Therapeutic administration of hMSCs failed to modify pulmonary inflammation or alter acute lung injury in experimental severe influenza.

Eight week old male C57Bl/6 mice were infected with 425 EID₅₀ influenza A/PR/8 virus and administered 5×10⁵ hMSCs (passage 3) on day 2 or day 5 P.I. Mice were sacrificed and BAL was performed on day 7 P.I. (A) Representative images of hematoxylin and eosin stained lung sections demonstrate similar cellularity and lung injury in hMSC treated mice compared to infected controls. (B,C) No significant difference in markers of ALI (total protein or IgM) was observed between mice administered hMSCs on day 2 or day 5 P.I. and infected control mice administered PBS (one-way ANOVA, n = 5/group, representative of 2 independent experiments). Error bars represent interquartile range (IQR). ND = nondetectable.