Fig. 4

Culture of endometrial epithelial cells with human embryonic stem cell-derived mesenchymal cells. a Microscopic appearance of endometrial epithelial cells with hESCFCs (hESCFC-1, 2, 3) in serial passage. Black bar is 500 μm. b–d Cumulative area of colonies (b), colony formation (number) (c), and area of colonies (d) of endometrial epithelial cells in serial passages with hESCFCs. Error bar indicates SEM. An asterisk means P < 0.05. ns means “not significant”. e Population doubling levels of endometrial epithelial cells when cultured with endometrial stromal cells and hESCFCs. Endometrial stromal cells showed the best feeder activities among these feeder cells (P = 0.015 when comparing with hESCFC-1, P = 0.0177 when compared with hESCFC-2, and P = 0.0035 when comparing with hESCFC-3). Endometrial epithelial cells continued to proliferate on endometrial stromal cells for 81 days. Error bar indicates SEM. Dotted line indicated the observation period until the culture was terminated. f Immunocytochemical staining for endometrial epithelial cells and hESCFCs at passage 4. Endometrial epithelial cells kept positive for pan-cytokeratin with serial passage. The endometrial epithelial cells did not express vimentin. hESCFCs expressed vimentin. Nuclei were stained with DAPI. Yellow bar is 500 μm. Each experiment was done in triplicate. Abbreviation: EMSC, endometrial stromal cells; hESCFCs, human embryonic stem cell-derived feeder cells; SEM, standard error of the mean