Until now, real progress in iPS cell research has been tough to achieve. The Chinese team described prior efforts to reprogram the cells as "slow and inefficient." As well, past attempts to prove the "complete developmental potential" of IPS cells -- by producing a live animal -- had failed.
In their study, Zeng, Zhou and their colleagues focused on the generation of 37 new lines of iPS cells, using cells from mice with varying genetic backgrounds.
But iPS cells cannot, in and of themselves, generate placental material. Therefore, the research team injected some of the iPS cell lines into mouse embryonic material, a complex technique known as "tetraploid complementation" (TC).
They then transferred the resulting embryos into female mice.
According to the team, TC injection with cells from three iPS lines (out of the six lines available) successfully resulted in the production of dozens of healthy mouse pups.
What's more, the iPS-generated pups were mated as adults and were fertile enough to produce more than 200 healthy offspring, who subsequently produced a third generation.
The current work has not produced any shortcuts when it comes to creating viable iPS stem cells, the researchers cautioned. And they said a lot of unanswered questions remain, including the results of an in-depth analysis of potential abnormalities among the first generation of iPS mice. More research, including exploring a range of alternative stem cell methods, is underway.
And, as with most animal studies, "a lot of mouse models don't translate into the human model", Zeng said. She said the immediate focus was on exploring mouse research strictly on its own terms, as an animal model.
Zeng acknowledged, however, "that some of the mouse studies will have some potential application in humans," and that this possibility carries its own s
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