Abstract
Purpose:
Vitreous injections of ranibuzumab, an antibody fragment against the vascular endogenous growth factor type A (VEGF-A), are largely used against neovascularisation and edema occurring both in age-related macular degeneration and diabetic retinopathy. VEGF-A was recently reported to exert a neuroprotective effect on RGCs in different pathological models. We here report that purified retinal ganglion cells (RGCs) can produce VEGF-A in culture to promote their own survival. We further show that VEGF antibodies, including lucentis, can suppress this VEGF autocrine effect on purified RGCs
Methods:
RGCs from the adult rat retina were purified by immunopanning and seeded in a 96-well at different cell densities (from 8 000 to 50 000 cells/well) and cultured in a serum deprived medium. After 6 days in vitro (DIV), culture media were harvested in order to measure the amounts of VEGF-A164 by ELISA. After their calceinAM labeling, viable RGCs were counted on automated platform d to quantify RGC survival.
Results:
After 6 DIV the medium used for RGC culture was found to contain detectable amounts of VEGF-A164. Interestingly, the VEGF-A concentration was correlated to the RGC initial seeding density. Concentrations of VEGF-A were even increasing in an exponential manner with the number of surviving RGC cells. To assess if VEGF was contributing to the RGC survival, the rabbit polyclonal antibody against murine VEGF-A164 was applied in the RGC culture medium (2 µg/ml for 6 DIV). As a consequence, measured VEGF-A164 concentrations were significantly reduced and the RGC survival was decreased significantly by 52%. Similarly, application of different concentrations of Lucentis (2, 50, 150, 500 and 1000 µg/ml) on RGC cultures reduced the VEGF-A amounts into culture medium. This effect was associated to a dose-dependent decrease of the RGC survival.
Conclusions:
These data showed that RGCs are able to produce VEGF-A in culture in order to maintain their own survival. This autocrine neurotrophic effect was neutralized by VEGF-A antibodies, including ranibuzumab,. These results raise questions on anti-VEGF strategies.
Keywords: 531 ganglion cells •
748 vascular endothelial growth factor •
615 neuroprotection