Figure 4. MSCs inhibit lung edema and inflammatory cells in HS rats.

Figure 4A, MSCs inhibit interstitial lung edema. Wet-to-dry ratios of lung tissue calculated as described in materials and methods demonstrate that mild edema is produced by HS in rat lungs. (* indicates p<0.05 between LR and LR+MSC). This small increase in edema remains with the administration of LR, but is diminished in animals receiving LR+MSCs, thereby indicating that MSCs inhibit HS induced lung edema. Figure 4B shows H&E staining of MSC treated lungs suggested decreased edema and injury. Representative lung sections from the four groups were stained for H&E. Gross histopathological analysis demonstrates decreased edema and inflammation in MSC treated lungs. HS and HS+LR treated groups show edema and inflammatory infiltrates (see arrows). Figures 4C and 4D show that inflammatory CD68 positive cells are decreased in MSC treated lungs. Lung sections were stained for CD68, a marker of inflammatory monocytes and macrophage infiltrates. Five sections were analyzed per animal (n = 5) and 8–10 high power fields were counted for fluorescent positive (CD68+) cells. Figure 4C shows that CD68+ cells are significantly decreased in MSC treated animals (* indicates p<0.05). MSC treated animals were not significantly different from Shams. Figure 4D shows representative fluorescent images of the CD68+ cells in the lungs. Figures 4E and 4F, Myeloperoxidase positive cells are decreased in MSC treated lungs. Myeloperoxidase (MPO) staining of MSC treated lungs shows decreased MPO positive cells. Representative stained sections are shown in Figure 4F.