In Dr Humphries' lab, he initiated studies on the molecular genetics of stem cells with the aim of identifying key regulators of HSC self-renewal. He focused his studies on Hox genes and showed, in collaboration with Dr Unnur Thorsteinsdottir, that at least one member of this family has the potential to enhance HSC self-renewal. With the help of Dr Jana Krosl and through an ongoing collaboration with Dr Humphries, he has recently developed a recombinant HOXB4 protein, which induces unprecedented HSC expansion in vitro. These findings may open new therapeutic avenues in the field of stem cell transplantation and blood banking.
In 1996, he accepted a position at the Institute for Clinical Research in Montreal where he continued his studies on Hox genes with a new interest in the oncogenic potential of these genes and on the biology of leukemia stem cells. With Dr Julie Lessard, he developed a new program on the Polycomb Group (PcG) genes and demonstrated that primitive hematopoietic cell proliferation is regulated by the relative contribution of repressive (Eed-containing) and enhancing (Bmi1-containing) PcG gene complexes. Moreover, they recently showed that bmi-1 is required for the self-renewal activity of the normal and leukemia stem cells. Without self-renewal, stem cells lack the ability to self-perpetuate and are eventually lost. These findings open new possibilities for eliminating tumor stem cells.
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