Fig. 1

Direct reprogramming of human urine cells into iKCs. a Schematic diagram of the induction of iKCs from human urine cells. Transcription factors (TFs). b Morphological changes of urine cells during direct reprogramming. At passage 3, urine cells were infected with retroviruses encoding BN in urine proliferation medium. BN-infected urine cells were plated in 2% FKGM on a 3 T3-J2 feeder layer to form holoclones. At day 12, the holoclones were picked for further expansion and characterization. Scale bars = 500 μm. c Immunostaining of the stem cell markers KRT15 and ITGA6 in BNK-, BN-, BK-, and NK-infected cells with specific antibodies at day 12 post-induction. Nuclei were counterstained with DAPI. The lower row shows magnified images of the boxed areas in the upper row. Scale bars = 200 μm (upper), 100 μm (lower). d Number of ITGA6⁺KRT15⁺ colonies formed by BNK-, BN-, BK-, NK-, B-, N-, and K-infected cells and urine cells at 12 days post-induction. Cells were seeded at a density of 2 × 10⁴ cells per well in a 12-well plate. Data represent the mean ± SEM. *** P < 0.001. e qRT-PCR analysis of relative expression of stem cell markers in BNK-, BN-, BK-, NK-, B-, N-, and K-infected cells, urine cells, and pKCs at 12 days post-induction. Data represent the mean ± SEM. GAPDH was used as a loading control. B, BMI1; N, △NP63α; and K, KLF4