Preclinical evaluation for engraftment of CD34+ cells gene-edited at the sickle cell disease locus in xenograft mouse and non-human primate models

Sickle cell disease (SCD) is caused by a 20A > T mutation in the β-globin gene. Genome-editing technologies have the potential to correct the SCD mutation in hematopoietic stem cells (HSCs), producing adult hemoglobin while simultaneously eliminating sickle hemoglobin. Here, we developed high-efficiency viral vector-free non-footprint gene correction in SCD CD34+ cells with electroporation to deliver SCD mutation-targeting guide RNA, Cas9 endonuclease, and 100-mer single-strand donor DNA encoding intact β-globin sequence, achieving therapeutic-level gene correction at DNA (∼30%) and protein (∼80%) levels. Gene-edited SCD CD34+ cells contributed corrected cells 6 months post-xenograft mouse transplant without off-target δ-globin editing. We then developed a rhesus β-to-βs-globin gene conversion strategy to model HSC-targeted genome editing for SCD and demonstrate the engraftment of gene-edited CD34+ cells 10–12 months post-transplant in rhesus macaques. In summary, gene-corrected CD34+ HSCs are engraftable in xenograft mice and non-human primates. These findings are helpful in designing HSC-targeted gene correction trials. [Display omitted] Sickle cell disease (SCD) is a blood disease caused by a mutation in the β-globin geneA viral vector-free non-footprint gene correction is developed for SCD CD34+ cellsAchieve therapeutic-level SCD gene correction of DNA (∼30%) and protein (∼80%)Demonstrate engraftment of gene-edited CD34+ cells in xenografts and non-human primates Sickle cell disease (SCD) is caused by a point mutation in the β-globin gene and can be cured by the replacement of hematopoietic stem cells (HSCs). Uchida et al. demonstrate a high-efficiency gene correction method for the SCD mutation and engraftment of gene-edited CD34+ HSCs in xenograft mice and non-human primates.