Department of Medicine, Imperial College London, London, UK.
Gene Ther. 2019 Sep;26(9):363-372. doi: 10.1038/s41434-019-0095-2. Epub 2019 Jul 12.
Self-amplifying RNA (saRNA) is a promising biotherapeutic tool that has been used as a vaccine against both infectious diseases and cancer. saRNA has been shown to induce protein expression for up to 60 days and elicit immune responses with lower dosing than messenger RNA (mRNA). Because saRNA is a large (~9500 nt), negatively charged molecule, it requires a delivery vehicle for efficient cellular uptake and degradation protection. Lipid nanoparticles (LNPs) have been widely used for RNA formulations, where the prevailing paradigm is to encapsulate RNA within the particle, including the first FDA-approved small-interfering siRNA therapy. Here, we compared LNP formulations with cationic and ionizable lipids with saRNA either on the interior or exterior of the particle. We show that LNPs formulated with cationic lipids protect saRNA from RNAse degradation, even when it is adsorbed to the surface. Furthermore, cationic LNPs deliver saRNA equivalently to particles formulated with saRNA encapsulated in an ionizable lipid particle, both in vitro and in vivo. Finally, we show that cationic and ionizable LNP formulations induce equivalent antibodies against HIV-1 Env gp140 as a model antigen. These studies establish formulating saRNA on the surface of cationic LNPs as an alternative to the paradigm of encapsulating RNA.
自扩增 RNA（saRNA）是一种很有前途的生物治疗工具，已被用作针对传染病和癌症的疫苗。saRNA 已被证明可以诱导长达 60 天的蛋白质表达，并以低于信使 RNA（mRNA）的剂量引发免疫反应。由于 saRNA 是一种较大的（约 9500nt）、带负电荷的分子，因此需要一种输送载体来实现有效的细胞摄取和降解保护。脂质纳米颗粒（LNPs）已被广泛用于 RNA 制剂，其中流行的范例是将 RNA 封装在颗粒内，包括第一个获得 FDA 批准的小干扰 RNA 疗法。在这里，我们比较了具有阳离子和可离子化脂质的 LNP 制剂，以及将 saRNA 置于颗粒内部或外部的制剂。我们表明，即使吸附在表面上，阳离子 LNP 也能保护 saRNA 免受 RNAse 降解。此外，阳离子 LNP 在体外和体内都能等效地递送 saRNA，与用可离子化脂质颗粒封装的 saRNA 制成的颗粒一样。最后，我们表明阳离子和可离子化 LNP 制剂诱导针对 HIV-1 Env gp140 的等效抗体作为模型抗原。这些研究确立了将 saRNA 表面制剂化作为封装 RNA 范例的替代方案。
