No, they are taking an unfertilized egg from one mother, removing its ooplasm---the material surrounding the nucleus, where the chromosomes are---and injecting that ooplasm into the fertilized egg. I'm not sure whether it is a full replacement of the fertilized egg's ooplasm or whether it is simply an addition to it.
The reason they would do this is to counter genetic defects in the embryo's mitochondrial DNA. This is DNA that is passed only from the mother and is not in the 46 chromosomes themselves. If that DNA is defective it can lead to certain disorders like some muscular dystrophy-like symptoms.
Again, not to defend the practice as ethical necessarily, but it is worth pointing out that this is NOT done simply to create a designer baby but rather to correct known and significant defects. It likely wouldn't pass the ethical test for anyone who believes life should be protected from conception, however, because it puts the egg at risk not commensurate with the severity of the disorder.
I'm curious what effect totally foreign mitochondrial DNA might have down the road on the person. I mean, in nature, the mitochondrial DNA has a connection to one of the people who provided chromosomes (the mother). Is it possible that this could create a problem they've not thought of?
Additionally, this is interesting since they have used mitochondrial DNA to track ancestry. This will surely put a kink in that down the road.
Anyway, I think it's unethical to create human embryos to study them and kill them. I used to think in vitro fertilization was fine since it's goal was to help nature along in producing a baby. However I'm more squeemish about it now because so many extras are produced that are killed or studied.
People would raise an outcry if I poduced puppies for sale and then just killed the ones I didn't sell once they were past the cute stage. And yes, for the record I have 2 family members who did in vitro.
susie