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Adult stem cells may aid the infertile

January 26, 2009 |  6:08 pm

UCLA researchers have reprogrammed a special class of adult stem cells to become the precursor cells of human eggs and sperm, suggesting a way for infertile couples to conceive a child using their own DNA in the future.

In a first-of-its-kind effort, researchers at UCLA's Broad Stem Cell Research Center used "induced pluripotent stem cells" -- typically simple skin cells that have been engineered to return to an embryonic state -- from which they could develop into a wide range of different tissues. Those induced pluripotent stem (or iPS) cells were then coaxed to become germ line cells capable of giving rise to sperm and egg.

Many uncertainties and dangers must still be resolved before an experiment like this could yield techniques of clinical use in infertility treatment. The reprogramming process, for instance, involves viruses and genes, which may increase the likelihood of genetic abnormalities and cancers.

But if such reprogramming can be done safely, the skin cells of men and women incapable of conceiving on their own could be used to "grow" eggs and sperm bearing their own genetic material. For many infertile couples, that would be simpler and preferable to turning to an egg- or sperm-donor, who becomes one of the resulting child's genetic parents.

"These germ cells would be specific and genetically related to the patient," said UCLA researcher Amander Clark.

Even as it raised new hopes for the clinical use of adult stem cells, Clark's research underscored that embryonic stem cells -- the subject of heated ethical and political debate -- currently are a safer and more reliable means of developing germ lines capable of growing a wide range of human tissues, including eggs and sperm. Clark and others have found that cells generated from embryonic cell germ lines regulate themselves more effectively -- and thus raise less risk of runaway growth or chromosomal errors.

For that reason, it's crucial that work on embryonic stem cells continue, Clark said. President Obama is expected in the next several weeks to reverse longstanding restrictions on embryonic stem cell research adopted by President George W. Bush.

-- Melissa Healy