You may be able to teach an old and wounded brain new tricks.
Researchers have injected a naturally occurring protein, called a growth factor, into damaged brains of adult experimental rats and helped restore their ability to move. The scientists had destroyed those parts of the brain responsible for movement in the rats.
The experiments are apparently the first to show that brain damage can be reversed in an adult animal, a finding that may have implications for stroke victims, Alzheimer’s and Parkinson’s disease patients and people with nervous system and spinal cord injury.
Scientists Mobilized Rats’ Stem Cells
Based on tissue analysis of the brains, the scientists, led by James Fallon, professor of anatomy and neurobiology at the University of California at Irvine, believe the protein was able to mobilize immature cells inside the brain, called stem cells, which then replaced the damaged nerve cells.
Stem cells are like clay which can be molded to fit numerous purposes. During the formation of a mammal, stem cells divide, migrate to specific parts of the body and develop into specialized tissues, such as brain, liver, hair and skin. Stem cells exist during the development of embryos but decrease in number before birth and throughout life and only exist in small numbers in the adult brain.
“The study finally shows that stem cells can be induced naturally in large enough numbers and drawn to specific sites of damage, restoring function and replacing damaged cells in the brain,” Fallon says.
“The stem cells are already in the brain and other organs in small numbers. They can be stimulated in the brain to develop by a growth factor without the need for transplanting stem cells, embryonic tissue or altered cells from outside.”
The work is being reported in the current issue of the Proceedings of the National Academy of Sciences.
Precludes Need for Transplants
Prior studies have implanted either adult or embryonic stem cells grown outside the body into brain tissue to help restore function. The results of this latest study suggest doctors may be able to nurture stem cells inside the brain to do regenerative work.
Many researchers are focusing attention on harnessing the stem cells’ ability to mature into other cells. Fallon’s work employed the use of a naturally occurring protein in the body, called transforming growth factor alpha, to channel the stem cells.
Experts in stem cell research met the findings with cautious enthusiasm.
The research adds a new and important chapter in stem cell biology, says Angie Rizzino, professor, and program leader of the Molecular, Cellular, and Structural Biology Program of the Eppley Cancer Institute at the University of Nebraska Medical Center in Omaha. But Rizzino questioned whether the growth factor stimulated proliferation of these restorative cells or acted more indirectly.
“This is a significant step forward in deciphering the signals required to direct stem cells to grow and differentiate into specific cell types,” says David Prentice, professor of life sciences at Indiana State University, and adjunct professor of molecular and medical genetics at Indiana University School of Medicine. “It should have significant impact for the treatment of neurodegenerative problems, such as Parkinson’s and Alzheimer’s. Because the treatment uses the patients’ own cells, the ethical controversy of [using aborted tissue for stem cells] as well as the potential for transplant rejection are avoided.”
Human Studies Remain Difficult
But translating the findings to humans will be difficult, researchers warned.
“There is a history of very powerful growth factors doing amazing things in the lab, but when giving them to humans, it is extremely difficult to determine correct dosage, with too high a dose having a bad outcome,” says Dr. Darwin Prockop, director of the Tulane Center for Gene Therapy at Tulane University Health Sciences Center in New Orleans.
Stem Cell Pharmaceuticals, of Seattle, Wash., supplied the growth factor for the experiments. The American Parkinson’s Disease Foundation, the American Foundation for Aging Research and the the University of California at Irvine also supported the work.
Scott Terranella, of ABCNEWS, and Robin Eisner, of ABCNEWS.com contributed to this report.