Public Summary for: CIRM New Cell Line Project - Progress Report.
Our research team has been working over the last year on developing new human stem cell lines that are specifically useful for studying human diseases and developing new therapeutic strategies. Human embryonic stem (hES) cells were first established in 1998 and in the past decade have been shown to be capable to differentiating to a vast array of different cell types. This full developmental potential is termed pluripotency. Until recently these were the only established human cell type that could be robustly grown in the laboratory setting and still maintain full pluripotent developmental potential. In November of 1997, a new type of human pluripotent cell was created. By turning on a set of 4 genes, researchers succeeded in reprogramming human skin cells back into a cell type that appeared to have very similar properties and potential as the hES cell. These new stem cells are called induced pluripotent stem (iPS) cells in order to keep the name distinct from their embryonic derived counterpart. One of the scientific limitations of hES cells is the impracticality of generating patient or disease specific stem cell lines. This opportunity now becomes theoretically practical with the advent of human iPS cell line generation. We report here on significant progress demonstrating the practicality of generating disease-linked cellular models of human diseases.
We have identified 2 specific human neurological diseases that have a known, or strongly suggested genetic component, and have set about to generate disease-linked iPS cell lines. We have obtained skin cell samples from patients with these neurological diseases and have successfully reprogrammed them back to iPS cells. These disease-linked pluripotent stem cells have been carefully characterized and we have demonstrated that they do indeed behave very similar to existing hES cells and also to the genetically healthy control iPS cell lines that we have generated. Therefore the disease phenotype is not detrimental to reprogramming or proliferation as a stem cell. Furthermore, we have succeeded in coaxing these disease-linked iPS cells to turn into specific types of human neurons, the very cells that are suspected to be involved in the neurological disorders. We now have established a viable model for studying human neural disorders in the laboratory, and have already observed some potentially important functional differences between the disease-linked and control iPS generated neurons. In the coming year we will be evaluating the differences between the disease-linked and control neurons and investigating potential therapeutic approaches to stop or reverse the defects.
We have also been working on developing new methods for generating iPS cells that will make them more useful in clinical or pre-clinical settings where it is important that the original set of 4 genes used to reprogram the skin cells are removed once they have become iPS cells. Significant progress has been made in this regard and will be completed in the coming year. Looking forward we will also be applying this approach to generate human disease-linked iPS cells for specific hematological (blood) related disorders. The derivation of iPS-based models of hematological disorders will allow us develop gene therapy approaches to correct the disease causing defects and establish proof of principle for therapeutic approaches.
Reporting Period:
Year 2
This research project is focused on developing new human stem cell lines that are specifically useful for studying human diseases and developing new therapeutic strategies. Human embryonic stem (hES) cells were first established in 1998 and in the past decade have been shown to be capable of differentiating to a vast array of different cell types. This full developmental potential is termed "pluripotency." Until recently these were the only established human cell types that could be robustly grown in the laboratory setting and still maintain full pluripotent developmental potential. In November 1997 a new type of human pluripotent cell was created. By turning on a set of 4 genes, researchers succeeded in reprogramming human skin cells back into a cell type that appeared to have very similar properties and potential as the hES cell. These new stem cells are called induced pluripotent stem (iPS) cells in order to keep the name distinct from their embryonic derived counterpart. One of the scientific limitations of hES cells is the impracticality of generating patient or disease specific stem cell lines. This opportunity now becomes theoretically practical with the advent of human iPS cell line generation. We report here on significant progress demonstrating the practicality of generating disease-linked cellular models of human diseases.
We have identified 2 specific human neurological diseases that have known, or strongly suggested, genetic components and have set about to generate disease-linked iPS cell lines. We have obtained skin cell samples from patients with these neurological diseases and have successfully reprogrammed them back to iPS cells. These disease-linked pluripotent stem cells have been carefully characterized and we have demonstrated that they do indeed behave very similar to existing hES cells and also to the genetically healthy control iPS cell lines that we have generated. Therefore, the disease phenotype is not detrimental to reprogramming or proliferation as a stem cell. Furthermore, we have succeeded in coaxing these disease-linked iPS cells to turn into specific types of human neurons, the very cells that are suspected to be involved in the neurological disorders. We now have established a viable model for studying human neural disorders in the laboratory, and have already observed some potentially important functional differences between the disease-linked and control iPS-generated neurons. Importantly, we have found defects in the function of disease-linked neurons that can be corrected in part following specific drug treatments. This discovery demonstrates the potential utility to use this method of modeling human diseases in the laboratory as a tool for understanding the detailed pathways, which might contribute to the development of the disease state and, importantly, as a target for screening potential therapeutic compounds that might be used to block or slow the progress of human neural disorders. In the coming year we will finalize our efforts on this project.
We have also succeeded in developing an improved method for the delivery of the reprogramming genes into the patient cells in order to become iPS cells. This method allows the reprogramming genes to be removed thus mitigating the potential for unwanted and potentially detrimental reactivation of these reprogramming genes subsequent to the iPS cell state. We have begun work using this new reprogramming methodology to generate iPS cell lines that are specifically linked to diseases of the blood and immune system. The new methodology appears to be working well and we anticipate completing the generation and characterization of these new disease-linked stem cell lines within the next year of this project.
Reporting Period:
Year 3
This research project has been focused on developing new human stem cell lines that are specifically useful for studying human diseases and developing new therapeutic strategies. Human embryonic stem (hES) cells were first established in 1998 and in the past decade have been shown to be capable to differentiating of a vast array of different cell types. This full developmental potential is termed "pluripotency". Until recently these were the only established human cell type that could be robustly grown in the laboratory setting and still maintain full pluripotent developmental potential. In November of 2007, a new type of human pluripotent cell was created. By turning on a set of 4 genes, researchers succeeded in reprogramming human skin cells back into a cell type that appears to have very similar properties and potential as the hES cell. These new stem cells are called induced pluripotent stem (iPS) cells in order to keep the name distinct from their embryonic derived counterpart. One of the scientific limitations of hES cells is the impracticality of generating patient or disease specific stem cell lines. This opportunity now becomes theoretically practical with the advent of human iPS cell line generation. We report here on significant progress demonstrating the practicality of generating disease-linked cellular models of human diseases.
We have identified 2 specific human neurological diseases, Rett’s Syndrome and Schizophrenia that have a known, or strongly suggested genetic components, and have set about to generate disease-linked iPS cell lines. We have obtained skin cell samples from patients with these neurological diseases and have successfully reprogrammed them back to iPS cells. These disease-linked pluripotent stem cells have been carefully characterized and we have demonstrated that they do indeed behave very similar to existing hES cells and also to the healthy control iPS cell lines that we have generated. Therefore, the disease phenotype is not detrimental to reprogramming or proliferation as a stem cell. Furthermore, we have succeeded in coaxing these disease-linked iPS cells to turn into specific types of functional human neurons, the very cells that are suspected to be involved in the neurological disorders. We now have established a viable model for studying human neural disorders in the laboratory, and have already observed some potentially important functional differences between the disease-linked and control iPS generated neurons. Importantly, we have found defects in the function of disease-linked neurons that can be corrected in part following specific drug treatments. This discovery demonstrates the potential utility to use this method of modeling human diseases in the laboratory as a tool for understanding the detailed pathways that might contribute to the development of the disease state and importantly as a target for screening potential therapeutic compounds that might be used to block or slow the progress of human neural disorders.
We have also succeeded in developing an improved method for the delivery of the reprogramming genes into the patient cells in order to become iPS cells. This method combines all the of the reprogramming genes into a single cassette, and also allows the reprogramming genes to be removed thus mitigating the potential for unwanted and potentially detrimental reactivation of these reprogramming genes subsequent to the iPS cell state. We have demonstrated the success of this new reprogramming methodology to generate iPS cell lines that are specifically linked to a disease of the immune system. In addition to creating a panel of disease-linked iPS cell lines that are free of the externally introduced reprogramming transgenes, we have shown progress in achieving correction of the DNA mutation that leads to the disease state. Our extended research on these new disease specific iPS cell lines has shown utility for creating in vitro models of human neural disorders, and potential for genetically corrected patient specific iPS cell lines that could be used for cell based transplantation therapies.
Grant Application Details
Application Title:
Development of Induced Pluripotent Stem Cells for Modeling Human Disease
Public Abstract:
Human embryonic stem cells (hESC) hold great promise in regenerative medicine and cell replacement therapies because of their unique ability to self-renew and their developmental potential to form all cell lineages in the body. Traditional techniques for generating hESC rely on surplus IVF embryos and are incompatible with the generation of genetically diverse, patient or disease specific stem cells. Recently, it was reported that adult human skin cells could be induced to revert back to earlier stages of development and exhibit properties of authentic hES cells. The exact method for “reprogramming” has not been optimized but currently involves putting multiple genes into skin cells and then exposing the cells to specific chemical environments tailored to hES cell growth. While these cells appear to have similar developmental potential as hES cells, they are not derived from human embryos. To distinguish these reprogrammed cells from the embryonic sourced hES cells, they are termed induced pluripotent stem (iPS) cells. Validating and optimizing the reprogramming method would prove very useful for the generation of individual cell lines from many different patients to study the nature and complexity of disease. In addition, the problems of immune rejection for future therapeutic applications of this work will be greatly relieved by being able to generate reprogrammed cells from individual patients. We have initiated a series of studies to reprogram human and mouse fibroblasts to iPS cells using the genes that have already been suggested. While induction of these genes in various combinations have been reported to reprogram human cells, we plan to optimize conditions for generating iPS cells using methods that can control the level of the “reprogramming” genes, and also can be used to excise the inducing genes once reprogramming is complete; thus avoiding unanticipated effects on the iPS cells. Once we have optimized the methods of inducing human iPS cells from human fibroblasts, we will make iPS cells from patients with 2 different neurological diseases. We will then coax these iPS cells into specific types of neurons using methods pioneered and established in our lab to explore the biological processes that lead to these neurological diseases. Once we generate these cell based models of neural diseases, we can use these cells to screen for drugs that block the progress, or reverse the detrimental effects of neural degeneration. Additionally, we will use the reprogramming technique to study models of human blood and liver disease. In these cases, genetically healthy skin cells will be reprogrammed to iPS cells, followed by introduction of the deficient gene and then coaxed to differentiate into therapeutic cell types to be used in transplantation studies in animal models of these diseases. The ability of the reprogrammed cell types to rescue the disease state will serve as a proof of principle for therapeutic grafting in
Statement of Benefit to California:
It has been close to a decade since the culture of human embryonic stem (hES) cells was first established. To this day there are still a fairly limited number of stem cell lines that are available for study due in part to historic federal funding restrictions and the challenges associated with deriving hES cell lines from human female egg cells or discarded embryos. In this proposal we aim to advance the revolutionary new reprogramming technique for generating new stem cell lines from adult cells, thus avoiding the technical and ethical challenges associated with the use of human eggs or embryos, and creating the tools and environment to generate the much needed next generation of human stem cell lines. Stem cells offer a great potential to treat a vast array of diseases that affect the citizens of our state. The establishment of these reprogramming techniques will enable the development of cellular models of human disease via the creation of new cell lines with genetic predisposition for specific diseases. Our proposal aims to establish cellular models of two specific neurological diseases, as well as developing methods for studying blood and liver disorders that can be alleviated by stem cell therapies. California has thrived as a state with a diverse population, but the stem cell lines currently available represent a very limited genetic diversity. In order to understand the variation in response to therapeutics, we need to generate cell lines that match the rich genetic diversity of our state. The generation of disease-specific and genetically diverse stem cell lines will represent great potential not only for CA health care patients but also for our state’s pharmaceutical and biotechnology industries in terms of improved models for drug discovery and toxicological testing. California is a strong leader in clinical research developments. To maintain this position we need to be able to create stem cell lines that are specific to individual patients to overcome the challenges of immune rejection and create safe and effective transplantation therapies. Our proposal advances the very technology needed to address these issues. As a further benefit to California stem cell researchers, we will be making available the new stem cell lines created by our work.
