Investigating the epigenetic basis of preleukemic hematopoietic stem and progenitor cells

Hematopoietic stem and progenitor cells (HSPCs) reside in the bone marrow, where they are responsible for production of mature blood progeny. Somatic mutations acquired in ageing can promote HSPC expansion, and thereafter mutations can be observed in differentiated cells released into the bloodstream. This is a condition known as clonal hematopoiesis (CH), a common blood disorder in the over-60 population. CH has been linked to increased risk of cardiovascular disease and hematological malignancies, including acute myeloid leukemia (AML). Whilst mutations in over 60 genes are known to drive human CH, mutations in the antagonistic DNA methylation enzymes, DNMT3A and TET2, account for 70% of cases. However, research into the consequences of these mutations have been limited by difficulty in maintaining HSPCs in vitro; and therefore, most work has been performed in vivo using mouse models, which are relatively difficult to control and exhibit heterogeneous phenotypes. Without an improved model system, we may fail to discover targetable pathways which could intervene against AML development and progression.
This project aims to develop an in vitro model system which successfully recapitulates the key features of human clonal hematopoiesis driven by TET2- and DNMT3A-mutations. This system will use cell lines derived and immortalised from the HSPC population in mouse bone marrow. These cells can be grown long-term in vitro, where they retain their stem cell capacity, as demonstrated upon transplantation into lethally irradiated mice. Through combined use of this model system with high throughput sequencing techniques, this project aims to uncover the molecular consequences of DNMT3A- and TET2-mutations in HSPCs. Dysregulated pathways can then be genetically or pharmacologically modulated in our system to test whether this counteracts the expansion of TET2- or DNMT3A-mutant HSPCs. All results will be validated in an independent HSPC system.