Methylene blue protects hair follicle stem cells from oxidative and metabolic stress to enhance hair regeneration.

Hair follicle stem cells (HFSCs) are vital for maintaining hair growth and regeneration. Their dysfunction, often caused by oxidative stress or metabolic imbalance, leads to hair loss and scalp aging. β-catenin is a key protein in the Wnt signaling pathway, and its activity is crucial for HFSC maintenance and regeneration. In this study, we show that methylene blue (MB), a mitochondrial-targeted antioxidant, promotes HFSC proliferation and viability by both reducing reactive oxygen species (ROS) and activating the β-catenin signaling pathway. Functional tests demonstrated that MB significantly sped up wound healing in HFSC cultures, indicating enhanced regenerative ability. Although co-treatment with antioxidants like vitamins A and C improved ROS scavenging, it surprisingly reduced MB-induced β-catenin activation. Conversely, minoxidil, a clinically approved hair growth stimulant, synergized with MB to further activate β-catenin signaling and enhance HFSC viability. Lastly, exposure to glucagon-like peptide-1 receptor agonists (GLP-1 RAs) resulted in a dose-dependent decrease in HFSC survival, consistent with emerging reports of treatment-related hair loss. Remarkably, pre-treatment with MB protected HFSCs from GLP-1 RA-induced metabolic stress and premature cell death. Overall, these findings identify methylene blue as a multifunctional therapeutic candidate that reduces oxidative and metabolic stress while supporting HFSC-mediated hair regeneration.