Abstract
Abstract: :
Purpose: To study plasma levels of vascular endothelial growth factor (VEGF), its receptors Flt–1 and Flk–1, Tie2 (an endothelial–specific receptor tyrosine kinase) and E–selectin (an inducible leukocyte adhesion molecule specifically expressed by endothelial cells) in premature infants. To search for changes in plasma levels at onset of retinopathy of prematurity (ROP). Methods: Residual blood samples of 68 preterm infants (23 to 32 weeks of gestational age) were obtained between age 1 and 15 weeks. 47 infants had no ROP, 21 developed ROP (grade1–3). Plasma levels of VEGF, Flt–1, Flk–1, Tie2, and E–selectin were measured with a sandwich–enzyme–immunoassay technique using factor–specific monoclonal mouse antibodies. We evaluated the time course of plasma concentrations and compared plasma levels between infants with and without ROP. Since the number of available blood samples varied among patients, the statistical analysis was supported by kernel smoothing analysis. Results: ROP patients had raised plasma levels of Flk–1, Tie2 and E–selectin compared to prematures without ROP. Flt–1 showed slightly raised plasma levels in ROP, whereas VEGF levels were similar in both groups. Comparing a selected time course (32 to 36 weeks of gestational age) between the two groups, E–selectin increased significantly only in ROP and decreased in non–ROP patients (p<0.001). Tie2 and E–selectin plasma levels increased markedly in both groups during the time course. Conclusions: In this study, preterm infants who developed ROP demonstrated elevated plasma levels of Flk–1, Tie2 and E–selectin as compared to preterm infants without ROP. It has yet to be determined whether measurements of angiogenic plasma levels may identify infants before they develop ROP.
Keywords: retinopathy of prematurity • retinal neovascularization • clinical laboratory testing