A specific type of human cell, generated from stem cells and transplanted into spinal cord injured rats, provide tremendous benefit, not only repairing damage to the nervous system but helping the animals regain locomotor function as well, scientists have found.
Their study 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.
But 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.
The research teams 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.
To create the different types of astrocytes used in the experiment, researchers isolated human glial precursor cells and exposed these precursor cells to two different signaling molecules used to instruct different astrocytic cell fate - BMP (bone morphogenetic protein) or CNTF (ciliary neurotrophic factor).
Transplantation of the BMP human astrocytes provided extensive benefit, including up to a 70pc increase in protection of injured spinal cord neurons, support for nerve fiber growth and recovery of locomotor function, as measured by a rat's ability to cross a ladder-like track.
In contrast, transplantation of the CNTF astrocytes, or of the stem cells themselves, failed to provide these benefits. Researchers are currently investigating why BMP astrocytes performed so much better than CNTF astrocytes, but believe multiple complex cellular mechanisms are probably involved.
The findings are published in the journal PLoS ONE.