Protein Stability in Polymer Delivery Systems

描述（由申请人提供）：蛋白质药物目前通过全身注射给药。对于需要慢性治疗的人来说，用针给药是一种不愉快的日常经历。可注射的可生物降解聚合物的开发，例如聚乳酸-羟基乙酸（PLGA），能够在注射之间缓慢持续释放蛋白质数月，可能为痛苦的每日注射提供现实的替代方案。PLGA输送系统也用于局部治疗和疫苗输送。开发蛋白质的PLGA递送系统的主要障碍是这些药物在体内释放之前的不可逆不稳定性。这些研究的总体目标是确定导致PLGA中蛋白质不稳定性的潜在分子机制，并利用这些信息开发广泛适用的稳定方法。在这个提议中，聚合物中的pH将被操纵，以提高模型蛋白和肽封装在PLGA的稳定性。这种方法和其他稳定方法将应用于促进血管生成的治疗性蛋白质。缓释血管生成药物在缺血性心脏病（美国每年有60万例死亡）患者中有重要应用。随后的部位特异性新生血管形成将促进心肌灌注，减少心肌梗死、心绞痛、心力衰竭和/或心源性猝死等心脏并发症。考虑到PLGA递送系统缓慢释放天然治疗蛋白（如促进血管生成的蛋白）可能对人类健康产生的潜在影响，解决PLGA包裹蛋白不稳定性差的重要性变得不容置疑。该提案将验证以下假设：PLGA内部的湿度与不受控制的酸性pH值相结合，是导致PLGA递送系统（包括微球）中蛋白质不稳定的两种最常见的压力。开发控制聚合物微气候pH值的方法将成为稳定被封装蛋白的一种广泛适用的方法。这一假设将在以下具体目标中得到验证：1)表征聚合物微气候中影响封装蛋白稳定性和释放的物理化学过程，2)研究PLGA递送系统中模型蛋白和肽的稳定性，3)稳定方法在血管生成蛋白递送中的应用，以及4)生物活性血管生成蛋白控制释放的体内评估

DESCRIPTION (provided by applicant): Protein drugs are currently administered systemically by injections. For individuals requiring chronic therapy, self administration with a needle is an unpleasant everyday experience. Development of injectable biodegradable polymers, e.g. poly(lactic-co-glycolic acid) (PLGA), capable of slowly and continuously releasing proteins for months between injections may provide a realistic alternative to painful daily injections. PLGA delivery systems are also used for local therapy and for delivery of vaccines. The primary obstacle to develop PLGA delivery systems for proteins is the irreversible instability of these agents prior to their release in vivo. The overall goal of these studies is to determine the underlying molecular mechanisms responsible for 'the instability of proteins in PLGA and to use this information to develop widely applicable stablization approaches. In this proposal, the pH in the polymer will be manipulated to improve the stability of model proteins and peptides encapsulated in PLGA. This and other stabilization approaches will be applied to therapeutic proteins that promote angiogenesis. Slow-release angiogenic agents have important applications for patients with ischemic heart disease (responsible for >600,000 deaths annually in the US). The ensuing site-specific neovascularization would facilitate myocardial perfusion and reduce cardiac complications such as myocardial infarction, angina pectoris, heart failure, and/or sudden cardiac death. Considering the potential impact of PLGA delivery systems that slowly release native therapeutic proteins, such as those that promote angiogenesis, could have on human heath, the importance in resolving the poor instability of proteins encapsulated in PLGAs becomes unmistakeable. This proposal will test the following hypothesis: Moisture combined with uncontrolled and frequently acidic pH inside PLGAs are the two most common stresses responsible for instability of proteins in PLGA delivery systems, including microspheres. Development of methods to control polymer microclimate pH will become a widely applicable method to stabilize encapsulated proteins. This hypothesis will be tested in the following specific aims: 1) characterization of physical chemical processes in the polymer microclimate that influence stability and release of encapsulated proteins, 2) investigation of stability of model proteins and peptides in PLGA delivery systems, 3) application of the stabilization methodology to the delivery of angiogenic proteins, and 4) in vivo assessment of the controlled release of biologically active angiogenic proteins