Simulated Microgravity Damage in Human Retinal Pigment Epithelial Cells

Abstract

Abstract: : Purpose: To mimic the stress and to determine the potential damage to the human retina that occurs from weightlessness during space flight using simulated microgravity. Methods: Human retinal pigment epithelial (hRPE) cells were subjected to simulated microgravity for 24 hours using a NASA–designed RWV bioreactor. Single stranded breaks in hRPE DNA induced by simulated gravity were measured using the Comet Assay. In addition the production of the inflammatory mediator prostaglandin E₂ (PGE2) was measured in these cells 48 hours after the simulated microgravity exposure.Results: Simulated microgravity induced single stranded breaks in the hRPE DNA that were not repaired in 48 hours. Furthermore, prostaglandin E₂ was dramatically increased 48 hours after the initial microgravity damage indicating an inflammatory resonse. There was less DNA damage and no prostaglandin E₂ release with microgravity in hRPE cells pretreated with the anti–inflammatory agent cysteine. Conclusions:Space travel subjects the human eye to the stress of both solar/cosmic radiation and microgravity inducing both early cataracts and retinal degeneration. Simulated gravity has allowed us to measure microgravity induced damage independent of radiation damage. We determined microgravity alone can induce DNA damage and an inflammatory response in human retinal pigment epithelial cells. We have previously found that cyteine and its derivatives suppress radiation damage to the both the lens and retina. (Roberts et al. 1991, Photochem. Photobiol. 53, 33–38). Our present work suggests that these same derivatives may also suppress the inflammatory damage induced by microgravity. These views are independent of the views of the FDA.

Keywords: inflammation • oxidation/oxidative or free radical damage • radiation damage: light/UV