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Proceedings Paper

Time-lapse microscopy studies of bystander effects induced by photosensitization
Author(s): Yin-Chu Chen; Robert W. Redmond
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Paper Abstract

Reactive oxygen species (ROS) are involved in the pathogenesis of many critical diseases and are also utilized as cytotoxic agents in a variety of treatments for eradication of diseased tissue, including cancer. Oxidative stress ensues when the level of ROS in a system exceeds the antioxidant capacity. Oxidative stress can have local (direct) and long-range (bystander) effects in cells and tissue and this research was carried out to determine the spatial and temporal nature of the photosensitized bystander effect using time-lapse fluorescence microscopy. By initiating photosensitization in only a portion of the microscopic imaging field it was possible to differentiate direct from bystander effects in EMT-6 murine breast cancer cells in 6-well plates. Elevated ROS levels are seen immediately following photodynamic treatment in direct cells with a delayed increase in oxidative stress observed in bystander cells. Cytotoxicity is also seen at earlier times in direct cells and occurs in bystander cells in a delayed fashion. These studies confirm the existence of a bystander effect following photosensitization and implicate mediators capable of diffusing in an intercellular manner from directly photosensitized cells to bystander cells and also implicate increased oxidative stress as a mechanistic factor in generating damage in bystander cells.

Paper Details

Date Published: 23 February 2006
PDF: 9 pages
Proc. SPIE 6087, Biophotonics and Immune Responses, 60870S (23 February 2006); doi: 10.1117/12.673641
Show Author Affiliations
Yin-Chu Chen, Wellman Ctr. for Photomedicine, Harvard Medical School, Massachusetts General Hospital (United States)
Robert W. Redmond, Wellman Ctr. for Photomedicine, Harvard Medical School, Massachusetts General Hospital (United States)

Published in SPIE Proceedings Vol. 6087:
Biophotonics and Immune Responses
Wei R. Chen, Editor(s)

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