Lipid Nanoparticle Systems for Enabling Gene Therapies

Abstract

Genetic drugs such as small interfering RNA (siRNA), mRNA, or plasmid DNA provide potential gene therapies to treat most diseases by silencing pathological genes, expressing therapeutic proteins, or through gene-editing applications. In order for genetic drugs to be used clinically, however, sophisticated delivery systems are required. Lipid nanoparticle (LNP) systems are currently the lead non-viral delivery systems for enabling the clinical potential of genetic drugs. Application will be made to the Food and Drug Administration (FDA) in 2017 for approval of an LNP siRNA drug to treat transthyretin-induced amyloidosis, presently an untreatable disease. Here, we first review research leading to the development of LNP siRNA systems capable of silencing target genes in hepatocytes following systemic administration. Subsequently, progress made to extend LNP technology to mRNA and plasmids for protein replacement, vaccine, and gene-editing applications is summarized. Finally, we address current limitations of LNP technology as applied to genetic drugs and ways in which such limitations may be overcome. It is concluded that LNP technology, by virtue of robust and efficient formulation processes, as well as advantages in potency, payload, and design flexibility, will be a dominant non-viral technology to enable the enormous potential of gene therapy.

Biomedical applications of mRNA nanomedicine

“…LNPs are currently the most popular non-viral delivery system in clinical trials for genetic drugs [98, 99]. In fact, Alnylam has just announced positive data from the Phase III APOLLO trial (NCT01960348) of Patisiran (an RNAi therapeutic formulated using LNP technology) for the treatment of transthyretin (TTR)-mediated amyloidosis.…”

Advances in the Understanding and Treatment of Mitochondrial Fatty Acid Oxidation Disorders

“…New technologies in gene therapy such as stabilized therapeutic mRNAs and gene-editing methods such as CRISPR offer the promise of modifying disease genes or replacing them, temporarily if not permanently. Progress in gene therapy has been reviewed elsewhere and will not be covered here [89, 90]. In the interim, while the inborn errors community awaits the clinical availability of gene replacement therapies, other strategies continue to be pursued.…”

Development of an Alcohol Dilution–Lyophilization Method for Preparing Lipid Nanoparticles Containing Encapsulated siRNA

“…As the solubility of the lipids decreases, the lipids and nucleic acids are precipitated into nano-sized particles via electrostatic and hydrophobic interactions. The residual alcohol is generally removed by means of dialysis, 1,4,5) tangential flow filtration, 6) and ultrafiltration.7) In these methods, the residual alcohol is removed by solvent/small-solute selective dilution via a semipermeable membrane. These methods have technical problems associated with them when used in large-scale production; dilution of the residual alcohol to an acceptable level and the concentration of the samples are both costly.…”

“…Among the numerous nucleic acid delivery systems, Lipidnanoparticles (LNPs) that encapsulate short interfering RNA (siRNA) have been extensively investigated for clinical application. 1) We previously reported on the development of a series of ionizable lipids, which we refer as to an SS-cleavable Proton-Activated Lipid-like Material (ssPalm), as a component of LNPs.…”

“…As the solubility of the lipids decreases, the lipids and nucleic acids are precipitated into nano-sized particles via electrostatic and hydrophobic interactions. The residual alcohol is generally removed by means of dialysis, 1,4,5) tangential flow filtration, 6) and ultrafiltration. 7) In these methods, the residual alcohol is removed by solvent/small-solute selective dilution via a semipermeable membrane.…”