Insulin-like Growth Factor 1 (IGF-1) in Hair Regeneration: Mechanistic Pathways and Therapeutic Potential.

IGF-1 (insulin-like growth factor 1) is a growth factor primarily secreted by dermal papilla cells on hair-bearing skin that stimulates hair follicle proliferation and vascularization, and promotes the transition to the anagen growth phase of the hair follicle by activating key pathways such as PI3K/Akt and MAPK/ERK. IGF-1 also inhibits apoptosis, prolongs the follicular growth phase, and boosts VEGF expression, which supports microcirculation and nutrient delivery to hair follicles. The combined effects of IGF-1 and other growth factors, including VEGF, KGF (FGF-7), and PDGF, further amplify its effects on follicular cell proliferation and tissue repair. IGF-1's ability to regulate the hair growth cycle and its interactions with other signaling pathways make it a compelling therapeutic target for hair loss disorders. Both preclinical models and clinical evidence highlight IGF-1 as a promising therapeutic option for conditions like androgenetic alopecia (AGA), where IGF-1 levels are typically diminished. While topical IGF-1 treatments have shown efficacy and safety with minimal systemic absorption, additional research is needed to improve delivery methods, such as liposomal gels and exosome-based carriers, and to evaluate long-term effects.