Therapeutically relevant engraftment of a CRISPR/Cas9-edited HSC-enriched population with HbF reactivation in nonhuman primates

Reactivation of fetal hemoglobin (HbF) is being pursued as treatment strategy for hemoglobinopathies. Here, we evaluated the therapeutic potential of CRISPR/Cas9-edited hematopoietic stem and progenitor cells (HSPCs) recapitulating a hereditary persistence of fetal hemoglobin deletion in a nonhuman primate (NHP) autologous transplantation model. CRISPR/Cas9 treatment and transplantation of NHP CD34+ HSPCs resulted in up to 30% engraftment of gene-edited cells for >1 year with stable HbF reactivation and up to 18% circulating F-cells. Similar results were obtained by editing highly enriched CD34+CD90+CD45RA– stem cells, allowing for a 10-fold reduction in the number of transplanted target cells. The level of engrafted, gene-edited cells persisting in vivo using this approach may be sufficient to provide therapeutic benefit for a number of genetic diseases.