Fig. 1

Culture of human HFSCs under standard 2D culture conditions. a After microscopic separation combined with enzyme digestion, the remaining hair follicle tissue containing the outer root sheath was obtained. Scale bars: 200 µm. b Flow cytometry analysis showed that the proportion of CD200⁺a6⁺ HFSCs in freshly isolated HFSCs from human hair follicles was 14.6% ± 3.7% (± SD). c The growth status of HFSCs was examined using a microscope in passage 0 (P0) and passage 2 (P2) under standard 2D culture conditions. Scale bars:200 µm. d, e Flow cytometry was performed on day 7 after culture. The results showed that CD200⁺a6⁺ HFSCs were significantly down-regulated under standard 2D culture conditions, and that no CD200⁺a6⁺ HFSCs were present in P2 (mean ± SD; n = 3; **p < 0.01, Student’s t-test). f, g Immunofluorescence staining was conducted on day 7 after culture, and the results showed that the proportion of CD200⁺a6⁺ cells decreased significantly under standard 2D culture conditions. No red-stained CD200⁺ HFSCs were present at P2 (mean ± SD; n = 4; **p < 0.01, Student’s t-test). DAPI (blue); CD200 (red); a6 (green); Scale bars: 20 µm