The nuclear transfer technique would involve removing the nucleus of a cow egg - which contains most of its genetic information - and fusing the cow egg with the nucleus of a human cell such as a skin cell. The egg will then be encouraged to divide until it is a cluster of cells only a few days old called a blastocyst, or an early-stage cloned embryo.
Hybrid Human-Animal Embryo Research Approved In The UK
Two research groups in the United Kingdom have been given permission to use hybrid human-animal embryos in research which aims to lead to the development of new therapies for debilitating human conditions such as Parkinson's disease and stroke.
Newcastle University stem cell scientist Dr. Lyle Armstrong, who is based at the North East England Stem Cell Institute (NESCI) at the International Centre for Life in Newcastle, has received a licence from the Human Fertilisation and Embryology Authority (HFEA) to carry out research using human-animal cytoplasmic embryos. Another group -- the Stem Cell Biology Laboratory Wolfson Centre for Age-Related Diseases, at King's College London -- has also received a research license by HFEA to carry out research using hybrid embryos.
Dr. Armstrong says: "The award of the HFEA licence is great news. We initially applied for approval to use cow eggs as a means to understand the way they can convert skin cells into embryonic stem cells. Finding better ways to make human embryonic stem cells is the long term objective of our work and understanding reprogramming is central to this."
"Cow eggs seem to be every bit as good at doing this job as human eggs so it makes sense to use them since they are much more readily available but it is important to stress that we will only use them as a scientific tool and we need not worry about cells derived from them ever being used to treat human diseases," he said.
"Now that we have the licence we can start work as soon as possible. We have already done a lot of the work by transferring animal cells into cow eggs so we hope to make rapid progress."
Background information
Until now, work on the development of therapeutic cloning has used human eggs from consenting IVF patients but these are in short supply. Animal eggs are considered to be a viable alternative for research to understand more about how cells behave.
At first the NESCI team would be working with cow eggs. The nuclear transfer technique would involve removing the nucleus of a cow egg - which contains most of its genetic information - and fusing the cow egg with the nucleus of a human cell such as a skin cell. The egg will then be encouraged to divide until it is a cluster of cells only a few days old called a blastocyst, or an early-stage cloned embryo.
The scientists would attempt to extract stem cells from the blastocyst after six days. Stem cells are building blocks that can grow into any type of tissue such as liver, heart and muscle cells. The quality and the viability of stem cells would then be checked to see if nuclear transfer technique has worked. The scientists would also be observing the way that the cells are reprogrammed after fusion to see if there are useful processes they could replicate in the laboratory. The embryo would have to be destroyed at 14 days old in accordance with the licence.
The eventual aim is to develop a way of creating stem cells to grow new tissue that is genetically matched to individual patients. For example, scientists hope to take a cell from a patient and re-programme it so that stem cells can be extracted to grow new tissue for damaged body parts without fear of immune rejection.
There is no possibility of allowing any of the animal hybrid cells to be used to treat patients but this approach will protect precious resources of human eggs at this early development stage and complement existing NESCI research using human eggs.
The studies will be heavily regulated under the conditions of the HFEA licence.
Scientists Hope to Create Human-Animal Embryo
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.
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