Telocyte networks are an essential stem cell niche component in hair follicle regeneration

Self-renewing tissues rely on stem cells (SCs) to regenerate differentiated cells, requiring precise coordination between SCs and their progeny. Here, we investigated how SC activity is regulated across multiple epithelial layers, using the hair follicle (HF) as a model system. We uncovered an extensive, interconnected network of telocytes, specialized mesenchymal cells, that spans all HF layers, including regions previously thought to lack mesenchymal or connective tissue components. These telocyte networks remain in constant contact with SCs and their progeny throughout regeneration, dynamically adapting their structure and molecular profile to provide localized, phase-specific signals. By employing two independent mouse models to ablate telocytes or disrupt their Wnt signaling, we demonstrate that telocyte networks are an essential component of the SC niche. Our findings propose a revised, integrative model of the SC niche, in which telocyte networks and their Wnt production play a central role in adult SC biology and tissue regeneration.