In Vitro Differences Between Keratinocyte Stem Cells and Transit-Amplifying Cells of the Human Hair Follicle

The study compared keratinocyte stem cells and transit-amplifying (TA) cells from human hair follicles, revealing that stem cells, located in the bulge area, had greater clonogenicity, adhered more rapidly to collagen IV, and expressed higher levels of β1 integrin compared to TA cells from the hair matrix. Stem cells also had a longer in vitro lifespan, forming colonies until passage 6, while TA cells differentiated by passage 3. TA cells exhibited 7-fold greater mobility than stem cells. These findings highlighted the distinct phenotypes and behaviors of hair follicle stem cells and TA cells, providing insights into their roles in hair follicle renewal and differentiation, and potential applications in regenerative medicine.