Virus-free Technique Yields Pluripotent Stem Cells

Stem cells in fat hold intrigue for scientists because most of us have excess to spare, and the cells seem to be quite versatile. Now a team at Stanford has found a way to transform them into induced pluripotent stem (iPS) cells without using potentially dangerous viruses to carry the reprogramming genes into the cells.

This paper marks another step toward the holy grail of reprogramming, which is to find a safe, efficient way of returning adult cells to their embryonic-like state, called pluripotency. So far, most techniques are either not efficient or require inserting genes that may make the cells unsafe for therapeutic use.

The team used so-called minicircles of DNA to reprogram the cells into pluripotency. These minicircles contain just the four genes needed to transform the cells along with a fluorescence gene that allows the cells to be tracked. The minicricles are about half the size of naturally occurring plasmid rings that have been used in some other iPS transformations, and unlike integrating viruses, the minicircles do not get replicated as the cells multiply so the extra genes are lost over time, making the cells safer for therapy.

A press release from Stanford University quoted co-author Michael Longaker saying:

"This technique is not only safer, it's relatively simple. It will be a relatively straightforward process for labs around the world to begin using this technique. We are moving toward clinically applicable regenerative medicine."

Another co-author, Mark Kay, developed the minicircle technology a few years ago for use in gene therapy trials. This paper provides a great example of discoveries in one field impacting another, and moving them both forward.

Nature Methods, February 7, 2010
CIRM funding: Michael Longaker (RL1-00662-1); (T1-00001)


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