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Dryad

Genomic profile of gene edited hematopoietic stem cells

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Dec 06, 2024 version files 26.01 MB

Abstract

Sickle cell disease (SCD) and β-thalassemia patients with elevated gamma globin (HBG1/G2) levels exhibit mild or no symptoms. To recapitulate this natural phenomenon, the most coveted gene therapy approach is to edit the regulatory sequences of HBG1/G2 to reactivate them, with a magnified effect by simultaneous targeting of multiple sequences. Here, we used Cas9 RNP-ssODN-mediated homology-directed gene editing to mimic two naturally occurring HBG promoter point mutations, namely, -175T>C, which is linked to high HbF levels, and -158C>T, the most common polymorphism in the Indian population that induces HbF under erythropoietic stress, in HSPCs. We observed high complete HDR conversions, with at least 30% of HSPCs exhibiting both -175T>C and -158C>T mutations, which increased to over 50% under optimized conditions. In NBSGW mice, up to 30% of long-term engrafted human HSPCs showed both -175T>C and -158C>T HDR conversions, with the efficiency peaking with up to 57% of HSPCs containing at least one of the beneficial mutations. Cas9 RNP-ssODN-based nucleotide conversion at the HBG promoter offers a promising gene therapy approach to ameliorate the disease phenotypes of both β-thalassemia and SCD. The developed approach can simplify and broaden applications that require multiple nucleotide modifications in HSPCs.