Half Human, Half Cow, All Baloney

Britain has recently become the latest battleground of what appears to be a momentous struggle for the human soul. On one side are scientists who would usher in a brave new world of weird human-animal hybrids. On the other side are religious leaders and politicians of conscience who would draw the line once and for all against these perceived monstrosities. One of the most outspoken religious figures is Cardinal Keith O'Brien, leader of the Roman Catholic Church in Scotland. He launched an extraordinary attack during his Easter sermon on Prime Minister Gordon Brown. By supporting a bill that would legalize experiments in which scientists implant human DNA into a cow's egg cell, Brown was endorsing "experiments of Frankenstein proportion," said O'Brien. Facing mounting disapproval from the public at large, a rebellion in his own party and threats of resignation from three Catholic cabinet ministers, the prime minister was forced to retreat and allow Labour M.P.s to "vote their conscience" on the issue of animal-human embryos. Last month, while Parliament was debating the bill, the BBC broke the news that Newcastle University scientist Lyle Armstrong had successfully created just such a hybrid embryo.

The ensuing imbroglio, the latest battle in the tiresome war over stem-cell research, was great fodder for the tabloids. What neither side in this peculiarly British tussle understands is that the embryonic-stem-cell war is over, and the public is the big winner. A new technology has removed the entire basis of this longstanding dispute, though neither side is widely aware of it.

To understand what has happened, it's important to remember the original goal of the work of Armstrong and his biologist colleagues. They have never had any intention of creating hybrid animals or babies, of course, but rather to generate human embryonic stem cells, which have the power to turn into any type of human cell—liver, bone marrow, muscle, brain and so forth. To this end, scientists have tried to exploit knowledge of the molecular signals that naturally guide embryonic development. If scientists could master these signals, the thinking goes, they could one day have a means of transforming a clump of stem cells into perfectly compatible tissue for transplantation into a particular patient. Such a breakthrough would allow doctors to grow replacement organs or limbs, or replace brain tissue damaged by Parkinson's.

Many scientists have assumed that unfertilized eggs are an essential ingredient in the process of making patient-compatible embryonic stem cells. But human eggs are difficult to obtain and procuring them has raised ethical concerns. Armstrong was working to circumvent these problems by seeking an alternative method of making stem cells. He took an easy-to-come-by cow's egg, removed the genetic material and replaced it with human DNA from an ordinary skin cell. The resulting hybrid began behaving like a human embryonic stem cell.

Catholics reject standard embryonic-stem-cell work because it involves the creation and manipulation of human embryos. But Cardinal O'Brien and other Christian leaders object to this new research on different grounds: that the scientists were violating human dignity by combining human and animal ingredients in a weird ungodly hybrid life form.

While Armstrong and other cell biologists were pursuing the hybrid approach, other scientists have been taking a different approach to stem-cell research. They began with the assumption that a just few specific proteins in the unfertilized egg bear full responsibility for reprogramming a skin cell and causing it to become an embryonic cell. After all, it's proteins—not genes—that makes liver cells different from brain cells and muscle cells. Every cell in your body contains a complete and identical copy of your genome, but your liver cells may run one part of your genome's program while your muscle cells run another. In each case there's a prime mover—a single protein or set of proteins that makes a cell behave as a liver or a brain cell, or an embryonic cell. By decoding and isolating the prime movers of embryonic cells, stem-cell scientists hoped to do away altogether with a requirement for eggs of any kind. With the right proteins, they could kick start their own embryonic stem cell.