Stem cells -- essentially the body's master cells that have the potential to become any tissue in the human body -- are found in five-day-old human embryos. The problem with stem cell research is that thousands of embryos are needed for research, and human eggs are in short supply.
The Newcastle and King College researchers propose inserting human DNA into a cow's egg that has had its genetic material removed, which would theoretically result in an embryo that is 99.9 percent human. Stem cells could then be extracted from the hybrid eggs after six days, before the eggs are destroyed, reducing the need for surgically removing stem cells from human women.
"If we can learn from the egg cell how to make embryonic stem cells without having to use an animal egg at all, then someday we may be able to cure diseases such as Parkinson's disease, or better still some of the age-related diseases which are creating such a burden on society," said lead researcher Dr. Lyle Armstrong.
According to researcher Dr. Stephen Minger of King's College London, "The current state of the technology is such that literally hundreds of human oocytes (eggs) from young women will be required to generate a single human embryonic stem cell line. Therefore we consider it more appropriate to use non-human oocytes from livestock as a surrogate."
However, the researchers' proposal has garnered some criticism from those who feel combining human and animal embryos is unethical. Calum MacKellar of the Scottish Council on Human Bioethics said the research blurs the distinction between humans and animals.
"In the history of humankind, animals and human species have been separated," MacKellar said. "In this kind of procedure, you are mixing at a very intimate level animal eggs and human chromosomes, and you may begin to undermine the whole distinction between humans and animals. If that happens, it might also undermine human dignity and human rights."
Consumer health advocate Mike Adams, author of "The Ten Most Important Technologies for Humanity," said the researchers' proposal equates to "mad scientist experiments," and creating a human-cow hybrid embryo is much like opening Pandora's Box.
"Combining the life seeds of animals and humans is an invitation for unanticipated disasters, and it is a serious violation of fundamental medical ethics," Adams said.