Differential effects of epidermal growth factor and interleukin 6 on corneal epithelial cells and vascular endothelial cells

Purpose. Epidermal growth factor (EGF) and interleukin 6 (IL-6) stimulate c orneal epithelial wound healing. When applied to the cornea, these cytokine s act on various types of cells and therefore may induce corneal neovascula rization. We investigated the effects of EGF and IL-6 on cell proliferation and cell migration in rabbit corneal epithelial cells and human umbilical vein endothelial cells (HUVECs). Methods. Corneal epithelial cells or HUVEC s were cultured with EGF or IL-6 in the presence of 1% fetal bovine serum, and the number of cells were counted, or the radioactivity of [H-3]thymidin e-incorporated cells was measured. Monolayered cultured corneal epithelial cells or HUVECs were mechanically wounded, and then the cells were cultured with serum-free basal medium containing EGF or IL-6. After 12 or 24 h, the wounded area was measured. Corneal blocks were cultured with serum-free TC -199 medium containing EGF or IL-6 for 24 h, and then the length of the pat h of the corneal epithelium was measured. Results, Estimated cell count and [3H]thymidine uptake showed that EGF stimulated cell proliferation in both corneal epithelial cells and HUVECs in a dose-dependent manner. Zn contras t. IL-6 did not affect cell proliferation in either cell type. Furthermore, EGF also stimulated cell migration by increasing the monolayer and organ-c ulture system in both cells in a dose-dependent fashion. However, IL-6 stim ulated cell migration only in corneal epithelial cells and not in HUVECs. C onclusion. These results demonstrated that EGF stimulated cell proliferatio n and migration in both corneal epithelial cells and HUVECs. In contrast, I L-6 stimulated only corneal epithelial cell migration and did not affect ce ll proliferation in either cell type or cell migration in HUVECs. These res ults suggest that, when applied to the cornea, EGF might induce corneal neo vascularization, and IL-6 probably would not.