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Expectations for stem cells undergo some reprogramming at annual research meeting

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reprogramming adult stem cells betterNEW YORK—Despite a cloud of regulatory uncertainty hanging over the U.S. stem cell research field, many young scientists spoke excitedly about their research Wednesday afternoon at the New York Stem Cell Foundation's annual Translational Stem Cell Research Conference here at The Rockefeller University.


Some of the most recent big-news breakthroughs have come in the realm of cell reprogramming, which can coax adult cells back into a more flexible stem-like state, thus skirting many (but not all of) of the ethical and political issues that currently surround human embryonic stem cell research.


Although these induced pluripotent stem (iPS) cells have not proven to be identical to embryonic stem (ES) cells (for one, they seem to retain some traces of the cell types from whence they came), they are "extremely similar" to the ES cells, Dieter Egli, a senior research fellow with the New York Stem Cell Foundation, said at the meeting.


Many of the most promising news hit in late September, when a team from the Harvard Stem Cell Institute announced a method of generating a new category of programmable cells, so-called RNA-induced pluripotent (RiPS) cells. To make these cells, researchers devised synthetic RNA to sneak into skin cells with a message that signals the cell to revert back to a stem state.


The challenge of finding a good way into cells' genetic command centers has vexed scientists for decades. Thanks to eons of viral onslaught, "cells have been developing mechanisms to defend themselves" against most would-be intruders, said Derrick Rossi, a researcher at Harvard.


The standard iPS method has relied on viruses to enter the cell, which linger in the nucleus and can cause cancer and other complications. "We wanted to make iPS cells without hitting the genome," Rossi said at the meeting.


Like many significant achievements in the lab, arriving at a viable synthetic RNA approach required trial and error—and patience. Running with the idea, Rossi and his colleagues took an initial stab at it, and "it completely didn't work," he recounted. But after tweaking the method, we weren't just getting iPS cells, he said, "we were getting them out the wazoo." The method, described in a September Cell Stem Cell paper, created cells in about half the time and with some 100 times the efficiency of virus-based methods.


Despite the recent advance, which many labs already plan to adopt, iPS cells are not approved for any treatments. The new method creates plenty of research-ready cells, but because the RNA material does not persist in the cells, it must be reintroduced daily. Even Rossi was quick to acknowledge that "iPS cells are but a starting point therapeutically."


Image of cell culture dish courtesy of Wikimedia Commons/kaibara87

The views expressed are those of the author and are not necessarily those of Scientific American.

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