Effect of Retinoids on Follicular Cells
TLDR Retinoids can change the hair growth cycle by extending the growth phase and shortening the rest phase.
The study demonstrated that topical application of all-trans retinoic acid and other retinoids could alter the hair-growth cycle in C3H mice by prolonging the anagen phase and shortening the telogen phase, similar to minoxidil. Elevated levels of cellular retinoic acid-binding protein (cRABP) were observed in the skin during both phases when retinoids were applied. The retinoids that most effectively increased cRABP levels also significantly altered hair-cycle dynamics. In human cultured cells, only cRABP-II was detectable, with higher amounts in dermal fibroblasts compared to dermal papilla cells, potentially explaining their distinct responses to retinoic acid. However, retinoic acid treatment did not affect the proliferation of human dermal papilla cells at the doses tested.
