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Thanks to a little mouse named Tiny, researchers have now shown that full, living mammals can be grown from so-called induced pluripotent stem cells—cells from an adult that act in many ways like embryonic stem cells. 

Xiao Xiao, as the rodent is called in its native Chinese, was one of dozens created from induced pluripotent stem cells (iPS cells) and born to a surrogate mother. The process is described in a study published yesterday in Nature (Scientific American is part of Nature Publishing Group).

Researchers used a virus to deliver four genes into fibroblast cells taken from adult mice, triggering the change to iPS cells. These cells were then implanted into an embryo that didn’t have the requisite genetic information for it to develop beyond a placenta. That these implanted embryos developed into full baby mice proved that these cells could indeed do all the work of natural embryonic stem cells.

“This gives us hope for future therapeutic interventions using patients’ own reprogrammed cells,” study author Fanyi Zeng of Jiao Tong University said in a statement, The Washington Post reported.

The team had a birth rate of just 3.5 percent of the 624 embryos they injected. Even the mice that were born alive frequently died after just a couple days. But of those that did live, a dozen were mated and produced reportedly healthy offspring—offspring that have now mated, producing even third-generation mice.

Another team, based out of the National Institute of Biological Sciences in Beijing, has been working on a parallel project and also produced a live mouse from iPS cells. They published their results in Cell's Stem Cell yesterday.

The results have generated renewed concern about human cloning, but the lead author of the Nature paper, Qi Zhou of Beijing’s Institute of Zoology, told Nature News that it is “an important model for understanding reprogramming. … It is not intended to be a first step towards using iPS cells to create a human being.”


Photo of the first iPS mouse, “Tiny,” courtesy of Qi Zhou

3 Comments

1. 1. Truth_coming 04:12 AM 8/2/09

   It is an enigma why a fully pluripotent iPS cell would require two disabled embryos to sandwich it and then be able to develop into a viable clone. How about implant just the fully pluripotent iPS cell along? The damaged embryo-based sandwich technique, which is called tetraploid complementation, is an exchange of one potential life with the assured death of two lives. This is because the two tetraploids used in one sandwich are each made by fusing one normal two 2-cell stage embryo into an abnormal tetraploids. It is hard to believe that, murdering two lives in order to produce one clone would be any more ethical than any other cloning techniques. For example, SCNT (Somatic Cell Nuclear Transfer) uses only one egg per transfer but has been condemned as unethical for therapeutic cloning. Tetraploid complementation kills two early lives to produce less then 3% of viable clone but is now praised as This gives us hope for future therapeutic interventions. Come on, my fellow scientists, can we be objective and not double-blinded (with lacking both scientific and ethical visions)? By the way, the safety of these iPS mice need more evaluations because the cancer risk of iPS cells may show up only in the late stage of their life span and the iPS cells used in this study was generated in the same way as reported by Yamanaka who just recently admitted tumor/cancer formation for his iPS cells.

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2. 2. rendev 09:53 AM 8/12/09

   Hi
   Induced pluripotent stem (iPS) cells is an alternative methods for studying diseases that are more robust and better simulate how the disease develops in humans. The concerns expressed regarding chimerism may be a bit strong. Technological improvements with traditional ES cell microinjections have resulted in embryos which are 100% derived from the donor, not receipient, cells. Thus the first mice born are true clones of the source ES cells.
   Thanks!
   My url: www.biotechnology-genetic-humancells.blogspot.com
   I also invite people to use my links and read more.
   

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3. 3. sent2null 03:39 PM 10/11/09

   Truth_coming, if you are indeed a scientist (and I doubt it) you would not be interjecting your ideas of "life" and "murder" into this process which no credible scientist would do. That said, the process that Yamanaka first published in 2007 has already been refined to eliminate the oncogenic triggering methods (viral component) , iPSC induction can occur purely with modifications to proteins.

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