Dennis Turner's Parkinson's disease had become so
severe by 1999 that he could not use his right arm. That was the year he
underwent an experimental treatment with his own brain adult stem cells. "Soon
after having the cells injected, my Parkinson's symptoms began to improve,"
Turner testified in 2004 before the U.S. Senate. "My trembling grew less and
less, until to all appearances it was gone."
He also said this: "I can't say with certainty what my
condition would have become if Dr. Levesque had not used my own adult stem
cells to treat me. But I have no doubt that because of this treatment, I've
enjoyed five years of quality life that I feared had passed me by."
Turner is not alone in benefiting from adult stem-cell
therapy. Thousands of other patients have experienced relief from conditions
that include leukemia, multiple sclerosis, lupus, sickle-cell anemia, and heart
damage. Adult stem cells have grown new blood vessels to prevent amputation
from gangrene, new corneas to restore sight, new cartilage and bone to replace
those lost through accident or disease. They've prevented life-threatening
problems from genetic diseases for children. Spinal cord injuries have also
shown improvement; Laura Dominguez, testifying at the same hearing as Turner,
told of regaining feeling and movement after treatment with her own nasal adult
stem cells.
British doctors are starting trials to test bone marrow
adult stem cells to treat liver disease. And a Harvard team now has FDA
approval to begin patient trials for juvenile diabetes, after scientists showed
in mice that adult stem cells could achieve "permanent reversal" of
diabetes.
Adult stem cells have now helped patients with at least 65
different human diseases. It's real help for real patients. For embryonic stem
cells the score is zero—not a single patient has benefited from embryonic
stem cells. After 24 years of research with embryonic stem cells, they are
still risky even for experimental animals, all too often forming tumors or
misplaced tissue in rats and mice.
Why then the obsession with embryonic stem cells? One reason
is the claim that only embryonic stem cells are pluripotent, meaning they have
the flexibility, or plasticity, to form most or all tissues of the body. This
ability to morph into virtually any tissue type would make a stem cell useful
for treating a host of diseases, slipping into any organ to replace damaged or
missing cells. This is certainly a characteristic of embryonic stem cells if
left in the intact embryo. But scientists have not been successful at directing
the same range of tissue formation from embryonic stem cells in the lab dish.
For adult stem cells, the dogma has been that they are not
as flexible, only forming the tissue from which they originated. They have been
useful for decades at replacing bone marrow and forming blood, but it was
thought that they were limited in forming other tissues.
Not so. Since the mid-1990s, a rapidly growing volume of
scientific evidence has documented that adult stem cells possess much greater
abilities than scientists imagined, and some show the same pluripotent
flexibility as embryonic stem cells. Within the last four years, researchers
from around the world have documented that adult stem cells from bone marrow,
blood, amniotic fluid, placenta, umbilical cord blood, and nasal tissue show
this same remarkable plasticity, but without the problems of tumors seen with
embryonic stem cells.
A few recent examples include a Texas-U.K. team that has
shown human umbilical-cord-blood stem cells can be grown in large numbers in
the lab and show the same flexibility as embryonic stem cells. University of
Pittsburgh scientists recently found the same for placenta stem cells. (One
researcher saved his newborn's placenta because of his experiments showing that
these adult stem cells were so flexible.) And several groups have shown that
bone marrow stem cells also are pluripotent.
Cardiologist Douglas Losordo at Tufts University said that
bone marrow "is like a repair kit. Nature provided us with these tools to
repair organ damage." He also noted that "embryonic stem cells are going to
fade in the rearview mirror of adult stem cells."
Hundreds of scientific studies over the last few years
document that adult stem cells can repair diseased and damaged tissue. The
contrast between adult stem cells and embryonic stem cells is the difference
between live patients and dead mice. While the focus has been on ethically
controversial embryonic stem cells, adult stem cells—which don't involve
the destruction of human lives—have quietly progressed in treating human
patients.
It's time the focus shifted to the real promise for treating
patients—and the real successes of adult stem cells.
David A. Prentice is senior fellow for life sciences at the
Family Research Council, an adjunct faculty member at Georgetown Medical
School, and a founding member of Do No Harm (
www.stemcellresearch.org). He was selected by the President's Council on
Bioethics to write a comprehensive review of adult stem-cell therapies.
Our weekly bioethics column, Life Matters, discusses stem cells and related life ethics issues. Nigel M. de S. Cameron's latest column was "Leon Kass, a Bioethics Legend, Steps Down."
More CT articles on stem-cell research includes:
The Stem-Cell Conspiracy | The Washington Post muddles a major breakthrough in adult stem-cell research, while the U.K. marches blindly on. (Aug. 29, 2005)
Post-Election Education | Pro-lifers weigh options after Californians fund embryonic stem-cell research. (Dec. 1, 2004)
The Politics of Stem Cells | Why do some scientists and politicians insist on exploiting embryos? (Nov. 17, 2004)
It's Not About Stem Cells | Why we must clarify the debate over harvesting embryos. (A Christianity Today editorialSept. 29, 2004)