In vitro Culture and Histological Characterization of Extracted Human Hair Follicles

Background: In vitro-cultured hair, follicles can serve as an excellent model system for exploring the hair follicle biology as well as drug delivery targets. In this study, we aimed to investigate how to maintain whole human hair follicles in vitro and histologically characterize the hair follicles thereof. Methods: Donated hair follicle specimens from hair transplant operation were cultured in vitro using a medium consisting of Williams` medium E, L-glutamine, insulin, hydrocortisone, penicillin, streptomycin, and amphotericin B. The growth of hair follicles was examined daily using a digital microscope. Their histological features were studied at day 0, 7, and 14 to characterize the changes of hair follicles maintained in culture. Results: Cultured hair follicles continued to grow at a rate of about 200 μm/day during the first four days. Then the growth rate declined and stopped after an average (range) of 8.4 (7-11) days in culture. Histological study showed an upward regression of the hair follicles with scattered apoptosis of outer root sheath cells, resembling the follicles in a catagen stage. Conclusion: Human hair follicles can be cultured in vitro for at least 7 days before progressing to catagen.