Over the past decade, mRNA-based therapy has displayed significant promise in a wide range of clinical applications. The most striking example of the leap in the development of mRNA technologies was the mass vaccination against COVID-19 during the pandemic. The emergence of large-scale technology and positive experience of mRNA immunization sparked the development of antiviral and anti-cancer mRNA vaccines as well as therapeutic mRNA agents for genetic and other diseases. To facilitate mRNA delivery, lipid nanoparticles (LNPs) have been successfully employed. However, the diverse use of mRNA therapeutic approaches requires the development of adaptable LNP delivery systems that can control the kinetics of mRNA uptake and expression in target cells. Here, we report effective mRNA delivery into cultured mammalian cells (HEK293T, HeLa, DC2.4) and living mouse muscle tissues by liposomes containing either 1,26-bis(cholest-5-en-3β-yloxycarbonylamino)-7,11,16,20-tetraazahexacosane tetrahydrochloride (2X3) or the newly applied 1,30-bis(cholest-5-en-3β-yloxycarbonylamino)-9,13,18,22-tetraaza-3,6,25,28-tetraoxatriacontane tetrahydrochloride (2X7) cationic lipids. Using end-point and real-time monitoring of Fluc mRNA expression, we showed that these LNPs exhibited an unusually delayed (of over 10 h in the case of the 2X7-based system) but had highly efficient and prolonged reporter activity in cells. Accordingly, both LNP formulations decorated with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000] (DSPE-PEG₂₀₀₀) provided efficient luciferase production in mice, peaking on day 3 after intramuscular injection. Notably, the bioluminescence was observed only at the site of injection in caudal thigh muscles, thereby demonstrating local expression of the model gene of interest. The developed mRNA delivery systems hold promise for prophylactic applications, where sustained synthesis of defensive proteins is required, and open doors to new possibilities in mRNA-based therapies.

The delivery of therapeutic nucleic acids is a prospective method for the treatment of both inherited and acquired diseases including cancer. To achieve maximal delivery efficiency and selectivity, nucleic acids should be targeted to the cells of interest. In the case of cancer, such targeting may be provided through folate receptors overexpressed in many tumor cells. For this purpose, folic acid and its lipoconjugates are used. Compared to other targeting ligands, folic acid provides low immunogenicity, rapid tumor penetration, high affinity to a wide range of tumors, chemical stability, and easy production. Different delivery systems can utilize targeting by folate ligand including liposomal forms of anticancer drugs, viruses, and lipid and polymer nanoparticles. This review focuses on the liposomal gene delivery systems that provide targeted nucleic acid transport into tumor cells due to folate lipoconjugates. Moreover, important development step, such as rational design of lipoconjugates, folic acid content, size, and ζ-potential of lipoplexes are discussed.

Gene therapy requires an effective and safe delivery vehicle for nucleic acids. In the case of non-viral vehicles, including cationic liposomes, the structure of compounds composing them determines the efficiency a lot. Currently, cationic amphiphiles are the most frequently used compounds in liposomal formulations. In their structure, which is a combination of hydrophobic and cationic domains and includes spacer groups, each component contributes to the resulting delivery efficiency. This review focuses on polycationic and disulfide amphiphiles as prospective cationic amphiphiles for gene therapy and includes a discussion of the mutual influence of structural components.

The absence of highly effective delivery systems is a major challenge for gene therapy. Our work was aimed at the development of novel cationic liposomes possessing high transfection efficiency. For this purpose, a novel disulfide polycationic amphiphile 2S4 was synthesized. Cationic liposomes based on 2S4 and a helper lipid DOPE were formed by the thin film hydration method and exhibited effective plasmid DNA delivery into the HEK293 cells, with a transfection activity superior to that of the commercial agent Lipofectamine^® 2000. Our results suggest that the polycationic amphiphile 2S4 is a promising candidate for in vitro nucleic acid delivery.

Some new polycationic amphiphiles containing a disulfide group were synthesized. Cationic liposomes formed from the compounds synthesized and a helper lipid 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine were not toxic for HEK293 and HeLa cells and were highly effective when delivering a fluorescently labeled oligodeoxyribonucleotide. The efficacy of plasmid DNA delivery depended on the cell line and the amphiphile structure, liposomes based on tetracationic amphiphiles being the most effective transfectants. These liposomes can be used for in vitro transfection of eukaryotic cells as well as for further in vivo biological studies.

Objectives. Gene therapy involves the administration of various types of therapeutic nucleic acids into the organism, in order to treat severe hereditary diseases, as well as cancer. Furthermore, the COVID-19 pandemic demonstrated the possibility of rapid development and the effectiveness of both DNA and mRNA vaccines for the prevention of viral diseases. Numerous studies in the field of gene therapy have revealed that in most cases successful delivery of nucleic acids requires a special delivery system which protects nucleic acids from the effects of external and internal biological factors. Among the various types of such tools, non-viral delivery systems have proven to be the most versatile and safe ones. In the case of mRNA delivery, such systems are usually called mRNA vaccines, consisting of cationic or ionizable lipids. The purpose of this review is to justify the choice of the optimal structure of lipid components of mRNA vaccines and highlight the current prospects for their clinical use. Results. In this review, we have considered the evolution of lipid structures, from cationic to ionizable, as the main components of mRNA delivery systems. Furthermore, the study demonstrated the necessity to use other types of lipids in mRNA vaccines. It also presents a review of clinical trials of mRNA vaccines against viral and oncological diseases, and provides recommendations for the design of the optimal structure of both cationic and ionizable lipids. Conclusions. The most promising lipids for the development of mRNA vaccines are ionizable. They do not have a permanent positive charge which reduces their cytotoxicity and undesirable binding to components of the immune system. In general, mRNA vaccines can be universal and effective means for treating various types of diseases. However, their composition needs to be careful optimized.