Abstract
Background: Epithelial-to-mesenchymal transition (EMT) of AEC induced by TGF-β1 or hypoxia (HX) may contribute to pulmonary fibrosis. In animal models of lung fibrosis, administration of allogenic MSC reduced fibrosis and mortality by an unknown mechanism. We hypothesized that MSC may favor alveolar wound healing by preventing hypoxia-induced EMT. We tested in vitro the paracrine effects of MSC on the phenotypic changes of AEC induced by HX.
Methods: Rat AEC cultured on Transwell filters were exposed to HX (3 or 1.5% O2) for up to 12 days in the presence/absence of human MSC on the bottom of the well. Transepithelial electrical resistance (TER) as well as epithelial markers (E-cadherin, ZO-1, TTF-1) and mesenchymal markers (smooth muscle α-actine, vimentin) were assessed by ohm-meter, immunofluorescence and Western blot at d6 and d12.
Results: Exposure of AEC to HX resulted in a dose- and time-dependent decrease of TER and of epithelial marker expression, together with an increase in mesenchymal marker expression. These effects were reproduced by treatment with cobalt chloride and were partially prevented by anti-oxydant drugs (Euk134 or N-acetyl-cystein). Co-culture with MSC (or MSC-conditioned medium) partially prevented the effects of HX regarding TER and phenotypic changes.
Conclusion: These results indicate that MSC alleviate the phenotypic changes of AEC induced by HX in vitro through a paracrine mechanism. Preservation of AEC phenotype by MSC may limit EMT and could partly explain the anti-fibrotic effect of MSC in vivo.
Funded by: College des Enseignants de Pneumologie, Chancellerie des Universites de Paris (Fondation du Legs Poix).
- © 2012 ERS
