Effects of an Environmentally Relevant Level of Blue Light Exposure on Cultured RPE Cells

Title Effects of an Environmentally Relevant Level of Blue Light Exposure on Cultured RPE Cells
Author, Co-Author Michael Kozlowski, Nicholas Steinshouer, Zachary Bird, Jason Chmielewski, Joshua Meske, Joshua Baker, Roni Kozlowski, Nicole Putnam
Topic Treatment and Management of Posterior Sgmt Disease
Year
2016
Day
Thursday
Program Number
165149
Room
Ballroom A-B
Affiliation
Midwestern University, Arizona College of Optometry
Abstract

Introduction: It has been known for over 35 years that blue light exposure can damage retinal pigment epithelium (RPE) cells. Much of the work on the effects of blue light on RPE cells has employed short exposures to high intensity light, a type of exposure unlikely to occur during normal daily activities. In this study, we examine the effects of low level blue light exposure over an extended period of time on the physiology of cultured RPE cells.

Methods: Cells of the human RPE cell line, ARPE-19, were grown to confluence in T25 cell culture flasks. The flasks were then exposed to blue light for 8 hours per day at a peak wavelength of 475nm and intensity of 0.6mW/cm2. Control cells were exposed to red light or no light. The flask were periodically observed and photographed to record integrity of the cell layer. After 1, 2 3, or 4 weeks of exposure, the cells were counted (including measurement of viability) and re-plated in 2, 6-well plates. One plate was stained with crystal violet (CV) to study cell morphology. The other plate was stained with senescence associated beta-galactosidase (SABG) which is a marker for altered lysosomal activity, such as occurs in senescent cells.

Results and Discussion: Exposure to blue light reduced SABG staining after one week of exposure, and this effect persisted through the experiment (average reduction ~ 70%; p < .001, t-test). After three weeks of exposure, defects began to appear in the RPE layer and cell size was reduced (CV-stained cells). By four weeks of exposure, the RPE layer was significantly disrupted and there was a reduction in cell number (~34%) and viability. Exposure to red light did not produce these changes. These results suggest that exposure to levels of blue light that might occur in a normal environmental setting can damage RPE cells. The nature of the damage that occurs (e.g. loss of cell layer integrity and altered lysosomal functioning) is consistent with the pathology seen in AMD.

Affiliation of Co-Authors Arizona College of Optometry, Arizona College of Optometry, Arizona College of Optometry, Arizona College of Optometry, Arizona College of Optometry, Arizona College of Optometry, Arizona College of Optometry
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