Iron oxide-coupled CRISPR-nCas9-based genome editing assessment in mucopolysaccharidosis IVA mice

Mucopolysaccharidosis (MPS) IVA is a lysosomal storage dis -order caused by mutations in the GALNS gene that leads to the lysosomal accumulation of keratan sulfate (KS) and chon-droitin 6-sulfate, causing skeletal dysplasia and cardiopulmo-nary complications. Current enzyme replacement therapy does not impact the bone manifestation of the disease, support -ing that new therapeutic alternatives are required. We previ-ously demonstrated the suitability of the CRISPR-nCas9 sys-tem to rescue the phenotype of human MPS IVA fibroblasts using iron oxide nanoparticles (IONPs) as non-viral vectors. Here, we have extended this strategy to an MPS IVA mouse model by inserting the human GALNS cDNA into the ROSA26 locus. The results showed increased GALNS activity, mono-KS reduction, partial recovery of the bone pathology, and non-IONPs-related toxicity or antibody-mediated immune response activation. This study provides, for the first time, in vivo evidence of the potential of a CRISPR-nCas9-based gene therapy strategy for treating MPS IVA using non-viral vectors as carriers.