Researchers believe they have identified a new way, using an advance in stem-cell technology, to promote recovery after spinal cord injury of rats, according to a study published in today's Journal of Biology.
Scientists from the New York State Center of Research Excellence in Spinal Cord Injury showed that rats receiving a transplant of a certain type of immature support cell from the central nervous system (generated from stem cells) had more than 60 percent of their sensory nerve fibers regenerate. Just as importantly, the study showed that more than two-thirds of the nerve fibers grew all the way through the injury sites eight days later, a result that is much more promising than previous research. The rats that received the cell transplants also walked normally in two weeks.
The University of Rochester Medical Center, Rochester, N.Y., and Baylor College of Medicine, Houston, collaborated on the work. Researchers believe they made an important advance in stem cell technology by focusing on a new cell type that appears to have the capability of repairing the adult nervous system.
"These studies provide a way to make cells do what we want them to do, instead of simply putting stem cells into the damaged area and hoping the injury will cause the stem cells to turn into the most useful cell types," explains Mark Noble, Ph.D., co-author of the paper, professor of Genetics at the University of Rochester, and a pioneer in the field of stem cell research. "It really changes the way we think about this problem."
The breakthrough is based on many years of stem cell biology research led by Margot Mayer-Proschel, Ph.D., associate professor of Genetics at the University of Rochester. In the laboratory, Mayer-Proschel and colleagues took embryonic glial stem cells and induced them to change into a specific type of support cell called an astrocyte, which is known to be highly supportive of nerve fiber growth. These astrocytes, called glial precursor-derived astrocytes or GDAs, were then transplanted into the injured spinal cords of adult rats. Healing and recovery of the GDA rats was compared to other injured rats that received either no treatment at all or treatment with undifferentiated stem cells.
The rats without the GDA cell transplant did not show any nerve fiber regeneration and still had difficulty walking four weeks after surgery.
"We demonstrated that we can treat these precursor cells, in culture, with signals we know to be important in the development of astrocytes and push these stem cell-like cells down a pathway that supports regeneration of the nervous system," said Stephen Davies, Ph.D., the study's lead investigator and assistant professor of Neurosurgery at Baylor.
"At the heart of stem cell transplantation research is finding the right cell for the right job," Noble added. "In this case the work of this team has identified a cell that provides many more benefits than those seen with other cell types and thus, it gives us hope that we are on a better track."
The GDA cells seem to work by signaling the tissue to repair in several ways, such as by suppressing scar tissue, rescuing motor pathway neurons in the brain and aligning damaged tissue at the injured site. More investigation is needed, however, before the new technology could be used in humans, researchers said.
The New York State Spinal Injury Program funded the research, as well as the National Institutes of Health and the Christopher Reeve Foundation.
Co-authors from the University of Rochester are Noble, Mayer-Proschel and Chris Proschel. In addition to Davies, co-authors from Baylor's Department of Neurosurgery are Jeannette E. Davies and Carol Huang. All of the scientists are all members of the New York State Center of Research Excellence in Spinal Cord Injury.
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