Notably, the reparative effects of hAECs on lung tissue density, collagen content and α-SMA expression only emerged when the cells were delivered during the fibrotic phase of injury at day 14, but not when they were administered earlier at day 7, which is the time point of peak inflammation [10], indicating that hAECs exerted therapeutic effects on the early phase but not the peak phase of inflammation in mouse models of pulmonary fibrosis. The gene discussed is ACTA1; the disease is pulmonary fibrosis.