RNA delivery by self-assembling phagocytic-competent protein crystals

药物在给药后（例如通过静脉注射）到达其分子靶点的机制对疗效至关重要。药物输送方面的创新是许多医学进步的基础。最近，RNA药物，包括广泛使用的针对SARS-CoV-2的疫苗，已经进入市场。RNA药物需要新的药物传递机制来克服特定的挑战：传统药物在细胞外起作用，或者小到足以渗透到细胞内靶点，而RNA药物只在细胞内有效，它们的大尺寸需要一种特定的传递机制来携带它们穿过细胞壁进入它们起作用的细胞质。病毒和脂质纳米颗粒（LNPs，类似于小的空心脂肪球体）被用于递送目前批准的RNA药物。在细胞外，病毒和LNPs包膜并保护RNA免受损伤，并能够与细胞壁对接或融合，最终递送RNA。然而，这些技术存在显著的缺点，包括生产成本、批量一致性、储存稳定性、免疫原性、缺乏靶向性、细胞进入效率和内体逃逸。虽然这些技术正在得到改进，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的过程（在0.3 - 5微米范围内最有效）。这个过程在专业单核吞噬细胞（MP）中特别有效。这些免疫细胞呈递疫苗抗原，摄取碎片并消灭入侵的病原体。它们还迁移到患病和受伤的组织，并参与多种过程，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MPs，如肝脏的Kupfer细胞，不是来源于造血。国会议员也藏匿着许多重要的病原体。有效靶向MPs的RNA药物有可能影响许多毁灭性的疾病。我们设计了微小的蛋白质晶体颗粒，称为pod晶体，其中包含特定的生物活性蛋白质货物。MPs摄取pod晶体并完整地分泌它们的货物蛋白。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，我们计划生成蛋白质晶体颗粒，将RNA传递到MP细胞。一旦证明了这一点，我们将在一系列生物医学应用中测试rna修饰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.