UF scientists explore adult stem cell potential

April 13, 2001

GAINESVILLE, Fla. — The political battle over medical use of embryonic tissue continues to rage, but out of the glare of the spotlight, scientists have been learning that some adult cells also hold vast treatment potential.

Many scientists view adult and embryonic stem cell research as complementary rather than competing disciplines because the cells differ enough that they are likely to offer distinct therapeutic options, according to a University of Florida neuroscientist who focuses on the adult variety.

But while the possibilities for adult stem cells were once thought to be sharply limited, recent discoveries suggest that like their younger brethren, they also may one day be manipulated to generate transplant tissues or awaken the body’s dormant powers of self-repair. And surprisingly, the research also is shedding light on the biology and treatment of cancer.

“These adult tissues don’t appear to be as restricted in their fate as we thought they were,” said Dennis A. Steindler a professor of neuroscience and neurosurgery at UF’s College of Medicine who also is affiliated with UF’s Evelyn F. and William L. McKnight Brain Institute and the UF Shands Cancer Center. “In some ways they may not have the same potential as embryonic cells, but once we figure out their molecular genetics, we should be able to coax them into becoming almost anything we want them to be.”

Many scientists have prized embryonic stem cells because their early stage of development gives them the ability to generate all of the body’s tissue types – a gold mine for efforts to develop treatments for a wide range of diseases or even to grow whole organs to replace damaged or dying body parts. It’s long been assumed that the adult body would have much less capacity for renewal, but recent discoveries have forced scientists to rewrite what had appeared to be established truths of biology.

Consider the brain. Just a few years ago, the assumption was that people were born with all of the brain cells they would ever have. But then scientists discovered the adult brain has its own population of stem cells that can mint other new cells.

Two years ago, Steindler and his colleagues (then at the University of Tennessee) demonstrated that in tissue cultures they could multiply the numbers of brain stem cells culled from cadavers and patients undergoing surgery for epilepsy. That finding, based on technology developed by Valery G. Kukekov, in Steindler’s laboratory, opened the door to ongoing efforts to generate enough tissue for transplant therapies.

Then in December, Eric D. Laywell and the rest of the Steindler team reported in the Proceedings of the National Academy of Sciences that they had developed special techniques to transform mature brain cells back into stem cells, a sort of “cellular time machine.” They did this by experimenting with special growth factors in tissue culture. The new stem cells, in turn, can create a variety of cell types.

“There also are other labs that have shown that they can take one tissue type and turn it into another, converting blood cells into brain cells, for example,” said Steindler, who joined the UF faculty in March. Other leading researchers from his lab also are beginning to work at UF this spring.

Experiments across the country are offering a glimpse of what adult stem cells may offer in coming years as scientists build on successes in test tubes and animal studies.

“Our goal in the long run is to develop neural stem cell techniques for repairing a damaged spinal cord or treating brain diseases such as Huntington’s, Parkinson’s and Alzheimer’s,” Steindler said. “Ideally, we would do this not through tissue transplants but by finding the growth factors that induce existing cells within one’s own brain to begin making a lot of new cells.

“We’re really beginning to see that we are a self-reparative organism,” Steindler said. “We have the potential to repair and make new brain cells throughout life. Because we have these cells in there, we can now talk about new ways to try to postpone death or promote quality of life.”

Along the way, scientists also will be learning more about differences between adult and embryonic stem cells. One such distinction, Steindler said, is that adult cells may be less adaptable to new surroundings because they are influenced by their old “neighborhood” – the place where they’ve been living in the body.

“If you take a baby cell and an adult cell and put them into a new part of the body, the young cell may be more accepting of cues from the surrounding tissue about what to do, but the old cell has memories of the old neighborhood,” he said.

Such differences, he noted, may affect the types of treatments for which the cells are suited.

Meanwhile, scientists also are beginning to view cancer through the lens of stem cell biology. With the finding that mature cells can return to the primitive stem cell state, Steindler and other researchers, including Tanya Ignatova in his lab, are investigating whether some tumors may originate from a newly created stem cell whose DNA has been damaged.

“Perhaps a mature cell was exposed to something that turned it back into a stem cell and now it can produce a lot of bad relatives – a proliferation of cells that form a tumor,” said Steindler, who discussed his lab’s research in a symposium at last month’s meeting of the American Association of Cancer Research in New Orleans. “We have ways to study this. As we get a better understanding of tumor origins and as we improve our ability to manipulate cellular behavior, we hope this will lead to improved ways of battling cancer.”