Abstract

Nuclease-based genome editing strategies hold great promise for the treatment of blood disorders. However, a major drawback of these approaches is the generation of potentially harmful double strand breaks (DSBs). Base editing is a CRISPR-Cas9-based genome editing technology that allows the introduction of point mutations in the DNA without generating DSBs. Two major classes of base editors have been developed: cytidine base editors or CBEs allowing C>T conversions and adenine base editors or ABEs allowing A>G conversions. The scope of base editing tools has been extensively broadened, allowing higher efficiency, specificity, accessibility to previously inaccessible genetic loci and multiplexing, while maintaining a low rate of Insertions and Deletions (InDels). Base editing is a promising therapeutic strategy for genetic diseases caused by point mutations, such as many blood disorders and might be more effective than approaches based on homology-directed repair, which is moderately efficient in hematopoietic stem cells, the target cell population of many gene therapy approaches. In this review, we describe the development and evolution of the base editing system and its potential to correct blood disorders. We also discuss challenges of base editing approaches–including the delivery of base editors and the off-target events–and the advantages and disadvantages of base editing compared to classical genome editing strategies. Finally, we summarize the recent technologies that have further expanded the potential to correct genetic mutations, such as the novel base editing system allowing base transversions and the more versatile prime editing strategy.

Highlights

  • The vast majority of human genetic diseases are due to point mutations

  • The low frequency of double strand breaks (DSBs) generated by base editors (BEs) is undoubtedly one of the most significant advantages, placing base editing in the top spot amongst the different genome editing tools in terms of safety

  • Avoiding p53-mediated apoptosis that can result from DSBs formation allows the safe genetic manipulation of p53-sensitive cells, such as hematopoietic stem cells (HSCs) (Milyavsky et al, 2010), and the safe treatment of genetic blood disorders

Read more

Summary

Introduction

The vast majority of human genetic diseases are due to point mutations. Human blood genetic disorders are due to mutations affecting hematopoietic stem cells (HSCs) or their committed progeny leading to general hematopoiesis defects or lineage-specific damages (e.g., in leukocytes or erythrocytes). Β-hemoglobinopathies are due to >300 mutations affecting the β-globin gene (HBB), resulting in red blood cell (RBC) defects and anemia (Cavazzana et al, 2017; Amaya-Uribe et al, 2019). Allogeneic HSC transplantation is the only curative treatment for many blood genetic disorders. It is limited by the availability of sibling donors and is associated with risks of graft rejection and graft vs host disease (Cavazzana et al, 2017; Castagnoli et al, 2019). Ex vivo gene therapy approaches based on autologous transplantation of genetically corrected HSCs have been developed to offer a permanent and safer

Methods
Findings
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call