SOLUBLE AND INSOLUBLE FIBRONECTIN INCREASES ALVEOLAR EPITHELIAL WOUND-HEALING IN-VITRO

Adhesive interactions between cells and extracellular matrix proteins are important in cell attachment, migration, and proliferation. The pr esent work defines the role of fibronectin (soluble and insoluble) com pared with type I and type IV collagen on in vitro alveolar epithelial wound healing. Repeated video microscopy experiments demonstrated tha t the half-time of wound closure was decreased in the presence of solu ble fibronectin (6.6 +/- 2.1 vs. 17.4 +/- 0.8 h in serum-free medium, P < 0.05). Video microscopy, electron microscopy, and vinculin distrib ution demonstrated the contribution of two main events during the repa ir process: the migration of epithelial cell sheets and the spreading of the cells. During the wound healing, the internuclear distance betw een two adjacent cells at the migrating edge of the wound was signific antly increased 10 h after wounding in the presence of soluble fibrone ctin (67 +/- 3.0 vs. 45 +/- 1.5 mu m in serum-free medium, P < 0.05), indicating that cell spreading is involved as part of the mechanism fo r wound closure. Compared with type I and type IV collagen, insoluble fibronectin was the most potent stimulus for alveolar type II cell mot ility and wound healing in the absence of other serum factors. These r esults demonstrate that alveolar epithelial wound healing can be modul ated in vitro by the composition of the extracellular matrix, an effec t that may be mediated by changes in cell shape.