Abstract
Abstract: :
Purpose: We have previously generated smooth-muscle-alpha-actin GFP (SMAA-GFP) mice whose smooth muscle cells and some pericytes express GFP. To better understand the interaction between pericytes and newly formed vessels, we have investigated the expression patterns of GFP positive cells in retina of these mice during physiological and pathological retinal neovascularization. Methods: Retinal neovascularization was induced by treating postnatal day 7 (P7) SMAA-GFP mice in 75% oxygen for 5 days (P12) and returning them to room air for 5 days (P17). Those hyper-oxygen treated retina of P12 and P17 mice as well as untreated retinas from P2 to P17 mice were dissected, immunostained and examined with regular or confocal fluorescent microscopy. Retinal vessels were visualized with CD31 or isolectin-IB4. Astrocytes were identified with GFAP. Results: In SMAA-GFP mice, the developing capillary networks of early postnatal retina were almost entirely covered with GFP positive cells. In contrast, only a portion of the mature capillaries in adult retina remained GFP positive. In hyperoxia treated mice, the surviving capillaries in P12 retina and the proliferating new capillaries in P17 retina are all associated with pericytes. Conclusion: Proliferating vessels from both physiological and pathological neovascularization appear to acquire pericytes immediately. The SMAA promoter seems highly active in newly recruited pericytes but varies significantly among pericytes associated with mature capillaries.
Keywords: 566 retinal neovascularization • 614 vascular cells • 606 transgenics/knock-outs