Growth Factors Specifically Alter Hair Follicle Cell Proliferation and Collagenolytic Activity Alone or in Combination

The study utilized a three-dimensional culture model to investigate the effects of growth factors on murine hair follicle cell proliferation and collagenolytic activity. It was found that transforming growth factor-alpha (TGF-α) stimulated DNA synthesis in a dose-dependent manner, particularly in outer root sheath cells, while TGF-β1 and TGF-β2 inhibited this proliferation and countered TGF-α's effects. Epidermal growth factor (EGF) and TGF-α promoted collagen gel lysis, whereas TGF-β1, TGF-β2, and cholera toxin did not. The study also noted that combinations of EGF or TGF-α with TGF-β1 or TGF-β2 enhanced collagenase release, with 92-kDa and 72-kDa type IV procollagenases being predominant. These findings suggested that growth factors could have synergistic or opposing roles in hair follicle development, influencing cell replication and dermal invasion.