Modeling leukemia stem cells using human ESC

Funding Type: 
SEED Grant
Grant Number: 
RB2-01645
ICOC Funds Committed: 
$0
Stem Cell Use: 
Embryonic Stem Cell
iPS Cell
Public Abstract: 
Normal hematopoietic stem cells generate all the different mature blood cell types. Similarly leukemia stem cells represent a small subpopulation that generates the other cells that represent the bulk of the leukemic clone. Effective targeting and elimination of the leukemia stem cell population is likely to be required in order to achieve long term remission and cure from leukemia. Leukemia stem cells are often resistant to treatment and may contribute to disease persistence and relapse. Here we plan to use human embryonic stem cells to derive leukemia stem cells to identify the mechanisms underlying malignant transformation of hematopoietic stem cells in leukemia and to develop improved treatments directed against these cells. Currently investigations of leukemia stem cells are hampered by the very small numbers of such cells that are available for study. Since human embryonic stem cells possess almost infinite proliferative capacity and can differentiate into hematopoietic stem cells, we reason that expression of leukemia-related oncogenes in human embryonic stem cells or their progeny can lead to the development of a novel, innovative model system to study leukemia stem cells. Chronic myeloid leukemia (CML) is a lethal hematological disorder resulting from hematopoietic stem cell transformation by the BCR/ABL oncogene. Here we propose to model leukemia stem cell transformation in CML through expression of the BCR/ABL oncogene in hematopoietic stem cells derived from human embryonic stem cells. These studies are highly significant since successful establishment of an efficient and representative human stem cell model of CML will allow detailed investigation of altered mechanisms of stem cell regulation in this disease, and will allow identification of molecular targets for anti-leukemia therapy that can effectively target leukemia stem cells. Development of human leukemia stem cell model will also facilitate screening of libraries of candidate therapeutic agents for activity against leukemia stem cells. Successful completion of these studies will support the use of similar technologies to model other leukemia such as acute myeloid leukemia. Finally, expression of BCR/ABL may enhance expansion and in vivo engraftment of hematopoietic stem cells derived from human embryonic stem cell, and may thereby provide improved insights into the process of hematopoietic stem cell differentiation from embryonic stem cells which could be applied towards improved methods to generate hematopoietic stem cells for transplantation and gene therapy purposes in the future.
Statement of Benefit to California: 
Each year 35,000 new cases of leukemia are diagnosed in the US, with 3500 new patients being diagnosed in California last year. About 32 percent of cancers in children ages 0-14 years are leukemia. Hispanic children of all races under the age of 20 have the highest rates of leukemia. Although the relative five-year survival rate has more than tripled in the past 46 years for patients with leukemia, and in 1996-2002 was nearly 49 percent, approximately 22,280 deaths in the United States will be attributed to leukemia in 2006. Therefore, despite advances in treatment leukemia continues to be a devastating, life-threatening and often incurable illness which imposes a huge burden on the individual, society and the state. The leukemia stem cell subpopulation generates all other cells that represent the bulk of the leukemic clone and is often resistant to treatment and may contribute to disease persistence and relapse. More effective targeting and elimination of the leukemia stem cells is needed to improve long term remission and cure from leukemia. Here we propose to express a leukemia oncogene in hematopoietic stem cells derived from human embryonic stem cells to model human leukemia stem cells. Successful completion of these studies have the potential to significantly benefit the State of California and its residents in several ways: (1) Establishment of an efficient and representative human stem cell model of CML will allow improved understanding of the differences between leukemia stem cells and normal hematopoietic stem cells and could lead to the identification of novel, new molecular targets for therapy directed against leukemia stem cells; (2) Development of human leukemia stem cell model will facilitate screening of libraries of candidate therapeutic agents for activity against leukemia stem cells.; Development of candidate compounds would be pursued within our institution and in partnership with collaborators from industry. (3) Successful completion of these studies will support the use of similar technologies to model other leukemia such as AML; (4) Finally, these studies may provide improved insights into the process of hematopoietic stem cell differentiation from human embryonic stem cells which could be applied towards improved methods to generate hematopoietic stem cells for therapeutic transplantation and gene therapy purposes in the future. The intermediate and long-term aim of the proposed research is therefore to improve the outcomes for treatment of leukemia and hematological malignancies. Successful therapeutic and diagnostic strategies to emerge from these studies could immensely benefit patients and families within and outside California.
Progress Report: 
  • The ultimate goal of the proposed study is to identify approaches to increase the production of therapeutically useful blood cells from human ESCs and patient-specific iPSCs. Currently, bone marrow transplantation is the best way to cure many blood-related disorders, such as sickle cell anemia, thalassemia, and blood cancers like leukemia. Furthermore, blood transfusion is an effective way to rapidly counteract blood cell loss due to ablative treatments, such as chemotherapy and radiation therapy. Unfortunately, the limiting factor in transplantation and transfusion treatments is the lack of matched donors. The ability to producing unlimited numbers of blood stem cells and/or functioning differentiated blood cells from human ESCs and patient-derived iPSCs will greatly improve the opportunity of such treatments. Transcription factors play important roles in regulating cell proliferation and differentiation. RUNX1 is a transcription factor that is expressed in blood cells and regulates the expression of many blood cell related genes. Therefore, the specific aim of our studies is to examine the effect of RUNX1 on blood cell formation, expansion, and differentiation from human embryonic stem cells and induced pluripotent stem cells. During the first year of funding period, we have established the cell culture and differentiation systems in our laboratory, generated necessary DNA constructs for the proposed studies, and produced transcription factors for testing the effect.
  • The ultimate goal of the proposed study is to identify approaches to increase the production of therapeutically useful blood cells from human ESCs and patient-specific iPSCs. Currently, bone marrow transplantation is the best way to cure many blood-related disorders, such as sickle cell anemia, thalassemia, and blood cancers like leukemia. Furthermore, blood transfusion is an effective way to rapidly counteract blood cell loss due to ablative treatments, such as chemotherapy and radiation therapy. Unfortunately, the limiting factor in transplantation and transfusion treatments is the lack of matched donors. The ability to producing unlimited numbers of blood stem cells and/or functioning differentiated blood cells from human ESCs and patient-derived iPSCs will greatly improve the opportunity of such treatments. Transcription factors play important roles in regulating cell proliferation and differentiation. RUNX1 is a transcription factor that is expressed in blood cells and regulates the expression of many blood cell related genes. Therefore, the specific aim of our studies is to examine the effect of RUNX1 on blood cell formation, expansion, and differentiation from human embryonic stem cells and induced pluripotent stem cells. During the second year of funding period, we have performed hematopoietic cell differentiation using both human ESCs and iPSCs in the presence and absence of this transcription factor. Our results indicate that this factor promotes the production of blood stem cells and progenitors. We will make additional amount of this factor and further confirm our initial finding.
  • The ultimate goal of the proposed study is to identify approaches to increase the production of therapeutically useful blood cells from human ESCs and patient-specific iPSCs. Currently, bone marrow transplantation is the best way to cure many blood-related disorders, such as sickle cell anemia, thalassemia, and blood cancers like leukemia. Furthermore, blood transfusion is an effective way to rapidly counteract blood cell loss due to ablative treatments, such as chemotherapy and radiation therapy. Unfortunately, the limiting factor in transplantation and transfusion treatments is the lack of matched donors. The ability to producing unlimited numbers of blood stem cells and/or functioning differentiated blood cells from human ESCs and patient-derived iPSCs will greatly improve the opportunity of such treatments. Transcription factors play important roles in regulating cell proliferation and differentiation. RUNX1 is a transcription factor that is expressed in blood cells and regulates the expression of many blood cell related genes. Therefore, the specific aim of our studies is to examine the effect of RUNX1 on blood cell formation, expansion, and differentiation from human embryonic stem cells and induced pluripotent stem cells. During the second year of funding period, we have performed hematopoietic cell differentiation using both human ESCs and iPSCs in the presence and absence of this transcription factor. Our results indicate that this factor promotes the production of blood stem cells and progenitors. We will make additional amount of this factor and further confirm our initial finding.

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