Abstract
Purpose :
Vascular endothelial growth factor (VEGF)-A/VEGF-receptor (R)-2 signaling is essential for the development of pathological angiogenesis and for the pathogenesis of many retinal disorders. However, it is also important for the homeostasis of healthy blood vessels and is suggested to be an autocrine survival factor for retinal pigment epithelial (RPE) cells. In recent years, combination treatment of anti-VEGF with minimally invasive thermal laser irradiation is introduced as a new therapy option for retinal disorders. In this study, possible influence of VEGF-A/VEGFR2 inhibition on RPE cell responses to sublethal hyperthermia was investigated.
Methods :
Confluent porcine RPE cell culture was heated over 10s by a thulium laser (wavelength: 1940 nm) to a maximal temperature of 43°C, which was previously confirmed as a sublethal heating. Some cultures were irradiated in the presence of anti-VEGFR2, which was added 2h before irradiation in the culture medium. At indicated time points (3h or 24h) after heating, cell viability was investigated with flow cytometry, extracellular VEGF-A with enzyme-linked immunosorbent assay (ELISA), and intracellular heat shock protein (Hsp) 70 with western blotting.
Results :
While sublethal hyperthermia increased the number of vital RPE cells (117±9% of the non-irradiated cells) 24h after irradiation, this effect was significantly reduced under concomitant VEGFR2 inhibition (100±7%). Regarding the influence on intracellular Hsp70, the RPE cultures treated with VEGFR2 inhibitor contained significantly less amount of intracellular Hsp70 (63%) shortly (3h) after irradiation, whereas there was no more difference after 24h.
Conclusions :
Results suggest that VEGF-A/VEGFR2 signaling pathway may be involved in RPE cell viability and in the activation of Hsp70 shortly after sublethal hyperthermia. Although further investigations are necessary, it is important to note, that the VEGF depletive condition may largely affect the RPE cell responses to sublethal retinal laser treatment. In other words, the timing between the injection of anti-VEGF agents and laser treatment might play a role in the treatment effect.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.