Nine Genes At Heart Of Epigenetic Changes In Induced Pluripotent Stem Cells

In 2006, scientists discovered how to revert mature cells, which had already differentiated into particular cell types, such as skin cells or hair cells, back into a pluripotent state. These "induced pluripotent stem cells" (iPSCs), which could be developed from the patient's own cells, would theoretically carry no risk of immune rejection.

However, scientists found that iPSCs had molecular differences from embryonic stem cells. Specifically, there were epigenetic changes, chemical modifications in DNA that might alter genetic activity. At certain points in the iPSC's genome, scientists could see the presence of different patterns of methyl groups when compared to the genomes of ESCs. It seemed these changes occurred randomly.

Unlike previous studies, which had primarily analyzed iPSCs derived from only one mature type of cells (mainly connective tissue cells called fibroblasts), Salk and UCSD researchers examined iPSCs derived

from six different mature cell types to see if there were any commonalities. They discovered that while there were hundreds of unpredictable changes, there were some that remained consistent across the cell types: the same nine genes were associated with these common changes in all iPSCs.

"We knew there were differences between iPSCs and ESCs," says Sergio Ruiz, research associate who works with Juan Carlos Izpisua Belmonte, Professor, in the Salk Gene Expression Laboratory. "We now have an identifying mark for what they are."

The therapeutic significance of these nine genes awaits further research. The importance of the current study is that it gives stem cells researchers a new and more precise understanding of iPSCs.

 Condensed from the Salk Institute announcement.