Protein Stability in Polymer Delivery Systems

描述（由申请方提供）：蛋白质药物目前通过注射全身给药。对于需要慢性治疗的个体，用针自我给药是不愉快的日常经历。开发可注射的生物可降解聚合物，例如聚（乳酸-共-乙醇酸）（PLGA），能够在注射之间缓慢和连续释放蛋白质数月，可以为痛苦的每日注射提供现实的替代方案。PLGA递送系统也用于局部治疗和疫苗递送。开发蛋白质的PLGA递送系统的主要障碍是这些试剂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。在该提议中，将操纵聚合物中的pH以改善包封在PLGA中的模型蛋白质和肽的稳定性。这种和其他稳定方法将应用于促进血管生成的治疗性蛋白质。缓释血管生成剂对于患有缺血性心脏病的患者具有重要应用（在美国每年造成> 600，000例死亡）。随后的部位特异性新血管形成将促进心肌灌注并减少心脏并发症，如心肌梗死、心绞痛、心力衰竭和/或心脏性猝死。考虑到缓慢释放天然治疗性蛋白质（如促进血管生成的蛋白质）的PLGA递送系统可能对人类健康产生的潜在影响，解决封装在PLGA中的蛋白质的不良不稳定性的重要性变得明确无误。本提案将检验以下假设：PLGA内的水分与不受控制且经常呈酸性的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应力。开发控制聚合物微气候pH的方法将成为稳定包封蛋白质的广泛适用的方法。将在以下具体目标中检验这一假设：1）表征聚合物微气候中影响包封蛋白质的稳定性和释放的物理化学过程，2）研究模型蛋白质和肽在PLGA递送系统中的稳定性，3）将稳定化方法应用于血管生成蛋白质的递送，和4）生物活性血管生成蛋白的受控释放的体内评估

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