Researchers have shown the reversal of long-term hind-limb paralysis.
The UC Irvine study demonstrated that human neural stem cells can restore mobility in cases of chronic spinal cord injury, suggesting the prospect of treating a much broader population of patients.
Previous breakthrough stem cell studies have focused on the acute, or early, phase of spinal cord injury, a period of up to a few weeks after the initial trauma when drug treatments can lead to some functional recovery.
The study, led by Aileen Anderson and Brian Cummings of the Sue and Bill Gross Stem Cell Research Center, is significant because the therapy can restore mobility during the later chronic phase, the period after spinal cord injury in which inflammation has stabilized and recovery has reached a plateau.
There are no drug treatments to help restore function in such cases.
For the study, the researchers transplanted human neural stem cells into mice 30 days after a spinal cord injury caused hind-limb paralysis.
The cells then differentiated into neural tissue cells, such as oligodendrocytes and early neurons, and migrated to spinal cord injury sites.
Three months after initial treatment, the mice demonstrated significant and persistent recovery of walking ability in two separate tests of motor function when compared to control groups.
"Human neural stem cells are a novel therapeutic approach that holds much promise for spinal cord injury. This study builds on the extensive work we previously published in the acute phase of injury and offers additional hope to those who are paralyzed or have impaired motor function," said Anderson.
The study appears in the open-access, peer-reviewed journal PLoS ONE and is available online.