Human embryonic stem (hES) show great promise in both therapeutics and basic research. They are a potential source of cells to treat conditions such as diabetes, spinal cord injury, and cardiomyopathy. Several roadblocks remain before the potential of hES cells can be realized. One roadblock is the poor growth of hES cells. Growth of hES cells requires a balance between survival, proliferation and differentiation signals. Neurotrophins (NTs) were recently identified as potent survival factors for hES cells. NTs cause a dramatic increase in survival of single hES cells from about 6% to about 30%. In this project, we will further define the effects of NTs on the derivation and maintenance of hES cell lines. HES cells are often grown in the presence of mouse feeder cells. These cells provide factors that support the growth of hES cells, however, efforts are being made to reduce the exposure of hES cells to animal products. We will determine whether NTs promote survival of hES cells in the absence of mouse feeder cells. Further, we will determine whether NTs will improve the efficiency of deriving new hES cells lines from embryos and the genetic stability of the new lines. HES cells sometimes acquire additional chromosomes. NTs may improve culture conditions and reduce the incidence of acquisition of extra chromosomes in hES cells. Lastly, we will use hES cell lines that have extra chromosomes to identify genes that improve the growth of hES cells. Chromosomal abnormalities are thought to alter gene expression leading to improved cell growth in suboptimal culture conditions. Any hES cell line with an abnormal karyotype represents a powerful tool to identify genes that affect the growth of hES cells. Identifying novel genes that promote hES cell growth and using those factors along with NTs to promote cell survival will improve our ability to maintain and derive hES cells. This ability will have a significant impact on the use of hES cells in the future.
Human embryonic stem (hES) cells are derived from the pluripotent stem cells of the inner cell mass (ICM) of the blastocyst-stage embryo. They retain many properties of the ICM cells including the dual abilities to self-renew and differentiate. HES cells show great promise as both research and therapeutic reagents. They provide an excellent opportunity to study disease processes in vitro and to produce differentiated cells for use as therapeutic agents to treat conditions such as diabetes, neurological disorders, and cardiomyopathy. Several roadblocks remain before the potential of hES cells can be realized. One of these roadblocks is the inability to control the proliferation, survival, and differentiation of hES cells. Insight into the factors that control the survival of hES cells will aid in the production of relatively pure populations of either undifferentiated cells or specific differentiated cell types. The studies described in this proposal will further the knowledge of the factors that control survival of hES cells. A second roadblock to the realizing the potential of hES cells for therapy is the occurrence of chromosomal abnormalities in hES cultures. These abnormalities can affect the growth properties of the cells and potentially increase the tumorigenicity of the cells. The results of this study will determine whether the addition of specific growth factors and growth factor combinations affects the accumulation of chromosomal abnormalities in hES cell cultures. Information from this study will improve the efficacy and safety of the therapeutic uses of hES cells.