COL1A1 and pulmonary fibrosis: Regarding the expression of pulmonary fibrosis markers, Col1a1, Col1a2, and α-SMA mRNA levels were significantly decreased in the hUC-MSCs combined with the P30 group compared with the model group (Fig. 3G–I, p < 0.01, n = 3), where the reduced levels of Col1a1 and Col1a2 were significantly different compared to the P100 group alone, while the levels of α-SMA compared to the P100 group tended to be lower (p = 0.09).