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Abstract
This work utilises models of normal and abnormal human hematopoiesis to improve the ex
vivo expansion of cord blood hematopoietic stem and progenitor cells (HSPC) for therapeutic
use and to increase our understanding of ERG in human leukemogenesis. The majority of
experimental work in this study has been published in peer reviewed journals Cytotherapy and
Leukemia.
HSPC transplantation remains the most effective curative therapy for leukemia, and cord blood
HSPC have considerable advantages compared to other sources, however their use is limited
by the low number of cells harvested. Therefore, improvements to the ex vivo expansion of
cord blood HSPC have high clinical relevance. This study addresses both the limited
investigation of the combinatorial effects of growth factors and oxygen level, and the difficulty
in translating laboratory research into clinical practice. Systematic investigation using
phenotypic markers, colony forming assays and gene expression identified enhanced HPC ex
vivo expansion with growth factor combination TSFI in 10% oxygen. Additionally, through use
of clinically approvable methods and reagents, this study established a baseline methodology
for the assessment of additional factors to increase cord blood transplantable cell dose.
Ets transcription factor ERG is a member of self-sustaining transcriptional networks that
maintain human and murine HSPC, and ERG is a prime human leukemogenic candidate. High
ERG expression is prognostic of poor patient outcome in acute myeloid leukemia (AML) and Tcell
lymphoblastic leukemia (T-ALL), and high ERG expression induces both AML and T-ALL in
murine models. However, no human model of high ERG expression in normal HSPC exists. This
study established a human model of high ERG expression in cord blood CD34+ HSPC, which
allowed investigation of the effect of high ERG expression in primitive HSPC and lineage
committed progenitors. High ERG expression induced a gene expression signature that
recapitulated hematopoietic stem cells and signatures of both AML and T-ALL. This signature
was associated with enhanced expansion of functional progenitors, which potentially provide
the opportunity for the acquisition and propagation of mutations that may lead to the
development of leukemia. As such, high ERG may mark a pre-disposition to development of
high risk leukemia.