Inherited mutations in telomerase and other telomere-related proteins result in abnormally short ends of chromosomes (telomeres) and lead to a spectrum of diseases known as telomere biology disorders (TBDs). One of their major clinical manifestations, depletion of haematopoietic stem cells, can result in bone marrow failure (BMF), the leading cause of death (~65%) in TBD patients. The only curative treatment, haematopoietic stem cell transplantation, has a low success rate for short-telomere patients and is associated with various complications. However, there is no physiologically relevant animal model available for elucidating disease mechanisms and developing novel therapeutics.
We are optimising a gene-editing strategy in clinically relevant human haematopoietic stem and progenitor cells (HSPCs), in order to establish in vitro and in vivo models of telomere-related BMF syndromes. A single nucleotide polymorphism of TERC was successfully introduced into immortal K562 leukemic stem cell line and HSPCs, through CRISPR-based homology-directed1 or homology-independent targeted2 integration. Our data compares the efficiency and sequence accuracy between these two editing strategies and analyses the expression and processing of the gene products.
Engraftment of these CRISPR-edited HSPCs into immunodeficient mice will enable the first “humanised” mice model for not only the functional characterisation of novel mutations and fundamental research into TBD mechanisms, but also for the development of a preclinical gene therapy strategy for inherited BMF.