Damage thresholds for cultured retinal pigment epithelial cells exposed to lasers at 532 nm and 458 nm

Abstract

The determination of safe exposure levels for lasers has come from damage assessment experiments in live animals, which typically involve correlating visually identifiable damage with laser dosimetry. Studying basic mechanisms of laser damage in animal retinal systems often requires tissue sampling (animal sacrifice), making justification and animal availability problematic. We determined laser damage thresholds in cultured monolayers of a human retinal pigment epithelial (RPE) cell line. By varying exposure duration and laser wavelength, we identified conditions leading to damage by presumed photochemical or thermal mechanisms. A comparison with literature values for ocular damage thresholds validates the in vitro model. The in vitro system described will facilitate molecular and cellular approaches for understanding laser-tissue interaction.

In vitro model that approximates retinal damage threshold trends

“…The materials and methods used to generate ED 50 values in this report ͑514 and 413 nm͒, including the use of the same batch of isolated melanosomes, were identical to those used previously, 6 and thus, all data described here are comparable. Artificial pigmentation of hTERT-RPE1 cells ͑in 96-well microtiter plates͒ was carried out using volumes of stock MPs corresponding to equivalents of either 160 or 1600 particles per cell.…”

“…6 Damage threshold irradiance values ͑ED 50 ͒ were determined using the Probit 4 method. 6 Damage threshold irradiance values ͑ED 50 ͒ were determined using the Probit 4 method.…”

Real-time monitoring of chemical and structural changes induced by light irradiation of cells and tissues

“…Human RPE cell line was purchased from BD Biosciences (ClonTech Labs, Palo Alto, CA), and is now available from American Type Culture Collection (ATCC, Manassas, VA). Those cells were artificially pigmented using stock solution of melansomes, which were isolated from bovine eyecups [11][12].…”

Thermal lensing in the ocular media

“…In vitro experimental models have been an increasing interest in laser-tissue research (Denton, Foltz et al 2007;Denton, Foltz et al 2008;Denton, Foltz et al 2009). These models use cell cultures designed to simulate a target tissue in the body.…”

“…These models use cell cultures designed to simulate a target tissue in the body. Studies by Denton, Foltz et al 2007-2009 investigating the role of melanin in laser-tissue interaction use extracted melanin granules from the retinas of bovine eyes which are fed to a live cell culture. The cells ingest the melanin granules, causing them to optically mimic the pigment epithelium layer of the retina.…”