Studying the redistribution of lipids in clinically relevant lipid nanoparticles as a consequence of formulation protocols

Lipid nanoparticles (also known as LNPs) are revolutionizing genetic medicine. However, a significant bottleneck in the LNP field is a limited understanding of how LNP structure impacts performance. This is because most studies of structure – function relationships in LNPs, focus on LNPs with different lipid compositions. We have formulated clinical LNP formulations (Pfizer lipid composition) loaded with mRNA using different formulation buffers to generate different LNP structures with identical lipid compositions. A likely consequence of these differences in structure, is the redistribution of the lipid components in the LNPs. Our key question is to quantify how LNP formulation conditions can be used to control the overall LNP structure and how this impacts the distribution of lipids between the LNP shell and core. Contrast matching SANS will be used to quantify how DSPC and cholesterol redistribute between the LNP shell and core as a function of LNP size and formulation buffer in systems with identical lipid compositions.
This information will be linked to in vitro cell performance data to enable us to decouple the impact of lipid distribution in an LNP and LNP internal structure on LNP performance. Longer term this information (i.e. the location of the different lipids in the LNP) will also be used to develop starting structures for coarse grain and atomistic models of LNPs to study structure and dynamics in simulations.