The aim of the study was morphological substantiation of clinical efficacy of platelet rich plasma (PRP) in the treatment of patients with androgenetic alopecia (AGA).

Materials and Methods: The study included 25 men aged from 20 to 43 years. AGA degree II-IV on the Hamilton-Norwood scale was diagnosed in 23 (92%) patients and degree I in 2 patients. All patients received intradermal injections of PRP. The course of treatment consisted of 4 procedures with an interval of 4 weeks between each procedure. The clinical efficacy of the therapy was evaluated by the dynamics of morphometric indicators of hair growth. The morphological analysis included an assessment of indicators in horizontal sections and was carried out at 4 levels: at the level of subcutaneous adipose tissue, sweat glands, sebaceous glands, and mouths of hair follicle (HF). Sections were stained with H&E. Histological examination was performed before and after treatment. Against the background of treatment with PRP, hair density increased by 12% (P=0.000), average hair diameter by 12% (P=0.002), and the share of vellus and telogen hair decreased by 17% (P=0.002) and 16% (P=0.028), respectively. At the same time, the amount of anagen hair in relation to telogen hair increased by 18% (P=0.016). Histologically, the increase in hair density was accompanied by a significant increase in the number of HF at the mouth level (Delta+96%, P=0.004) and at the level of sweat glands (Delta+54%, P=0.037), as well as a tendency for their number to increase at the level of the sebaceous glands. These increases were combined with a significant decrease in the proportion of telogen hair (Delta-43%, P=0.023) and vellus hair (Delta-29%, P=0.037).

Conclusion: The positive clinical effect of PRP therapy is due to significant morphofunctional changes in hair follicles.