British regulators decided Wednesday to allow, at least in principle, the creation of hybrid human-animal embryos for research into degenerative diseases. The move came despite fierce opposition from some church and ethics groups.
Two teams of British scientists had applied to Britain's Human Fertilisation and Embryology Authority (HFEA) for permission to create what are known in Britain as cytoplastic hybrids, or cybrids, in order to overcome a shortage of donated human eggs.
The process involves injecting human DNA into an animal egg cell from which the nucleus has been removed.
Researchers hope to use the hybrid embryos, which must be destroyed after 14 days, which would create stem cells. The stem cells could be used to help find new medical treatments for diseases such as Alzheimer's, Lou Gehrig's, and Parkinson's.
The chief executive of HFEA, Angela McNabb, says the legal and ethical pros and cons were weighed very carefully.
"We've been able to weigh those up and take what's a very strong decision where we're saying we can move forward with cytoplasmic hybrid embryos and the creation of those in some research, so we can gain the potent benefits but only in the framework of very strong regulation," McNabb says.
Scientists have said they understand that the idea of the process — which would create a hybrid embryo that is 99.9 percent human and 0.1 percent animal — might be shocking to some people. But Dr. Stephen Minger of Kings College London says the public should not be alarmed.
"What we do when we take an animal egg, is we remove the nucleus from the egg. We remove not only the genetic identity but we remove the species identity. What makes a cow egg a cow is its nuclear DNA. And we take that out — it's no longer a cow," Minger says.
The regulators' consultation included an opinion poll of more than 2,000 British people. The survey found people supported the creation of the kind of hybrid embryos proposed by the two research teams — but only when they were given a reason for the experiments.
Some 61 percent of those asked gave their backing if the hybrids would help understand some diseases. That support fell to 35 percent if the hybrids were being created purely for nonspecific research.
But Dr. Helen Watt, a medical ethicist at the Catholic organization Linacre Centre for Healthcare Ethics, told the BBC the move is wrong and immoral.
"If we're looking at a model for studying disease, these embryos … will be highly abnormal," Watt says. "There's a limit to how much we're going to be able to learn from embryos containing animal material in this way. In any case, there are ways of doing science that respect both human life and human dignity. In these experiments, we not only risk creating a genuine human embryo who has no human parents and who has a nonhuman partial mother, but we also offend against human dignity by entering into animal reproduction."
HFEA deferred a decision on other types of human-animal embryos, such as what are known as "true hybrids" — created by the fusion of a human sperm and an animal egg — and so-called "human chimeras," where human cells are injected into animal embryos. The group said there was no evidence that British scientists are at present considering using such hybrids in research.