Cloning-like method targets mitochondrial diseases

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http://www.sciencenews.org/view/generic/id/346024/description/Cloning-like_method_targets_mitochondrial_diseases

A technique that puts one woman’s nuclear DNA into another woman’s donor egg cell may be feasible for correcting inherited diseases caused by faulty cellular power sources. The technique has already produced healthy baby rhesus monkeys, and now it raises the possibility of preventing mitochondrial diseases in thousands of people each year.

Mitochondria, energy-producing organelles inside cells, carry circles of DNA important for the power plants’ function. Mutations of the mitochondrial DNA, which is passed to offspring directly by their mothers, can cause diseases that often affect energy-greedy organs such as the brain, heart, muscles, pancreas and kidneys with varying severity. An estimated 1,000 to 4,000 U.S. babies are born each year with mitochondrial diseases.

Swapping the nucleus, the cellular compartment where chromosomes are housed, from an egg with mutant mitochondria into one containing functional power plants could stop those diseases from happening in the first place. Offspring would inherit healthy mitochondria from the egg donor, while the rest of their genetic makeup would come from the mother and father.

Researchers led by Shoukhrat Mitalipov, a reproductive and developmental biologist at Oregon Health & Science University in Beaverton, previously demonstrated that the technique works with rhesus monkeys. Now the team has succeeded in transferring the nuclei of unfertilized human eggs into donor eggs and then fertilizing those eggs to create embryos that produce embryonic stem cells, the team reports online October 24 in Nature. Short of actually transplanting the embryos into women to grow into babies, stem cell production is the clearest sign that the embryos are normal.