A novel approach for long term protein delivery

描述（由申请人提供）：聚丙交酯-羟基乙酸酯（PLGA）作为蛋白质递送载体已广泛应用于微球（MS）中。然而，在制备PLGA质谱的过程中，蛋白质经历了物理和化学变性，并在体内释放。此外，这种配方通常会导致不希望的和不可预测的释放曲线，其特征是爆裂效应和不完全释放。这使得PLGA MS方法对大多数不稳定蛋白不成功。我们的初步研究结果清楚地表明，PEG-polycation（聚l -组氨酸）作为pH依赖的“可逆分子屏蔽”在以下方面的作用是有效的：1)保护蛋白质结构并防止水/有机界面聚集；2)在PLGA质谱中发挥pH缓冲作用（蛋白质海绵效应）；3)增强蛋白质在溶液和质谱中的物理稳定性。4)更好地控制PLGA MS中蛋白质的释放（“all-in-one”概念）。虽然我们的初步结果证明了可行性，但仍有许多变量可以改变，以优化或定制特定蛋白质（如胰岛素）的聚合物设计。这包括改变聚his的大小和与其他氨基酸共聚以改变电荷间距或聚his的构象。这一提议远远超出了治疗性蛋白质，它暗示了酶和其他应用的潜在应用。该项目的长期目标是在PLGA质谱中释放胰岛素模型蛋白时保持90%的生物活性，并在体外和体内测试中实现超过一个月的伪零级释放动力学。研究的具体目标包括：1)实验验证优化后的PEG-polyHis（或peg -修饰的polyHis）/胰岛素复合物在水溶液、PLGA MS和释放过程中获得最大的胰岛素稳定性；2)更好地控制释放曲线；3)结合生物相容性和二嵌段共聚物命运的体内性能测试。

DESCRIPTION (provided by applicant): Poly(lactide-co-glycolide) (PLGA) has been widely applied in microspheres (MS) as a protein delivery carrier. However, proteins undergo physical and chemical denaturation during the fabrication of PLGA MS and release in the body. In addition, such formulations often cause undesirable and unpredictable release profiles, characterized by a burst effect and incomplete release. This makes PLGA MS appraoch unsuccessful for most labile proteins. The results from our preliminary study are a clear pointer to the validity of the role played by PEG-polycation (poly(L-histidine)) as a pH-dependent 'reversible molecular shield' in 1) preserving protein structure and preventing aggregation at water/organic interface, 2) exerting a pH buffering (protein sponge effect) in PLGA MS, 3) enhancing protein's physical stability in solution and in MS, and 4) an overall better control over release of the proteins from the PLGA MS ('all-in-one' concept). Although our preliminary results demonstrate the feasibility, there are still a number of variables which can be altered to optimize or tailor this polymer design for specific proteins, such as insulin. This includes changing the size of polyHis and copolymerizing with other amino acids to alter charge spacing or polyHis conformation. The proposal goes well beyond therapeutic proteins in suggesting potential applications for enzymes and other applications. The long-term goal of this project is to preserve >90 % bioactivity of a model protein, insulin, when released from PLGA MS and to achieve pseudozero-order release kinetics for more than one month period in in vitro and in vivo tests. The research specific aims include 1) experimental verification of optimized PEG-polyHis (or PEG-modified polyHis)/insulin complex for maximum insulin stability in aqueous solutions, in PLGA MS and during release, 2) a better control over release profile and 3) in vivo performance tests combined with biocompatibility and the fate of the diblock copolymer.