Development of novel adenosine polymers for coating medical devices

描述（由申请人提供）：经皮冠状动脉介入治疗（PCI）是原生冠状动脉和隐静脉移植物动脉粥样硬化性狭窄的最常用策略。PCI术后组织灌注经常受损，尤其是ST段抬高型心肌梗死（STEMI）患者。这导致了“无回流”现象，这是死亡率的一个重要预测指标。腺苷是一种内源性核苷，它减弱了导致“无回流”现象的许多机制。实验和临床研究证实腺苷具有增强心肌抢救和改善微血管血流的作用。腺嘌呤的全部治疗潜力受到影响，因为它的半衰期极短，需要大剂量才能在靶器官获得足够的血液水平。由于导丝是第一个干扰血管床的PCI设备，我们已经开发了通过腺苷聚合物涂层导丝连续洗脱腺苷的概念。我们已经开发了一些独特的生理聚合物，其中腺苷可以共价结合并放置在导丝上。我们在一个小动物模型中测试了第一代聚合物（ldi -甘油和ldi -腺苷），并证实它导致血流量大幅增加。然而，在大型动物模型中，动力学剖面对于典型的介入手术来说太快了（~45分钟）。我们随后开发了两种新的聚合物，LDI-半胱氨酸和LDI- peg。在开始第二阶段的大型动物研究之前，我们必须优化聚合物结构、导丝涂层方法和动力学释放曲线。因此，我们建议用新聚合物进行以下研究，以确定理想的产品。首先，我们将开发和表征聚合物的结构及其排列，并评估多种涂层方法以优化释放动力学剖面。其次，我们将利用温度控制的循环水浴系统评估腺苷洗脱，并使用高效液相色谱法连续测量腺苷释放。第三，我们将通过采用基于NAMSA的细胞毒性、热原性、溶血和致敏性筛选试验来确定所选聚合物是否安全用于临床。最后，我们将通过玻璃化转变温度实验和涂覆导线穿过模拟病变来评估聚合物的稳定性和耐久性。如果“抗无回流”导线被证明在改善介入手术后的预后方面是有效的，这将代表着冠状动脉疾病患者接受PCI治疗的重大进步。由于每年在美国进行大量的冠状动脉疾病介入手术，这将具有重要的社会效益。

DESCRIPTION (provided by applicant): Percutaneous coronary intervention (PCI) is the most frequently employed strategy to revascularize atherosclerotic stenosis of native coronary arteries and saphenous vein grafts. Tissue perfusion is frequently impaired following PCI, particularly in patients with ST segment elevation myocardial infarction (STEMI). This results in the "no-reflow" phenomenon which is an important predictor of mortality. Adenosine is an endogenous nucleoside that attenuates many of the mechanisms responsible for the "no-reflow" phenomenon. Experimental and clinical studies have confirmed adenosine's efficacy in enhancing myocardial salvage and improving microvascular blood flow. Adensoine's full therapeutic potential is compromised due to its ultra short half life requiring large doses to obtain adequate blood levels at the target organ. Since the guidewire is the first PCI device that perturbs the vascular bed, we have developed the concept of elution of adenosine continuously via an adenosine-polymer-coated guidewire. We have developed a number of unique physiologic polymers in which adenosine can be covalently incorporated and placed on a guidewire. We tested out first generation polymers (LDI-glycerol and LDI-adenosine) in a small animal model and verified that it resulted in a substantial increase in blood flow. However in a large animal model the kinetic profile was too rapid for a typical interventional procedure (~45 mins). We have subsequently developed two new polymers, LDI- cysteine and LDI-PEG. Prior to initiating large animal studies in a Phase 2 study it is imperative we optimize the polymer structure, guidewire-coating methodology and kinetic release profile. We therefore propose the following studies with the new polymers to identify an ideal product. First we will develop and characterize the structure of the polymers and permutations thereof and evaluate numerous coating methodologies to optimize release kinetic profile. Second we will evaluate adenosine elution utilizing a temperature controlled recirculating water bath system and measure adenosine release serially with HPLC. Third we will determine if the selected polymer is safe for clinical use by employing NAMSA- based screening tests for cytotoxicity, pyrogenicity, hemolysis, and sensitization. Finally we will evaluate the stability and durability of the polymer with glass transition temperature experiments and by passing coated wires through simulated lesions. If the "anti-no-reflow" wire is shown to be effective in improving outcomes after interventional procedures it will represent a major advance in the treatment of patients with coronary artery disease undergoing PCI. This will have important societal benefits due to the large number of interventional procedures performed in the US each year for coronary artery disease. PUBLIC HEALTH RELEVANCE: The improved outcomes that may potentially occur with the device would have important societal benefits due to the large number of interventional procedures performed in the US each year for atherosclerotic disease.