Lipid nanoparticles loaded with ribonucleoprotein-oligonucleotide complexes synthesized using a microfluidic device exhibit robust genome editing and hepatitis B virus inhibition.

The clustered regularly interspaced short palindromic repeats (CRISPR)-associated (Cas) system has considerable therapeutic potential for use in treating a wide range of intractable genetic and infectious diseases including hepatitis B virus (HBV) infections. While non-viral delivery technologies for the CRISPR/Cas system are expected to have clinical applications, difficulties associated with the clinically relevant synthesis of formulations and the poor efficiency of delivery severely hinder therapeutic genome editing. We report herein on the production of a lipid nanoparticle (LNP)-based CRISPR/Cas ribonucleoprotein (RNP) delivery nanoplatform synthesized using a clinically relevant mixer-equipped microfluidic device. DNA cleavage activity and the aggregation of Cas enzymes was completely avoided under the optimized synthetic conditions. The optimized formulation, which was identified through 2 steps of design of experiments, exhibited excellent gene disruption (up to 97%) and base substitution (up to 23%) without any apparent cytotoxicity. The addition of negative charges to the RNPs by complexing single-stranded oligonucleotide (ssON) significantly enhanced the delivery of both Cas9 and Cpf1 RNPs. The optimized formulation significantly suppressed both HBV DNA and covalently closed circular DNA (cccDNA) in HBV-infected human liver cells compared to adeno-associated virus type 2 (AAV2). These findings represent a significant contribution to the development of CRISPR/Cas RNP delivery technology and its practical applications in genome editing therapy.

The use of design of experiments with multiple responses to determine optimal formulations for in vivo hepatic mRNA delivery.

Although great advances have been made in the delivery of short RNAs by lipid nanoparticles (LNPs), the optimal formulation composition and physicochemical properties of LNPs for long RNA (including mRNA) remain unclear. In the present study, we optimized the lipid composition of liver-targeted mRNA-loaded LNPs that were prepared with pH-sensitive cationic lipids that had been previously designed for siRNA delivery through a two stepped design of experiment (DoE). Multiple responses including physicochemical properties, gene expression, and liver-specificity were analyzed in order, not only to understand the role of each formulation parameter, but also to examine parameters that would be difficult to predict. We found that particle size and the PEG-to-phospholipid (PEG/PL) ratio were additional key factors for liver-specific gene expression in addition to the other formulation factors. The optimized formulation showed a better gene expression compared to other lipid formulations from industry leaders. These findings suggest that a "DoE with multiple responses" approach can be used to predict significant parameters and permit optimized formulations to be prepared more efficiently.