Secreted Expression of mRNA‐Encoded Truncated ACE2 Variants for SARS‐CoV‐2 via Lipid‐Like Nanoassemblies

Abstract The transfer of foreign synthetic messenger RNA (mRNA) into cells is essential for mRNA‐based protein‐replacement therapies. Prophylactic mRNA COVID‐19 vaccines commonly utilize nanotechnology to deliver mRNA encoding SARS‐CoV‐2 vaccine antigens, thereby triggering the body's immune response and preventing infections. In this study, a new combinatorial library of symmetric lipid‐like compounds is constructed, and among which a lead compound is selected to prepare lipid‐like nanoassemblies (LLNs) for intracellular delivery of mRNA. After multiround optimization, the mRNA formulated into core–shell‐structured LLNs exhibits more than three orders of magnitude higher resistance to serum than the unprotected mRNA, and leads to sustained and high‐level protein expression in mammalian cells. A single intravenous injection of LLNs into mice achieves over 95% mRNA translation in the spleen, without causing significant hematological and histological changes. Delivery of in‐vitro‐transcribed mRNA that encodes high‐affinity truncated ACE2 variants (tACE2v mRNA) through LLNs induces elevated expression and secretion of tACE2v decoys, which is able to effectively block the binding of the receptor‐binding domain of the SARS‐CoV‐2 to the human ACE2 receptor. The robust neutralization activity in vitro suggests that intracellular delivery of mRNA encoding ACE2 receptor mimics via LLNs may represent a potential intervention strategy for COVID‐19.