vitro, particularly platelets, placenta and spleen, and by human skin and cultured keratinocytes. It has multiple activities, some of which are synergistic for or inhibitory to the activities of other growth factors. It inhibits proliferation of epithelial cells.18 TGF-βactivates extracellular matrix production and seems to be the most responsible for excessive scar tissue formation. Fibroblasts on hypertrophic scars and keloids proved to be more sensitive to and respond to a lower concentration of TGF-β.19 In vitro, TGF-β reduces the collagenase-mediated degradation of wound matrix.
20 Inhibitors of TGF-β reduce scarring.21 Recent studies have indicated that targeting of TGF-β might result in accelerated wound healing and reduced scarring.17,22
A group of receptors called integrins regulate cell attachment in tissue growth, wound healing, and leucocyte extravascular emigration. They are the expression of a family of supergenes. Fibronectin, laminin, and collagen type I are some of the integrin receptor ligands.18 Fibronectin functions to promote cell adhesion,
cell shape and spreading, organization of the cytoskeleton, hemostasis and thrombosis, cell migration, and phagocytosis. In normal conditions skin fibronectin receptors in basal cells were few, but following experimental wounds, when granulation tissue was abundant, greater amounts of fibronectin receptors
were evident in epidermis and fibroblasts.18 Laminin is a multifunctional protein with diverse biological activities. Like
