Electrosprayed Core-Shell Microparticles as a Pulsatile Vaccine Delivery Platform

项目摘要/摘要 每年估计有1940万儿童没有接种世界卫生组织推荐的疫苗 卫生组织，导致150万可预防的疫苗死亡。1，2大多数未接种疫苗的儿童 生活在低收入和中等收入国家，获得医疗保健的机会往往有限。2、3其中近600万人 儿童至少接种一剂疫苗，但仍有风险，因为他们没有完成全部剂量 方案4、5一次注射所有剂量的疫苗或多种疫苗的接种方法 将使即使是一次性获得医疗保健的儿童也能得到充分保护，使其免受相应的 传染病。不幸的是，大多数控释给药系统表现出持续释放。 Kinetics，这与传统的可溶性疫苗在一年内以多个离散剂量接种有很大不同 当然是几个月了。最近的一项研究描述了生物可降解微粒平台的发展 一种包裹疫苗装载核心的聚合物外壳，在一段时间后表现出延迟的脉冲式释放 由聚合物降解率确定。6通过给患者注射混合颗粒群体 不同的降解率，疫苗可以作为离散的脉冲释放，从而模仿传统的疫苗接种 已知的安全有效的时间表。不幸的是，最初的微粒生产方法是负面的 影响抗原稳定性，需要使用大口径针头，而且产量低。这一项目旨在 通过使用同轴电喷射法(一步法)制备微粒来克服这些挑战 这一过程可以产生一个由聚合物外壳包裹的单一水基疫苗核心。这项建议 第一个目标是创造具有致密聚合物外壳的小核壳微粒，以展示延迟的， 大分子在体外和体内的脉冲式释放。将使用荧光标记的蛋白质作为模型 研究疫苗颗粒大小、壳层密度、相对壁厚和后处理对释放的影响 运动学。在确定了实现脉冲式释放的配方后，我们将优化工艺条件 以最大限度地提高包埋抗原的稳定性。一个酶报告和一个pH敏感的染料将被添加到 在粒子生命周期的几个阶段进行测试，以监测微环境条件 制造、储存和释放。将调整电喷材料和参数，以将变化降至最低 到可能由溶剂相互作用、热不稳定性和颗粒酸化导致的蛋白质构象， 这可能会影响免疫系统产生中和抗体的能力。尽管进一步的优化将 需要对特定疫苗的条件进行微调，该项目将为快速 开发控释疫苗配方。最终，这些粒子可能会成为 在资源有限的发展中国家和发达国家与传染病作斗争 世界各地，没有保险的儿童和农村社区的疫苗接种率始终较低。

PROJECT SUMMARY/ABSTRACT Every year an estimated 19.4 million children do not receive the set of vaccines recommended by the World Health Organization, leading to 1.5 million vaccine-preventable deaths.1,2 A majority of undervaccinated children live in low- and middle-income countries and often have limited access to healthcare.2,3 Nearly 6 million of these children receive at least one vaccine dose, but remain at risk because they have not completed the full dosing regimen.4,5 A vaccination method that delivers all doses of a vaccine, or multiple vaccines, in a single injection would enable children with even one-time access to healthcare to be fully protected from the corresponding infectious disease. Unfortunately, most controlled-release drug delivery systems exhibit continuous release kinetics, which is vastly different from traditional soluble vaccines administered in multiple discrete doses over a course of months. One recent study has described the development of biodegradable microparticle platform with a polymer shell encapsulating a vaccine-loaded core that exhibits delayed, pulsatile release after a period determined by the polymer degradation rate.6 By injecting patients with a mixed population of particles with different degradation rates, vaccine can be released as discrete pulses, thereby mimicking traditional vaccination schedules known to be safe and effective. Unfortunately, the original microparticle production method negatively affects antigen stability, requires the use of large-gauge needles, and is low-throughput. This project seeks to overcome these challenges by preparing microparticles using coaxial electrospraying, a single-step fabrication process that can produce a single aqueous, vaccine-loaded core surrounded by a shell of polymer. This proposal first aims to create small core-shell microparticles with dense polymeric shells that demonstrate the delayed, pulsatile release of macromolecules in vitro and in vivo. Fluorescently tagged proteins will be used as model vaccines to study the effects of particle size, shell density, relative wall thickness, and post-processing on release kinetics. After identifying formulations that achieve pulsatile release, we will then optimize processing conditions to maximize encapsulated antigen stability. An enzymatic reporter and a pH-sensitive dye will be added to the core and tested at several stages of the particle life cycle to monitor microenvironmental conditions during fabrication, storage, and release. Electrospraying materials and parameters will be adjusted to minimize changes to protein conformation that could result from solvent interactions, thermal instability, and particle acidification, which may affect the immune system's ability to create neutralizing antibodies. Although further optimization will be required to fine-tune conditions for specific vaccines, this project will provide a framework for quickly developing controlled-release vaccine formulations. Ultimately, these particles could serve as a key tool in the fight against infectious disease both in the developing world where resources are limited and in the developed world, where uninsured children and rural communities show consistently lower vaccination coverage.7