When White House political adviser Karl Rove signaled last week that President Bush planned to veto the stem cell bill being considered by the Senate, the reasons he gave went beyond the president’s moral qualms with research on human embryos.
In fact, Rove waded into deeply contentious scientific territory, telling the Denver Post’s editorial board that researchers have found “far more promise from adult stem cells than from embryonic stem cells.”
The administration’s assessment of stem cell science has extra meaning in the wake of the Senate’s 63-37 vote Tuesday to expand federal funding of embryonic stem cell research. The measure, which passed the House last year, will now head to Bush, who has vowed to veto it.
But Rove’s negative appraisal of embryonic stem cell research – echoed by many opponents of funding for embryonic stem cells – is inaccurate, according to most stem cell scientists, including a dozen contacted for this story.
The field of stem cell medicine is too young and unproven to make such judgments, experts say. Many of those researchers either specialize in adult stem cells or share Bush’s moral reservations about embryonic stem cells.
“(Rove’s) statement is just not true,” said Dr. Michael Clarke, associate director of the stem cell institute at Stanford University, who in 2003 published the first study showing how adult stem cells replenish themselves.
If opponents of embryonic research object on moral grounds, “I’m willing to live with that,” Clarke said, though he disagrees. But, he said, “I’m not willing to live with statements that are misleading.”
Dr. Markus Grompe, director of the stem cell center at the Oregon Health and Science University, is a Roman Catholic who objects to research involving the destruction of embryos and is seeking alternate ways of making stem cells. But Grompe said there is “no factual basis to compare the promise” of adult stem cells and cells taken from embryos.
Grompe said, “I think it’s a problem when (opponents of embryonic research) make a scientific argument as opposed to stating the real reason they are opposed – which is (that) it’s a moral, ethical problem.”
Last week, the journal Science published a letter from three researchers criticizing the claim that adult stem cells are preferable to embryonic stem cells. The authors included Dr. Steven Teitelbaum of Washington University in St. Louis, who has used adult stem cells to treat bone diseases in children. The authors wrote that the exaggerated claims for adult stem cells “mislead laypeople and cruelly deceive patients.”
The bill headed for Bush’s desk would expand federal funding of work on stem cells taken from embryos. Such cells come from extra embryos originally created for in vitro fertilization. Many experts believe embryonic stem cells one day could help regenerate damaged tissue for patients with conditions such as diabetes, spinal cord injury or Parkinson’s disease – though embryonic cells have not yet been tested in humans.
Adult stem cells, which usually come from bone marrow transplants or umbilical cord blood, are widely considered less flexible than embryonic stem cells in forming many types of tissue. Yet adult stem cells already are in common use for certain conditions, such as replenishing immune cells after cancer treatment and treating some bone and blood disorders.
Bush allowed limited funding of embryonic stem cell work in Aug. 2001, but he banned funding of cells taken from embryos after that date. Many scientists and lawmakers argue that the limitation has hindered progress – a view shared by several officials at the National Institutes of Health who submitted testimony to the Senate in April 2005.
“The NIH has ceded leadership in this field,” wrote Elizabeth Nabel, director of the National Heart, Lung and Blood Institute.
White House spokesman Ken Lisaius on Tuesday could not provide the name of a stem cell researcher who shares Rove’s views on the superior promise of adult stem cells.
One of the only published scientists arguing that adult stem cells are better is David Prentice, a former professor of life sciences at Indiana State University and now a fellow at the Family Research Council, a conservative advocacy group.
The letter to Science last week was critical of a list Prentice compiled of 72 diseases that have been treated with adult stem cells. U.S. Sen. Sam Brownback (R-Kan.), an opponent of embryonic research, entered Prentice’s list into the Senate record in May.
Yet most of the treatments on the list “remain unproven,” wrote Teitelbaum of Washington University and his co-authors, who claimed that Prentice “misrepresents existing adult stem cell treatments.”
Prentice said in an interview that the Science authors “put words in our mouths” – he never claimed that the adult stem cell therapies were proven, only that they had benefited some patients. But he said some of his citations were unwarranted.
“We’ve cleaned up that list now,” he said. Asked how the errors occurred, he said, “I think things just got stuck in.”
One of the scientists on Prentice’s list is Dr. Joanne Kurtzberg, a pediatric hematologist at Duke University Medical Center who has used umbilical cord blood to treat Tay-Sachs disease and other rare disorders. Kurtzberg said it’s wrong to see stem cell science as a competition with only one winner.
“We don’t know enough about the potential of either kind of cell,” Kurtzberg said. “I don’t think one type is going to be the answer to everything.”
By Jeremy Manier and Judith Graham
© 2006, Chicago Tribune.