Accelerator Funds

Post-transcriptional gene regulatory modules that control stem cell differentiation

Project PI: James Ellis
Developmental & Stem Cell Biology, Hospital for Sick Children
Department of Molecular Genetics, University of Toronto

Co-PIs: Ben Blencowe, John Calarco, Freda Miller, Quaid Morris

Project Description: This project will discover RNA binding proteins (RBPs) that promote stem cell expansion and neuron specification. The team comprises University of Toronto professors with world-leading expertise in RNA biology, nervous system development, and stem cell research. James Ellis will conduct studies on regulation of RNA stability and translation into proteins in pluripotent stem cells and their progeny during neurodevelopment and disease. Ben Blencowe will define RNA alternative splicing profiles that identify neuronal subtypes from specific brain regions and elucidate the regulatory modules that control these processes. Computational biology required to predict RBPs that control modules will be led by Quaid Morris. Freda Miller will discover novel RBP interactions with a translational repression complex and utilize this knowledge to enhance methods to specify neuron fate and to induce production of new-born neurons in vivo as a crucial step towards endogenous repair. John Calarco will decipher the map of RBP expression at single neuron resolution and test the role of RBPs in translational repression. The deliverables are discovery-driven findings of RNA biology that result in novel resources for identifying and specifying types of neurons, thereby enabling improved stem cell differentiation methods and induction of endogenous repair. This team is globally competitive and has an extensive record of discoveries that have transformed our knowledge of post-transcriptional regulatory mechanisms. The proposed research will result in novel intellectual property and be clinically translatable into stem cell based methods for use in drug testing and regenerative medicine.

Systems-level analysis of blood progenitor development from human PSCs

Project PI: Jason Moffat
Department of Molecular Genetics, University of Toronto

Co-PIs: Gordon Keller, Brenda Andrews, Charlie Boone, Stephane Angers

Project Description: Source material for hematopoietic (bone marrow) transplantation is in great demand as at least 20,000 allogeneic transplants are performed each year. Despite advances in using umbilical cord blood, donor material remains restricted by limited stem cells and the lack of ethnic diversity to provide sufficiently matched material. Thus, alternative sources of patient-specific hematopoietic stem cells (HSCs) are required. The generation of HSCs has been a long-standing goal of stem cell biologists working in the field of developmental hematopoiesis. Despite extensive efforts in this area over the past two decades, it is not yet possible to derive HSCs in vitro. This failure is largely due to a lack of fundamental insights into genes and pathways that control HSC development. This team, which brings together expertise in stem cell biology, cell biology, developmental signalling pathways, and genetic screens, aims at improving methods to achieve generation of HSC. The group plans to identify better markers to track and purify key cell intermediates as well as uncover key genes/pathways that lead to HSC development. The ultimate goal is to establish a robust platform that can be used to identify and validate novel genetic factors and protein tools to improve understanding of the process that will lead to our ability to re-constitute the entire blood ontogeny in a patient-specific manner. The methods proposed are cutting-edge and no other team in the world has this combination of technologies, approaches and expertise to make advances in hematopoietic cell therapies.

Cell transplantation for stroke repair

Project PI: Cindi Morshead
Division of Anatomy, Department of Surgery, University of Toronto

Co-PIs: Andras Nagy, Molly Shoichet, Nir Lipsman

Project Description: Stroke is a leading cause of death and disability worldwide. There are no current treatments to repair the stroke-injured brain and promote recovery. Recovery of lost brain function after stroke involves relearning skills based on the ability of the nervous system to undergo structural and functional changes in response to new experiences, a phenomenon called neuroplasticity. Research is focused on developing new ways to encourage neuroplasticity, and stem cell based therapies offer promise in this area. Indeed, stem cell transplantation has shown some promise in animal models of stroke. However, greater insight into the mechanisms that underlie the success of neural stem cells transplantation is needed. This research team has come together to solve an unmet challenge, namely to find a source of stem cells that can be used safely and to understand the mechanisms by which transplanted cells promote neural repair. The group’s pioneering work will enable this project to engineer cells and cell delivery materials to further understanding of the mechanisms underlying the success of cell transplantation paradigms. The combined expertise in stem cell biology, tissue engineering, biomaterials, stroke and neuroplasticity, will allow the team to:

  • use genetic tools to generate clinically relevant stem cell populations for transplantation;
  • bioengineer materials that encourage cell survival and cell integration in the injured brain;
  • use novel approaches to gain insight into the underlying mechanisms that promote recovery; and
  • create a roadmap to the clinic for cell-based strategies to treat stroke.

Introducing fail-safe pluripotent cells into clinically relevant cell therapy applications

Project PI: Andras Nagy
Lunenfeld-Tanenbaum Research Institute, Sinai Health System
Department of Obstetrics and Gynaecology and Institute of Medical Science, University of Toronto

Co-PIs: Martin Post, Tom Waddell

Project Description: The transplantation of pluripotent stem cell (PSC)-derived therapeutic cells to treat disease is challenged by the risk of introducing malignant cell types to the patient. Cell transplants leading to uncontrolled growth can arise due to genetic mutations that arise from in vitro expansion of PSCs. The Nagy lab has pioneered the generation of mouse and human PSCs carrying a “fail-safe” genetic system that enables selective ablation of “ill-behaving,” highly proliferating cells post-transplantation. The Nagy lab will further extend the “fail-safe” system by identifying novel genes whose function is critically important for cell division. The goal is to use genes that, when knocked out or turned off, lock cells into a quiescent state. Controlling the expression of such genes will allow the progression or stalling of the dividing cells with the ON/OFF administration of a small drug. The Post and Waddell labs will lead the generation of fail-safe therapeutic cells and their testing after transplantation into a model organism/disease, respectively. The Team will test the ability of “fail-safe” blood and lung cells to 1) respond to our engineered stop switch in vitro and in vivo and 2) ameliorate pathologies in our animal models of lung diseases, which include cystic fibrosis and chronic obstructive pulmonary disease. The use of “fail-safe” cells in preclinical studies will accelerate the development of safe cell clinical therapies in human that will bring Canada into a leading role for stem cell therapies and ultimately help patients suffering from debilitating degenerative disease.

Dynamic cell polarity networks in regenerative medicine

Project PI: Ulrich Tepass
Department of Cell and Systems Biology, University of Toronto

Co-PIs: Helen McNeill, Anne-Claude Gingras, Rodrigo Fernandez-Gonzalez, Juri Reimand, Christopher Yip

Project Description: Effective strategies in tissue and organ regeneration would improve the treatment options for a large number of pathologies that compromise organ function. This is particularly true for aging populations in which failure of organs, such as the heart, the retina, the kidney, the lung or the liver, will occur with greater frequency. Re-establishing functional tissues and organs from stem cells or small populations of progenitor cells requires the carefully controlled process to establish tissues of the correct size while preventing tumour formation. At the same time, cells must undergo differentiation to attain normal tissue structure and function. The most common type of tissue is the epithelium, a sheet-like tissue of tightly adherent polarized cells that forms a crucial component of virtually all organs in the human body. It is important to understand how the mechanisms that regulate tissue growth interplay with the cellular machinery that controls the anatomical and physiological features of epithelial tissues to regenerate a stable, functional tissue of normal size. We lack a comprehensive understanding of the molecular networks that couples epithelial cell architecture to cellular signaling that regulates tissue and organ growth during regenerative processes. Our team will elucidate the molecular basis of tissue regeneration using a set of complementary approaches at the leading edge of biomedical research. Understanding this network is a key prerequisite for developing rational strategies to control and manipulate tissue regeneration in a therapeutic context.

Induction and maintenance of allograft tolerance in the absence of systemic immunosuppression

Project PI: JC Zúñiga-Pflücker
Biological Sciences, Sunnybrook Research Institute
Department of Immunology, University of Toronto

Co-PIs: Naoto Hirano, Tracy McGaha, David Brooks, Andras Nagy, Cristina Nostro, Derek van der Kooy

Project Description: The immune system remains one of the major barriers to effectively translate the advances in the generation of stem cell-derived tissues for regenerative medicine applications. New immunomodulation therapies such as using regulatory T-cells or tolerogenic/biomaterial activated innate immune cells (macrophages/dendritic cells) are needed. There is also a need to induce/produce tolerogenic innate cells, macrophages and dendritic cells (DCs) to suppress the pathogenic T cells and promote Treg subsets. The proposed immune suppression strategies together with the ability to generate donor cell lines with decreased immunogenicity and will likely lead to improved and more effective allograft therapies. The goal is to take advantage of the immune system and its regulation as key components to controlling chronic disease and inflammation, activating regeneration and allowing for robust cell, tissue and organ transplantation. There is a critical barrier to this above vision: deriving and testing the safety of individual iPSC lines takes an incredible amount of time and resources, and creating one for each patient who needs a cell-based therapy is economically and practically unrealistic. This team proposes a solution by engineering an iPSC line to expresses local immunomodulatory genes. The expression of these transgenes makes the cells “cloaked”, which prevents immune recognition and rejection when grafted in allogeneic hosts. Cloaked cells would allow a single cell line to be used as a source of therapeutic cells. Ultimately, these transformative properties would overcome some of the most critical economic and biological barriers that will emerge in the future of cell-based therapies.