Abstract
Alopecia areata (AA) is an autoimmune condition that causes non-scarring hair loss on the scalp or other hair-bearing surfaces. Various signalling molecules regulate the hair cycle and hair follicle regeneration. These include genes, growth factors, nuclear receptors, cytokines, and subcellular signalling pathways. Growth factors can cause the vascular endothelium and dermal fibroblasts to proliferate, extend the anagen phase, and delay the initiation of catagen in the hair follicle, thereby promoting hair growth. Microneedling causes the release of growth factors and has been shown to help high-molecular-weight drugs penetrate the stratum corneum and hair follicles. These recent discoveries regarding the pathogenesis of AA have resulted in the development of promising therapies. Herein, this article reviews the use of growth factors and microneedling in the treatment of AA and explores their efficacy and safety. Treatment with growth factors and microneedling appears to be highly effective for AA, with no major adverse effects, and may provide a new option for hair regeneration therapy. To support the efficacy of growth factors and microneedling for AA treatment, additional large-scale studies of patients with AA are needed.