Collagen also plays an essential role in the wound healing process. Acting as a tissue scaffold, it is used as a carrier vehicle for cells in tissue engineered products for dermal wound repair and as a carrier vehicle for growth factors in bond repair. Collagen fibers are one of the best scaffolds for cell migration and proliferation. Collagen interact with fibronectin and other adhesion protiens to promote cellular in-growth which speeds up wound healing. Type I collagen has been shown to attract fibroblasts in cell culture and appears to cause directed migration of cells. Drugs, cells, and growth factors use collagen as both the delivery vehicle and structural support for tissue development and in-growth.