This is a comparative retrospective study of the efficacy of platelet-rich plasma injections and injections with commercial products advertised to promote hair regrowth for patients with androgenetic alopecia.

Platelet-rich plasma (PRP) has been used for more than a decade in the treatment of androgenetic alopecia and hair loss. Platelets contain a range of growth factors , namely vascular endothelial growth factor (VEGF), insulin-like growth factor (IGF), epidermal growth factor (EGF) and transforming growth factor beta (TGF-beta) which stimulate and support hair growth. Several studies have been performed on patients with conflicting but generally positive results.

Mesotherapy is the technique of injecting a product into the dermis and subcutaneous tissue in order to rejuvenate the skin, induce lipolysis or promote hair growth. Various products exist with different formulations marketed to induce hair growth and sustain hair loss. Even though these products have been used for years, clinical evidence is lacking.

In this retrospective study, we will compare the efficacy of PRP and mesotherapy on hair growth based on the trichoscopic photos and phototrichographic analyses of our patients who underwent these procedures between 2011 and 2020.

Inclusion Criteria:

• Patients who underwent either PRP or mesotherapy at our dermatology clinic during 1/1/2011 and 30/12/2020
• Male patients with a clinical/ trichoscopic/ histologic diagnosis of androgenetic alopecia (stage II to V according to the Hamilton-Norwood Scale)
• Female patients with a clinical/ trichoscopic/ histologic diagnosis of androgenetic alopecia (stage I to III according to Ludwig Classification)
• Patients receiving no treatment or being treated for more than six months for androgenetic alopecia without change in medication. Examples of medications and interventions include, oral/topical finasteride, oral/topical minoxidil, antiandrogens, hormonal substitution, hormonal contraceptives, phototherapy/laser, cryotherapy, microneedling.
• Patients who underwent trichoscopic examination and phototrichographic evaluation with our digital dermatoscope, before treatment, a month after the last injection and 3 months after treatment.
• Trichoscopic photos are required to be taken from the midfrontal area and from the vertex -defined as the intersection of the line through the midsagittal line and the line passing through the external auditory canals in the coronal plane.

Exclusion Criteria:

• Patients with other types of alopecia, other than androgenetic alopecia
• Patients with two or more diagnoses of hair loss , for example androgenetic alopecia and telogen effluvium or alopecia areata.
• Patients who started concomitant medication for hair loss within six months of treatment with PRP or mesotherapy. Medications and interventions include, oral/topical finasteride, oral/topical minoxidil, antiandrogens, hormonal substitution, hormonal contraceptives, phototherapy/laser, cryotherapy, microneedling.
• Hair transplantation to the vertex /midfrontal area
• Patients with no trichoscopic examination/ phototrichographic evaluation
• Patients lost to follow-up / withdrew from treatment

Patients with androgenetic alopecia who visited the outpatients department of our dermatology clinic of our university hospital. Patients were mostly Czech citizens but also expats who worked and lived in the country at the time of visit.