ABSTRACT
To unlock the full promise of messenger (mRNA) therapies, expanding the toolkit of lipid nanoparticles is paramount. However, a pivotal component of lipid nanoparticle development that remains a bottleneck is identifying new ionizable lipids. Here we describe an accelerated approach to discovering effective ionizable lipids for mRNA delivery that combines machine learning with advanced combinatorial chemistry tools. Starting from a simple four-component reaction platform, we create a chemically diverse library of 584 ionizable lipids. We screen the mRNA transfection potencies of lipid nanoparticles containing those lipids and use the data as a foundational dataset for training various machine learning models. We choose the best-performing model to probe an expansive virtual library of 40,000 lipids, synthesizing and experimentally evaluating the top 16 lipids flagged. We identify lipid 119-23, which outperforms established benchmark lipids in transfecting muscle and immune cells in several tissues. This approach facilitates the creation and evaluation of versatile ionizable lipid libraries, advancing the formulation of lipid nanoparticles for precise mRNA delivery.
Subject(s)
Combinatorial Chemistry Techniques , Lipids , Machine Learning , RNA, Messenger , Lipids/chemistry , RNA, Messenger/genetics , RNA, Messenger/chemistry , Nanoparticles/chemistry , Animals , Humans , MiceABSTRACT
To elicit optimal immune responses, messenger RNA vaccines require intracellular delivery of the mRNA and the careful use of adjuvants. Here we report a multiply adjuvanted mRNA vaccine consisting of lipid nanoparticles encapsulating an mRNA-encoded antigen, optimized for efficient mRNA delivery and for the enhanced activation of innate and adaptive responses. We optimized the vaccine by screening a library of 480 biodegradable ionizable lipids with headgroups adjuvanted with cyclic amines and by adjuvanting the mRNA-encoded antigen by fusing it with a natural adjuvant derived from the C3 complement protein. In mice, intramuscular or intranasal administration of nanoparticles with the lead ionizable lipid and with mRNA encoding for the fusion protein (either the spike protein or the receptor-binding domain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)) increased the titres of antibodies against SARS-CoV-2 tenfold with respect to the vaccine encoding for the unadjuvanted antigen. Multiply adjuvanted mRNA vaccines may improve the efficacy, safety and ease of administration of mRNA-based immunization.
ABSTRACT
The encapsulation of water-soluble therapeutics and biologics into nanocarriers to produce novel therapeutics has been envisioned for decades, but clinical translation has been hampered by complex synthesis strategies. The methods that have been developed are often limited by poor encapsulation efficiency/loading or complex processing to achieve therapeutic loadings high enough to be medically relevant. To address this unmet need, we introduce a solubility-driven self-assembly process to form polymeric nanocarriers comprising a biologic in a hydrophilic core, encapsulated by a poly(lactic acid) shell, and stabilized by a poly(ethylene glycol) brush. Called "inverse Flash NanoPrecipitation (iFNP)," the technique achieves biologic loadings (wt% of total formulation) that are 5-15× higher than typical values (9-27% versus < 2%). In contrast to liposomes and polymersomes, we sequentially assemble the polymer layers to form the final nanocarrier. Installation of the poly(lactic acid) shell before water exposure sequesters the biologic in the core and results in the improved loadings that are achieved. We demonstrate the broad applicability of the process and illustrate its implementation by formulating over a dozen different oligosaccharides, antibiotics, peptides, proteins, and RNA into nanocarriers with narrow size distributions, at high loadings, and with high reproducibility. Lysozyme and horseradish peroxidase are shown to retain 99% activity after processing. These results demonstrate the potential for commercial implementation of this technology, enabling the translation of novel treatments in immunology, oncology, or enzyme therapies.