ROCKVILLE, Md., Sept. 13, 2012 /PRNewswire/ -- Neuralstem, Inc. (NYSE MKT: CUR) announced that its neural stem cells were part of a study, "Long-Distance Growth and Connectivity of Neural Stem Cells After Severe Spinal Cord Injury: Cell-Intrinsic Mechanisms Overcome Spinal Inhibition," published online today in a leading scientific journal CELL ( http://www.cell.com/current). In the study, rats with surgically transected spinal cords, which rendered them permanently and completely paraplegic, were transplanted with Neuralstem's spinal cord stem cells (NSI-566). The study reports that the animals recovered significant locomotor function, regaining movement in all lower extremity joints, and that the transplanted neural stem cells turned into neurons which grew a "remarkable" number of axons that extended for "very long distances" over 17 spinal segments, making connections both above and below the point of severance. These axons reached up to the cervical region (C4) and down to the lumbar region (L1). They also appeared to make reciprocal synaptic connectivity with the host rat spinal cord neurons in the gray matter for several segments below the injury.
Further study showed that re-transecting the spinal cord immediately above the graft abolished the functional gain, indicating that the regeneration of host axons into the human stem cell graft was responsible for the functional recovery. The cells that Neuralstem contributed to the study, NSI-566, are the same cells used in the recently completed Phase 1 clinical trial for the treatment of amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease). Neuralstem has also submitted an application to the FDA for a trial to treat chronic spinal cord injury with these cells.
"This study demonstrates that our neural stem cells can induce regeneration of injured spinal cord axons into the graft and serve as a bridge to reconnect to gray matter motor neurons for many spinal cord segments below the injury," said Karl Johe, PhD, Chairman of Neuralstem's Board of Directors and Chief Scientific Officer. "This is important in spinal cord injury because the nerve connections below the point of injury die, causing paralysis. Our cells built a bridge that received inputs from regenerating rat axons above the injury. They also sent out new human axons which made new synaptic connections with the host motor neurons in the gray matter below the injury. The fact that these cells induce regeneration of axons and partial recovery of motor function makes them relevant for testing for the treatment of human spinal cord injury."About the Study In a study of 12 rats, all 12 underwent complete spinal transections at vertebrae, T3. Six of these were subsequently transplanted with Neuralstem spinal cord stem cells (NSI-566) seven days after the injury. This group was assessed over the next seven weeks and compared to the control group, which had not received transplants. The transplanted rats exhibited significant locomotor recovery, regaining movement in all lower extremity joints. A majority of the grafted cells (57%) turned into neurons. From these, the study reported, a remarkable number of axons emerged, extending both above and below the point of spinal cord lesion. These axons expressed synaptic proteins in the host gray matter, which suggests they made synaptic contact with the host spinal neurons.