Transgenic expression of leukemia inhibitory factor (LIF) blocks normal vascular development but not pathological neovascularization in the eye.

PURPOSE Vascular development in the eye has been described as a complex process involving both vasculogenesis and angiogenesis. Multiple cell types are involved in the process including angioblasts, vascular endothelial cells, astrocytes, pericytes, and Muller glial cells. This suggests that multiple growth factors and cytokines are required to regulate retinal vascular development. Leukemia inhibitory factor (LIF) is a member of the interleukin 6 family of cytokines. LIF is expressed during inflammation and has been reported to affect vascular development in culture; however, its effects in vivo have not been demonstrated. The purpose of this study was to determine how LIF could regulate ocular vascular development. METHODS We have analyzed ocular vascular development in transgenic mice that express LIF in the ocular lens from embryonic day 11. RESULTS In transgenic mice, LIF reduced development of embryonic vasculature in the eye, and inhibited retinal vascular development. Inhibition in vivo was independent of vascular endothelial cell growth factor (VEGF) expression. In older transgenic mice, the absence of a retinal vasculature resulted in retinal ischemia and elevated VEGF levels. The upregulation of VEGF resulted in the proliferation of pathological vascular membranes in the vitreous and neovascularization penetrating the retina, which in turn resulted in tractional retinal detachment. CONCLUSIONS LIF is a potent inhibitor of retinal vascular development. These transgenic mice will be useful as a model of persistent fetal vasculature and to study the mechanism for the development of neovascular membranes in the vitreous and could be used to develop inhibitors of tractional detachment.