STUDIES IN-VITRO ON THE ROLE OF ALPHA-V AND BETA-1 INTEGRINS IN THE ADHESION OF HUMAN DERMAL FIBROBLASTS TO PROVISIONAL MATRIX PROTEINS FIBRONECTIN, VIBRONECTIN, AND FIBRINOGEN

Fibroblasts that migrate into a wound during the early stages of repai r use cell surface integrins to interact with extracellular molecules as they move away from the interstitial matrix of normal tissue and in to the provisional matrix of the wound. Therefore, to understand a cri tical phase of wound healing, it is necessary to understand the detail s of integrin involvement. Normal adult human dermal fibroblasts in cu lture express many receptors for the provisional matrix proteins fibro nectin, vitronectin, and fibrinogen, including the integrins alpha 3 b eta 1, alpha 4 beta 1, alpha 5 beta 1, alpha v beta 1, alpha v beta 3, and alpha v beta 5. We used quantitative flow cytometry to estimate t he relative numbers of these receptors and immunoprecipitation to conf irm the expression of alpha v beta 1. Adult human dermal fibroblasts p rimarily use beta 1 integrins, alpha 4 beta 1, alpha 5 beta 1, and pos sibly alpha v beta 1, for attachment to fibronectin. alpha v beta 3 an d perhaps other integrins containing the alpha v subunit serve fibrobl asts as secondary or auxiliary receptors for fibronectin. In contrast, these cells use alpha v integrins but probably not beta 1 integrins f or attachment to vitronectin, alpha v beta 3 and alpha v beta 5 appare ntly act in concert to mediate attachment to vitronectin, and these tw o integrins may perform different functions during wound repair. Fibro blast adhesion to certain preparations of fibrinogen occurs, at least partially, through the small amount of fibronectin present in the prep arations. Fibroblast attachment to fibrinogen purified free of fibrone ctin also occurs, and that was demonstrated with a sensitive new assay called electrical cell-substrate impedance sensing. Fibroblast attach ment to pure fibrinogen can be inhibited by RGD peptide, suggesting th at integrins are involved.