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Gregory A Newby

Publications and source records attributed to Gregory A Newby.

3 recordsLinked to original sources
PubMed2025

Engraftment and persistence of HBB base-edited hematopoietic stem cells in nonhuman primates.

Sickle cell disease (SCD) is caused by a single nucleotide change in the β-globin gene that adenine base editors can convert to the nonpathogenic Makassar β-globin variant. Here, we evaluated the long-term efficiency and off-target editing potential of autologous Makassar base editing in three rhesus macaques as a step toward human translation. Base editing of CD34+CD90+ hematopoietic stem cells (HSCs) at the Makassar locus reached greater than 60% efficiency using a bystander nucleotide as a proxy for the sickle cell target in cells from healthy macaques. No impact on myeloid and erythroid colony formation was seen, and clonal analysis revealed that >90% of HSCs were edited, >20% with biallelic editing. After transplantation of autologous gene-edited HSCs, all three macaques rapidly recovered neutrophils, red blood cells, and platelets with stable editing of 25.6%, on average, observed across nucleated blood cells. Similarly, the bone marrow stem cell compartment maintained over 20% of cells harboring mono- or biallelic edits. Off-target editing was assessed at over 900 candidate sites, with editing observed at eight sites, but no selection for or impact of these edits was observed throughout engraftment. These data support further translation of base editing of autologous HSCs for the treatment of patients with SCD.

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PubMed2024

Introducing a hemoglobin G-Makassar variant in HSCs by in vivo base editing treats sickle cell disease in mice.

Precise repair of the pathogenic mutation in hematopoietic stem cells (HSCs) represents an ideal cure for patients with sickle cell disease (SCD). Here, we demonstrate correction of the SCD phenotype by converting the sickle mutation codon (GTG) into a benign G-Makassar variant (GCG) using in vivo base editing in HSCs. We show successful production of helper-dependent adenoviral vectors expressing an all-in-one base editor mapping to the sickle mutation site. In HSC-enriched cells from SCD patients, transduction with the base editing vector in vitro resulted in 35% GTG > GCG conversion and phenotypic improvements in the derived red blood cells. After ex vivo transduction of HSCs from an SCD mouse model and subsequent transplantation, we achieved an average of 88% editing at the target site in transplanted mice. Importantly, in vivo HSC base editing followed by selection generated 24.5% Makassar variant in long-term repopulating HSCs of SCD mice. The treated animals demonstrated correction of disease hallmarks without any noticeable side effects. Off-target analyses at top-scored genomic sites revealed no off-target editing. This in vivo approach requires a single non-integrating vector, only intravenous/subcutaneous injections, and minimal in vivo selection. This technically simple approach holds potential for scalable applications in resource-limiting regions where SCD is prevalent.

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PubMed2024

Bone-marrow-homing lipid nanoparticles for genome editing in diseased and malignant haematopoietic stem cells.

Therapeutic genome editing of haematopoietic stem cells (HSCs) would provide long-lasting treatments for multiple diseases. However, the in vivo delivery of genetic medicines to HSCs remains challenging, especially in diseased and malignant settings. Here we report on a series of bone-marrow-homing lipid nanoparticles that deliver mRNA to a broad group of at least 14 unique cell types in the bone marrow, including healthy and diseased HSCs, leukaemic stem cells, B cells, T cells, macrophages and leukaemia cells. CRISPR/Cas and base editing is achieved in a mouse model expressing human sickle cell disease phenotypes for potential foetal haemoglobin reactivation and conversion from sickle to non-sickle alleles. Bone-marrow-homing lipid nanoparticles were also able to achieve Cre-recombinase-mediated genetic deletion in bone-marrow-engrafted leukaemic stem cells and leukaemia cells. We show evidence that diverse cell types in the bone marrow niche can be edited using bone-marrow-homing lipid nanoparticles.

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