Cryopreservation of human hair follicles for organ culture

Extracted human hair follicles are critically useful specimens for various purposes, ranging from basic research, such as skin and hair follicle biology, to applications, including hair drug testing and cell sources for regenerative medicine. The ability to cryopreserve hair follicles enables their use in large quantities at any desired time. This study investigated the feasibility of human hair follicles after cryopreservation using two approaches: slow freezing and vitrification. Slow freezing resulted in severe cell death and loss of hair shaft elongation in subsequent organ culture. Vitrification resulted in less cell death than slow freezing and approximately 75% hair shaft elongation relative to fresh hair follicles. Interestingly, vitrification induced a transition of the hair cycle from the anagen to catagen phase, which is a typical undesirable change in patients with alopecia. This transition was partially suppressed by minoxidil treatment in organ culture. These results suggest that, under the conditions tested, the vitrification protocol (15% DMSO and 15% EG with rapid cooling in liquid nitrogen) preserves human hair follicles substantially better than the slow freezing protocol (10% DMSO with cooling at 1 °C/min), and vitrification may provide beneficial hair follicle samples for testing hair drugs to alleviate the transition to the catagen phase.