Chinese researchers said on Thursday they had created healthy mice from reprogrammed skin cells, a feat marking a further step in the dream of growing tissue to replenish organs ravaged by disease or accident.
Mice created from the newly-made "pluripotent" cells went on to have babies, the first of which has been called Xiao Xiao, or Tiny, they said.
In a study published by the British journal Nature, the scientists said the mice confirmed that a new technique to reprogramme adult cells to a youthful, versatile state had passed a key test.
The research builds on award-winning work in 2006 and 2007 by Shinya Yamanaka of Kyoto University.
He and his team introduced four genes into skin cells, reprogramming them so that they became indistinguishable from embryonic stem cells -- the famously versatile cells that can develop into almost any type of tissue.
That achievement conjured the allure of an almost limitless source of transplant material that would be free of controversy, for no cells would have to be derived from embryos.
Scientists have so far created lines of cells from this exciting source, called iPS, for induced pluripotent stem cells.
But until now, no-one has been able to meet a crucial test, using lab mice, that proves iPS to be as versatile as claimed.
The gold standard is a technique called tetraploid complementation, in which a stemcell is injected into a cluster of special cells, and the result is then used to create a mouse embryo.
The technique is designed to show that the mouse embryo is made from the DNA of the injected stem cell, and not from any other source.
Until now, only embryonic stem cells had successfully passed the tetraploid test, creating mice that were clones of the embryonic source.
But, the new study demonstrates that iPS cells also work.
The researchers, led by Qi Zhou of the Chinese Academy of Sciences in Beijing, created 37 lines of mice iPS cell lines.
Three of these led to the birth of 27 baby mice -- the first of which was Tiny.
One of these, a brown-coated seven-week-old male, then impregnated a white-coated female mouse, creating second-generation mice that were also in good health. Since then, a third generation has been born.
Ultimately, the goal is take an adult cell from a patient with chronic disease or organ loss, and then reprogramme it so that it becomes pluripotent.
The cell would be allowed to replicate and then coaxed into becoming replacement tissue.
"The bottom line is... we confirm that iPS cell lines can attain true pluripotency... that was very similar to the ES [embryonic stem] cells," Zeng said in teleconference on Wednesday.
"This gives us hope for future therapeutic interventions, using the patient's own reprogrammed cells in the far future."