In vitro evaluation of bevacizumab toxicity on a retinal ganglion cell line

The effects of bevacizumab on cell viability and proliferation in a commonly used retinal ganglion cell line, RGC-5, were examined.

RGC-5 cells were exposed to 0.1 mg/ml, 1 mg/ml and 2 mg/ml of commercially available bevacizumab in vitro. To examine the specificity of effects, cells were also cultured with increasing and comparable concentrations of proteins (increasing the concentration of proteins in the culture media by 0.1 mg/ml, 1 mg/ml and 2 mg/ml by using additional fetal bovine serum [FBS] and bovine serum albumin [BSA]). Cell proliferation was assessed using a WST-1 kit, crystal violet staining and bromodeoxyuridine (BrdU) incorporation. Cytotoxic effects were assessed by quantifying cell numbers in proliferation-deficient RGC-5 following exposure to bevacizumab using the WST-1 kit, microscopic examination of cells stained with propidium iodide (PI) cells and flow cytometry for differential staining with PI.

Bevacizumab was not toxic to RGC-5 cells in the tested concentrations. It had a stimulatory effect on cell proliferation. A stimulatory effect on proliferation was also noted when equivalent amounts of proteins from FBS or BSA were used, which suggests that bevacizumab may stimulate proliferation non-specifically by increasing the protein contents of the cell growth environment.

Results suggest that intravitreal injection of bevacizumab could alter the internal milieu of the eye by increasing protein concentrations to elicit functional responses in retinotypic cells. This may be especially relevant for cells outwith the control of vascular endothelial growth factor.