Less than two years ago, scientists at Cambridge University in Britain announced they had engineered artificial mouse embryos from stem cells rather than from an egg and sperm. Ethicists warned the new technique would lead to the production of synthetic human embryos—and it did.
Researchers at the University of Michigan have learned how to use stem cells to manufacture models of human embryos that can grow and develop, according to a recent study published in Nature. The scientists allowed the embryo models to live only four days, but even in their short life span, the cells multiplied and formed the initial stage of an amniotic sac and the inner cells that would eventually become a body.
“It’s uncanny how much it is like a human embryo,” Alfonso Martinez Arias, a geneticist at the University of Cambridge, told MIT Technology Review.
The researchers, who hope to use their discovery to test fertility drugs and study embryonic development, said they have successfully turned stem cells into embryo-like structures in 90 percent of their trials, producing hundreds of them. The embryo models lack the tissues necessary to form a placenta and could never become a human being, the scientists said.
Now is the time, according to ethicists, to implement laws to prevent scientists from using the technology to create genetically modified people.
Jianping Fu, one of the Michigan researchers, told MIT Technology Review that regulators must oversee such scientific experiments and ban using stem cell–based embryos to produce a human baby. “Many scientists are trying to push boundaries, and people are crossing lines,” he said. “I don’t trust self-regulation.”
It remains unclear whether the federal laws that prohibit the funding of research using fetal tissue from abortions also applies to human embryo models made from stem cells.
Eric Siggia, a scientist at Rockefeller University in New York who works with embryonic research, told MIT Technology Review the government regulatory agencies are in a “state of confusion” as they struggle to define “what is an embryo and what is not.” He said funding decisions do not affect his research because “we just use private funds.”
Ethical problems have plagued human embryonic research from the beginning because it involves the destruction of human life, said David Prentice, vice president and research director for the Charlotte Lozier Institute. Artificially creating embryos doesn’t change that.
“Any organism that is a human being should not be a matter for experimentation,” he said. “It is the technique used to create them that is artificial, not the embryos.” Prentice added that we need regulations that confine the study of embryonic development to animal models to avoid crossing “any sort of line using human material.”