Effect of zinc on tPA induced thrombolysis

中风是全球第二大死亡原因，也是美国第五大死亡原因。与 随着人口老龄化，中风患者的数量可能会增加。尽管进行了大量的研究 包括许多临床试验，有效的治疗仍然是难以捉摸的。大量既往临床前 对非栓塞性卒中进行了研究，这可能是平移失败的因素之一。组织 纤溶酶原激活剂（tPA）仍然是FDA批准的用于急性缺血性卒中的唯一治疗。 不幸的是，在美国只有2-5%的中风患者接受这种治疗，因为时间窗狭窄 和严重的副作用。tPA最致命和破坏性的副作用是 颅内出血或出血。出于这个原因，tPA的剂量及其总体给药低于 严格控制，而溶栓的效果可能会受到影响。研究的重点是改善 tPA对提高再灌注率、增强安全性和减少不良出血的有效性 插曲。在本研究中，我们将探讨金属离子锌（Zn 2+）如何影响体外和体内血栓溶解。 我们已经提出了一种方法来改善tPA诱导的血栓溶解。背后的总体假设 提出的研究是研究Zn 2+的存在改变tPA诱导的血栓溶解。这种假设是 基于以下基于现有文献的关键观察结果，以及我们已发表和初步的 研究：1。在血液中，存在最富Zn 2+的部位，血小板的α颗粒，其中锌 浓度达到500µM（血小板中的锌水平几乎是血清中的30倍）。月2 Zn 2+游戏 在血液凝固和血小板聚集中起关键作用。3日在血栓形成过程中，大量的 Zn 2+从血小板中释放，导致局部微环境中Zn 2+浓度激增， 随后血小板聚集。因此，血栓成为Zn 2+的来源，因为Zn 2+被“捕获”在血栓中。 血栓月4我们发表的研究结果表明，Zn 2+减弱了链激酶诱导的 血栓溶解在初步研究中，我们观察到类似的相互作用之间的Zn 2+和tPA。的 特异性目的1将确定Zn 2+对tPA诱导的体外溶栓的影响。具体目标2将 探讨Zn ~（2+）螯合物对tPA诱导的栓塞性MCAO体内溶栓的促进作用。的 初步研究的主要发现是，当Zn 2+共同应用时，其对血栓溶解具有抑制作用 tPA。我们假设Zn 2+螯合可以促进tPA诱导的血栓溶解在血栓模型， 缺血性中风与锌螯合剂组合的较少量tPA的应用可以实现 在中风治疗中具有相同或更好的治疗效果。因此，这个建议是一个基本的翻译 研究解决NIH中风研究的优先事项，并解决复杂的问题，如时间， 治疗窗、细胞毒性和潜在联合治疗的再灌注。

Stroke is the second leading cause of death worldwide, and the fifth leading cause of death in the US. With the aging of the population, the number of stroke patients is likely to grow. Despite enormous research efforts including many clinical trials, effective therapy has remained elusive. A large number of previous preclinical studies was performed on non-embolic stroke, which could be one of the factors for translational failure. Tissue plasminogen activator (tPA) remains the only FDA-approved treatment for acute ischemic stroke. Unfortunately, only 2-5% of stroke patients in the US receive this therapy because of the narrow time window and severe side effects for using tPA. The most deadly and damaging side effect of tPA is the risk of intracranial bleeding or hemorrhage. For that reason, the dose of tPA and its overall administration are under tight control, while the effect of thrombolysis may be compromised. Studies have been focused on improving efficacy of tPA for higher rate of reperfusion, and for enhancement of safety and less adverse bleeding episode. In this proposal, we will investigate how metal ion zinc (Zn2+) affect thrombolysis in vitro and in vivo. We have proposed a method to improve tPA-induced thrombolysis. The overall hypothesis behind the proposed research is that study is that the presence of Zn2+ alters tPA-induced thrombolysis. This hypothesis is based on the following key observations based on the available literature, and our published and preliminary studies: 1st. In the bloodstream there is the most Zn2+-enriched site, α-granule of platelets, where the zinc concentration reaches 500µM (almost 30 fold higher zinc level in platelets than in the serum). 2nd. Zn2+ play critical roles in blood coagulation and platelets aggregation. 3rd. During the clot formation, a large amount of Zn2+ are released from platelets leading to the surge in Zn2+ concentrations in the local microenvironment and subsequent platelet aggregation. Therefore, thrombi become a source of Zn2+ as Zn2+ is “trapped” in the thrombi. 4th. Results from our published study showed that Zn2+ attenuated streptokinase-induced thrombolysis. In the preliminary studies, we observed the similar interaction between Zn2+ and tPA. The specific Aim 1 will determine the effect of Zn2+ on tPA-induced thrombolysis in vitro. Specific Aim 2 will investigate the promoting effect of Zn2+ chelation on tPA-induced thrombolysis in embolic MCAO in vivo. The major finding in the preliminary study is that Zn2+ has an inhibitory effect on thrombolysis when it is co-applied with tPA. We hypothesize that Zn2+ chelation can facilitate the tPA-induced thrombolysis in the clot model of ischemic stroke. The application of smaller amount tPA, in combination with a zinc chelator, can achieve the same or better therapeutic outcome in the treatment of stroke. Therefore, this proposal is a basic translation research addressing priorities of NIH stroke research, and addressing complex issues such as timing, therapeutic window, cytotoxicity and reperfusion of a potential combination therapy.