In vitro and in vivo evaluation of clinically-approved ionizable cationic lipids shows divergent results between mRNA transfection and vaccine efficacy

The Expression Kinetics and Immunogenicity of Lipid Nanoparticles Delivering Plasmid DNA and mRNA in Mice

“…In another recent publication, the authors observed several lipid structure activity relationships that correlated with improved protein expression, including number of carbons on the lipid tails on the ester side and the effect of carbon spacing on the disulfide arm of the lipids [41]. The results of our study are consistent with a recent publication by Escalona-Rayo et al that demonstrated that SM102-RNA particles resulted in greater in vitro protein expression than ALC0315-RNA particles following transfection into mouse primary bone marrow dendritic cells [42].…”

“…This result is most likely due to the branched ester chains of the SM-102 and ALC-0315 lipid tails, which have been shown to increase functional delivery of mRNA, and not the apparent pKa of the ionizable lipid [43,44]. These results are in accordance with a previous study comparing ALC0315-RNA, SM102-RNA, and MC3-RNA particles administered intravenously into zebrafish embryos, in which ALC0315-RNA and SM102-RNA demonstrated elevated EGFP protein expression compared to MC3-RNA (pKa = 6.4) [42]. In addition, we observed some similarities between the in vitro and in vivo potency, with SM102-RNA and ALC0315-RNA resulting in higher luciferase expression than all other groups in both cases.…”

“…In addition to humoral immunity, effective vaccines may also induce a cellular immune response against the desired pathogen. Although T cell responses were not investigated in the present study, a previous comparison of SM102-RNA, AL0315-RNA, and MC3-RNA found that subcutaneous injection of all three particles induced similar levels of intracellular cytokine production by antigen-specific T cells [42]. We suggest that further analyses of the immune mechanisms stimulated by leading LNP formulations are required to better inform the development of effective DNA vaccines.…”

Advances in lipid nanoparticle mRNA therapeutics beyond COVID-19 vaccines

“…The chemical identity of the ionizable lipid has also been seen to impact the biodistribution profile of lipid nanoparticles. 36–40 Escalona-Rayo et al demonstrated in vivo biodistribution of DiD-labeled lipid nanoparticles containing clinically approved ionizable cationic lipids (MC3, SM-102, and ALC-0315). They discovered that 24 hours after injection, these lipid nanoparticles had accumulated in endothelial cells and the extravascular space throughout the zebrafish embryo body.…”

“…Notably, ALC-0315-based lipid nanoparticles accumulated the most in the extravascular space. 36 Lam et al compared intramuscular administration of firefly luciferase mRNA encapsulated in lipid nanoparticles containing lipid benchmarks (MC3, SM-102, and ALC-0315), in mice. Six hours post-injection, ALC-0315 and SM-102 nanoparticles provided comparable luciferase expression levels at the injection site, which outperformed those observed with MC3 lipids.…”