Our Focus

Generating transplantable blood cells

Regeneration of the blood system through the transplantation of blood-forming stem cells (commonly referred to as bone marrow transplantation) is an effective treatment for a range of blood cell diseases, including leukemia. The transplantation of blood-forming stem cells and specific blood cell types is already being used in the clinic or under investigation for the treatment of an expanded list of diseases, such as cancers, autoimmune diseases and inflammation. Cells for these therapies are currently obtained from immune-matched donors or from the patients themselves. Although effective, reliance on donor and patient-derived cells limits the number of patients that can be treated and the benefit of these transplantation-based therapies. The generation of blood-forming stem cells and specific blood cell types from human pluripotent stem cells (hPSCs) would provide a new and potentially unlimited supply of these cells for treating a much broader patient population.

Our Discoveries

• Demonstrated that it is possible to generate the blood cells produced in the early embryo, in the Petri dish from hPSCs.
• Developed methods to make the different types of blood cells including red blood cells, myeloid cells and immune cells from hPSCs.

Our Research

Using insights from blood cell development in different organisms, the Keller lab has successfully modelled human hematopoietic development from hPSCs differentiated in vitro. Through manipulation of specific signalling pathways, they have demonstrated that it is possible to generate the two major hematopoietic programs — primitive and definitive — which are known to develop in the embryo. While the main function of primitive hematopoiesis is to generate the cohort of blood cells required to sustain embryonic life, recent studies have shown that this program also contributes to a specialized immune cell population, the tissue-resident macrophage that persists in different organs into adulthood. These macrophages are thought to play important roles in maintaining normal organ function. Definitive hematopoiesis gives rise to all the hematopoietic cell types found in the adult, including the hematopoietic stem cell (HSC). Through our ability to specify these two programs, we have been able to develop protocols for the generation of most of the hematopoietic cells found in the embryo as well as in the adult. Additionally, we have been able to identify developmentally staged progenitors that display the properties of the progenitors that give rise to the HSC in the embryo. These advances have brought us an important step closer to generating hPSC-derived HSCs, immune cells and tissue-resident macrophages for the development of new cell-based therapies to treat different diseases.

Current projects include:

• Generation of HSCs from hPSCs.
• Generation and functional characterization of immune cells from hPSCs.
• Generation and functional characterization of tissue-resident macrophages from hPSCs.

Eliminating Insulin Injections

More than 300,000 Canadians live with type 1 diabetes. A chronic and sometimes fatal disease, type 1 diabetes is an autoimmune disease that results in the destruction and elimination of insulin-producing beta cells in the pancreas. The loss of beta cells ultimately leads to insulin dependence and major complications that are difficult to manage with insulin injections. Recent improvements in islet transplantations for the treatment of type 1 diabetes are increasing the likelihood of finding a possible cure for this disease. However, the requirement for 2-3 donors per transplantation, and the scarcity of donor pancreata, coupled with the requirement for life-long immunosuppression, has led to the search for an alternative source of beta cells for cell therapy. Beta cells produced from human pluripotent stem cells (hPSCs) represent a new and potentially unlimited source of these cells for transplantation for the treatment of type 1 diabetes.

Our Discoveries

• A method to generate pancreatic progenitors from hPSCs.
• A strategy to identify and purify hPSC-derived pancreatic progenitors and the demonstration that they can develop into insulin-producing beta cells.
• A transplantation approach to improve engraftment and long-term survival of pancreatic cells in diabetic models.

Our Research

The focus of Dr. Cristina Nostro's lab is to elucidate the signalling pathways governing the formation, expansion and maturation of pancreatic progenitors using human pluripotent stem cell-directed differentiation. Through this in vitro approach, the lab aims to understand the genetic and epigenetic program that dictates pancreatic development and the differentiation and maturation of islet-like cells. Due to the very limited accessibility of the human embryo, this represents a powerful and unparalleled system to understand key human developmental processes. Furthermore, through the use of patient-specific iPSC-directed differentiation, the Nostro lab will be able to study disease development and progression in ways that were previously inconceivable.

In 2017 and 2021, Dr. Nostro published ground-breaking studies in Nature Communications and Cell Stem Cell showing methods to effectively purify populations of pancreatic progenitor cells and improve graft survival and functionality in models of diabetes. As these cells can successfully develop into insulin-producing beta-like cells, these discoveries will enable safer and more efficient testing of these cells across a larger number of laboratories, increasing the odds — and the speed — of changing the way we treat type 1 diabetes.

Repairing a Damaged Heart

Ischemic heart disease remains the leading cause of death in Canada and worldwide. Modern medical management has improved the prognosis of patients after a myocardial infarction (MI), commonly known as a heart attack, but existing therapies are largely aimed at slowing disease progression rather than restoring lost contractile function. Transplantation of cardiomyocytes (heart muscle cells) produced from human pluripotent stem cells (hPSCs) offers a potential new therapy that could, for the first time, remuscularize and repair the heart.

Our Discoveries

• Identified methods to guide hPSCs to differentiate to heart muscle cells (cardiomyocytes).
• Generated pure populations of specialized types of human heart cells, including atrial, ventricular and pacemaker cells.
• Demonstrated that hPSC-derived cardiomyocytes can regenerate heart muscle in preclinical models of heart disease.
• Establish scalable methods for manufacturing mature hPSC-derived ventricular cells and demonstrated that these more mature cells yield better outcomes than their immature counterparts after transplantation.

Our Research

Drs. Gordon Keller and Michael Laflamme's laboratories are collaborating on the development of novel therapies for post-MI heart failure based on the transplantation of cardiomyocytes into the damaged area of the heart. Our goal is to restore the electrical and contractile function of injured hearts by generating new muscle in the scarred (damaged) area with hPSC-derived cardiomyocytes.

Their laboratories have already made a number of important advances in this area, including the development of efficient protocols to guide hPSCs to generate specialized cardiac subtypes, proof-of-concept transplantation studies with hPSC-derived cardiomyocytes in rodent MI models, and the first direct demonstration that hPSC-derived cardiomyocytes can become electrically integrated and beat synchronously with the host heart tissue. Our ongoing work builds on these successes to advance the development of a viable cell therapy for heart disease.

Current projects in the labs include:

• Developing methods to more efficiently produce the specific type of cardiomyocyte that is damaged following a heart attack.
• Developing approaches to produce more mature cardiomyocytes for transplantation.
• Developing methods to produce other cell types found in the heart from hPSCs and test if they improve (enhance) regeneration and repair of the heart when transplanted together with cardiomyocytes.
• Creating and validating new tools to study and characterize the electrical behaviour of hPSC-derived cardiac tissue grafts in the damaged heart.
• Exploring novel approaches to improve electromechanical integration of new the heart tissue that develops from the transplanted cells with the surround undamaged tissue of the host heart.
• Testing the ability of the hPSC-derived tissue to improve heart function in highly relevant preclinical MI models that most closely recapitulate human heart disease.
• Testing the safety of hPSC-derived cardiomyocyte transplantation in the same relevant preclinical MI models.

Eliminating Pacemakers

The heartbeat is initiated and regulated by specialized group of cardiomyocytes known as pacemaker cells. Failure of these pacemakers due to either age or disease can result in life-threatening irregular or slow heart rhythm. The current treatment option for these conditions is the implantation of an electronic pacemaker device that takes over control of activating the heartbeat. Although effective, these devices have a number of disadvantages including the need for periodic battery replacement, a risk of lead infections, a lack of communication with the autonomous nervous system and a lack of adaption to growth in paediatric patients. Transplantation of pluripotent stem cell-derived pacemaker cells could overcome these disadvantages and present an attractive future therapy for patients with pacemaker dysfunction.

Our Discoveries

• Methods to direct the differentiation of hPSCs to make primary pacemaker cells.
• Methods to generate and isolate highly enriched populations of these pacemaker cells.
• Proof of concept studies in small, pre-clinical laboratory models demonstrating that these pacemaker cells can function as biological pacemaker and pace the heart.

Our Research

Dr. Stephanie Protze's lab is using developmental biology-based approaches to establish strategies to guide the differentiation of hPSCs into the two different types of pacemaker cells found in the heart. One goal of these studies is to generate 'biological pacemakers' from these cells that can be transplanted into patients with pacemaker dysfunction. A second goal of Dr. Protze's work is to use these hPSC-derived pacemaker cells to study specific diseases that affect pacemaker function, such as congenital heart block. These studies are carried out in the Petri dish and are aimed at identifying the causes of such diseases and ultimately identifying potential drugs to treat them.

Current projects include:

• Developing methods to generate atrioventricular node pacemaker cells from hPSCs.
• Establishing new in vitro models for conduction system diseases including congenital heart block and inappropriate sinus tachycardia.
• Implementing synthetic biology to enhance the function of stem cell-derived cardiomyocytes.
• Developing new 3D models to study human heart development and congenital heart diseases.

Treating a Failing Liver

It is estimated that more than three million Canadians have chronic liver disease and the incidence of some forms is increasing dramatically. Although treatments exist for early stages of the disease, progression to liver failure requires transplantation of a new organ. As the demand for transplantation far exceeds the number of available donor organs, only a limited number of patients will receive this treatment. The regeneration and repair of damaged and diseased livers through transplantation of new liver cells made from human pluripotent stem cells (hPSCs) offers a potential new therapy to treat these patients.

Our Discoveries

• Developed methods to make liver progenitors (hepatoblasts) from hPSCs.
• Identified methods to generated functional liver cells (hepatocytes) and bile duct cells (cholangiocytes) from the hPSC-derived hepatoblasts.
• Demonstrated that hPSC-derived cholangiocytes can be used to study Cystic Fibrosis in the Petri dish and to identify new drugs to treat this disease.

Our Research

The McEwen Institute's liver regeneration program is directed by Dr. Shinichiro Ogawa. By translating knowledge of human liver development to the differentiation cultures, Dr. Ogawa has identified the regulatory pathways that promote the development of two of the main cell types in the liver —hepatocytes and cholangiocytes (bile duct cells) — from hPSCs. The cells generated under these conditions display many characteristics and properties of hepatocytes and cholangiocytes found in the adult organ. Based on these advances, it has been possible to establish differentiation protocols that promote the efficient development of both cell types in culture. With access to the hPSC-derived hepatocytes, we have begun transplantation experiments using laboratory models engineered to undergo liver failure as pre-clinical studies to determine if it is possible to restore liver function with this approach.

Our studies using hPSC-derived cholangiocytes are focused on developing models to study Cystic Fibrosis liver disease (CFLD), which impairs the function of bile ducts in the liver. Using this model, it is possible to establish high throughput screens to identify new drugs to treat CFLD. In addition to the hepatocytes and cholangiocytes, the liver contains a number of other cell types including immune cells, stellate cells and sinusoidal endothelial cells that play important roles in normal liver function and in liver disease. Given this, it will be important to be able to generate all of these cell types from hPSCs to develop cell-based therapies to treat a broad range of diseases.

Current projects include:

• Further specification and maturation of hepatocytes and cholangiocytes.
• Testing the regenerative potential of hPSC-derived hepatocytes in pre-clinical models of liver failure.
• Development of functional liver sinusoidal endothelial cells, stellate cells, and macrophages from hPSCs.
• Generation of engineered liver tissue using hPSC-derived liver cell types.
• Transplantation of engineered liver tissue into pre-clinical models of liver failure.
• Modelling liver disease in vitro using hPSC-derived liver cell types.