MIGRATION OF BOVINE BRONCHIAL EPITHELIAL-CELLS TO EXTRACELLULAR-MATRIX COMPONENTS

Migration of epithelial cells is an important feature of wound healing. Components of extracellular matrix stimulate migration of other cells, and we hypothesized that basement membrane components, laminin and type IV collagen, stimulate migration of bovine bronchial epithelial cells (BBEC). BBEC cultured for 3 days were used in migration assays using the blindwell chamber technique. BBEC migrated in a concentration-dependent manner to laminin, type IV collagen, and fibronectin, ''Checkerboard'' analysis demonstrated that the migration was directional for each of the components studied. We also evaluated the stimulatory activity of fibronectin fragments. A fragment containing the RGDS peptide was stimulatory of migration while other fragments were much less so, suggesting a role for RGDS-sensitive, integrin-mediated mechanisms. In order to evaluate whether bound or soluble matrix components were required to direct cell migration, we performed haptotaxis assays with precoated filters in the migration chambers. Fibronectin-precoated filters demonstrated significant stimulation of migration, suggesting that some of the migration in our original assays with fibronectin present in the lower chambers could be termed haptotactic. Laminin- and type IV collagen-precoated filters were less active. When insulin was used as a chemoattractant, the fibronectin-precoated filters were more facilitatory of migration than the other matrix coatings. In summary, BBEC can, chemotactically migrate to extracellular matrix components. Thus, the composition of the provisional matrix that forms at sites of epithelial injury may play an important role in the repair processes that occur after injury to the bronchial epithelium.