Kathrin Plath
UCLA researchers have found that embryonic stem cells and skin cells reprogrammed into embryonic-like cells have inherent molecular differences, demonstrating for the first time that the two cell types are clearly distinguishable from one another.
The data from the study suggest that embryonic stem cells and the reprogrammed cells, known as induced pluripotent stem (iPS) cells, have overlapping but still distinct gene expression signatures. The differing signatures were evident regardless of where the cell lines were generated, the methods by which they were derived or the species from which they were isolated, said William Lowry, a researcher with the Broad stem cell research center and a study author.
“We need to keep in mind that iPS cells are not perfectly similar to embryonic stem cells,” said Lowry, an assistant professor of molecular, cell and developmental biology. “We’re not sure what this means with regard to the biology of pluripotent stem cells. At this point our analyses comprise just an observation. It could be biologically irrelevant, or it could be manifested as an advantage or a disadvantage.”
The study appears in the July 2 issue of the journal Cell Stem Cell.
The iPS cells, like embryonic stem cells, have the potential to become all of the tissues in the body. However, iPS cells don’t require the destruction of an embryo. Some have touted iPS cells as replacements for embryonic stem cells. However, this study finds they are not identical as previously surmised. Researchers have maintained it is important to continue to study both cell types.
The study was a collaboration between the labs of Lowry and UCLA researcher Kathrin Plath. Lowry and Plath were among the first scientists worldwide and the first in California to reprogram human skin cells into iPS cells. The researchers performed microarray gene expression profiles on embryonic stem cells and iPS cells to measure the expression of thousands of genes at once, creating a global picture of cellular function.
Lowry and Plath noted that, when the molecular signatures were compared, it was clear that certain genes were expressed differently in embryonic stem cells than they were in iPS cells. They then compared their data to that stored on a National Institutes of Health data base, submitted by laboratories worldwide. They analyzed that data to see if the genetic profiling conducted in other labs validated their findings, and again they found overlapping but distinct differences in gene expression, Lowry said.
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