Epigenetic modulation of ?-globin expression as a new therapeutic approach for sickle cell disease
Sickle cell disease (SCD) is a severe genetic disease caused by a mutation affecting the production of the ß-globin chain. Its clinical severity is mitigated by the co-inheritance of mutations that reactivate the production of fetal hemoglobin (HbF) in adults. Here, we investigated the epigenetic regulation of the HBG genes and developed a novel approach based on programmable epigenome editing. Analysis of epigenetic marks at the HBG promoters revealed a distinct pattern of modifications in adult versus fetal erythroid cells. Our studies showed efficient HBG reactivation in the HEK293T cell line and in the progeny of hematopoietic stem and progenitor cells (HSPCs) when using activating epigenome editors targeting the HBG promoters, reaching up to 50% of HbF production and a substantial correction of the sickling phenotype. Our findings highlight the pivotal role of epigenetic modifications in the regulation of the ß-globin locus and demonstrate that epigenome reprogramming represents a promising alternative to DNA-cleaving enzymes. This approach mitigates the risks associated with genotoxicity, providing a safe and effective strategy for treating SCD. Overall design: We performed RNA-seq analysis in SCD and HD CD34+ HSPCs (4 donors) that were preactivated for 2 days, then electroporated with a combination of epigenome editors mRNA and sgRNA targeting the HBG promoters, and then cultured for 3 additional days. Cells electroporated with TE buffer only or with epigenome editors mRNA only were used as controls.