Currently, messenger RNA (mRNA)-based lipid nanoparticle formulations revolutionize the clinical field. Cationic polymer-based complexes (polyplexes) represent an alternative compound class for mRNA delivery. After establishing branched polyethylenimine with a succinylation degree of 10% (succPEI) as highly effective positive mRNA transfection standard, a diverse library of PEI-like peptides termed sequence-defined oligoaminoamides (OAAs) was screened for mRNA delivery. Notably, sequences, which had previously been identified as potent plasmid DNA (pDNA) or small-interfering RNA (siRNA) carriers, displayed only moderate mRNA transfection activity. A second round of screening combined the cationizable building block succinoyl tetraethylene pentamine and histidines for endosomal buffering, tyrosine tripeptides and various fatty acids for mRNA polyplex stabilization, as well as redox-sensitive units for programmed intracellular release. For the tested OAA carriers, balancing of extracellular stability, endosomal lytic activity, and intracellular release capability was found to be of utmost importance for optimum mRNA transfection efficiency. OAAs with T-shape topology containing two oleic acids as well-stabilizing fatty acids, attached via a dynamic bioreducible building block, displayed superior activity with up to 1000-fold increased transfection efficiency compared to their non-reducible analogs. In the absence of the dynamic linkage, incorporation of shorter less stabilizing fatty acids could only partly compensate for mRNA delivery. Highest GFP expression and the largest fraction of transfected cells (96%) could be detected for the bioreducible OAA with incorporated histidines and a dioleoyl motif, outperforming all other tested carriers as well as the positive control succPEI. The good in vitro performance of the dynamic lead structure was verified in vivo upon intratracheal administration of mRNA complexes in mice.

目前，基于信使 RNA (mRNA) 的脂质纳米颗粒配方彻底改变了临床领域。基于阳离子聚合物的复合物 (polyplexes) 代表了 mRNA 传递的替代化合物类别。在建立琥珀酰化度为 10% 的支链聚乙烯亚胺 (succPEI) 作为高效阳性 mRNA 转染标准后，筛选了称为序列定义寡氨基酰胺 (OAAs) 的多样化 PEI 样肽库以进行 mRNA 递送。值得注意的是，之前已被鉴定为有效质粒 DNA (pDNA) 或小干扰 RNA (siRNA) 载体的序列仅显示出中等的 mRNA 转染活性。第二轮筛选结合了可阳离子化的结构单元琥珀酰四亚乙基五胺和组氨酸用于内体缓冲，酪氨酸三肽和各种脂肪酸用于稳定 mRNA 复合物，以及用于程序化细胞内释放的氧化还原敏感单位。对于测试的 OAA 载体，发现平衡细胞外稳定性、内体裂解活性和细胞内释放能力对于最佳 mRNA 转染效率至关重要。具有 T 形拓扑结构的 OAA 含有两种油酸作为稳定脂肪酸，通过动态生物可还原结构单元连接，显示出优异的活性，与其不可还原的类似物相比，转染效率提高了 1000 倍。在没有动态连接的情况下，加入较短的稳定性较差的脂肪酸只能部分补偿 mRNA 的传递。对于具有掺入组氨酸和二油酰基基序的生物可还原 OAA，可以检测到最高的 GFP 表达和最大比例的转染细胞 (96%)，优于所有其他测试载体以及阳性对照 succPEI。好的通过在小鼠中气管内施用 mRNA 复合物，在体内验证了动态引线结构的体外性能。