ocular safety of intravitreal anti connective tissue growth factor neutralizing antibody

purpose: to determine the maximum safe dose for intravitreal injection of anti-ctgf (ivac) in rat eyes in order to decrease gene and protein expression of connective tissue growth factor (ctgf) for the treatment of ocular fibrotic disorders. methods: forty-five lister hooded pigmented rats were divided into one of the five groups of 9 rats; 4 out of these 5 groups received different doses of ivac (2μl); 10 mg/ml in group b, 20 mg/ml in group c, 50 mg/ml in group d, and 100 mg/ml in group e. the sham group (group a) received 2μl of normal saline. full field electroretinography (erg) was performed at baseline and on days 7 and 28 after the ivac injection. at end of the study, the animals were euthanized and the injected eyes were subjected to routine histopathology, immunohistochemistry for glial fibrillaryacidic protein (gfap), and terminal transferase dutp nick end-labeling (tunel) assay. results: in group e, baseline scotopic rod b-wave amplitude and maximal combined b-wave amplitude were 111.89±71.2 μv and 178.57 ±55.58 μv, respectively, which significantly reduced to 79.31 ± 52.59 μv and 128.73 ± 41.61 μv, respectively, after 28 days (p<0.05). there was no significant reduction in the amplitudes of erg in other groups that received lower doses of anti-ctgf antibody and in the sham group. reduction in oscillatory potentials was also noticed after 7 and 28 days in group e (46.24±18.05 μv at baseline, 30.03±15.95 μv on day 7, p<0.05 and 29.79±12.20 μv on day 28, p<0.001) but not in other groups. photopic erg responses did not show any significant change in any groups. imagej software cell counter indicated that retinal ganglion cells were significantly decreased in group e as compared to other groups. gfap immune reactivity was not significant in any of the groups. tunel test showed inner retinal neural cell apoptosis only in group e. conclusion: erg, histopathologic, and apoptotic assays revealed no toxic effects of 10 to 50 mg/ml of ivac in the rat eyes. the injection of 100mg/ml ivac, however, caused significant deleterious effects on both retinal function and structure as demonstrated by functional tests, and histopathologic and tunel findings.