The delivery of CRISPR genome-editing molecules via nanoparticles rather than via viruses is described in a paper published online this week in Nature Biomedical Engineering. The non-viral approach is also shown to efficiently correct the genetic mutation causing Duchenne muscular dystrophy in mice.

The potential of CRISPR technology for healthcare applications depends on the effective delivery of three DNA-editing components - the Cas9 DNA-cleaving enzyme, the guide RNA that targets the gene to be corrected, and the DNA donor to be inserted into the genome - to the specific target cells. Viruses can be used to carry these molecules, but they are associated with safety concerns, limited cargo capacity and can decrease the editing efficiency of the CRISPR components.

Niren Murthy and colleagues show that the CRISPR components can be packaged around individual gold nanoparticles and wrapped up in a protecting polymer, and that the nanoparticles deliver the CRISPR components into a wide variety of cells efficiently. The researchers also show that gene editing occurs via homology-directed repair - the most accurate mechanism for repairing the double-strand DNA breaks created by the Cas9 DNA-cleaving enzyme - and that the levels of off-target editing in muscle tissue of the mice treated for Duchenne muscular dystrophy were minimal.