We previously reported on hair-shaft elongation from human scalp and mouse skin in Gelfoam® histoculture [9, 10]. However, in the Gelfoam® histoculture of human scalp skin, hair-shaft growth was 0.86 ± 0.18 mm over 5 days [9] and 0.7–1.10 ± 0.22 mm over 5–14 days of the histocultured mouse skin [10]. Isolated human hair follicles in Gelfoam® histoculture grew only 0.49 ± 0.06 mm for 5 days [9].
The present report demonstrates improved hair shaft growth of isolated hair follicles on Gelfoam®. Isolated free-floating follicles were previously observed to produce elongating hair shafts but apparently were not viable for very long periods of time [12, 13]. Gelfoam® supports both hair shaft and nerve growth [8] of isolated whisker follicles and maintained viability of the follicles for at least 63 days, much longer than free-floating follicles, which can enable long-term experimentation. Thus, the present report demonstrates an improvement of hair follicle histoculture with increased hair-shaft growth, increased period of histoculture, as well as increasing stem cell fluorescence intensity and fluorescent area for at least 63 days. The strong increase in hair-follicle stem-cell ND-GFP fluorescence indicates increased activity and the proliferation of the stem cells. It is notable that the greatest increase in stem cell fluorescence is during the period of hair-shaft elongation (Figs (Figs22 and and33).
Future experiments will explore the use of Gelfoam® hair follicle histoculture for enhancement of hair growth by experimental agents which could be tested over long periods of time which provides the opportunity to evaluate long-term efficacy and to determine on the rate and extent of hair-shaft elongation. Gelfoam® histoculture of whisker follicles is useful to study both hair shaft and follicle sensory nerve growth [8] over a long time period. Future experiments will also investigate the relationship of nestin-expressing stem cell activity and proliferation to hair-shaft elongation and why the elongation ceases before day 20.