A study from Rockefeller University, published in Cell Metabolism, has identified the amino acid serine as a key factor in determining whether hair follicle stem cells (HFSCs) maintain hair growth or participate in skin repair.  

Using mouse models, the researchers found that limiting serine – either through diet or by disrupting its production – triggered the integrated stress response (ISR) in HFSCs. This change redirected the cells away from hair production and toward re-epithelialising wounds, leading to faster closure but reduced hair regeneration. Pharmacological activation of the ISR produced similar effects, while higher serine levels partially reversed them.  

The team also detected signs of ISR activation in human skin samples at the margins of healing wounds, suggesting that the mechanism may operate in people as well. The authors note that while these findings highlight a potential way to influence the balance between hair growth and skin repair, further research will be needed to understand the safety and feasibility of modulating serine metabolism in clinical settings.