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Scientists Create Mouse Embryos Without Sperm

Scientists have created mouse embryos, without male fertilization, and, from them, derived potentially therapeutic stem cells. Stem cells are master cells that can be manipulated to grow into any tissue in the body to possibly treat or cure a range of diseases. Experts say deriving stem cells from embryos that do not require sperm is both extremely promising and challenging. VOA's Jessica Berman reports.

The promise of therapeutic stem cell therapy is that, some day, you would be able to receive a new organ that is grown from your own cells, so your body would not reject the new tissue.

While researchers are still a long way from achieving that, one path to customizing stem cells is to create an embryo by combining a donor egg with the genetic material of the person set to receive the tissue.

But George Daley of Harvard University Stem Cell Institute says the procedure, known as nuclear transfer, is extremely hard to do, which is why he and his colleagues are experimenting with something called parthenogenesis.

"Parthenogenisis means literally virgin birth," he noted. "And there are many plants and some animal species that reproduce by parthenogenisis, in the absence of sperm."

Daley is lead author of a paper appearing in the journal Science describing the creation of mouse embryos from eggs alone.

Daley's team used chemical treatments to stimulate unfertilized mouse eggs to become embryos, from which they extracted and grew stem cells.

"This is an alternative method, which is more efficient than nuclear transfer, and something we can reduce to practice today," he added.

But there is a major problem that needs to be overcome.

Because the embryos contain only female chromosomes, instead of male and female DNA, Daley says, the female-fertilized embryos are genetically unstable.

"There are abnormalities in the cells that would create a very high hurdle," he said. "We would have to prove beyond a shadow of a doubt that these cells could be delivered safely."

Researchers will now see if they can produce human embryos without male fertilization.