Just eight months ago, Elaine Elyzen was losing her 52-year struggle with severe, uncontrollable diabetes. Although she had meticulously followed doctors’ advice, the complications of diabetes were catching up with her.Frequent blackouts, caused by very low blood sugar, made her afraid to go anywhere unless accompanied by someone who knew exactly how to care for her. “I felt guilty because close friends and family always had to be responsible for me. So I stayed in my house and rarely went out.”
On March 3, 2005, Elaine’s life changed dramatically. An islet transplant replaced the insulin-producing cells that diabetes had destroyed. While she still had to take insulin, it was less than half her regular dose, and her blood sugar was under control. Now, since a second transplant in July, Elaine does not require insulin injections at all.
“It’s like I was in a cocoon and now I’m free— physically and mentally. I’m alert. I feel so much better. Life is starting all over for me.”
A resident of Claresholm, northwest of Lethbridge, Elaine says there’s something special about benefiting from a medical breakthrough that was pioneered here in Alberta. “I’ve always read up on diabetes, hoping there would be something for me or my daughter, who also has diabetes. My husband and I marvel that the breakthrough was made in our own province.”
Elaine is referring to the Edmonton Protocol, a procedure for transplanting healthy islets into patients with type 1 diabetes to regain control of blood sugar. The protocol introduced a unique steroid-free combination of anti-rejection drugs together with a sufficient mass of islets to allow a measure of insulin independence. Islets are the cells in the pancreas that produce insulin—a hormone that helps the body use sugar for energy. (In type 1 diabetes, which is an autoimmune disease, the immune system destroys islets. Type 2 diabetes, which accounts for 90% of all diabetes cases, is not an autoimmune disease and is largely preventable.)
Islets for transplantation are removed from the pancreas of a deceased donor and injected into the recipient’s liver, where they begin to release insulin. Recipients must take immunosuppressive drugs for the rest of their lives to stop their immune systems from rejecting the transplanted islets.
The breakthrough was based on years of research into islet transplantation at the University of Alberta. It all began with the formation in 1983 of the Islet Transplantation Group: Dr. Ray Rajotte, Dr. Garth Warnock, and Dr. Norm Kneteman. About 15 years later, Dr. James Shapiro joined the group, and went on to lead the Clinical Islet Transplant Program, the team that first performed the Edmonton Protocol in 1999. Now funded as a Heritage Scholar, Dr. Shapiro and Heritage Senior Scholar Dr. Jonathan Lakey have guided the clinical team to its current success.Cellular therapy
The impact of the Edmonton Protocol is evident in the fact that there are now 40 centres in 34 countries doing islet transplantation; globally, more than 550 people have received islet transplants. The Edmonton Protocol is the most successful and widely replicated method of islet transplantation in the world. In Alberta, islet transplantation is now considered part of “standard care” for certain patients with type 1 diabetes—patients like Elaine Elyzen.In November 2001, Dr. Shapiro and his colleagues were awarded a five-year, $22.3-million grant from the Juvenile Diabetes Research Foundation (JDRF) to launch the JDRF Center for Clinical Islet Transplantation at the University of Alberta. Their work is focused on making the Edmonton Protocol safer, more efficient, and more accessible. This includes developing new drug combinations to suppress the immune system without compromising its effectiveness, and developing better methods of harvesting, storing, and preserving islets prior to transplantation. Dr. Jonathan Lakey, head of the Clinical Islet Laboratory, leads the latter research effort.
“Despite the promise of islet transplantation, we face a limiting factor—the number of pancreas donations,” explains Dr. Lakey. “Even with the most up-to-date methods for islet isolation and retrieval, it usually takes two pancreases to provide sufficient numbers of islets for one transplant recipient. It is vital that we learn how to maximize every pancreas donation. Isolation procedures have improved immensely, but there is more to be done. We need to increase the yield of islets by keeping donor pancreases in better condition and protecting the islets during the isolation process.”
Dr. Lakey’s team is exploring new means of islet culture; for example, culturing islets in very low gravity. By improving oxygen delivery to islets and maintaining energy stores within them, their goal is to see transplanted islets survive longer and function better in patients. Another aspect of this work is developing better, more precise tests of islet function, tests that go beyond simply measuring insulin production. The team is investigating several markers of overall islet health, including membrane integrity, apoptosis (programmed cell death), cell-division activity, and oxygen consumption.
Dr. Lakey is applying the knowledge gained from working with islets to other types of tissue, such as cartilage, heart valves, and stem cells. (He is director of Capital Health’s Comprehensive Tissue Centre, the largest tissue bank in Canada.) “We’re developing the whole area of cellular therapy—transplanting cells and tissues instead of whole organs. The approach has a number of advantages, and it makes sense to capitalize on the expertise we have with islets.”
Sources of islets
Even with improved islet survival, there are still far too few donors to supply the demand. That is why Heritage Senior Scholar Dr. Greg Korbutt’s research at the University of Alberta is aimed at developing a larger supply of insulin-producing islets. One approach is transplanting islets from newborn pigs. Dr. Korbutt’s team has been able to reverse diabetes in mice and, more recently, in larger animals with this procedure. “Because this is a preclinical model, it will still be a couple of years before this method can be transferred to humans,” he notes, “but the results so far are promising.”
Dr. Korbutt acknowledges that cross-species transplantation (known as xenotransplantation) is controversial. The dangers include risk of rejection and risk of infection. Risk of rejection can be diminished by using specially bred pigs that have been genetically altered to remove genes that cause rejection. Risk of infection can be addressed with precautions such as raising the pigs in sterile conditions. However, even with a super-clean pig, there is still risk of infection from porcine endogenous retroviruses (PERV)—tiny remnants of viruses scattered throughout the animal’s DNA. Dr. Korbutt has completed a study showing that PERV is not transmitted from pig islets into mice. “We need to learn more about this, and that is part of the reason behind preclinical studies. We want to make sure this will be safe for humans.”
Another potential source of islets is stem cells, and Dr. Korbutt is also pursuing this line of research. One project involves studying stem cells in the adult pancreas. These cells are capable of becoming islets, and the challenge is to push them to develop in that direction. So far the team has had only limited success. “There’s a complex signalling process that pushes stem cells a certain way, and that’s what we’re trying to mimic,” explains Dr. Korbutt. “It’s not just a matter of turning a signal on; there are other signals that need to be turned off. Many more studies are needed before we can figure this out.”
Tolerance
Other diabetes researchers are focusing on the immune system. At the University of Alberta, Heritage Scholar Dr. Colin Anderson is studying tolerance—the mechanism by which the immune system learns to live with certain molecules while at the same time attacking others. Understanding tolerance could be the foundation for helping islet transplant recipients avoid the lifelong use of immunosuppressive drugs. These drugs have long-term side effects which limit the use of transplantation, especially in children. Is it possible to devise a way for the recipient’s immune system to tolerate donor islets? “Our immune system already knows how to develop tolerance; we have to figure how it does it,” says Dr. Anderson. Tolerance develops in the thymus, a specialized gland in the upper chest. T cells (white blood cells that are critical to the immune response) originate from stem cells in the bone marrow and migrate to the thymus, where they learn how to recognize “self” and “non-self”.
Dr. Anderson has made key contributions to understanding T-cell development in the thymus, teasing out factors that control tolerance. Using the results of his basic research, he is designing interventions to develop tolerance. One of them could involve getting donor T cells into the recipient’s thymus, which would train the immune system to tolerate the donor’s cells. While this is promising in theory, there are huge practical issues to overcome. Such a scheme would require a stem-cell transplant into the bone marrow, which would mean eliminating the recipient’s immune response prior to transplant. (This is similar to what is done currently in the case of bone-marrow transplants to treat leukemia.) Dr. Anderson’s lab is experimenting with a combination of specially produced antibodies, radiation, and drugs to help donor cells establish in the bone marrow.
At the same time, his team is also developing a new way of encouraging tolerance using “B1B” immune-system cells. Since these cells don’t need stem cells to replicate, the stem-cell transplant to shut off the immune response could be avoided. However, it’s not yet known whether B1B cells will be effective enough to stimulate tolerance. “We need to try innovative ideas like this because of the problems with immunosuppression,” says Dr. Anderson. “The immune system is very complex and doesn’t give up its secrets easily.”
Genes
At the University of Calgary, Heritage Scientist Dr. Pere Santamaria is also wrestling with this complexity. “We know there are more than 20 genes involved in type 1 diabetes. While we know approximately where they are located, we don’t know exactly what they are and how they control both disease susceptibility and disease resistance. In addition, all cells of the immune system are involved in diabetes, and their response is very coordinated. My approach has been to simplify this complexity in order to study diabetes more easily.”Dr. Santamaria’s lab has engineered a particular kind of non-obese diabetic (NOD) mouse. (NOD mice develop a form of diabetes very similar to human type 1 diabetes.) The immune system of Dr. Santamaria’s NOD mouse has been engineered so that all T cells kill islets. By making genetic variations of this mouse, he can investigate the effects of specific genes. “We want to know more about certain variants of genes, and how they afford resistance or susceptibility. We want to know exactly how the T cells kill the islets, and how the protective variants of genes stop this from happening.”
Dr. Santamaria points out that diabetes is not a matter of a single defective gene, as is the case in a disease like cystic fibrosis. The genes that favour diabetes or protect from diabetes are not abnormal genes; rather, they are normal variants that give some selective advantage. “Autoimmunity should be viewed as an unlucky combination of genes that would be good in isolation but are bad in combination,” he explains. “The differences between these variants are extremely small, but can cause tremendous differences in susceptibility to disease.”
Considerable progress has been made in understanding the variants of certain genes linked to diabetes. Dr. Santamaria’s team has already identified certain protein interactions that cause diabetes, and shown that his NOD mice are completely protected from the disease when this interaction is blocked. “Promising results like this highlight the need for a better understanding of the pathways that the protective variants of genes use to stop the immune system from destroying cells,” he says. “By learning from nature, I’m confident that we can design something intelligently to prevent diabetes.”
Disease resistance
Several of the genes that Dr. Santamaria studies are located in a particular region of human chromosome 6 called the major histocompatibility complex (MHC). These genes are key to our ability to resist disease. Like teachers in front of a class, MHC genes make a substance that helps display pieces of foreign invaders—such as bits of virus or bacteria—for their students, the immune cells, to recognize. A colleague of Dr. Santamaria’s at the University of Alberta, Heritage Scientist Dr. John Elliott, is studying genetic variations in the MHC.Dr. Elliott calls the MHC the “Mount Everest of genes” because it is one of the most variable and gene-rich regions of the human genome; it is the place where most of the genetic differences between individuals are found. These differences result in varying abilities to resist disease.
For the past five years, Dr. Elliott has participated in an international effort to detail the DNA sequence of the MHC region for two different example genomes associated with diabetes or multiple sclerosis. The MHC Haplotype Project is run by the Wellcome Trust Sanger Institute in the United Kingdom. For the project, Dr. Elliott’s lab grew cell lines, prepared DNA, and generated gene libraries. “This project is important because it is analyzing the genome of different individuals in the finest detail. These variations are the difference between being healthy and having an autoimmune disease.”
Part of this work involved developing expertise in a number of new DNA cloning technologies, a particular interest of Dr. Elliott’s. “We’re trying to push the technical edge with this work. It’s something I really enjoy. We need a blueprint of the whole MHC to sort out the puzzle of diabetes. That’s a huge undertaking—the MHC consists of 4.5 million base pairs. The technology to do this is coming, but it’s not there yet. I believe that this understanding will lead to new therapies, perhaps vaccines, that will treat diabetes and other autoimmune diseases.”
Dr. Elliott’s interest in molecular technologies has also led him to explore the use of gene therapy to improve the islets’ chances of survival after transplant. Recent promising results suggest that islets from a single donor pancreas may someday be used to treat two patients with diabetes.
Vision and perseverance
The belief that there is a better way to treat type 1 diabetes is what drives researchers like Dr. Elliott forward, and when it comes to diabetes research in Alberta, there’s no greater believer than the University of Alberta’s Dr. Ray Rajotte. He saw the potential for islet transplantation years ago, and recognized that this multi-faceted research problem would require a team approach. He set about building the islet transplantation team in 1983, when he first received funding from AHFMR. That team carried out Canada’s first islet transplant in 1989. The excellence of the multidisciplinary research team and the success of the Edmonton Protocol is testament to Dr. Rajotte’s vision and perseverance. Now his influence has gone beyond islet transplantation, as he is the prime mover behind the creation of the Alberta Diabetes Institute. When construction is finished in 2006, all basic diabetes researchers at the University of Alberta will work under one roof.“We need a new facility that can house diverse research groups in surgery, exercise physiology, nutrition, epidemiology, immunology, and more,” says Dr. Rajotte, who is scientific director of the Alberta Diabetes Institute, as well as director of the Islet Transplantation Group and the Surgical-Medical Research Institute. “The Alberta Diabetes Institute will be a world-class centre that will tackle all aspects of type 1 and type 2 diabetes. In a way, this is the culmination of my career.
“What I’m most proud of is the young colleagues who came into my lab and learned about research. They’ve developed into first-class academic researchers who are now leaders in the field. I looked at this big puzzle of diabetes and knew there was no way I was going to solve it on my own. If you surround yourself with bright, energetic people, you’re going to move science forward. And that’s exactly what we’ve done.”
Dr. James Shapiro is an AHFMR Scholar, director of the Clinical Islet Transplant Program, and assistant professor in the Department of Surgery at the University of Alberta. He holds the CIHR-Wyeth-Ayerst Clinical Research Professorial Chair in Transplantation and also receives funding from the Juvenile Diabetes Research Foundation and the National Institutes of Health in the United States.
Dr. Jonathan Lakey is an AHFMR Senior Scholar and an associate professor in the Department of Surgery at the University of Alberta. He is director of the Islet Isolation Laboratory and director of the Comprehensive Tissue Centre for the Capital Health Authority. He also receives funding from the University of Alberta, Capital Health, the Juvenile Diabetes Research Foundation, the Diabetes Research Institute Canada, as well as several private donors to the Clinical Islet Transplant Program.
Dr. Gregory Korbutt is an AHFMR Senior Scholar and an associate professor with the Surgical-Medical Research Institute in the Faculty of Medicine and Dentistry at the University of Alberta. He receives funding from CIHR (Canadian Institutes of Health Research), the Juvenile Diabetes Research Foundation, and the Stem Cell Network.
Dr. Colin Anderson is an AHFMR Scholar and an assistant professor in the departments of Surgery and Medical Microbiology & Immunology, University of Alberta’s Faculty of Medicine and Dentistry. He also receives funding from CIHR, the National Institutes of Health in the US, the Edmonton Civic Employees Charitable Assistance Fund, and the Alberta Diabetes Institute.
Dr. Pere Santamaria is an AHFMR Scientist and a full professor and chair of Microbiology and Infectious Diseases in the Faculty of Medicine at the University of Calgary. He is chair and director of the Julia McFarlane Diabetes Research Centre. He also receives funding from CIHR, the Juvenile Diabetes Research Foundation, the Canadian Diabetes Association, NSERC, and the National Institutes of Health in the United States.
Dr. John Elliott is an AHFMR Scientist and a full professor in the Department of Medical Microbiology and Immunology in the Faculty of Medicine and Dentistry at the University of Alberta. He chairs the M.D./Ph.D. Committee. Dr. Elliott receives additional funding from CIHR and the Juvenile Diabetes Research Foundation.
Dr. Raymond Rajotte is a full professor at the University of Alberta, director of the Surgical-Medical Research Institute, director of the Islet Transplantation Group, and scientific director of the Alberta Diabetes Institute in the Faculty of Medicine and Dentistry at the University of Alberta. He receives funding from CIHR and the Alberta Diabetes Foundation.
Selected publications
Street CN, Lakey JRT, Shapiro AMJ, Imes S, Rajotte RV, Ryan EA, Lyon JG, Kin T, Avila J, Tsujimura T, Korbutt GS. Islet graft assessment in the Edmonton Protocol: implications for predicting long-term clinical outcome. Diabetes 2004 Dec;53(12):3107-3114.
Emamaullee JA, Rajotte RV, Liston P, Korneluk RG, Lakey JRT, Shapiro AMJ, Elliott JF. XIAP overexpression in human islets prevents early posttransplant apoptosis and reduces the islet mass needed to treat diabetes. Diabetes 2005 Sep;54(9):2541-2548.
Anderson CC, Chan WFN. Mechanisms and models of peripheral CD4 T cell self-tolerance. Frontiers in Bioscience 2004 Sep 1;9:2947-2963.