Effects of bevacizumab on neuronal viability of retinal ganglion cells in rats

The aim of this study was to investigate the effects of single and repeated intravitreal injections of bevacizumab on various retinal layers focusing more on retinal ganglion cells (RGCs) in healthy rats. Male Wistar rats were treated with intravitreal injection of bevacizimab (4 μL) within right eye. Left eyes were injected with the same volume of balanced salt solution (BSS) and used as control. Ten rats received a single intravitreal injection and ten rats had three injections, with seven days time interval. Histological and immunohistochemical evaluations and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay were performed in order to find out if some degree of apoptosis could occur on RGCs. Histological and immunohistochemical analyses showed that bevacizumab induces neuronal loss compared to control eyes, after multiple injections. RGCs apoptosis after multiple treatments was demonstrated to occur by TUNEL, Annexin V and Bax assays. The loss of ganglion cells following repeated injections was confirmed and quantified by the decrease in RGC specific protein Brn3a measured by western blotting in ten additional rats. The present results need to be considered when multiple intravitreal injection of bevacizumab are performed to treat retinal diseases.

► Multiple intravitreal injections of bevacizumab produce retinal toxicity.
► Immunohistochemistry demonstrates neuronal loss in several retinal layers.
► The retinal ganglion cell layer is mostly affected.
► Bevacizumab-induced cell loss occurs mainly through apoptosis.