. Experts tattooed two 7.6-cm × 7.6-cm squares on the scalps of participants. They randomly assigned areas to intradermal injection with PRP or saline. Three monthly treatment sessions were given and 3 months after the final treatment, patients were assessed. At all visits, a significant increase in hair density, vs baseline, was evident in the PRP-treated area. An increase in hair density in PRP-treated areas was noted at the final assessment, which was from 151 ± 39.82 hairs/cm² at baseline to 170.96 ± 37.14 hairs/cm², a mean increase of nearly 20 hairs/cm². Hair density change did not differ significantly between the 2 groups. There were no serious adverse events. Based on these data, experts concluded that PRP may be beneficial for increasing hair density.