Developing Biodegradable Lipid Nanoparticles for Intracellular mRNA Delivery and Genome Editing

Abstract

Conspectus Since the U.S. Food and Drug Administration (FDA) granted emergency use authorization for two mRNA vaccines against SARS-CoV-2, mRNA-based technology has attracted broad attention from the scientific community to investors. When delivered intracellularly, mRNA has the ability to produce various therapeutic proteins, enabling the treatment of a variety of illnesses, including but not limited to infectious diseases, cancers, and genetic diseases. Accordingly, mRNA holds significant therapeutic potential and provides a promising means to target historically hard-to-treat diseases. Current clinical efforts harnessing mRNA-based technology are focused on vaccination, cancer immunotherapy, protein replacement therapy, and genome editing. The clinical translation of mRNA-based technology has been made possible by leveraging nanoparticle delivery methods. However, the application of mRNA for therapeutic purposes is still challenged by the need for specific, efficient, and safe delivery systems. This Account highlights key advances in designing and developing combinatorial synthetic lipid nanoparticles (LNPs) with distinct chemical structures and properties for in vitro and in vivo intracellular mRNA delivery. LNPs represent the most advanced nonviral nanoparticle delivery systems that have been extensively investigated for nucleic acid delivery. The aforementioned COVID-19 mRNA vaccines and one LNP-based small interfering RNA (siRNA) drug (ONPATTRO) have received clinical approval from the FDA, highlighting the success of synthetic ionizable lipids for in vivo nucleic acid delivery. In this Account, we first summarize the research efforts from our group on the development of bioreducible and biodegradable LNPs by leveraging the combinatorial chemistry strategy, such as the Michael addition reaction, which allows us to easily generate a large set of lipidoids with diverse chemical structures. Next, we discuss the utilization of a library screening strategy to identify optimal LNPs for targeted mRNA delivery and showcase the applications of the optimized LNPs in cell engineering and genome editing. Finally, we outline key challenges to the clinical translation of mRNA-based therapies and propose an outlook for future directions of the chemical design and optimization of LNPs to improve the safety and specificity of mRNA drugs. We hope this Account provides insight into the rational design of LNPs for facilitating the development of mRNA therapeutics, a transformative technology that promises to revolutionize future medicine.

Tailoring combinatorial lipid nanoparticles for intracellular delivery of nucleic acids, proteins, and drugs

“…In addition to other studies, the studies published by our laboratory have demonstrated that the combinatorial library of LNPs can be used for the delivery of nucleic acids, proteins, and small molecule drugs, for a variety of applications in gene silencing, genome editing, cell engineering and tissue regeneration, cancer therapy, antimicrobial applications, and many others 38 , 85 , 121 , 122 , 123 . Nonetheless, challenges still exist in the successful clinical translation of these new drug formulations.…”

“…This study was significant because it firstly showed that LNP-mediated CRISRP/Cas9 mRNA delivery can induce sufficient and long-term hepatic Angptl3 knockout in mouse model without evident side-effects. We expect that our bioreducible LNPs will advance the systemic delivery of CRISPR/Cas9 genome editing therapeutics for the treatment of hyperlipidemia and other types of liver-associated diseases and disorders 38 , 39 .…”

Nonviral Delivery Systems of mRNA Vaccines for Cancer Gene Therapy

“…For targeted delivery, scientists have observed that the targeting functionalities of LNPs are largely related to the chemical structure of the active lipids [ 98 ]. For instance, imidazole-based LNPs preferentially target splenic T cells [ 99 ]; Zukancic et al found that PEGylation is critical for achieving selective organ targeting, even though it is at the lowest ratio in LNPs [ 100 ]. For immunogenicity, Hassett et al found that the particle size may influence LNP immunogenicity; they demonstrated that LNPs at a smaller diameter were substantially less immunogenic in mice, but all the particle sizes tested induced a robust immune response in nonhuman primates (NHPs), suggesting that an optimal mRNA vaccine particle size as determined for rodents may not translate to primates [ 101 ].…”

Engineering optimal vaccination strategies: effects of physical properties of the delivery system on functions

“…In 1995, one of the first nanomedicine doxorubicin liposomal medication, Doxil, was approved for Kaposi's sarcoma; since then, many materialcomposite drugs have been approved by the US Food and Drug Administration (FDA). [2][3][4] Drug delivery systems (DDSs) have realized degradable biological macromolecular drug payload, targeted delivery, controllable release, and favourable pharmacokinetics of drugs. [5][6][7][8][9] Therefore, DDSs have the ability to improve vaccination.…”