hMSCs attenuate LPS-induced lung inflammation in immunocompetent mice. BALB/C mice were treated with LPS or PBS via oropharyngeal aspiration (OA) and four hours later 5 × 105 hMSCs and HLFs or PBS as controls, were delivered by OA. Differential cell counts, myeloperoxidase (MPO) enzyme activity assay and ELISA for MIP-2 were performed on BAL fluid samples collected 24 h after LPS exposure. Total cells (a), neutrophils (b), myeloperoxidase (MPO) activity (c) and MIP-2 levels (d) were all significantly reduced in LPS-exposed lungs after treatment with hMSCs. HLFs had no effect on any of these measures. Data are expressed as mean ± SEM (n = 6 per group). *P < 0.05 compared with LPS + PBS treated mice; † P < 0.05 compared with LPS + HLF treated mice, and ‡ P < 0.01 versus mice treated with PBS + PBS.