Abstract
Abstract: :
Purpose: Study the influence of the presence or absence of the ApoE gene on the retinal wound healing process following laser photocoagulation. Method: C57BL/6J (wild type-WT), ApoE deficient (KO) and ApoE 3,4 transgenic mice (TG 3,4), six to eight weeks old underwent krypton laser (50µm spot size, 0.05'', 400mW) after pupil dilatation and ketamine anesthesia. One single lesion located one to two disc diameters nasal to the optic nerve was obtained in both eyes of each mouse. One or two mice from each group were sacrificed on the first day after photocoagulation and every 3 to 4 days thereafter for one month. At random, one eye of each mouse was snap frozen, cryopreserved in OCT and processed for immunohistochemical analysis using specific antibodies directed against GFAP and von-Willebrand factor and for binding to lectin extracted from Bandeiraea simplicifolia. DAPI staining for the visualization of nuclear material was also used. The second eye was preserved in 4% PAF and processed for conventional histology. The entire posterior segment was surveyed while a thorough systematic analysis of the staining and cell pattern within the laser lesion and its immediate vicinity were carried out. Results: Twenty four to 48 hours following laser treatment, a gradual posterior invagination of the retinal inner and outer nuclear layers towards the choroid was observed. This process appeared similar in all four groups of mice. The GFAP positive cells (Muller's and glia) activation was slightly delayed and less prominent in ApoE KO mice when compared to WT or TG mice. There was no detectable difference in the behavior of these types of cells between the WT, TG3 or TG4 mice. No differences between the four groups of mice were evident except for the ganglion cell layer. Conclusion: Retinochoroidal healing following krypton laser photocoagulation includes a posterior invagination of the inner and outer retinal nuclear layers along with a prominent activation of the retinal Muller's and glial cells. The absence of ApoE gene has no influence on the invagination process but appears to influence the activation (and expression) of GFAP positive cells.
Keywords: 316 animal model • 564 retinal development