Oxidative Stress Signatures in Human Stem Cell-Derived Neurons

Compelling evidence suggests that oxidative stress plays a significant role in the pathogenesis of many neurodegenerative diseases as well as the neuronal/glial demise resulting from exposure to environmental stressors. The cellular redox balance is maintained by a host of cellular redox systems with set points that are regulated at a subcellular level. Overwhelming deviations of these redox system balances result in oxidative stress and ultimately deficient functioning of cellular organelles and biomolecules such as protein, lipids, and nucleic acids. The analysis of cellular and subcellular redox states is challenging due to the spatiotemporal compartmentation of redox systems and the cell type, stressor, and exposure paradigm specificity of the responses to a particular insult. Due to this complexity, multiple approaches to examine the presence and nature of oxidative stress in biological systems can be used to enhance rigor and may include the analysis of the level of reactive oxygen/nitrogen species (RONS) present, the evaluation of cellular redox systems, and the modification of biomolecules. We describe here three such methods applied to stem cell-derived neurons: (1) the chloromethyl 2′, 7′-dichlorodihydrofluorescein diacetate (DCF) assay to assess cellular RONS levels, (2) a method to determine the state of the cellular GSH redox system, and (3) a procedure to assess oxidative stress-induced lipid modification. This multifold approach to assess the cellular redox state can establish an “oxidative stress signature” specific for a stressor, a cell type, and exposure paradigm. This threefold approach allows for a better comparison of how different biological systems react to a particular stressor or how different stressors (or exposure paradigms) affect a particular biological model system.