Stem cells have garnered significant scientific interest for the treatment of hair loss and thinning, particularly in cases of androgenetic alopecia (pattern hair loss). The rationale is based on the ability of stem cells—especially mesenchymal stem cells (MSCs) and hair follicle stem cells—to promote hair follicle regeneration, stimulate hair growth, and improve the microenvironment of the scalp.

Several preclinical studies and early-phase clinical trials have investigated the use of autologous stem cells, stem cell-derived exosomes, or conditioned media for hair restoration. These studies indicate that stem cell-based therapies can enhance hair density and diameter, likely by promoting the activity of dermal papilla cells and facilitating the transition of hair follicles from the telogen (resting) phase to the anagen (growth) phase.

For example, a 2020 systematic review (J Dermatolog Treat, 2020) concluded that stem cell therapies show promise in increasing hair count and thickness, but emphasized the need for larger, longer-term randomized controlled trials. Another pilot study (Stem Cells Transl Med, 2017) demonstrated significant improvement in hair density with autologous stem cell injections. However, the available evidence is still limited by small sample sizes, variable methodologies, and lack of long-term safety data.

In summary, while there is growing scientific validation for the use of stem cells in treating hair loss, the quality and quantity of evidence are moderate (rated 3/5). More robust clinical trials are needed to confirm efficacy, optimize protocols, and establish safety.