There have been several recent developments in the potential treatment of spinal cord injury. A group of researchers showed they were able to enhance the regeneration of nerve connections after spinal cord injury by deleting an enzyme called PTEN. The enzyme controls a molecular pathway called mTOR that is a key regulator of cell growth. During development, when nerve growth and connections occur, PTEN activity is low, allowing cell growth. When growth is completed, PTEN is turned on to inhibit cell growth. Controlled stimulation of cell growth is important for tissue regeneration. The scientists disabled PTEN in mice and were able to achieve nerve growth past a spinal cord lesion. The study published in Nature Neuroscience points to possible strategies to encourage a damaged spinal cord to sprout new neuron growth for repair.
A Japanese group has shown that transplanting neural stem cells along with a chemical stimulus can enhance formation of new neurons and reform neuronal circuits in mice with spinal cord injury. The chemical stimulant valproic acid steered the transplanted neural stem cells to form neurons, and stimulated reconstruction of broken neural connections, resulting in significant recovery of hind-limb movement for the mice. The work was published in the Journal of Clinical Investigation.
A UC-Irvine team showed they were able to use neural stem cells to restore some motor function in mice with chronic spinal cord injury. Most studies have focused on acute injuries, attempting to initiate treatment soon after injury. This acute phase is what the Geron trial that endangers patients will focus on, since rat data has shown the embryonic stem cells have no effect on chronic injury. In the UC-Irvine study, mice were treated 30 days after spinal cord injury with fetal neural stem cells; three months later the mice showed statistical improvement in recovery of walking ability.