Growth factors: Importance in wound healing and maintenance of transparency of the cornea

The mechanism of corneal wound healing has not been clarified yet. However, evidence has accumulated that various kinds of growth factor such as epide rmal growth factor (EGF), fibroblast growth factor (FGF), transforming grow th factor (TGF). keratinocyte growth factor (KGF), hepatocyte growth factor (HGF), platelet-derived growth factor (PDGF) and insulin-like growth facto r (IGF) play a key role in corneal wound healing. For example, these growth factors are expressed in the corneal epithelial cells. keratocytes and end othelial cells, and their receptors are expressed in the corneal cells. Fur thermore. these growth factors promote the proliferation of corneal cells a nd induce the migration of corneal cells. In addition to the growth factors. inflammatory cytokines such as interleuk in (IL)1. IL-6 and TNF-alpha are involved in corneal wound healing. These c ytokines are expressed in the normal and inflammatory cornea after infectio ns, alkali-burn. etc. where they control the growth of corneal cells and in duce the migration of corneal cells. Thus. a number of growth factors and cytokines function in the regulation o f corneal cell proliferation and in the maintenance of corneal transparency . (C) 1999 Elsevier Science Ltd. All rights reserved.