Figure 1.

Demonstration of endothelial cell-derived fibroblasts in fibroblast cultures established from lung parenchyma of mice with bleomycin induced pulmonary fibrosis. Fibroblast cultures were established from lungs from mice injected intratrachealy with either normal saline or bleomycin. When the cultures reached confluency they were stained with x-gal to identify the cells from endothelial lineage. Note the absence of x-gal staining cells in the cultures from saline injected control mice (A) in contrast with the marked abundance of x-gal staining fibroblasts in the cultures from bleomycin injected mice (B). The inset in A shows the percentage of x-gal positive cells in four separate samples of cultured fibroblasts from saline injected mice (SLF) compared to eight separate samples of fibroblasts cultured from bleomycin injected mice (BLF). Figures C and D show sequential staining of a fibroblast culture from bleomycin injected mice with x-gal (C) followed by immunocytochemistry for the mesenchymal cell markers type I collagen (red) and α- SMA (green). The arrows indicate cells positive for x-gal, type I collagen, and α- SMA, whereas the arrowheads indicate cells positive for x-gal and type I collagen. Reproduced from reference 26 with permission.