Fig. 1

Cell characterization. (A) A representative phase-contrast microscopy of the mesenchymal cells isolated from human fetal lungs at both 16- and 18-week of gestation showing typical spindle-shaped morphology. (B) The results of flow cytometric identification of the cells expressing molecular markers of mesenchymal stem cells (> 95% expression; positive expression) and hematopoietic lineage (< 2% expression; negative expression); representative histograms are presented in supplementary Fig. S1 and Fig. S2. (C) Representative photomicrographs showing functional capacity of isolated human fetal lung mesenchymal cells to differentiate into osteogenic (Alizarin Red staining) and adipogenic (Oil Red O staining) phenotypes. White arrowhead points to a red-stained lipid droplet. (D) Cell replication analysis of the mesenchymal cells isolated from 16- and 18-week human fetal lungs showing the results of flow cytometric measurement of the percent of the cells in each phase of cell cycle (representative histograms are presented in supplementary Fig. S3) and the population doubling levels of these cells. Abbreviations: 16w, 16-week; 18w, 18-week; hFL-MSCs, human fetal lung mesenchymal stem cells; PDL, population doubling level.

Data are mean ± SD; *p < 0.05, **p < 0.01 (Only statistically significant differences between groups are indicated in the figure).