Microphthalmia, persistent hyperplastic hyaloid vasculature and lens anomalies following overexpression of VEGF-A188 from the αA-crystallin promoter

PURPOSE During growth of the embryonic eye, dose- and site-specific expression of heparin-binding growth factors is critical for the formation of an appropriate vascular supply. Overexpression of vascular endothelial growth factor-A(188) (VEGF-A(188)), a strongly heparin-binding, endothelial-specific mitogen, leads to severe disturbance of vascular and overall ocular morphology. This study aimed to evaluate the effects of VEGF-A(188) overexpression on growth of ocular tissue components. METHODS Stereological and immunohistochemical methods were employed to identify the vascular profiles, ocular tissue proportions, and cell types in VEGF-A(188) transgenic mice and compare them with wild-type mice. RESULTS In VEGF-A(188) transgenic mice, both lens tissue and total ocular volume were reduced, whereas cross-sectional areas of hyaloid blood vessels, retina, iris, and optic stalk tissues were significantly increased compared to wild-type mice. Endothelial and pericyte cell numbers in the hyaloid vasculature of transgenic mice were increased three fold, with pericytes assuming their characteristic extraluminal position. CONCLUSIONS Overexpression of VEGF-A(188) in the murine lens results in microphthalmia, in addition to hypertrophy and persistence of the hyaloid vasculature. This is similar to the human disorder persistent hyperplastic primary vitreous (PHPV). The murine model is a useful, experimental paradigm for investigation of this condition.