The Cow-Man Medley
(April 11th 2008) Human-cow hybrid embryos, claimed to be the latest breakthrough in stem cell research, are fuelling further moral, political and scientific debate. reports Melanie Estrella.
The news was made public on April 1st, but this was no April Fool's joke. The BBC reported that British scientists had successfully created the first European hybrid embryos, a blend of cow and human. Lyle Armstrong and his colleagues from the Institute of Human Genetics at the University of Newcastle, one of Europe's strongholds for stem cell research, generated human-cow chimeras that lived for three days to the 32-cell stage. This rather preliminary data was presented by Armstrong at a lecture in Israel on March 27th, to be broadcast to the world a few days later by the BBC - quite a departure from the procedure of first publishing in a peer-reviewed scientific journal!
This odd interspecies embryonic cross was generated in Armstrong's lab by enucleating eggs derived from cow ovaries and then injecting them with nuclei from a human embryonic stem cell line. Using bovine eggs, the UK researchers are trying to overcome the shortage of rare and precious human eggs, currently obtained from women undergoing in vitro fertilisation treatments. Bovine eggs, on the other hand, accumulate in large quantities as abattoir by-products during meat processing.
Even though the created chimeras contain human nuclear DNA, the remaining 0.1 percent, comprising the mitochondrial genes, is still of bovine origin. In fact, "it is amazing the experiments worked since animal mitochondria generally do not communicate properly with the human nucleus," commented Hans Schöler, stem cell expert and director of the Max-Planck-Institute for Cell- and Developmental Biology in Münster, Germany, to "Focus Online".
The hybrid embryos cannot be used for therapeutic cloning nor will they be allowed to develop for longer than 14 days, thereby avoiding any risk of creating some kind of cow-headed human like the ancient Egyptian goddess, Hathor. The British scientists are now planning to grow their embryos for six days in order to harvest stem cells; the remaining cells will be destroyed.
Indeed the underlying idea is that the hybrids will serve as a source of stem cells for experimental purposes, employed to unravel a variety of disease mechanisms. Armstrong believes that it is possible to monitor the development of human genetic diseases from their very onset by transferring nuclear DNA from genetically diseased tissue into the cytoplasm of healthy enucleated eggs.
As might be expected, Armstrong's work has provoked plenty of criticism by miscellaneous parties. The Catholic Church does not appreciate such "monstrous experiments of Frankenstein proportion" nor does the Pro Life organisation. Moreover, the scientific community is irked due to the circumvention of the peer-review process and is impatiently awaiting the promised publication. After all, Armstrong's chimeras might end up vanishing into thin air like the clones of Korean impostor, Woo-Suk Hwang.
Nevertheless, there is a reason why the UK research team chose to break the news so unconventionally: it is an attempt to influence the ongoing political debate on stem cell research in the UK parliament. In Britain, every stem cell experiment has to be approved by the Human Fertilisation and Embryology Authority (HFEA) and Armstrong's current experiments received approval in January. In May 2008, a new Human Fertilisation and Embryology Bill is scheduled for debate in parliament that proposes to authorise the creation of chimeric embryos for scientific purposes.
Although many countries, including France, Germany and Italy, forbid human-animal embryos, previous attempts have been made to generate them: the US Company, Advanced Cell Technology, has worked on miscellaneous crossings since 1998. While in 2003, Chinese scientists from the Shanghai Second Medical University reported the fusion of human cells with rabbit eggs. In the same year, the US scientist, Panayiotis Zavos, announced the generation of a human-cow embryo that lived for a fortnight.
