Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA.
Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
Theranostics. 2024 Jan 1;14(1):1-16. doi: 10.7150/thno.89913. eCollection 2024.
Lipid nanoparticles (LNPs) have emerged as a viable, clinically-validated platform for the delivery of mRNA therapeutics. LNPs have been utilized as mRNA delivery systems for applications including vaccines, gene therapy, and cancer immunotherapy. However, LNPs, which are typically composed of ionizable lipids, cholesterol, helper lipids, and lipid-anchored polyethylene glycol, often traffic to the liver which limits the therapeutic potential of the platform. Several approaches have been proposed to resolve this tropism such as post-synthesis surface modification or the addition of synthetic cationic lipids. Here, we present a strategy for achieving extrahepatic delivery of mRNA involving the incorporation of bile acids, a naturally-occurring class of cholesterol analogs, during LNP synthesis. We synthesized a series of bile acid-containing C14-4 LNPs by replacing cholesterol with bile acids (cholic acid, chenodeoxycholic acid, deoxycholic acid, or lithocholic acid) at various ratios. Bile acid-containing LNPs (BA-LNPs) were able to reduce delivery to liver cells and improve delivery in a variety of other cell types, including T cells, B cells, and epithelial cells. Our subsequent screening of selected LNP candidates injected intraperitoneally or intravenously identified a highly spleen tropic BA-LNP: CA-100, a four-component LNP containing cholic acid and no cholesterol. These screens also identified BA-LNP candidates demonstrating promise for other mRNA therapeutic applications such as for gastrointestinal or immune cell delivery. We further found that the substitution of cholic acid for cholesterol in an LNP formulation utilizing a different ionizable lipid, C12-200, also shifted mRNA delivery from the liver to the spleen, suggesting that this cholic acid replacement strategy may be generalizable. These results demonstrate the potential of a four-component BA-LNP formulation, CA-100, for extrahepatic mRNA delivery that could potentially be utilized for a range of therapeutic and vaccine applications.
脂质纳米颗粒 (LNPs) 已成为一种可行的、经过临床验证的信使 RNA 治疗药物递送平台。LNPs 已被用作信使 RNA 递送系统，用于疫苗、基因治疗和癌症免疫治疗等应用。然而，LNPs 通常由可离子化脂质、胆固醇、辅助脂质和脂质锚定聚乙二醇组成，通常会转移到肝脏，从而限制了该平台的治疗潜力。已经提出了几种方法来解决这种趋向性，例如合成后表面修饰或添加合成阳离子脂质。在这里，我们提出了一种通过在 LNP 合成过程中掺入胆汁酸（一种天然存在的胆固醇类似物）来实现信使 RNA 肝外递送的策略。我们通过用胆汁酸（胆酸、鹅脱氧胆酸、脱氧胆酸或石胆酸）替代胆固醇，合成了一系列胆汁酸含量为 C14-4 的 LNPs，并用不同的比例取代。含有胆汁酸的 LNPs（BA-LNPs）能够减少对肝细胞的递送，并提高在各种其他细胞类型中的递送效率，包括 T 细胞、B 细胞和上皮细胞。随后，我们对注射腹膜内或静脉内的选定 LNP 候选物进行筛选，鉴定出一种高度脾脏趋向性的 BA-LNP：CA-100，这是一种含有胆酸且不含胆固醇的四组分 LNP。这些筛选还鉴定出了一些 BA-LNP 候选物，它们在胃肠道或免疫细胞递送等其他信使 RNA 治疗应用中具有应用潜力。我们还发现，在一种使用不同可离子化脂质 C12-200 的 LNP 制剂中用胆酸替代胆固醇，也将信使 RNA 从肝脏递送到脾脏，这表明这种胆酸替代策略可能具有普遍性。这些结果表明，四组分 BA-LNP 制剂 CA-100 具有肝外信使 RNA 递送的潜力，可用于一系列治疗和疫苗应用。
