Advances in stem-cell technology cheer and alarm ethics watchers.
Sarah Eekhoff Zylstra
While scientists in the U.S. hailed sperm cells as a possible alternative to embryonic stem cells, regulators in Great Britain became the first to approve inter-species experimentation.
The U.K.'s Human Fertilisation and Embryology Authority, which reports to the Department of Health, ruled in September that there was no "fundamental reason" not to use animals as egg donors for the creation of animal-human hybrid embryos. Currently, researchers depend on human embryos from fertilization clinics.
Hybrid embryos are created by scraping an animal's DNA out of its egg and inserting a nucleus from a human cell. Researchers don't know yet if hybrid embryos will display the developmental flexibility that human embryos do. "But the odds are high," said William B. Neaves, president and CEO of the Stowers Institute for Medical Research. "It's worth trying."
The U.K. has not legalized the implantation of hybrid embryos, which are 99.9 percent human and 0.1 percent animal, into wombs. Still, development of a human-animal chimera should worry everyone who values human life, said Nigel Cameron, president of the Institute on Biotechnology & the Human Future.
"This is a wake-up call that really does catch people's moral imagination," he said. "The whole notion of manufacturing human or semi-human life for experimentation and destruction goes to the core of human dignity."
The director of the Center for Bioethics & Human Dignity, C. Ben Mitchell, said the "yuck factor" alone is not a good reason to ban hybrid embryos. People once found organ transplants and blood transfusions disgusting, too, he said.
"However, the intuitions, the yuckiness, the Franken-bunny [aspect] ought to raise a caution for us," Mitchell said. "We have no clue what we are doing, and we ought to have a respectful awe for the process of life, rather than a willy-nilly tinkering around with it."
A possible alternative to embryonic stem cells may be found in the work of researchers at Weill Medical College of Cornell University. A team there announced in September that it had turned early-stage sperm cells from mice into cells capable of growing into various tissues. Whether these cells have the potential to become any of the 200-plus cell types in the body, as embryonic stem cells do, remains to be seen, Neaves said. Another drawback: Manipulated sperm cells may only be used in men, meaning women would not benefit from any potential treatments.
While developments in stem-cell technology offer theoretical hope for many medical problems, Cameron warned that practical help for patients is still a long way off. "It's going to take a very long time," he said. "The notion that you are going to kill all sorts of diseases just around the corner is just fantasy."
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