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CANADIAN GENETIC DISEASES NETWORK |
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CANADIAN SCIENTISTS MAKE IMPORTANT ADVANCE IN THE STUDY OF HUMAN BLOOD DISEASE
Toronto - August 31, 1998: A team of researchers, led by Canadian Genetic Diseases Network scientist Dr. John Dick at Hospital for Sick Children, has discovered a new stem cell in human blood which provides novel insights into how the blood system works. The discovery may have an impact on the therapy currently used in the treatment of some blood diseases such as leukemia, thalassemia, and sickle cell anemia.
These latest findings, published in the August 31 issue of Nature Medicine, build on ground-breaking research results published by Dr. Dick and his team in December 1996 when a bone marrow cell which produces blood in the human body was identified. At that time it was anticipated that in a gene therapy process, a normal gene would be inserted into the stem cell of a patient and the altered cell would then begin to produce blood containing the normal gene.
Stem cell transplants are now widely used for treating different types of cancer, anemias and auto-immune disorders. While stem cells carrying a protein marker called CD34 are commonly selected for therapy and cell transplantation in many patients with blood disease, Dr. Dick's new findings indicate that stem cells which do not express the CD34 marker and which have previously been discarded in the therapy process may, in fact, provide a target for stem cell gene therapy.
In order to study the entire human blood system and how this system develops from stem cells, Dr. Dick's team over the last 10 years has developed a biological system and successfully reproduced the entire human blood system in mice. By transplanting human blood cells into special immune-deficient mice called NOD/SCID mice, this system provides scientists with a living organism in which to study the development of the human blood system. The significance of Dr. Dick's latest discovery which, in today's publication has been shown in animal models, will now be determined for human patients.
"The identification of this new type of stem cell is important biologically in order to understand how the blood system works. It is important clinically because we may be able to make stem cell transplants better and develop new therapies if we focus on this new stem cell," said Dr. Dick.
Dr. Michael Hayden, Scientific Director of the Canadian Genetic Diseases Network (CGDN) which is headquartered at the University of British Columbia, said "These are significant results which bring us one step closer to the better understanding and treatment of life threatening diseases, including anemias and cancer of different blood cells. The Canadian Genetic Diseases Network has been actively committed since 1990 to ongoing support and development of high calibre Canadian-led research in human genetic disease.
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SCIENTISTS IDENTIFY HUMAN BONE MARROW CELL RESPONSIBLE FOR PRODUCING BLOOD
Toronto, December 2, 1996: Ground-breaking research results which represent an important advance in the study of human blood diseases were announced today by an international team of scientists led by Network principal investigator, Dr. John Dick, at the Hospital for Sick Children, Toronto.
The team has identified a bone marrow cell which produces blood in the human body. The existence of the cell, called a 'stem cell', has been known to scientists for years but it was not until now that they were able to pinpoint it through its blood-producing activity in mouse models.
The discovery is a major step towards the evenual development of new therapies including gene therapy for blood diseases such as leukemia, thalassemia, and sickle cell anemia which affect over 3,000 Canadians annually (2,000 Canadians die of leukemia each year). In a gene therapy process, scientists anticipate that a normal gene will be inserted into the stem cell of a patient and the altered cell will then begin to produce blood containing the normal gene. Said Dr. Dick also a professor of molecular and medical genetics at the University of Toronto,"Now that we know what cell we are dealing with, we can work on understanding how best to deliver genes into the cell and determine how to make that mechanism work for gene therapy."
The results of the research are published today in the scientific journal Nature Medicine.
These new findings are based on the team's recent successful production of a mouse model of the human blood system in severe combined immune-deficient (SCID) mice. The team found after transplanting human bone marrow cells into the affected mice that a rare stem cell could regrow the human blood system in the mice. The scientists went on to determine that therapeutic genes could not be effectively inserted into this cell using commonly employed methods, a determination which has also been reported in human clinical trials.
The similarity in the results between the mouse model and the human trial shows that the mouse model will be a good predictor of what may happen in the human. Using this mouse model, researchers can begin to work towards overcoming the gene delivery problem in stem cells and the development of a gene therapy strategy. The control of stem cell functions, which have a direct impact on the occurence of leukemia, can now also be studied.
Commented Dr. Michael Hayden, Scientific Director of the Canadian Genetic Diseases Network "These significant results are an important step forward in the better understanding and treatment of devastating inherited and cancer-related blood diseases. The Canadian Genetic Diseases Network is actively committed to ongoing support and development of high calibre Canadian-led research."
The Canadian Genetic Diseases Network is a consortium of 38 of Canada's leading geneticists who are linked with 11 universities, 8 hospitals, and 9 core technology facilities across the country. The Network performs leading-edge research on common genetically transmitted diseases and works with industry partners on methods of detection and treatment of the diseases. Core funding for Network programs is provided by the federal Networks of Centres of Excellence Program through the Medical Research Council of Canada.