Experimental hematology, Myeloproliferative Neoplasms, Lab Dr. med. A. Theocharides
Myeloproliferative neoplasms (MPN) are pre-leukemic hematopoietic stem cell disorders characterized by increased proliferation of one or more hematopoietic cell lineages. The incidence of MPN is highest in the aging population and MPN prevalence will significantly increase in the next decades. Although recent advances in diagnosis and subsequent therapies led to improved MPN patient survival, most patients die from cardiovascular events or from transformation to acute leukemia.
The goal of our research is to gain understanding of the pathogenesis of MPN and to translate this knowledge into the development of novel therapeutic approaches. As murine models only partially reflect the complexity of human disease, a substantial part of the experiments are performed with primary patient cells
in vitro and
in vivo in patient-derived xenograft models. For this we have access to multiple next-generation immunodeficient mice that the group of M.G. Manz has generated within a consortium. I am also an attendig physician of the outpatient clinic for patients with MPN in the division of hematology at the University Hospital Zurich. The research platform and the strong interactions with the division of hematology constitute an ideal and attractive infrastructure to assess efficacy of therapeutic compounds and collaborate with the pharmaceutical industry to further translate evidence established in our laboratory to clinical trials.
Development of a patient-derived xenograft model for myelofibrosis
A growing number of patient-derived xenograft (PDX) mouse models have been developed over the past few decades that allow engraftment of human hematopoietic stem cell (HSC) malignancies in order to study their evolution, as well as disease heterogeneity. However, engraftment is often limited due to potential lack of supportive factors in the bone marrow (BM) microenvironment. This limitation facilitated the development of more advanced mouse strains that express human cytokines and growth factors that are needed for efficient human hematopoietic development
in vivo. Myelofibrosis (MF) is a HSC disorder characterized by bone marrow fibrosis that has the potential to transform into acute myeloid leukemia depending on the clonal evolution of MF stem cells (MF SCs). However, the engraftment of MF SCs in PDX models is poor (Wang et al., JCI 2012). We hypothesize that the constitutive expression of human cytokines and growth factors in a PDX model may promote the development of the human MF clone
in vivo. Therefore, the aim of my project will be to use next-generation mice in order to develop a pre-clinical MF PDX model and determine whether specific somatic mutations promote human MF engraftment. Moreover, track clonal evolution
in vivo and correlate with disease progression in patients.
The role of Calreticulin mutations in the pathogenesis of MPN
Myeloproliferative neoplasms (MPN) are characterized by frequent somatic mutations in the
Januskinase 2 (JAK2) and
Calreticulin (CALR). CALR is a highly conserved chaperone that resides in endoplasmic reticulum (ER) that folds N-linked glycoproteins (GP). Recently, our group has shown that MPN patients with homozygous
CALR mutations develop a maturation defect in Myeloperoxidase (MPO), a GP normally folded by CALR (Theocharides et al., Blood 2016). Based on these findings, we hypothesize that
CALR mutations affect GP maturation and potentially may lead to mutant-specific protein-protein interactions in signaling pathways that further contribute to the pathogenesis of MPN. We are currently in the process of generating human and mouse
CALR mutant cell lines using CRISPR/Cas9 technology that will help us investigate the functional implications of
CALR mutants on GP. This project is performed in collaboration with the laboratory of Prof. Wollscheid at the ETHZ.