Optimization of lipid nanoparticles loaded with ribonucleoprotein-oligonucleotide complexes for in vivo delivery of a CRISPR/Cas9 system targeting hepatitis B virus.

Patients with chronic hepatitis B virus (HBV) infection may benefit from clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9)-based gene therapy. We previously identified a guide RNA (WJ11) that suppressed HBV replication in vitro and in vivo; however, we were unable to achieve delivery at clinically feasible doses in vivo using an adeno-associated virus (AAV) vector. Lipid nanoparticle (LNP)-based WJ11/Cas9 ribonucleoprotein-oligonucleotide complex delivery suppressed HBV replication by 2-3-fold more than did AAV-based delivery. In the present study, we investigated the HBV replication-suppressive effects of LNP/WJ11/Cas9 complexes after intravenous administration to persistently HBV genotype C-infected humanized chimeric mice. CL4H6 (ionizable lipid) LNPs were selected as the first candidate for WJ11/Cas9 delivery based on their reported high encapsulation efficiency; however, no significant anti-HBV effect was noted in serum or hepatic tissue. The ionizable lipid candidate CL4F11_ε-3 improved absolute serum HBV values to a certain degree but had no significant effect on hepatic HBV DNA or covalently closed circular (ccc)DNA levels. CL4F11_ζ-2 LNP/WJ11/Cas9, a new complex prepared through structural optimization of the ionizable lipid and heat treatment of WJ11, showed suppressive effect for serum viral load along with a reduction of hepatic HBV DNA, HBV cccDNA, HBsAg, and HBcrAg levels when compared with controls. Therefore, LNP-based delivery of this CRISPR/Cas9 formula holds promise for the treatment of chronic HBV infection.