The promise of therapeutic cloning from human embryonic stem cells (hESC) is to provide engineered cell lines and tissues for patients whose own tissues have been damaged or lost through disease. Examples of potential therapeutic uses of hES-derived cell lines include the replacement of pancreatic beta cells in Type I diabetics, to provide insulin, and treatment of neurodegenerative disorders with hESC-derived neuronal lines.
Despite the promise of such therapeutic cloning, however, it is not currently clear how many different types of cell lines are potentially derivable from hES cells, as there has not been any systematic mapping of what scientists refer to as cell lineages. A lineage is an ordered developmental pathway, a route from one definable cell type to another, ultimately leading to a terminally differentiated cell type, such as an insulin-producing pancreatic beta cell. While there are estimated to be about 200 such specialized cell types in the human body, it is conceivable that there are thousands of intermediate, transient cell types that arise during development, representing steps in such lineages. With the exception of blood cell lineages, however, there is little detailed information about the routes by which these cell types arise from stem cell progenitors and from each other. Moreover, there is not an existing repository of cell lines that are known to be expandable into known cell types. To the extent that such lines are "raw materials" for therapeutic cloning, there is an urgent need to develop such a resource.
This project will provide these resources: a map of hESC-derivable cell lineages and a broad physical repository of cell lines for use as raw materials in therapeutic cloning. The technologies to be employed are straightforward in principle, but require a high degree of technical sophistication to be carried out at an appropriate scale. In this project, over one thousand hES-derived cell lines will be cloned and characterized using functional genomic profiling tools, including gene expression profiling using whole-genome microarrays and cutting-edge epigenomic profiling tools for the detection of "silenced" region of chromosomes that are known to be intimately involved in determining cell type.
Additionally, the project will address a critical and relatively neglected area, namely, the genomic stability of hESC-derived cell lines. Genomic stability refers to the ability of a cell to retain its integrity, in other words, to retain its cell type identity, and to avoid the accumulations of mutations (changes in the genetic code) and epimutations (the "turning on" or "turning off" of chromosomal regions. Cells with genomic instability are poor candidates for therapeutic use, as they may be prone to losing their desired characteristics and to developing undesirable traits, such as the ability to form tumors. In this project, genomic stability will be measured in hESC-derived cell lines using genomic tools.
Through their funding of the California Institute of Regenerative Medicine, the people of California are investing in the hope that the biotechnology industry will be able to deliver stem cell therapies for currently untreatable diseases. Like any industry, a future stem cell industry will require raw materials in the from of cell lines that can be directed to the formation of specific cell types, such as the pancreatic beta cells that produce insulin, or the the motor neurons that atrophy in amyotrophic lateral sclerosis.
The lack of Federal funding for human embryonic stem cell research, however, has prevented many of the basic studies that are required before such basic raw materials can be developed. There is no existing repository of cell lines that are known to be expandable into known cell types, and to the extent that such lines are "raw materials" for therapeutic cloning, there is an urgent need to develop such a resource.
This project will provide these resources: a map of how cell lines develop from human embryonic cell lines and a physical repository of cell lines differentiated from human embryonic stem cells for use as raw materials in therapeutic cloning. These cell lines will be developed here in California, and will provide materials for all other CIRM stem cell researchers. We envision that the database of information, and the cell lines generated and characterized in this project, will be leveraged by others developing targeted applications.