Bio-imaging of Surgical Stresses - Dynamic Analyses of Liver Oxidative Stress and Damage -

Abstract

Real-time monitoring of cellular and organ conditions lead to better understandings of various physiopathological phenomena, and will provide options in clinical diagnosis and therapy. We developed redox sensitive GFP (roGFP) and luciferase-based caspase-3 optical probes for in vivo imaging. We tried to visualize the dynamic changes of oxidative stress and the following damage in live cells and in mouse liver ischemia/reperfusion (I/R) model.

In live cell experiments, roGFP probe visualized realtime oxidation/reduction (redox) changes induced by hypoxia/ reoxygenation (H/R). On reoxygenation, roGFP successfully illustrated post-hypoxic cellular oxidation and the following recovery to the reductive basal condition. The optic probe for Caspase-3 activity showed signals in response to Fas-ligand challenge to AML12 liver cells, which paralleled to cellular apoptosis.

In the hepatic I/R model of mice, we successfully imaged liver oxidative stress (by roGFP probe) and apoptosis (by caspase-3 activity probe) non-invasively and chronologically in a single mouse. Duration of liver ischemia affected the intensity of post-ischemic oxidative stress and caspase-dependent apoptotic cell death (damage). Prolonged ischemia (until 60 min) enhanced liver oxidative stress and damage after reperfusion. Interestingly, 90 min of ischemia did not induce oxidative stress at all, but necrotic cell death.

Direct observations of the changes of organ conditions helped us understand the dynamism of organ functions/ conditions. These technologies clearly possess a clinical relevance and will provide a new diagnostic tool in various clinical settings in the future.

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