Proliferation rate of OECs and adult stem cells culture in transwell systems and in monoculture. Proliferation rate of (A) ASCs, (B) bmMSCs, and (C) HUCPVCs in monoculture or in co-culture with OECs. Proliferation rate of OECs in monoculture or in co-culture with (D) ASCs, (E) bmMSCs, and (F) HUCPVCs. Values are shown as mean±standard deviation (n=3 samples of 2×104 adult stem cells and 1×105 OECs/sample, **P<0.01; ***P<0.001).