gms | German Medical Science

The transmembrane ligand EphrinB2 and its membrane-bound receptor tyrosine-kinase, EphB4, are specifically expressed on arterial and venous endothelial cells, respectively. They are probably involved in angiogenesis. The purpose of this study was to examine the expression of EphrinB2, EphB4 and of vascular endothelial growth factor (VEGF) in a murine model of oxygen-induced retinal neovascularization.

Mice were kept at 75% oxygen between postnatal day 7 and 12. The return to room air induced a relative hypoxia of the retina and mice developed retinal neovascularization within five days. Within this time, retinae were collected to isolate RNA, and EphrinB2, EphB4 and VEGF expression were measured using quantitative RT-PCR.

VEGF showed a statistically significant increase of expression during the first 12 hours of relative hypoxia. Compared to VEGF, the upregulation of EphrinB2 started with a delay and reached a maximum (factor 2,5) at 48 hours. Subsequently, both factors displayed a slow decrease of transcription over the following days. EphB4 expression, however, did not change statistically significantly during the whole time.

In the mouse, EphrinB2 expression is statistically significantly increased during development of angioproliferative retinal disease while expression of its receptor EphB4 is constant. VEGF is expressed earlier than EphrinB2 pointing to VEGF being involved in the regulation of EphrinB2-gene expression.