RNA delivery by self-assembling phagocytic-competent protein crystals

药物在给药后（例如通过静脉注射）到达其分子靶标的机制对疗效至关重要。药物输送的创新是许多医学进步的基础。最近，RNA药物，包括广泛使用的SARS-CoV-2疫苗，已经进入市场。RNA药物需要克服特定挑战的新型药物递送机制：虽然常规药物在细胞外起作用或小到足以渗透到细胞内靶点，但RNA药物仅在细胞内有效，并且它们的大尺寸需要特定的递送机制来携带它们穿过细胞壁并进入它们起作用的细胞胞质溶胶。（LNP，类似于脂肪的小空心球）用于递送目前批准的RNA药物。病毒和LNP包裹并保护RNA在细胞外免受损伤，并且能够与细胞壁对接或融合以进行RNA的最终递送。然而，这些技术具有显著的缺点，包括生产成本、批次一致性、储存稳定性、免疫原性、缺乏靶向、细胞进入效率和内体逃逸。虽然这些技术正在不断改进，但一种新的方法可能会更好地解决这些挑战。粒子通过各种被动和主动机制进入细胞。吞噬作用是细胞主动摄取颗粒（在0.3 - 5微米尺寸范围内最有效）的过程。该过程在专职单核吞噬细胞（MP）中特别有效。这些免疫细胞呈递疫苗抗原，摄取碎片并消除入侵的病原体。它们还迁移到患病和受伤的组织，并参与各种过程，包括疫苗免疫的产生、自身免疫性疾病、伤口愈合和癌症。一些MP，如肝脏的Kupfer细胞，不是造血起源的。MP还窝藏许多重要的病原体。有效靶向MP的RNA药物具有影响许多毁灭性疾病的潜力。我们已经设计了包含特定生物活性蛋白质货物的微观蛋白质晶体颗粒，称为PODS晶体。MP摄取PODS晶体并完整地分泌其货物蛋白。我们还表明，货物蛋白进入细胞质-RNA活跃的细胞区域-表明有可能递送RNA。在这里，我们计划产生蛋白质晶体颗粒来将RNA递送到MP细胞。一旦这一点得到证明，我们将测试RNA在一系列生物医学应用中改变MP细胞行为的能力。

The mechanism by which a drug travels following administration (e.g. by intravenous injection) to reach its molecular target is critical to efficacy. Innovations in drug delivery have been fundamental to many medical advances. Most recently, RNA drugs, including widely used vaccines against SARS-CoV-2, have entered the market. RNA drugs required novel mechanisms of drug delivery which overcame specific challenges: Whilst conventional drugs act outside cells or are small enough to permeate through to intracellular targets, RNA drugs are only effective inside cells, and their large size necessitates a specific delivery mechanism to carry them across the cell wall and into the cell cytosol where they act.Viruses and lipid nanoparticles (LNPs, resembling small hollow spheres of fat) are used to deliver currently approved RNA drugs. Viruses and LNPs envelop and protect the RNA from damage whilst outside the cell and are able to dock or fuse with the cell wall to make the final delivery of RNA. However, these technologies have significant shortcomings including production costs, batch consistency, storage stability, immunogenicity, lack-of-targeting, the efficiency of cell entry, and endosomal escape. Whilst improvements in these technologies are being made, a fresh approach may better address these challenges.Particles access cells through a variety of passive and active mechanisms. Phagocytosis is a process in which cells actively ingest particles (most efficiently in the 0.3 - 5 microns size range). This process is particularly efficient in professional mononuclear phagocytic (MP) cells. These immune cells present vaccine antigens, ingest debris and eliminate invading pathogens. They also migrate to diseased and injured tissue and are involved in a variety of processes, including the generation of vaccine immunity, autoimmune diseases, wound healing and cancer. Some MPs, such as the liver's Kupfer cells, are not of haemopoietic origin. MPs also harbour many important pathogens. RNA drugs that effectively target MPs have the potential to impact many devastating diseases.We have engineered microscopic protein crystal particles, called PODS crystals, that contain specific bioactive protein cargos. MPs ingest PODS crystals and secrete their cargo proteins intact. We have also shown that cargo proteins enter the cytosol - the area of the cell where RNA is active - suggesting the possibility to deliver RNA. Here, we plan to generate protein crystal particles to deliver RNA to MP cells. Once this has been demonstrated, we will test RNAs' ability to modify MP cells' behaviour across a range of biomedical applications.