Generating fully functional human hematopoietic stem cells in vitro from pluripotent cells
Transplantation of donor hematopoietic (i.e. blood) stem cells (HSCs) into a patient’s bone marrow is the standard of care for a variety of inherited blood deficiencies and malignancies. However, this procedure relies on finding a genetically matched donor and can lead to problems if the match is not perfect. Thus, hematological disorders that require bone marrow transplants from a donor are accompanied by the risk of graft vs. host disease (GVHD), which can have fatal consequences. With the advent of induced pluripotent stem cell (iPSC) technologies (i.e. the ability to convert normal cells in our body to cells that have the potential to become any cell type) we are now at the forefront of unlimited potential to generate patient-specific therapies. The ability to obtain pluripotent cells from patients suffering from blood disorders that have the potential to be corrected (e.g. using gene therapy), and culturing them into HSCs that could then be transplanted back into the same patient, could provide opportunities to treat a variety of hematological diseases. We have shown the proof-of-principle of this possibility by deriving iPSCs from Fanconi anemia patients, and correcting them to generate disease-free blood cells. Yet despite these many advances, the problem remains that human HSCs derived from pluripotent cells in vitro are not able to fully reconstitute the blood system. In this project, we propose a method of comparing human HSCs of both in vitro and in vivo origin, to understand why this barrier exists. Using Next Generation Sequencing technology, we will determine gene network and genomic architecture differences between these two types of HSCs. We will test the ability of gene products identified as having a likely causative role in the functional differences between in vivo and in vitro HSCs to drive iPSCs into fully functional HSCs. Prominent researchers throughout the world have been working on ways to develop HSCs in vitro that could be used in the clinic. Despite creative and tireless efforts, this challenge remains. It is our goal that the results obtained from the proposed research provide a foundation by which researchers could more strategically address this obstacle, and enable this critical step towards the treatment of numerous hematological disorders.
The principle objective of this proposal is to develop methods to derive functional hematopoietic stem cells (HSCs) in vitro for use in regenerative medicine. This would potentially lead to improved treatment strategies for individuals with diseases affecting blood cells, such as sickle cell disease and Fanconi anemia, and reduced medical costs for the care of these patients in the State of California. Currently transplantation of donor HSCs into a patient’s bone marrow is standard of care for a variety of inherited blood deficiencies and malignancies. However, this procedure relies on finding a genetically matched donor and can lead to problems if the match is not perfect. The methods we propose to develop will enable the derivation of patient specific HSCs that are fully functional and capable of reconstituting the hematopoietic system. This will lay the ground work for future studies using gene therapy to correct inherited mutations in HSCs derived from somatic cells of a patient and the transplantation of these genetically corrected HSCs back into the bone marrow of the individual. The end goal of this work is to be able to provide a permanent cure for inherited diseases affecting blood cells which are often debilitating and common illnesses. Our project will also pilot new DNA sequencing methods that will have a substantial impact on stem cell biology research. These methods are likely to be used in the future to systematically validate the origin, quality and safety of stem cell derivatives, enabling the clinical implementation of stem cell based therapies. Our research will allow the State of California to continue to be at the forefront of stem cell research and regenerative medicine enabling our hopes for rapid translation of basic science to new therapies for disease to be fulfilled. All intellectual property generated by our research will be developed under CIRM guidelines for the maximum benefit of the State of California.