Combined 5‐aminolevulinic acid and ferric ammonium citrate treatment promotes hair follicle growth by activating dermal papilla cells

The study explored the effects of combining 5-aminolevulinic acid (5-ALA) with ferric ammonium citrate (FAC) on human hair follicle models. The treatment at low micromolar concentrations increased the proliferation of dermal papilla cells, keratinocytes, fibroblasts, and adipose-derived stem cells, while activating ERK and AKT signaling pathways. It also upregulated hair-inductive genes and counteracted their suppression by dihydrotestosterone or oxidative stress. Functionally, the treatment induced hair follicle-like structures and enhanced hair shaft elongation in ex vivo organ culture. These results suggest that 5-ALA/FAC treatment could be a promising therapeutic option for promoting hair growth and treating hair loss.