Abstract
Purpose::
An understanding of the pathogenesis of retinal neovascularization and the identification of rational therapeutic targets may be facilitated by knowledge gene expression during the course of neovascularization. This study was undertaken to identify genes showing a consistent change in level of expression at defined timepoints in a reproducible rat model of retinal neovascularization.
Methods::
Newborn Sprague-Dawley rats were exposed to a 14-day course of alternating 24-hour cycles of 50% and 10% oxygen and then removed to room air. Control animals were raised in room air. Animals were sacrificed at P15 (the ischemic phase preceding retinal neovascularization) and P20 (the peak of the proliferative phase of retinal neovascularization). RNA was prepared from three individual retinas harvested from control and oxygen-exposed animals at each timepoint and amplified to generate probe for high-density rat gene microarrays. This entire procedure was performed in 4 independent experiments. Genes/ESTs showing at least a 1.5-fold change in expression in all 4 experimental samples were identified, and their expression level was then analyzed statistically. A subset of genes was selected for confirmatory analysis by quantitative rt-PCR of independent retinal samples from P15 and P20.
Results::
At P15, all experimental runs showed a significant change in expression of 20 genes/ESTs, all of which were upregulated (range of change = +1.6 to +5.3). At P20, all experimental runs showed a significant change in expression of 35 genes/ESTs, of which 26 were upregulated (range = +1.6 to +4.0) and 9 were downregulated (range = -1.6 to -2.6). Significant changes in 5 upregulated genes and one downregulated gene were confirmed by quantitative rt-PCR.
Conclusions::
Our analyses have identified genes putatively involved with early and late phases of retinal neovascularization. These genes may serve as valuable subjects of further study into the pathophysiology of retinal angiogenesis and may represent targets of therapeutic intervention.
Keywords: retinal neovascularization • gene microarray • gene/expression