Figure 1.

DDR upon gene editing of HSPCs

Cas9-induced DSBs activate a DDR mediated by p53 activation in HSPCs, with the DDR magnitude dependent on the number of DSBs. The response is exacerbated by rAAV6 transduction because of p53 activation caused by the rAAV vector DNA in the nuclei of the cells. The DDR causes decreased proliferation, cell-cycle arrest, and apoptosis, ultimately leading to impaired engraftment and reduced clonality of the human graft upon xenotransplantation in mice. The DDR can be partially mitigated through p53 inhibition using a dominant-negative p53 mutant (GSE56), resulting in higher clonality and engraftment of gene-edited HSPCs.