The alpha 1 beta 1 integrin is expressed during neointima formation in rat arteries and mediates collagen matrix reorganization

Remodeling of the extracellular matrix by activated mesenchymal cells (myofibroblasts) is a critical aspect of wound repair in all adult organs. Collagen-dependent gel contraction, a process requiring integrin function, is an established in vitro assay thought to mimic in vivo matrix remodeling. Numerous data have implicated the alpha 2 beta 1 integrin in various cell types as the primary collagen receptor responsible for collagen gel contraction. However, evidence from the literature suggests that the major collagen binding integrin expressed on mesenchymally derived cells in situ is the alpha 1 beta 1 integrin, not the alpha 2 beta 1 integrin. In this report, we use a rat vascular injury model to illustrate that the alpha 1 beta 1 integrin is the major collagen receptor expressed on vascular smooth muscle cells after injury. Using two smooth muscle cell lines, expressing either the alpha 1 beta 1 integrin alone or both the alpha 1 beta 1 and alpha 1 beta 1 integrins, along with Chinese hamster ovary cells transfected with the alpha 1 integrin, we demonstrate that alpha 1 beta 1 supports not only collagen-dependent adhesion and migration, but also gel contraction. These data suggest that in vivo the alpha 1 beta 1 integrin is a critical collagen receptor on mesenchymally derived cells potentially involved in matrix remodeling after injury.