ENHANCED IN-VITRO HAIR-GROWTH AT THE AIR-LIQUID INTERFACE - MINOXIDILPRESERVES THE ROOT SHEATH IN CULTURED WHISKER FOLLICLES

Inasmuch as hair follicles are difficult to maintain in culture, the s tudy of hair biology using cultured hair follicles has met with only l imited success. In our attempts to solve the problem of follicle degen eration, we cultured follicles at the air-surface interface on a modif ied collagen matrix (Gelfoam). In follicles cultured at the air-surfac e or submerged, we examined follicular morphology, hair shaft growth, sulfotransferase levels, cysteine incorporation, an expression of a ti ssue inhibitor of metalloproteinase (TIMP), and ultra-high sulfur kera tin (UHSK). Follicles cultured at the air-liquid interface produced a 2.7-fold increase in hair growth and maintained an anagen-like morphol ogy. Substrates such as nylon mesh seeded with fibroblasts, Full Thick ness Skin(R), or 5-mum polycarbonate filter also supported hair growth , whereas Gelfilm, GF-A glass filter, filter paper, or 1-mum polycarbo nate filter did not. The UHSK expression was significantly higher in t he air-liquid interface cultures compared to the submerged culture. Se veral potassium channel openers, including minoxidil, a minoxidil anal og, and the pinacidil analog (P-1075), all stimulated significant cyst eine incorporation in follicles. Minoxidil and its analog specifically preserved the follicular root sheath, in contrast to P-1075 which did not, indicating a difference in the two drug types. The preservation of the root sheath was measured by increased TIMP expression and sulfo transferase activity and indicates that the root sheath is a target ti ssue for minoxidil. Our results show that follicles cultured at the ai r-liquid interface maintain a better morphology and produced greater h air growth than follicles cultured on tissue culture plastic.