Characterizing Intracellular Oxygen Production after Polyethylene Glycol-Conjugated Hydrophilic Carbon Cluster (PEG-HCC) Anioxidant Treatment
Oxidative stress, an overabundance of toxic reactive oxygen species (ROS) in the body, is a major pathophysiological factor in acute injury and ischemia/reperfusion that occurs in hypotensive shock and stroke. This evidence is exemplified by robust protection in multiple antioxidant overexpression models of ischemia/reperfusion. However, treatment following injury at relevant time points is not consistently beneficial and no clinical trial of antioxidant therapy in any form of brain injury has shown benefit. These failures are due to limitations in currently available antioxidants that hinder their effectiveness following injury. The limitations of current antioxidants can be summarized and include one or more of the following: i) a mechanism of action in which the radical is transferred to another unstable species; ii) the need for regeneration; iii) limited capacity that is inadequate to cope with the cascade of radicals following injury; and iv) selectivity in which an agent is effective against only one radical type. We have developed a new class of antioxidant called polyethylene glycol-functionalized hydrophilic carbon clusters (PEG-HCCs) that overcome these limitations while also possessing the highly favorable characteristic of generating oxygen (O2) upon superoxide (SO) consumption. This exemplifies an ideal situation in an ischemic environment where the radicals would simultaneously be quenched. The question we attempt to answer is whether the favorable characteristics of the ROS quenching ability of PEG-HCCs will also translate to enhanced protection in living cells. We will characterize whether O2 generation occurs under simulated ischemia/reperfusion conditions in living endothelial and neuronal cells using an adaptation of oxygen sensing fluorescent microscopy.