The Effects of Lower vs Higher Cell Number of Platelet-Rich Plasma (PRP) on Hair Density and Diameter in Androgenetic Alopecia (AGA): A Randomized, Double-Blinded, Placebo, Parallel-Group Half-Scalp IRB-Approved Study

Aesthet Surg J. 2021 Oct 15;41(11):NP1659-NP1672. doi: 10.1093/asj/sjab236.


Background: Androgenetic alopecia (AGA) is a common disorder in both males and females and may be improved by platelet-rich plasma (PRP) treatment.

Objectives: The aim of this study was to compare safety, efficacy, and satisfaction following treatment with a lower or higher number of platelets over 6 months.

Methods: This was a prospective randomized, double-blinded, placebo, parallel-group, half-scalp IRB-approved study involving 8 subjects with moderate AGA. Participants received intradermal PRP injections (baseline and Month 3), according to 2 treatment protocols (high vs low platelet numbers) to the frontal and crown portions of the hemiscalp and normal saline to control sites. Phototrichoscans were recorded at baseline and at 6 months, and global photography and subject and investigator satisfaction questionnaires were obtained at baseline, 3, and 6 months.

Results: At the end of 6-month evaluation period, both groups demonstrated absolute increases in total hair density, follicle diameter, and terminal hair density, as well as absolute and percentage changes at the frontal and crown targeted sites compared with baseline. These improvements tended to occur more often in areas treated with higher platelet numbers than with lower numbers. Vellus hair densities did not exhibit any significant changes with either PRP dosages. The investigator and 6 of the subjects were "satisfied" with the results at 3 months and no adverse reactions were associated with the treatments.

Conclusions: Intradermal injections with 2 therapeutic quantities of platelets were equally safe and efficacious for treating men and women with AGA. Higher numbers of platelets may have a greater effect than lower numbers of platelets in regard to hair density, follicle diameter, and terminal hair density but exhibited minimal effects on vellus hair densities at the 6-month evaluation point. Further studies are required to determine whether any significant advantages occur when delivering either lower or higher numbers of platelets in AGA treatments as long as therapeutic levels are administered.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Alopecia* / therapy
  • Cell Count
  • Ethics Committees, Research
  • Female
  • Humans
  • Male
  • Platelet-Rich Plasma*
  • Prospective Studies
  • Scalp
  • Treatment Outcome

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