Abstract
Purpose: :
RPCs are a therapeutic candidate for retinal degenerative diseases. Here we use in vitro assays to anticipate potential beneficial or toxic influences on arising from exposure to antioxidants and clinically important agents.
Methods: :
Human RPCs were grown under standard proliferation conditions and cultures were treated with one of the following agents: antioxidants (N-acetyl cysteine [NAC], ascorbic acid), local anesthetic (lidocaine hydrochloride), immunosuppressant (cyclosporine A), and corticosteroid (triamcinolone acetonide) at a range of concentrations estimated to overlap and exceed clinically relevant levels. Time course of the testing ranged from 2 hours to 4 days. Outcomes were assessed in terms of cell viability via Cell Counting Kit-3 assay; apoptosis via NucView 488 caspase-3 assay kit.
Results: :
hRPC viability was significantly decreased at 2 days by 10-3 M NAC or higher, whereas concentrations down to at least 10-7 M exhibited toxicity at 4 days. The other antioxidant, ascorbic acid, did not induce toxicity over a broad range and supported hRPC proliferation at many concentrations. The short-acting anesthetic lidocaine was tested at 2 hours and showed toxicity at concentrations of 1,250 ug/ml and higher. Apoptosis trended upward with dose and was notably elevated when the concentration reached 2500 ug/ml. After 4 days in culture, cyclosporin A decreased the viability of hRPCs in a concentration-dependant manner, beginning at 300 ng/ml. This threshold is approximately 5-fold greater than anticipated clinical exposure. Triamcinolone had no discernable effect over 4 days exposure until reaching 100 ug/ml, well in excess of potential clinical exposure.
Conclusions: :
There is marked difference in the response of hRPCs to the antioxidants tested: NAC is toxic to hRPCs, whereas ascorbic acid supports proliferation over a range of concentrations and is useful as a supplement. Concomitant use of lidocaine is permissible, but not at large concentrations. Cyclosporin and triamcinolone do not appear to be toxic to hRPCs until well beyond the clinical range. This latter information suggests that a number of drugs used in association with intraocular procedures will not impact negatively on hRPC viability following intraocular transplantation.
Keywords: retinal degenerations: cell biology • retina • transplantation