Neuroprotection with serpins during cardiac surgery

描述（由申请人提供）：成人和儿童在心脏手术期间和之后都会发生脑损伤。它可以表现为局灶性或全局性神经损伤，如中风或舞蹈病。或者，它可以表现为认知和运动技能的普遍下降。抑酶蛋白是一种SERPIN（丝氨酸蛋白酶抑制剂），可减少体外循环（CPB）后出血。一项广泛的心脏外科文献荟萃分析得出结论，抑酶蛋白也能降低CPB后卒中的发生率，尽管最近一份有影响力的报告表明，抑酶蛋白会增加脑损伤的风险。抑蛋白蛋白在CPB过程中直接的神经元和神经血管作用机制仍未被探索，尽管先前的工作已经证明抑蛋白蛋白对内皮功能的保护。此外，最近在神经科学文献中应用细胞培养模型的报道表明，一些蛇蛋白可能通过抑制兴奋毒性而具有神经保护作用。本研究将验证抑酶蛋白在CPB中具有神经保护作用的假设。将采用幼年仔猪模型，暴露于不同程度的流量减少，其程度已知会导致脑损伤。术后4天生存率允许通过盲法观察者的行为评估以及盲法神经病理学家确定的有意义的组织学来评估脑损伤的功能证据。血管完整性将通过活体显微镜进行研究，这可以直接观察大脑微循环。近红外光谱将监测脑氧输送的充分性。几个剂量水平的抑酶蛋白将被用来确定最佳剂量。该研究的第二个部分将检验一种假说，即抑肽蛋白具有神经保护作用的一种机制是通过抑制兴奋毒性。将采用神经细胞培养模型。不同剂量的抑肽素将与先前已被证明具有神经保护作用的其他蛇形蛋白进行比较。利用细胞培养模型研究可能在心脏外科中应用的新型蛇形蛋白。在研究的第三阶段，我们将在CPB的整个动物模型中对发现具有保护作用的蛇形蛋白进行详细的研究。最后阶段将研究抑肽蛋白对血管的保护机制。这项提议的研究有可能降低接受心脏手术的儿童和成人脑损伤的风险。

DESCRIPTION (provided by applicant): Brain injury occurs during and after cardiac surgery in both adults and children. It can take the form of either a focal or global neurological insult such as stroke or choreoathetosis. Alternatively it can manifest itself as a generalized decline in cognitive and motor skills. Aprotinin, a "SERPIN" (serine protease inhibitor), reduces bleeding after cardiopulmonary bypass (CPB). An extensive metaanalysis of the cardiac surgery literature concluded that aprotinin also decreases the incidence of stroke after CPB though a recent influential report suggests an increased risk of brain injury. Direct neuronal and neurovascular mechanisms of action of aprotinin during CPB remain largely unexplored though previous work has demonstrated protection of endothelial function by aprotinin. Furthermore recent reports in the neuroscience literature applying cell culture models suggest that some serpins may be neuroprotective through inhibition of excitotoxicity. The proposed study will test the hypothesis that aprotinin is neuroprotective in the setting of CPB. A juvenile piglet model will be employed with exposure to various degrees of flow reduction to a degree known to cause brain injury. Survival for 4 days postoperatively allows assessment of functional evidence of brain injury through behavioral assessment by a blinded observer as well as meaningful histology determined by a blinded neuropathologist. Vascular integrity will be studied with intravital microscopy which allows direct observation of the cerebral microcirculation. Adequacy of cerebral oxygen delivery will be monitored by near infrared spectroscopy. Several dosage levels of aprotinin will be employed to determine optimal dose. The second component of the study will test the hypothesis that one mechanism by which aprotinin is neuroprotective is through inhibition of excitotoxicity. Neuronal cell culture models will be employed. Aprotinin at various dosages will be compared with other serpins which have previously been demonstrated to be neuroprotective. Novel serpins which may have an application in cardiac surgery will also be studied with the cell culture model. Serpins which are found to be protective will be studied in detail in the whole animal model of CPB in the third phase of the study. The final phase will study mechanisms of vascular protection afforded by aprotinin. The proposed study has the potential to reduce the risk of brain injury in children and adults undergoing heart surgery.