The findings show the potential of skin cells that are reprogrammed to act like embryonic stem cells, note the researchers.
Stem cells are unspecialized cells that can become other types of cells. Embryonic stem cells can develop into a broader range of cells than adult stem cells. But in recent years, scientists have learned how to use retroviruses to reprogram skin cells to act like embryonic stem cells.
In the new studies, the Chinese researchers wanted to see whether reprogrammed skin cells really have as much potential as embryonic stem cells. They reasoned that if those reprogrammed skin cells could give rise to baby mice, that would be a favorable sign.
First, the scientists took skin cells from mouse embryos and reprogrammed those skin cells to act like embryonic stem cells. Those reprogrammed cells are called induced pluripotent stem cells (iPSCs).
Separately, the scientists fused two early-stage mouse embryos together, when each embryo only consisted of one or two cells. The resulting embryo couldn't develop on its own.
The researchers then inserted the iPSCs into that embryo and placed it into a surrogate mouse mother.
That technique led to the birth of 27 mice for one team of Chinese scientists, which has now had hundreds of baby mice born from that first generation of mice. That shows that the iPSCs were "pluripotent," or similar in their potential to embryonic stem cells.
There were "some abnormalities" in the first generation of those mice, Fanyi Zeng, MD, PhD, said in a news conference. Zeng didn't provide details about those abnormalities because she and her colleagues are still studying them.
So far, the second generation of mice doesn't have any obvious abnormalities, but those mice will be studied further, said Zeng, who is a professor and associate director of the Shanghai Institute of Medical Genetics and of the Shanghai Stem Cell Institute at Shanghai Jiao Tong University School of Medicine. Zeng's study appears online in Nature.
The other team of Chinese scientists, who included Shaorong Gao, PhD, of the National Institute of Biological Sciences in Beijing, reports the birth of four full-term mice, including one that lived into adulthood and appeared to be healthy. Of the other three mice, two died soon after birth, and one died three days after birth because its surrogate mother refused to feed it. The findings appear online in Cell Stem Cell.
In a news conference, Zeng noted that the findings don't apply to people and that the point was to test the potential of iPSCs and to learn more about the cell reprogramming process.
The main finding is that the iPSCs behaved like embryonic stem cells, although the process wasn't very efficient, according to Zeng.
Still, Zeng supports continued research on embryonic stem cells. "We strongly believe that we should promote all kinds of stem cell research, not limited to iPSCs," Zeng said.