The study, published in the journal PLoS ONE, focuses on human astrocytes - the major support cells in the central nervous system - and indicates that transplantation of these cells represents a potential new avenue for the treatment of spinal cord injuries and other central nervous system disorders.
Working together closely, research teams at the University of Colorado School of Medicine and University of Rochester Medical Center have made a major breakthrough in the use of human astrocytes for repairing injured spinal cords in rats.
"We've shown in previous research that the right types of rat astrocytes are beneficial, but this study brings it up to the human level, which is a huge step," said Chris Proschel, Ph.D., lead study author and assistant professor of Genetics at the University of Rochester Medical Center. "What's really striking is the robustness of the effect. Scientists have claimed repair of spinal cord injuries in rats before, but the benefits have been variable and rarely as strong as what we've seen with our transplants."
There is one caveat to the finding - not just any old astrocyte will do. Using stem cells known as human fetal glial precursor cells, researchers generated two types of astrocytes by switching on or off different signals in the cells. Once implanted in the animals, they discovered that one type of human astrocyte promoted significant recovery following spinal cord injury, while another did not.
"Our study is unique in showing that different types of human astrocytes, derived from the exact same population of human precursor cells, have completely different effects when it comes to repairing the injured spinal cord," noted Stephen Davies, Ph.D., first author and associate professor in the Department of Neurosurgery at the University of Colorado Denver. "Clearly, not all human astrocytes are equal when it comes to promoting repair of the injured central nervous system."
The research teams from Rochester and Denver also found that transplanting the original stem cells directly into spinal cord injured rats did not aid recovery. Researchers believe this approach - transplanting undifferentiated stem cells into the damaged area and hoping the injury will cause the stem cells to turn into the most useful cell types - is probably not the best strategy for injury repair.
According to Mark Noble, director of the University of Rochester Stem Cell and Regenerative Medicine Institute, "This study is a critical step toward the development of improved therapies for spinal cord injury, both in providing very effective human astrocytes and in demonstrating that it is essential to first create the most beneficial cell type in tissue culture before transplantation. It is clear that we cannot rely on the injured tissue to induce the most useful differentiation of these precursor cells."