Ocular Safety of Intravitreal Connective Tissue Growth Factor Neutralizing Antibody

ABSTRACT

Purpose: To detect the safety of intravitreal injection of anti-connective tissue growth factor (CTGF) (IVAC) in rat eyes in order to apply this neutralizing antibody for experimental animal studies.

Methods: Forty-five Lister Hooded male pigmented rats were divided into five groups that received IVAC (2 μl) corresponding to the doses of 10 (B), 20 (C), 50 (D), and 100 μg/ml (E), equal to 1.25, 2.5, 6.25, and 12.5 µg/ml of antibody concentration in rat vitreous, respectively. The sham group (A) received 2 μl of normal saline. Full field electroretinography (ERG) was performed at baseline and on days 7 and 28 after IVAC. The animals were euthanized and the corresponding eyes were subjected to routine histopathology, immunohistochemistry for glial fibrillary acidic protein (GFAP), and terminal transferase dUTP nick end-labeling (TUNEL) assay.

Results: Scotopic rod b-wave amplitude and maximal combined b-wave amplitude were 111.89 ± 71.2 and 178.57 ± 55.58 μV, respectively, at baseline which significantly reduced to 79.31 ± 52.59 and 128.73 ± 41.61 μV, respectively, after 28 days in group E (p < 0.05). There was no significant reduction of amplitudes in other groups with lower doses of anti-CTGF antibody. 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.

Conclusions: ERG, histopathologic, and apoptotic assays revealed no toxic effects of 10–50 μg/ml of IVAC in rat eyes. Using 100 μg/ml IVAC led to a significant toxic effect in terms of functional, histopathologic, and TUNEL findings.

KEYWORDS:

• Connective tissue growth factor neutralizing antibody
• electroretinography
• GFAP
• intravitreal anti-CTGF
• intravitreal injections
• ocular safety
• TUNEL test

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.