Enhanced In Vitro Hair Growth at the Air-Liquid Interface: Minoxidil Preserves the Root Sheath in Cultured Whisker Follicles

The study demonstrated that culturing hair follicles at the air-liquid interface on a modified collagen matrix significantly enhanced hair growth, showing a 2.7-fold increase compared to other methods. This approach maintained an anagen-like morphology and higher expression of ultra-high sulfur keratin (UHSK). Minoxidil and its analogs were found to stimulate cysteine incorporation and specifically preserve the follicular root sheath, as indicated by increased TIMP expression and sulfotransferase activity, unlike the pinacidil analog. The findings suggested that the root sheath is a target tissue for minoxidil, and that the air-liquid interface method was superior for maintaining follicle morphology and promoting hair growth compared to traditional submerged culture methods.