Characterizing the Impact of the Cell Cycle on mRNA Lipid Nanoparticles.

To grow and divide, cells must pass through the cell cycle, a series of phases (G0/G1, S, and G2/M) where they ultimately split from one cell into two. Notably, each of these phases is characterized by dynamic changes in properties central to the mechanism and efficacy of leading nanomedicines such as mRNA lipid nanoparticle (LNP)-based genetic medicines. Despite this, the relationship between cell cycle phases and mRNA LNP mechanism and efficacy remains relatively understudied, potentially hindering the development of next-generation therapies. Here, we characterize how key steps of the mechanism and efficacy of mRNA LNPs (including endocytosis pathway, endosomal escape, and protein expression) are impacted across the G0/G1, S, and G2/M phases of the cell cycle. Specifically, we analyze each of these mechanistic properties across multiple cell types, multiple LNP chemistries, and multiple mRNA payloads to further generalize our findings. Notably, our results collectively highlight that while uptake mechanism remains similar across each phase of the cell cycle, LNP uptake and protein translation are different between G0/G1, S, and G2/M, following the pattern G0/G1 < S < G2/M for these LNP chemistries, mRNA payloads, and cell types. Taken collectively, we hope that this study not only provides fundamental insights into the relationship between the cell cycle and mRNA LNPs but more broadly lays the foundations for the creation of next-generation genetic medicines that could transfect specific phases of the cell cycle for maximal efficacy in applications such as cancer with dysregulated cell cycles.