Single-cell transcriptomics reveals hair growth retardation mediated by aberrant connective tissue sheath contraction in male androgenetic alopecia

Androgenetic alopecia (AGA) manifests as progressive hair follicle (HF) miniaturization; however, its drivers remain poorly elucidated. Combining spatial and single-cell transcriptomics, we generate a concise single-cell atlas of anagen HFs in male AGA, revealing early changes in cell subpopulations, altered HF stem cell fate determination, and disrupted cell-cell communications. Through ex vivo HF organ culture and humanized mouse models, we demonstrate that hypercontractility of connective tissue sheath (CTS) activates the mechanosensitive channel PIEZO1 in anagen HFs. This mechanotransduction induces ectopic apoptosis of HF progenitor cells and suppresses matrix/ORS cell proliferation, depleting progenitor pools and impairing HF growth, thereby driving progressive miniaturization. Critically, pharmacological inhibition of CTS contraction via ML-7, a selective myosin light chain kinase (MLCK) inhibitor, improves HF growth in both male AGA patient-derived ex vivo models and humanized mice. Our study delineates the cellular dynamics underlying male AGA pathogenesis and identifies mechanopathologically activated CTS as a key driver of HF miniaturization, positioning the peri-follicular CTS as a promising therapeutic target for AGA intervention. Androgenetic alopecia is the most common type of hair loss, but its drivers remain poorly elucidated. Here, the authors show that hyperactive contraction of the follicle connective tissue sheath impairs hair growth by activating mechanosensitive signaling, suggesting a tractable therapeutic target.