Lung Inflammation Determines Response to hMSCs. BAL fluid was obtained from mice treated with hMSCs just prior to challenge and initiation of inflammation (pre-) or 3 days after initiation of inflammation (post-). BAL differentials were obtained from each animal using cytospins and Wright-Giemsa stain. Neutrophil counts are in panel A, lymphocytes in panel B, monocytes in panel C and eosinophils in panel D. The first bar represents the differential in the model without hMSCs. No difference was observed in levels of neutrophils or lymphocytes after hMSC treatment. Pre-challenged mice had a decrease in eosinophils (panel D, n = 4, p = 0.05) compared to control mice. This decrease in eosinophils was amplified at post-treatment with hMSCs. Additionally, post-treatment mice had a significant increase in localized levels of monocyte/macrophages (panel C, n = 2, p = 0.05, 4 animals used in each group for each experiment).