Making Stem Cells Virus-Free

A report out today from the University of Wisconsin – Madison suggests that the first virus-free human induced pluripotent stem cells have been created. This is significant in the search for alternatives to embryonic stem cells, which have the ability to become any cell type.

To date, one major stumbling block to the use of adult stem cells induced to be pluripotent has been the use of viral vectors. Foreign genetic material from the viral vectors can integrate itself into the host cell DNA and have negative consequences on cell processes and experimental results.

From the press releaese:

The new work was accomplished using a plasmid, a circle of DNA, and cells from the foreskins of newborns. “The plasmids carry all the needed transgenes, but don’t integrate into the host DNA, they just float around as episomes” in the cell, Thomson says.

The plasmids replicate, but they do so somewhat inefficiently, Thomson explains, so that after they perform the job of reprogramming, they can subsequently be weeded out, leaving the induced cells free of any exotic genetic material. “Once the transgenes have done their job and are no longer needed, one can merely recover induced pluripotent stem cells that have lost their episomes.”

The resulting cells, says Thomson, are remarkably similar to embryonic stem cells and show the same capacity to proliferate indefinitely in culture and diversify into all the cell types of the human body.

The fact that these induced cells are so similar to embryonic cells suggests that the research is on the right track. However, there are several possible methods of reprogramming adult cells under investigation. Another method might turn out to be more efficient or successful at reaching the end goal of turning back the clock on adult cells.

I am waiting for the press releases to fill my inbox suggesting that science has solved all the problems with adult stem cell research, and that we no longer need embryonic stem cells. This is one more step in the process of understanding how our cells work, but it by no means has answered all the questions.

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