Abstract
Purpose: :
Previous studies suggested that the RPE can encapsulate choroidal neovascularization (CNV) in some cases of AMD and reduce severe vision loss. We studied mice with a knockout to an isoform of Rap1 (Rap1b), which has been reported to be important in junctional assembly and integrity of epithelial cells, to address the question whether Rap1 was important in containing CNV.
Methods: :
We used a well accepted laser induced model for CNV. A 532nm OcuLight GL laser (0.1sec, 100um, 150mW) (Iridex, CA) was used to cause laser injury in adult Rap1b knockout or control C57B16 mice. Four to six laser spots were delivered to each eye. Retinal images were taken using a spectral domain optical coherence tomography unit (sd-OCT; Bioptogen, NC) prior to and 3 and 7 days following laser. Seven days following laser injury, animals were euthanized and choroidal flat mounts were dissected and stained using isolectin B4 (GS-1B4, Alexa Flur 568, Invitrogen, CA). Confocal microscopy (Olympus, Japan) and image J were used to obtain CNV volumes for each lesion. The images were measured by two masked reviewers. Lesions with obvious hemorrhage or bridging of CNV were excluded from analysis. Lesions from each eye were averaged and analyzed using the Student t test.
Results: :
In both wild-type and knockout mice, disruption of the layers of the retina and Bruch’s membrane/RPE layers were found by sd-OCT. Over the ensuing days, less edema was noticed. CNV volume was significantly larger in knockout mice (749009± 364063 pixels) as compared to wild type (236913±143627; P<0.01).
Conclusions: :
The volumes of laser induced CNV in Rap1b-deficient mice were larger than those in control wild type mice. Rap1b may be important in containing the size of CNV induced by laser injury and warrants further study.
Keywords: choroid: neovascularization • laser