Key differences between stem cells discovered
People react differently to the idea of stem cells - many are scandalized by the thought of using a human embryo for lab work, while equally many encourage the research in hopes of developing treatments for various diseases.
However, scientists have more recently been examining the properties of induced pluripotent stem cells rather than the embryonic stem cells that have caused so much controversy.
Induced pluripotent stem cells (iPSCs) are stem cells derived from adult cells. Once mature cells are reprogrammed back into stem cells, they have the ability to self-renew and differentiate into any kind of cell, which seems analogous to the abilities of embryonic stem cells (ES cells).
However, in a joint study between Andrew Feinberg from the Hopkins School of Medicine and George Daley from Harvard University, it has been shown that although the genes altered in ES cells during normal cell differentiation are the same genes altered in iPSCs, there are fundamental differences between iPSCs and ES cells.
Feinberg, Daley and their colleagues studied the epigenetic nature of the iPSCs, or the external chemical modifications to the genome. Although they should be genetically identical to the mature cells from which they were derived, the iPSCs differ in what DNA is copied when the cell divides, even though the instructions for this difference are not included in the DNA sequence.
In order to "see" these differences, the team used a method called methylation to distinguish which genes were turned off or on after replication. Methylation will silence genes, but still will be copied when a cell divides. Researchers can then identify which genes were silenced and categorize them as differentially methylated regions (DMRs).
"We examined DNA methylation, an epigenetic modification involving a chemical change to cytosine. We found thousands of sites throughout the genome that are reprogrammed epigenetically during the creation of induced pluripotent stem cells," Feinberg said.
However, scientists have more recently been examining the properties of induced pluripotent stem cells rather than the embryonic stem cells that have caused so much controversy.
Induced pluripotent stem cells (iPSCs) are stem cells derived from adult cells. Once mature cells are reprogrammed back into stem cells, they have the ability to self-renew and differentiate into any kind of cell, which seems analogous to the abilities of embryonic stem cells (ES cells).
However, in a joint study between Andrew Feinberg from the Hopkins School of Medicine and George Daley from Harvard University, it has been shown that although the genes altered in ES cells during normal cell differentiation are the same genes altered in iPSCs, there are fundamental differences between iPSCs and ES cells.
Feinberg, Daley and their colleagues studied the epigenetic nature of the iPSCs, or the external chemical modifications to the genome. Although they should be genetically identical to the mature cells from which they were derived, the iPSCs differ in what DNA is copied when the cell divides, even though the instructions for this difference are not included in the DNA sequence.
In order to "see" these differences, the team used a method called methylation to distinguish which genes were turned off or on after replication. Methylation will silence genes, but still will be copied when a cell divides. Researchers can then identify which genes were silenced and categorize them as differentially methylated regions (DMRs).
"We examined DNA methylation, an epigenetic modification involving a chemical change to cytosine. We found thousands of sites throughout the genome that are reprogrammed epigenetically during the creation of induced pluripotent stem cells," Feinberg said.
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David Granovsky
posted 11/20/09 @ 9:50 PM EST
STEM CELL NEWSLETTER http://www.repairstemcells.org/newsletters/NL111909.htm
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Las Vegas Movers | Las Vegas Moving Company
posted 11/23/09 @ 5:34 PM EST
Quote:
"We examined DNA methylation, an epigenetic modification involving a chemical change to cytosine. We found thousands of sites throughout the genome that are reprogrammed epigenetically during the creation of induced pluripotent stem cells," Feinberg said. (Continued…)
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