Epigenetically stable integration sites

Site-specific integration into safe harbors is a strategy to overcome the problem of productivity loss over time in CHO cells. In this study, we established a CRISPR/Cas9-mediated site-specific integration strategy based on ChIP-seq data to improve stability of recombinant CHO cells. Targeted Cas9 nanopore sequencing showed site-specific integration in all pools. The cells with the predicted integration sites were compared with the randomly integrated donor vector in terms of transcript level, productivity, gene copy numbers and stability.