Modulation of cell adhesion and migration by poly-dispersed-acid-functionalized-single-walled carbon nanotubes in lung epithelial cells

Epithelial cell lining of the lung alveoli is under constant onslaught of airborne pathogens and pollutants that may cause injury and disruption of the epithelial lining. Repair mechanisms involve proliferation and migration of nearby healthy epithelial cells to the site of injury. Using murine LA4 and human A549 lung epithelial cell lines, and in vitro models of cell migration we have examined the modulation of cellular adhesion and migration by poly-dispersed acid-functionalized single-walled carbon nanotubes (AF-SWCNTs). Flow cytometric and confocal microscopy studies indicated that AF-SWCNTs were efficiently internalized by both cell lines and were localized essentially in the cytoplasmic area. In the scratch wound repair model, exposure to AF-SWCNTs blocked the filling of the scratched area of the cellular monolayers in both cells. Behaviour of the cells around the scratch area was examined in by live-cell imaging time-lapse micrography. The results indicated active cell proliferation around the scratch area that was totally blocked by AF-SWCNTs in LA4 cells and significantly inhibited in A549 cells. Cell migration across a porous membrane in transwell assay system also indicated a marked inhibition of migration of both cells across the membrane. Effect of AF-SWCNTs on the expression levels of important cell proteins involved in cell migration and adhesion were examined by western blotting and immunofluorescence staining. Expressions of proteins like {beta}-Catenin, NM-Myosin and Vimentin that play crucial role in cell migration were suppressed in AF-SWCNTs-exposed cells whereas the expression levels of E-cadherin and Claudin-1, involved in cell-cell adhesion remained unaltered. Our results provide an insight into the mechanism of repair of lung epithelial cell layers.