Scientists have created human eggs containing genes from adult skin cells, a step that one day could help infertile women or gay couples have babies with their own genes, but would also raise difficult ethical, social, and legal questions.
“It’s a significant step forward,” says Shoukhrat Mitalipov of Oregon Health & Science University in Portland, who led the research published in the journal Nature Communications.
Millions of women cannot have children using their own eggs due to age or other reasons. That’s why scientists have been trying to create human eggs in the lab that carry the genes of people struggling to have children. The field is known as in vitro gametogenesis, and it involves researchers worldwide, including in Japan, as well as biotechnology companies in the US.
“This technology would allow many of these women to have genetically their own eggs and a genetically related child,” says Mitalipov.
Mitalipov and his colleagues used a technique different from most researchers pursuing this goal.
The most common approach involves converting adult cells, such as skin or blood cells, into cells known as induced pluripotent stem cells, or iPS. Scientists then tried to induce these iPS cells to become eggs or sperm. The closest anyone has come to success with eggs are very primitive, immature human egg cells, too immature to be fertilized.
Mitalipov’s team, instead, used the technique employed to clone Dolly the sheep: the scientists removed most of the DNA from a healthy donor egg and replaced it with most of the DNA from a skin cell of another woman.
The researchers then basically tricked the reconstituted egg into skipping normal forms of cell division known as mitosis and meiosis. Instead, they induced the eggs to go through a different process they called “mitomeiosis.” This produced 82 functional eggs, the researchers reported.
The scientists then fertilized the eggs with sperm to see if they could develop into embryos. And it seems to have worked, at least in a small number of attempts, the researchers reported. Nine percent of the resulting embryos developed to the blastocyst stage, when embryos would be transferred to a woman’s uterus, the researchers reported.
Complicated issues with a promising technology
However, none of the embryos would be suitable for actual implantation in a uterus to develop further. That’s because all the embryos still showed genetic abnormalities that would prevent healthy development.
Mitalipov, however, is optimistic that he will eventually solve this problem. And other scientists are aggressively pursuing other approaches to achieve the same goal.
Some other scientists praised the new research.
“I think it’s a very significant step toward the ability to use skin cells to make egg cells for human reproduction at some point in the future, once we can prove it’s safe and effective,” says Dr. Sigal Klipstein, reproductive endocrinologist with the American Society for Reproductive Medicine. “The proof of concept is fascinating.” If IVG is ever perfected, the technology could have applications beyond helping infertile women. IVG could, for example, allow gay couples to have babies genetically related to both partners. Scientists could create eggs from a male partner’s skin cell and fertilize them with sperm from the other male partner.
“The implications are enormous,” says Mitalipov.
But some scientists warn that the genetic abnormalities in Mitalipov’s embryos raise doubts about whether this approach could ever work.
“It’s not clear if skipping meiosis in half the genome is compatible with human development,” says Amander Clark, professor of molecular biology and development at the University of California, Los Angeles. “Time and more fundamental research will tell.”
Ethical concerns abound
And even if it worked, the technology would create many complicated issues. Some fear it could help create “designer babies,” where parents can choose their children’s traits.
“We could see more efforts to try to use it for so-called enhancement purposes — to try to get embryos that are stronger or more athletic or more musical or better at math or smarter,” says Hank Greely, bioethicist at Stanford University and author of The End of Sex and the Future of Human Reproduction. “Some people see this as a terrible prospect. Some people see it as a wonderful prospect.”
Another concern is that it could allow people to steal a skin cell from another person, like a celebrity, and make a baby with their DNA without their knowledge or permission.
“We could have Taylor Swift babies all over the world. It’s a theoretical possibility, but not crazy,” says Ronald Green, bioethicist at Dartmouth College. “It’s a very promising technology. But it raises a number of challenging ethical issues.”
Another possibility is using this technology to create a “uni-baby,” a child containing only genetic material from one person.
“That’s a very strange possibility,” says Greely. “Would someone want to do that? Well, there are 8 billion people in the world and some of them have very strong egos and some are very rich. So I wouldn’t bet that no one would want to do it.”
While all these possibilities need to be debated, Greely and others argue that the technology is worth pursuing with proper oversight.
“If it were safe, it would offer relief to literally millions of people worldwide who desperately want to have genetically their own children,” says Greely.
Source: npr.org by Rob Stein