Design of Ionizable Lipids To Overcome the Limiting Step of Endosomal Escape: Application in the Intracellular Delivery of mRNA, DNA, and siRNA

Abstract

The intracellular delivery of nucleic acid molecules is a complex process involving several distinct steps; among these the endosomal escape appeared to be of particular importance for an efficient protein production (or inhibition) into host cells. In the present study, a new series of ionizable vectors, derived from naturally occurring aminoglycoside tobramycin, was prepared using improved synthetic procedures that allow structural variations on the linker and hydrophobic domain levels. Complexes formed between the new ionizable lipids and mRNA, DNA, or siRNA were characterized by cryo-TEM experiments and their transfection potency was evaluated using different cell types. We demonstrated that lead molecule 30, bearing a biodegradable diester linker, formed small complexes with nucleic acids and provided very high transfection efficiency with all nucleic acids and cell types tested. The obtained results suggested that the improved and "universal" delivery properties of 30 resulted from an optimized endosomal escape, through the lipid-mixing mechanism.

Charge-altering releasable transporters (CARTs) for the delivery and release of mRNA in living animals

“…Those that have emerged are largely inspired by or directly repurposed from DNA and siRNA delivery methods. However, multiple groups have observed that directly adapting DNA or siRNA vehicles to mRNA delivery can be ineffective, and in those cases it has been suggested that insufficient mRNA release from the carrier likely contributes to the observed failed or inefficient delivery (19)(20)(21)(22)(23). Nonetheless, there have been encouraging preliminary results of recent and ongoing clinical trials using mRNA, underscoring the rapidly emerging importance of mRNA therapeutics in the treatment or prevention of a range of diseases.…”

“…To date, naked, chemically modified, or protamine-complexed mRNA have shown promise in phase I/II cancer trials (24)(25)(26). Recently, preclinical development of materials specific for mRNA delivery has resulted in cationic polymers such as polymethacrylates (27)(28)(29), poly(aspartamides) (30,31), and polypeptides (32), as well as multicomponent cationic lipid or lipid-like formulations (21,(33)(34)(35)(36). In many of these examples, however, transfection efficiencies can be quite low, ranging 20-80% in cells (18), with likely much lower efficiencies in vivo, which requires either high mRNA doses or hydrodynamic injections (32,37).…”

Nanoscale platforms for messenger RNA delivery

“…Meanwhile, Habrant et al (2016) synthesized tobramycin-derived lipids using a biodegradable diester linker. A lead lipid was formulated with DOPE at a 1:1 M ratio and showed effective delivery of mRNA, siRNA and DNA in rat and human cell lines (Habrant et al, 2016). Their recently developed paromomycin-based cationic lipids were also used for delivery of these nucleic acid cargos (Colombani et al, 2017).…”

Organic Nanocarriers for Delivery and Targeting of Therapeutic Agents for Cancer Treatment

“…synthesized a new series of aminoglycoside tobramycin derived ionizable lipids to overcome endosome escape process in mRNA, DNA and siRNA delivery. Compound 30 loaded liposomes containing dioleylsuccinylserinyl‐tobramycin showed the highest transfection efficiency than other compounds that may be due to the presence of ester bond in compound 30 which favored hydrophobic interaction with natural anionic phospholipid and facilitated endosomal escape of all types of nucleic acids . Li et al.…”