Augmenting carbon nanoparticles as novel antioxidants for ischemic stroke

描述(申请人提供)：氧化应激伴随着正常和病理过程。因为我们生活在一个富氧的环境中，我们需要保护机制来处理由正常和病理事件(如中风)导致的不可避免的高活性氧自由基的释放。我们对氧化自由基的主要防御由一系列酶和蛋白质组成。然而，这些解毒步骤的产物可能会产生另一个自由基，例如羟基，或需要另一个解毒步骤的不稳定分子过氧化氢。正常情况下，有足够水平的保护酶来应对这些产品。然而，在病理情况下，这些中间步骤会被淹没，自由基及其有害产物会积累起来。在这一级联反应中只修饰一个自由基的抗氧化剂疗法可能会产生不稳定的中间体，在下游保护机制不足的情况下，可能会导致更多自由基的积累。因此，常规抗氧化剂疗法的临床试验普遍失败也就不足为奇了。我们的实验室开发了一种使用高度修饰的碳纳米颗粒的新型创新抗氧化剂，称为聚乙二醇化亲水碳簇(聚乙二醇化亲水碳簇)。这些颗粒具有很高的自由基猝灭能力，并在超氧化物歧化过程中产生氧气，可能是治疗缺血/再灌注的理想药物。此外，可以使用抗体、多肽和小分子来靶向聚乙二醇-羟基喜树碱。重要的是，它们在细胞培养中的氧化应激后有效，而传统的抗氧化剂需要预先处理。根据我们的发现，在创伤性脑损伤模型中，聚乙二醇-羟基喜树碱能迅速恢复脑血流量，我们假设我们可以开发出一种治疗中风的有效配方。在大鼠高血糖短暂性大脑中动脉闭塞(TMCAO)中进行的一项严格测试的初步结果表明，提高了存活率。在目标1中，我们将在正常血糖和高血糖的tMCAO模型中测试使用聚乙二醇-羟基喜树碱延长治疗窗口的能力。在目标2中，我们将测试旨在增强它们的靶向性和分布到大脑的修改。我们选择高血糖卒中是因为它是卒中常见的并发症，导致死亡率增加和预后变差，特别是在血栓清除等再通治疗之后。虽然氧化应激在正常血糖的中风中很重要，但在长时间的缺血和高血糖中，这种机制在数量上要大得多。如果这些成功，我们将继续进行额外的临床前研究，为IND申请人类中风测试作为一种潜在的治疗方法，否则将产生最糟糕的结果。

DESCRIPTION (provided by applicant): Oxidative stress accompanies both normal and pathological processes. Because we live in an oxygen rich environment, we need protective mechanisms to deal with inevitable release of highly reactive oxygen free radicals resulting from both normal and pathological events such as stroke. Our primary defense against oxidative radicals consists of a series of enzymes and proteins. However, the products of these detoxification steps can yield another radical, e.g. hydroxyl, or an unstable molecule, hydrogen peroxide requiring another step of detoxification. Normally, there are sufficient levels of protective enzymes to cope with these products. However, under pathological circumstances, these intermediate steps are overwhelmed; radicals and their deleterious products accumulate. Antioxidant therapies that modify only one radical in this cascade may generate unstable intermediates that, in the face of inadequate downstream protective mechanisms, can lead to the accumulation of more radicals. It is not therefore surprising that clinical trials of conventinal antioxidant therapies have generally failed. Our laboratories have developed a new, innovative class of antioxidant using highly modified carbon nanoparticles termed PEGylated hydrophilic carbon clusters (PEG-HCCs). These particles have a high radical quenching capacity and generate oxygen during superoxide quenching, potentially ideal to treat ischemia/reperfusion. Furthermore, PEG-HCCs can be targeted using antibodies, peptides and small molecules. Importantly, they were effective after oxidative stress in cell culture while conventional antioxidants required pre-treatment. Based on our finding that PEG-HCCs rapidly restored cerebral blood flow in a model of traumatic brain injury, we hypothesize that we can develop an effective formulation in stroke. Preliminary results in a severe test in hyperglycemic transient middle cerebral artery occlusion (tMCAO) in the rat suggested improved survival. In Aim 1, we will test the ability to extend the therapeutic window using PEG-HCCs in a model of normo- and hyper-glycemic tMCAO. In Aim 2, we will test modifications intended to augment their targeting and distribution to the brain. We selected hyperglycemic stroke since it is a common co-morbidity in stroke causing increased mortality and poorer outcomes, particularly afer recanalization therapies such as clot removal. While oxidative stress is important in normoglycemic stroke, the mechanisms are quantitatively much greater in extended periods of ischemia and in hyperglycemia. Should these be successful, we will pursue the additional pre-clinical studies necessary for an IND application for human testing in stroke as a potential treatment for those who otherwise would have the worst outcomes.