David Hess
Scientist
Molecular Medicine: Vascular and Brain Health Group,
Krembil Centre for Stem Cell Biology, Robarts Research Institute
Associate Professor, Department of Physiology and Pharmacology, UWO
Why I Became a Scientist
Growing up I was always interested in a career in medicine. As a teen I underwent bone marrow transplantation to treat severe aplastic anemia, a disease where stem cells within the bone marrow fail to produce red blood cells that carry oxygen to our tissues, leukocytes that fight infection, and platelets involved in blood coagulation. As a result, my focus and interest in stem cells and transplantation therapy was initiated. During my undergraduate and post-graduate education, I was fascinated by the immense potential of stem cell transplantation to treat a wide variety of potentially fatal diseases. Ultimately, I focused on the exciting field of stem cell research as my career path in order to develop cellular therapies for cancer, cardiovascular diseases, and diabetes. I feel my experiences as both a patient and a research scientist allows for a unique perspective in the preclinical and clinical development of cellular therapies.
Research Summary
The focus of Dr. Hess’s research is to understand the mechanisms by which distinct stem cell subsets co-ordinate hematopoiesis, angiogenesis, and tissue repair. Ultimately, Dr. Hess is interested in the development of cellular therapies to mediate the repair of diseased, damaged, or ischemic tissues. Specific applications for his work include the use of transplanted human stem cells to promote wound healing and blood vessel formation, and to regenerate insulin-producing beta cells during diabetes.
In an attempt to isolate and study the regenerative functions of human bone marrow-derived stem cells, Dr. Hess' lab has purified multiple (hematopoitic, endothelial, and mesenchymal) stem cell lineages simultaneously using high-speed fluorescence activated cell sorting based on a conserved stem cell function (high aldehyde dehydrogenase activity) and cell surface markers. These progenitor cell lineages can be expanded efficiently in vitro and their regenerative functions are studied by the transplantation in immune deficient mouse models specifically designed to track the contributions of human cells during blood vessel formation during critical limb ischemia, and during the regeneration of islet function in hyperglycemic recipients.
Research Questions
Can the transplantation of purified stem cells promote new blood vessel formation in ischemic tissues?
During diabetes and cardiovascular disease, damage to the cardiovascular system can result in ischemic heart disease and critical limb ischemia. Approximately 14 million individuals in North Americas suffer from ischemic heart disease, and greater than 100,000 diabetic patients will suffer limb amputation due to severe peripheral vascular disease. We have shown that several stem cell types co-ordinate together in the formation of new blood vessels. Ultimately, our goal is to optimize the selection and expansion of rare vessel–forming endothelial progenitor cells, and co-transplant them with supportive hematopoietic and mesenchymal stem cells to augment blood vessel regeneration in vivo.
Can the transplantation of purified stem cells support the regeneration of pancreatic beta-cell function during diabetes?
Diabetes involves a progressive loss of insulin-secreting beta cells within islets of Langerhans, and affects >250 million individuals worldwide. Islet transplantation can establish insulin-independence in severe diabetics, but critical shortages of donor tissue limits its widespread availability. However, regenerative therapies for diabetes are not limited to direct replacement of beta cells. We have established that aldehyde dehydrogenase expressing mixed progenitor cells from human umbilical cord blood and bone marrow mesenchymal stem cells (MSC) recruit to damaged islets after transplantation, induce proliferation of host beta cells, and enhance insulin secretion and glycemic control. We intend to identity how readily available stem cell populations can impact beta cell regeneration, a critical step towards the development of successful cellular therapies for diabetes.
What are the mechanisms by which distinct stem cell subsets co-ordinate complex biological processes such as tissue regeneration?
Although our research program focuses on the regeneration of blood vessels and beta cells to treat the complications of diabetes, the processes of angiogenesis and islet repair are applicable to multiple tissues and disease states. For example, further understanding of blood vessel formation may be useful in the development of cancer therapies to prevent solid tumour growth and vascularization. In addition, the formulation of a regenerative niche by the direct transplantation of pro-angiogenic and islet neogenic stem cells into the pancreas may be used to tip the balance in favour of islet regeneration versus destruction during diabetes. By understanding the ability of transplanted stem cells to mediate regenerative processes we hope to indentify critical secreated molecules and pathways to help the body heal and regenerate itself.
Education
- PhD, Department of Pharmacology and Toxicology, University of Western Ontario, London, ON
Training
- Post-doctoral Research Fellow, Stem Cell Biology and Regenerative Medicine, Robarts Research Institute, London, ON
- Post-doctoral Research Fellow/Research Associate, Department of Internal Medicine, Division of Oncology, Hematopoietic Development and Malignancy Group, Washington University School of Medicine, St. Louis, MO, USA
Awards
- MacDonald Scholarship, Heart and Stroke Foundation of Canada
- New Investigator Salary Award, Heart and Stroke Foundation of Canada
- Postdoctoral Fellowship, Canadian Institutes of Health Research
- Postdoctoral Fellowship, Ontario Research and Development Challenge Fund
- Harry and Gundrun Sharma Award for Research Excellence, Department of Pharmacology and Toxicology, The University of Western Ontario
- Medical Research Council PhD. Studentship, National Health Research and Development Program, Health Canada
- Medical Research Council MSc. Studentship, National Health Research and Development Program, Health Canada
Publications
Contact Info
David A. Hess PhD
Associate Professor, Department of Physiology and Pharmacology
The University of Western Ontario
Scientist, Molecular Medicine: Vascular and Brain Health Group
Krembil Centre for Stem Cell Biology
Robarts Research Institute
1151 Richmond St. N., Room 4245B
London, Ontario, Canada, N6A 5B7
Phone: 519-931-5777 ext. 24152
Fax: 519-663-3789
Email: dhess@robarts.ca
