Abstract
Abstract: :
Purpose: To analyze the retinal vascular network in transgenic SMAA–GFP mice in vivo with scanning–laser ophthalmoscopy (SLO) and angiography, and to investigate potential functional consequences of the abnormal GFP expression by electroretinography (ERG). Methods: SMAA transgenic mice (line E7) feature expression of GFP under control of a smooth muscle α–actin promotor in a number of tissues including the retinal vasculature. Mice of ages up to 14 month were examined in this study. We used the Heidelberg Engineering Retina Angiograph (HRA), a confocal SLO, for the assessment of cellular structures (the vascular walls) by their GFP–driven fluorescence, and the vascular contents by angiography (usually ICG). Functional testing to investigate age–dependent changes was performed with Ganzfeld electroretinography (Toennies Multiliner Vision). Results: In SMAA mice, GFP appears to be expressed in smooth muscle cells and pericytes. In autofluorescence mode (488 nm blue laser stimulus, barrier filter at 500 nm), the arterial side with strong muscular walls dominated the images, but also the venous side could be visualized without application of a dye. There was a remarkable difference between the GFP–marked wall thickness of arteries and their lumen in angiography. Vessels could be followed downto very small branches and capillaries whose walls were in some cases formed by single cells only. The functional examination did not reveal any sign of vascular impairment or retinal degeneration upto an age of 14 months. Conclusions: The SMAA transgenic line E7 is a valuable model for in vivo studies on retinal vessels, and the expression of GFP appears not to cause deficits in retinal function.
Keywords: transgenics/knock-outs • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • electroretinography: non-clinical