Expansion of hAEC.

The hAEC grew well in the xenobiotic-free media Epilife until passage 5 (P5) and plateaued thereafter. A similar trend was seen in control cultures grown in DMEM/F12+10% FCS but the cumulative cell number in Epilife was lower than controls (*p = 0.002; A). Cumulative population doubling of hAEC cultured in Epilife media was lower than DMEM/F12+10% FCS (*p = 0.0026; B). hAEC appeared stromal-like at P5 in Epilife and DMEM/F12+10% FCS (C). Stromal-like cells at P4 retained the CFSE label suggesting the stromal cells arose from the labeled P2 epithelial cells (D). Scale bars = 100 µm.