Extracellular matrix (ECM) has various kinds of types and important biological function.The important role of ECM during choroidal neovascularization (CNV) arouse attention.Intercellular adhesion molecule-1 (ICAM-1), which is one of ECMs, involves in the formation of blood vessels, but the relationship between CNV and ICAM-1 is still unknown.

This study was to observe the dynamic expression of ICAM-1 in krypton laser-induced CNV and explore the effect of ICAM-1 on CNV.

Forty-eight healthy male clean BN rats were randomly divided into post-photocoagulation 1-week group, 2-week group, 3-week group, 4-week group, 5-week group, 6-week group, 7-week group and 8-week group.Laser-induced CNV models were monocularly established and the fellow eyes served as the normal controls.Fundus fluorescein angiography (FFA) was carried out to quantitate the leakage degree (absorbency). The eyeballs were enucleated on various time points, and CNV areas were assessed by hematoxylin and eosin staining; immunohistochemistry and in situ hybridization assay were employed, respectively, for the detection of relative expression levels of ICAM-1 protein and mRNA (absorbency). The use and care of the animals complied with the Regulations for the Administration of Affair Concerning Experimental Animals by State Science and Technology Committee.

After laser photocoagulation, the retinal inner and outer nuclear layers were ruptured and invaginated.Disruption of Bruch membrane and macrophages migrating to the photocoagulation zone were seen under the optical microscope.The proliferation of fibroblasts and vascular endothelial cells was exhibited.ICAM-1 protein was mainly expressed in vascular endothelial cells, retinal pigment epithelium (RPE) cells and macrophages, and ICAM-1 mRNA was mainly expressed in the outer nuclear layer.Statistically significant differences were found in the fluorescence leakage degree, the relative expression levels of ICAM-1 protein and mRNA as well as CNV areas among the groups (F=178.839, 739.077, 2 463.508, 194.434, all at P<0.05). The gradually enlarged CNV area, increased fluorescence leakage, up-regulation of ICAM-1 protein and mRNA expressions were matched with the extension of time after photocoagulation and peaked in the post-photocoagulation 8-week group.

The expressions of ICAM-1 protein and mRNA up-regulate upon the increase of CNV area and fluorescein leakage, suggesting that ICAM-1 might play an important role in CNV development.

Choroidal neovascularization; Intercellular adhesion molecule-1/metabolism; Immunochemistry; In situ hybridization assay; Disease model; Brown Norway rats