Magnetic-activated nanosystem with liver-specific CRISPR nonviral vector to achieve spatiotemporal liver genome editing as hepatitis B therapeutics

Chronic hepatitis B infection remains incurable due to the stable presence of various forms of hepatitis B virus (HBV) genome, especially the HBV covalently closed circular DNA (cccDNA). The emergence of clustered regularly interspaced short palindromic repeat (CRISPR) technology provides a new opportunity to potentially cure the HBV infection. However, the efficiency and specificity remain unsatisfactory, especially for nonviral CRISPR/Cas9 delivery. To tackle these, a liver-specific CRISPR/Cas9 magnetic nanosystem FMNP_pAG333/sgXPP is constructed based on fluorinated polyethylenimine-coated magnetic nanoparticles and liver-specific ApoE.HCR.hAAT promoter-driven Cas9-T2A-EGFP plasmid with dual sgRNAs. The elaborate system enables magnetic field-induced spatially specific distribution and hepatocyte-specific promoter-driven liver-specific gene editing. Moreover, this CRISPR/Cas9 magnetic nanosystem is designed to disrupt the two conserved sites in X opening reading frame and Pol opening reading frame of the HBV genome, thereby significantly inactivating the HBV genome without showing off-target effects. Treatment with FMNP_pAG333/sgXPP for 7 days reduces serum HBsAg levels by 76% with a total editing efficiency of ≈20% in the two conserved sites. Collectively, this study demonstrates spatiotemporal liver genome editing as well as the feasibility of applying a nonviral CRISPR/Cas9 vector for HBV treatment, which may open up a new application for CRISPR therapeutics.