But just four days after Mitalipov’s discovery was announced, Jamie Thomson unveiled a discovery of his own. In the past several years—faced with the technical challenges of embryonic cloning, funding barriers and political opposition—the University of Wisconsin’s stem cell pioneer had begun exploring an alternative to embryonic cloning. By inserting a genetic engineering tool known as a retrovirus into an adult human skin cell, he was able to reprogram its DNA and coax it into behaving like an embryonic stem cell. He called these cells “induced pluripotent human stem cells” and proclaimed that his method had circumvented the need for cloning and the destruction of human embryos altogether.
Two weeks after the journal Science published Thomson’s results, the Weekly Standard ran the headline, “The End of the Stem Cell Wars: A Victory for Science, for the Pro-Life Movement, and for President Bush.” President Bush, in his 2008 State of the Union address, hailed Thomson’s breakthrough as the long-awaited answer to the divisive cloning debate, promising to fund the procedure exclusively and calling for a ban on “unethical” attempts to clone human embryos.
In the swell of publicity that followed, the normally reticent Thomson, who has since retreated from the public eye and who declined an interview with Portland Monthly, crowed to the Washington Post, “What a great bookend. Ten years of turmoil and now this nice ending. I can relax now.”
“It’s the most unbelievable medical advance in the last 25 years,” says Maureen Condic, a senior fellow at the Roman Catholic Westchester Institute who’s also an associate professor of neurobiology and anatomy at the University of Utah. “One little prick, and you get millions of skin cells that can be turned into stem cells. The only reason to clone now is that you’re likely to end up in an editorial in the New York Times.”
In an even more devastating blow to Mitalipov, Ian Wilmut, the “father” of cloning, declared that he, too, was abandoning the cloning process and adopting Thomson’s method, which he called “100 times more interesting” and “easier to accept, socially.”
Now, the University of Wisconsin is building a multimillion-dollar research center for Thomson. But despite Thomson’s popularity, there are at least a few scientists in the United States besides Mitalipov who still consider cloning a viable option. Robert Lanza, chief scientific officer at Advanced Cell Technology, a Los Angeles-based biotech firm that continues to pursue human embryonic stem cell cloning, warns that it’s too soon to write off Mitalipov’s research completely.
“Right now, we need to move ahead on both fronts and let the science play itself out,” says Lanza, who is also studying Thomson’s technique. “Despite the religious right wanting everybody to think that everything is solved, it’s not. We now have two possible ways to resolve this profoundly important problem, and it’s up in the air as to which is really going to succeed in doing this first.”
The primary problem with Thomson’s technique, says Lanza, is that it relies on retroviruses that the FDA would never allow to be used in humans. Mitalipov worries that if Thomson’s stem cells were turned into bone marrow and transplanted into a patient, it would take only one rogue stem cell to revert back to its pluripotent state and begin to spread through the patient’s body, becoming cancer.
“Because of the ethical debate,” says Mitalipov, “science is playing politics. If you use these in patients, it would be pure homicide.”
But, says Lanza, assuming Mitalipov’s protocol could be reproduced in humans, the technique’s fundamental hurdle is that it relies on human eggs. Lanza points out that more than a year ago his company ran over 100 ads asking for egg donors, but only one candidate actually went through the procedure.
Mitalipov notes that in the year since he announced his breakthrough, he’s reduced the number of eggs required to create a blastocyst from 150 to 15; and he believes he can reduce this number to 2 or 3 eggs. If he could make cloning that efficient, he could rely on the supply of leftover eggs from in vitro fertilization procedures—because such eggs are typically discarded anyway.
But what Mitalipov would really like to do is discover the as-yet-unknown protein inside the human egg that gives rise to stem cells. With that knowledge, he could do away with the egg entirely and use the protein alone to manufacture stem cells, essentially merging his advance with Thomson’s—but using the egg’s natural protein to do the job instead of mucking around with cells artificially created by genetic engineering.
“Nature has developed this system over millions of years,” says Mitalipov. “Instead of reinventing the wheel, we need to understand how it’s done in the egg.”