Chinese Stem-Cell Advance Met With Cautious Optimism
Chinese scientists have bred mice from cells that might offer an alternative to embryonic stem cells.
WASHINGTON — Three separate teams of researchers in China and the United States have published papers confirming that reprogrammed mouse skin cells could behave exactly like embryonic stem cells.
The scientific community — as well as pro-life groups eager to discourage the advance of embryo-destructive stem-cell research — applauded the promising news. But both camps caution that more work must be completed before the full promise of induced pluripotent skin stem cells, known as iPSCs, can be understood.
“The recent papers from China and the Scripps Institute are very interesting and hopeful. They advance the notion that iPSCs are capable of producing live-born mice,” said Dr. William Hurlbut, a consulting professor in neurology and the neurological sciences at Stanford University.
But Hurlbut, who has taught courses in bioethics, served on the President’s Council on Bioethics during the Bush administration, and is engaged in related scientific research, presents an ambiguous portrait of the impact of this new development on the culture wars. He noted that most of the reprogrammed stem cells failed to work and that only a few lines yielded an “apparently normal” adult mouse.
“It probably means there are a lot of technical barriers. To be commercially viable, they would have to be reliably pluripotent. They will have to look for what is in the lines of mice that work versus the ones that don’t work,” suggested Hurlbut. “I spoke with Shinya Yamanaka, the Kyoto University scientist that initiated this advance, and he says there is still a lot of work to do.”
According to the paper published in the science journal Nature, the researchers, led by Qi Zhou at the Chinese Academy of Sciences’ State Key Laboratory of Reproductive Biology, sought to establish whether the reprogrammed mouse skin cells could yield the same pluripotent characteristics common to embryonic stem cells; embryonic stem cells can morph into other cells in the body. The Chinese study confirmed that iPSCs were roughly equivalent to embryonic stem cells when they implanted the reprogrammed skin cells into a female mouse embryo and transferred that embryo to a female mouse, which later had pups.
Fanyi Zeng of the Shanghai Institute of Medical Genetics at Shanghai Jiao Tong University told Reuters that the research would help scientists target “the root causes of disease and lead to viable treatments and cures of human afflictions.”
Researchers and patient advocates have long contended that embryonic stem cells offer the potential to lead to medical miracles, such as regenerating tissue damaged by trauma and disease.
While states like California have designated billions of dollars for embryonic stem-cell research and President Obama fulfilled his campaign pledge to relax key restrictions on federal funding of embryonic stem-cell research, the “promise” of this work has yet to be realized.
Meanwhile, scientists working with adult stem cells have produced a string of new therapies, and hundreds of laboratories are now engaged in iPSC research.
The news from China has already fired pro-lifers’ hopes that the scientific community will reconsider its commitment to embryonic stem-cell research, but iPSC research also possesses a dark side: It may well facilitate the process of human cloning.
Zeng, from the Shanghai Institute, rejected this path, and U.S. scientists who work with stem cells insist they have no plans to bring a cloned human to term. At present, some engage in “therapeutic cloning” — embryos are created for the purpose of research and then killed.
“Any cell that is capable of producing a live-born mouse can produce a cloned being. The issue of cloning has existed for embryonic stem cells, and now it also exists for iPSC,” said Maureen Condic, associate professor of neurobiology and anatomy at the University of Utah.
Condic suggests that iPSC advances — “a less-specialized technology” — may even surpass the effectiveness of traditional cloning, which “rarely yields an embryo capable of developing up through live birth.”
In traditional cloning, a cell is obtained from a patient and then combined with a human egg cell that has had its own DNA removed. The combined cell is stimulated to divide, and once transferred to a surrogate mother, such clones can develop to live birth in rare cases.
This approach poses a number of significant challenges. Condic noted that “obtaining a sufficient number of human eggs is a barrier.” Few women want to undergo a risky and painful medical procedure for the sake of science.
Father Thomas Berg of the Westchester Institute for Ethics and the Human Person believes it will be critically important to get “laws on the books prohibiting the use of iPSC, as well as embryonic stem cells, for human cloning.”
“Right now, human cloning is taboo in the scientific community, but taboos don’t last forever,” observed Father Berg. “This procedure could be very attractive to the in vitro fertilization industry because it doesn’t have any of the complexity of cloning. If that industry wants to create a ‘savior sibling,’ for example, this procedure would produce the clone of whoever donated those skin cells.”
The “potential dark side of cloning” is a blow to Father Berg, who has collaborated for years with stem-cell researchers and bioethicists to initiate alternatives to embryo-destructive stem-cell research. Still, he is pleased that scientists have embraced the option of employing reprogrammed skin cells instead of stem cells stripped from early embryos.
Also hopeful is Father Tad Pacholczyk, director of education for the National Catholic Bioethics Center, given that iPSCs have opened up an alternative path for stem-cell research that may lead to major breakthroughs in the treatment of spinal cord injuries and neurological diseases. “We now have a cell type that will allow us to do the same experiments that we wanted to do using embryonic stem cells — and we won’t find ourselves in any ethical quagmire,” he said.
Father Pacholczyk believes that those championing embryo-destructive research are the minority: “When you look at the stem-cell field, you have a relatively small core group of scientists who will incessantly beat the drum of embryo destruction, [believing] no matter what, we have to be able to destroy human embryos.”
He suggests that a much larger segment of scientists “have always been sensitive to the ethical concerns in this field. An enormous number of them are doing research with the reprogrammed cells,” embracing the promise of iPSCs.
As iPSC research builds momentum, Father Pacholczyk is troubled that Obama has signaled plans for a larger federal role in embryonic stem-cell research. In his eyes, “This ends up being a kind of sanctioning of embryonic stem-cell research.”
Yet, Father Pacholczyk, a neuroscientist, is sympathetic to the concerns of the scientific community that now possesses the tools “to ask developmental questions we could never ask before.”
“Scientists can be a little bit naive when they say, ‘Don’t impede us too much with talk about ethics. After all, we are trying to achieve good things.’ That posture has always been present in the scientific community and always will be,” he said. “But the stem-cell field has exploded in front of us, and enormous possibilities do seem to be presenting themselves.”
If Catholic theologians and pro-life activists seek to engage the scientific community, Hurlbut suggests, they must do more than advance their own moral concerns.
Hurlbut is prepared to sound the alarm about new efforts to circumvent or even rescind the Dickey-Wicker Amendment, which banned taxpayer-funded research that engaged in the creation and killing of human embryos.
But Hurlbut also wants political activists concerned with life issues to establish a dialogue that acknowledges the profound curiosity that drives scientific innovation even as it seeks to guard against the excesses of this passion.
“The pro-life movement has made a mistake emphasizing adult stem cells over embryonic stem cells,” suggested Hurlbut. “There are scientific reasons to believe in the value of embryonic stem-cell research. Even as a pro-life person, I can see why scientists want to study embryonic stem cells — there is basic scientific information to be learned from them.”
Scientists devoted the past century to molecular biology, learning about the components of cells, he noted. “Now they’ve moved into the era of developmental biology, working with living beings. We need to use the simplest model — the embryo — to learn about this. That’s why I don’t think this will be the end of the culture wars. It’s the beginning of a whole series of conflicts of the meaning of developing life.”
Joan Frawley Desmond writes
from Chevy Chase, Maryland.
- August 23-September 5, 2009