In vivo systematic detection of the outcomes of CRISPR/Cas9 mediated DNA repair in skeletal muscle stem cells [control]

Here, we systematically profile CRISPR/Cas9 editing outcomes at 95 loci using our established CRISPR/Cas9/AAV9-sgRNA system in skeletal muscle stem cells (MuSCs). Through comprehensive characterization of the repair outcomes, our findings demonstrate that the general rules governing CRISPR/Cas9-mediated editing in vivo largely align with those observed in vitro.

Additional to the anticipated small editing indels such as MMEJ mediated deletions and NHEJ mediated templated insertions, we uncover a prevalent occurrence of large on-target modifications, including large deletions (LDs) characterized by microhomology (MH) and large insertions (LIs). Notably, the LIs comprise not only exogenous AAV vector integrations but also endogenous genomic DNA fragments (Endo-LIs). Endo-LIs preferentially originate from active genomic regions, with their integration shaped by three-dimensional chromatin architecture.