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Stem cells

March 08, 2002|BY Chris Copley & Kevin Clapp

Around the phone they gathered, a conference call in May to celebrate 50 years of marriage for Anderson and Julia Clark.

On the line, five friends who had helped make up the wedding party laughed and shared stories. They had attended Maryville (Tenn.) College together, traveled together, sung in the school's acappella choir together.

Someone suggested joining for one more round of their alma mater, the words burned in their brains years after learning them. So they sang. Everyone, including Julia.

As swiftly as the lyrics sparked in her, they drifted away. But for those few moments she was back. For Anderson, it was magical.

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"It was there for her. Boy, oh boy," recalls Anderson, 72. "It was quite a moment."

Julia Clark suffers from Alzheimer's disease, living out her days at Somerford Place in Hagerstown. Her mother had the disease. Two aunts had it. She was diagnosed in 1993. Some days, Anderson isn't sure if Julia, 72, knows who he is.

In the news, he reads and watches about an debate raging about stem cells, embryos and research possibilities. More power to it, he says.

"I think it's absolutely a gift to us from the gods. I endorse it, I applaud it, I will support it for whatever application," Clark says. "I just think God gave us a hell of a gift when he gave us the body, and to think it has these abilities. It makes the miracle of creation more miraculous."

Stem cell researchers say if they meet their goals, the advance in health care could, within five or 10 years, equal the impact - and controversy - of medical breakthroughs such as organ transplants, antibiotics or in vitro fertilization.

Proponents say stem cell research could yield tremendous improvements in health care and quality of life for sufferers of Alzheimer's, Parkinson's disease, diabetes or other conditions. Opponents, however, say stem cell research using human embryo tissue is essentially murder; they want tighter regulation.

Hanging in the balance - medically, ethically and politically - is the opportunity to take a scientific leap akin to landing on the moon.

The science of division

Stem cells are "master cells" that differentiate - divide and specialize - into a variety of human tissues, according to John D. Gearhart, Ph.D., professor of medicine, biochemistry and molecular biology at Johns Hopkins University in Baltimore.

Gearhart, a leading stem cell researcher, says the basis of his work is threefold: find out how these master cells operate; learn to manipulate cell development into a medical therapy; and make sure recipients don't reject tissue transplants.

"A stem cell has a unique property - to differentiate into one cell type or several cell types," Gearhart says. "But how can we make it do it and control it?"

There are three types of stem cells:

A totipotent stem cell, found in a human embryo several hours old, can form all 200-plus types of tissues found in a human being, including embryonic tissues such as the placenta and umbilical cord.

A pluripotent stem cell, found in a week-old embryo, can develop into all the tissues of a human being but not the embryonic tissues.

A multipotent stem cell, found in humans of all ages, can develop into a range of cells within an anatomical system, such as the blood system, nervous system or skeletal system.

Gearhart gained fame for pioneering a method of isolating pluripotent stem cells from aborted fetuses. Once isolated, he says, stem cells reproduce and divide indefinitely.

Chemical or electrical stimulation in a laboratory causes the cells to begin to specialize, forming one or more specific types of tissues. Some research labs have produced human tissues ranging from nerve to brain cells through trial and error experiments.

Producing tissues that can be used therapeutically is the aim of researchers, according to Rosemary Nickerson, a biology professor at Hagerstown Community College.

"The hope is that scientists will be able to take those cells, provide external cues and use these cells to produce tissue, then transplant those tissues back into adults whose tissues have been damaged," Nickerson says.

The concept sounds simple, but there are two difficult challenges facing Gearhart and others. First, how do stem cells differentiate? Researchers have had only limited success in regularly stimulating stem cells to predictably produce specific cell tissues.

The other challenge involves making sure a recipient's immune system accepts the engineered tissue.

"That is almost the Achilles heel of stem cell research," Gearhart says. "We can genetically manipulate the material, but how do you get the body to accept it? We can do all these things but unless you can get it to 'take,' what have you done?"

Heated debate

The controversy in stem cell research revolves around the source of the cells with which scientists work. Dr. Stacie M. Marrie, a pediatrician in Chambersburg, Pa., says the origin of some stem cells are not objectionable.

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