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一直是许多医学进步的基础。最近，包括广泛使用的SARS-CoV-2疫苗在内的RNA药物已经进入市场。RNA药物需要新的给药机制来克服特定的挑战：虽然传统药物在细胞外作用，或者小到足以渗透到细胞内靶点，但RNA药物只在细胞内有效，而且它们的大小需要特定的给药机制来携带它们穿过细胞壁，进入它们起作用的细胞胞浆。病毒和脂质纳米粒(LNPs，类似于小的中空脂肪球)被用来传递目前批准的RNA药物。病毒和LNPs在细胞外包裹并保护RNA免受损害，并能够与细胞壁对接或融合，以实现RNA的最终传递。然而，这些技术在生产成本、批次一致性、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等方面存在明显缺陷。虽然这些技术正在进行改进，但一种新的方法可能更好地解决这些挑战。粒子通过各种被动和主动机制访问细胞。吞噬作用是细胞主动摄取颗粒的过程(最有效的是0.3-5微米大小的颗粒)。这一过程在专业的单核吞噬细胞(MP)中尤其有效。这些免疫细胞提供疫苗抗原，摄取碎片并清除入侵的病原体。它们还迁移到患病和受伤的组织，并参与各种过程，包括产生疫苗免疫、自身免疫性疾病、伤口愈合和癌症。一些MPS，如肝脏的Kupfer细胞，不是造血来源的。MPS还含有许多重要的病原体。有效靶向MPS的RNA药物可能会影响许多毁灭性的疾病。我们已经设计了微小的蛋白质晶体颗粒，称为豆荚晶体，其中含有特定的生物活性蛋白质。MPS摄取豆荚晶体并原封不动地分泌它们的货物蛋白质。我们还表明，货物蛋白进入胞浆--细胞中RNA活跃的区域--表明有可能运送RNA。在这里，我们计划产生蛋白质晶体颗粒，将RNA运送到MP细胞。一旦证明了这一点，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.