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Stem cells grow cures, controversy

Saturday, July 19, 2003 - 10:28 pm
By Liv Osby
The Greenville News

A year ago, Jerry Sloan didn't have much hope he'd be alive today.
Diagnosed with a rare blood disorder, he was told he had about 12 months to live without high-dose chemotherapy that would destroy his bone marrow along with the illness.

Thanks to another treatment a stem cell transplant he survived the cure as well as the disease.

"My doctor was very blunt," said the 51-year-old Greenville businessman. "He said my prognosis might not be too good with the transplant, but I had no chance without it."

Sloan's transplant involved harvesting stem cells from his blood. They were put back in his body after chemotherapy to make healthy blood again.

Today, scientists around the world theorize stem cells can be used to treat a host of conditions from Parkinson's disease and spinal cord injury to heart disease and kidney failure.

ùIt's an idea that's given hope to millions suffering with painful, degenerative, crippling and sometimes fatal afflictions.

But the research has ignited intense religious and ethical debate that some researchers fear could impede progress. That's because it involves stem cells from 3- to 5-day-old human embryos, or clones of those embryos, that were created in a petri dish, a process known as in vitro fertilization, that were donated by infertile couples and that would otherwise be discarded.

Stem cell research

The body is made up of many types of adult stem cells that are constantly reproducing to regenerate blood, skin and other tissues. But embryonic stem cells have not yet been designated as specific tissues or organs, and the process by which they become heart or liver cells, for example, remains an enigma.

About five years ago, scientists discovered that these embryonic stem cells could be coaxed into becoming other cells, leading them to hypothesize they could grow new brain cells to treat Parkinson's or new cardiac cells to treat heart attacks, said Dr. Makio Ogawa, professor of medicine at the Medical University of South Carolina.

"There is some evidence that stem cells can make other tissues and organs, not just blood cells," said Ogawa, who has been conducting research on mouse stem cells, not embryonic stem cells, for the past 15 years. "And I think something exciting will come out of it."

Dr. Gary M. Spitzer, medical director of transplant services at CancerCenters of the Carolinas, was involved in some of the early work when scientists recognized bone marrow's potential.

"Bone marrow is like a tree, and we couldn't grow any of the branches or the trunk, let alone the roots, which would have been stem cells," he said. "Then people developed assays in animals where they were getting close to the roots."

That led to bone marrow transplants, in which marrow containing stem cells is harvested and replaced once chemotherapy or radiation has been administered to kill the invading disease, he said. Then came the discovery of stem cells in the blood, leading to the stem cell transplants performed today at Bon Secours St. Francis Health System.

Reduces the risk

Without stem cells, blood counts could take seven or eight weeks to rebound, putting the patient at great risk for infection and death, says Spitzer. With a transplant, it bounces back in seven to 10 days.

In widespread use today, stem cell transplants treat blood conditions such as lymphoma, myeloma and some leukemias, aplastic anemia, and immune system deficiencies and rare metabolic disorders in children, Spitzer said. They also are used experimentally for breast and testicular cancer.

When a patient's own cells are used, the procedure is called an autologous transplant, he said. A transplant from a compatible donor such as a brother or sister is called allogeneic and is performed when the patient's own cells are too diseased.

Stem cells are used elsewhere as well, according to the Mayo Clinic, for instance, in conjunction with a cornea transplant or to help regenerate damaged knee cartilage. And promising research is under way into the effectiveness of stem cell therapy on a host of serious automimmune diseases, Spitzer said, such as lupus, multiple sclerosis and scleroderma.

Brave new world

Once researchers learned that other organs were being replaced by stem cells, the field exploded, Ogawa said. And scientists are excited about the possibilities.

Recent research suggests that even some adult stem cells can change into different tissues.

But the scientific community is split over whether the cells are just fusing with the target organ say, the liver or becoming liver cells, said Ogawa. Based on findings of organ transplant patients, he said he's optimistic the cells will be shown to have adopted characteristics of the organ, not just fusing.

"When scientists examined the liver of a female patient who received transplantation of her brother's bone marrow cells, they found some of (her) liver cells had male chromosomes," said Ogawa. "And male recipients who receive heart transplants from female patients ... some of the heart muscle cells were male, which showed the recipient's bone marrow repairing the female heart."

But Spitzer said it's unknown whether skin cells implanted in the brain, for instance, will be able to grow anything but skin cells.

"That's the complexity of research," he said. "Is it possible to take cells from one organ ... and replace the damaged part? And what do we need to make them do that?"

Those are the mysteries that researchers are now hoping to unravel.

"If bone marrow cells have ability to make organs, it can change the way doctors approach a lot of disease in the future," Ogawa said. "They can use a person's own bone marrow to regenerate damaged organs."

A long way to go

But there are many obstacles to conquer before that dream becomes a reality. Each organ has many types of cells, for instance, and making one type of cell doesn't mean the whole organ can be grown easily, said Ogawa.

The phenomenon of tissue rejection, also a problem with organ transplants, also must be overcome, added Spitzer.

"Those embryonic stem cells from somebody else would be recognized just like a transplant as potentially foreign," he said, "and we would have to use immunosuppressive drugs to allow that cell to get in."

Besides mastering the technique of directing the stem cell to become a certain organ there's the question of whether a stem cell can be forced to multiply in quantities sufficient to repair an entire organ, Spitzer said.

Cures 'many years away'

And while Ogawa's optimistic that stem cell research eventually will yield treatment for many diseases, he predicts any real medical applications are a long time off.

"It's an exciting time," said Ogawa. "But we are many years away."

"The goal is very worthwhile," Spitzer said. "I think there's a lot of science that's going to come out in the next few years and really tell us if there's going to be hope."

Back running Greenville Meat Processing since January, Sloan, who has been free of the disease since his treatment last July, recognizes the sensitivity over embryonic stem cells. And even though they weren't used in his treatment, he believes he wouldn't be here today without scientific experimentation, and supports their use in research.

"If they're going to throw them in the trash anyway, why not make some good out of them?" he said. "I think that any means possible to fight terrible diseases like this and save people's lives, it would be a disservice if they didn't."

Copyright © 2003, The Greenville News