Tuesday, October 09, 2007

Human Therapeutic Cloning at a Standstill

A lack of human eggs has created a major roadblock in one of the most promising areas of stem-cell research.

By Emily Singer

Eggs needed: Scientists in Massachusetts have been unable to proceed with therapeutic-cloning research due to a lack of human eggs, shown here. Credit: M. I. Walker / Photo Researchers, Inc.

It's rare for a scientist to take the mike at a prominent conference, face his peers, and plaintively announce that he has made absolutely no progress on an important research project. But that's exactly what Kevin Eggan, a biologist at the Harvard Stem Cell Institute, did last week at the Stem Cell Summit, in Boston. A year and a half after a highly publicized approval to start human therapeutic-cloning research at Harvard, Eggan and his collaborators have gotten nowhere. Despite extensive outreach, they still lack a crucial resource for their experiments: human eggs. "We've spent $100,000 on advertising, but we have yet to have a single woman donate eggs," says Eggan.

Human therapeutic cloning shows great promise for medicine because it would produce stem cells genetically matched to whoever donated the adult cell. In the near term, scientists want to use stem cells derived from patients with specific diseases to pinpoint the molecular mishaps underlying these afflictions and to test new treatments. Longer term, cloned stem cells might be used to replace tissue damaged by diabetes, heart disease, and Parkinson's disease.

Unlike other embryonic stem-cell research, these experiments require unfertilized human eggs. However, egg-donation procedure is uncomfortable and potentially painful, and it carries some medical risk. Women must undergo counseling sessions to understand the risks involved, hormone treatments to stimulate ovulation, and a medical procedure in which a needle is inserted into the vagina to remove eggs from the ovary. A small percentage of donors develop ovarian hyperstimulation syndrome, which in rare cases can cause kidney damage.

After gaining approval from various regulatory boards at Harvard last year, Eggan and his collaborators began recruiting egg donors with advertisements in local papers and disease-advocacy magazines. "We've had hundreds of calls from women who are interested in donating, but when they find out about the time, effort, and pain involved, they simply can't take the time to go forward," says Eggan.

Eggan blames the dearth of donors on Massachusetts regulations that prohibit researchers from paying women for their eggs. The law is meant to prevent coercion of poor women who might undergo the procedure out of financial need. But women who undergo the same procedure to donate eggs for assisted reproductive technology (ART), in which infertile women use another woman's eggs to get pregnant, are paid anywhere from $3,000 to $10,000. "If we feel comfortable compensating women who donate eggs for ART--and infertility is a terrible disease--why aren't we comfortable compensating women for donations that could aid other serious diseases?" Eggan asks.