Predicting IVF Success on Film
It was a good week for the field of fertility. Robert Edwards, the British biologist who perfected in vitro fertilization (IVF) more than 30 years ago, earned a Nobel Prize. At the same time, scientists in California reported a major refinement in the technique that could help more couples have children.
Researchers at Stanford University found a way to film the development of embryos in the first 48 to 72 hours after fertilization in a lab dish. This early peek may be crucial in embryo selection. IVF technicians currently must play a guessing game when picking out the best embryos to transfer to a woman's womb; they generally wait until the fourth or fifth day to choose them, on the assumption that those embryos that can survive that long in a dish are healthier and more likely to result in pregnancy. But waiting too long can also be harmful, because the longer embryos are kept outside the body, the more likely they are to develop abnormally.
After observing movies of 242 embryos undergoing their first cell divisions, the scientists identified three factors that helped distinguish the most viable embryos: the time it took to cleave from a single fertilized egg into two cells and the time between each of the next two cell-division cycles. (Faster is better.) These features determined with 93% accuracy which embryos would survive to the fourth or fifth day, allowing doctors to transfer them as early as two days after fertilization.
The imaging technique could improve the current success rate of IVF, which is about 30% nationwide. It may also reduce the need to transfer several embryos at a time, which can result in risky multiple pregnancies.
Making Stem Cells Safer for Human Trials
Stem-Cell research has always promised a revolution in the treatment of diseases such as diabetes or Alzheimer's. The problem is, scientists have yet to ensure that stem-cell-based therapies will be safe. A team working with the newest type of stem cells--induced pluripotent stem (iPS) cells, which are made from adult skin cells--now reports that it has overcome a major hurdle in bringing the technique from the lab to the clinic.
In some ways, iPS cells are biologically favorable to embryonic stem cells, which come from excess IVF embryos. Not only can they give rise to any of the body's cells, but because they are generated by the patient's own skin cells, they also avoid the potential for rejection if used in treatment. Transforming skin cells into stem cells requires using viruses to ferry new genes into the cell's genome, which can activate cancer pathways. But scientists have found a way to replace the genes with RNA, a form of genetic material that does not integrate into the cell's genome. As a bonus, creating iPS cells with the new process is up to 100 times more efficient.
If the results hold, iPS-based treatments in human trials could be introduced in as few as four to five years.
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