Ischemic Spastic Paraplegia (ISP) is a painful form of extreme spasticity and rigidity, or muscle control failure in the lower limbs, which causes a permanent and untreatable loss of motor function and paralysis. In humans, ISP can result from surgery to repair aortic aneurysms, an operation that is performed on thousands of patients a year in the U.S.
During a surgical process called aortic cross-clamping, blood flow from the heart must be temporarily blocked with a clamp when repairing the aneurysms. The death of specialized spinal cord neurons called spinal inhibitory neurons can result due to this lack of blood flow.
Researchers from the University of California, San Diego (UCSD) School of Medicine report that rats paralyzed due to a loss of blood flow to the spine returned to near normal ambulatory function 6 weeks after receiving grafts of human spinal stem cells (hSSCs).
“We demonstrated that when damage has occurred due to a loss of blood flow to the spine’s neural cells, by grafting human neural stem cells directly into the spinal cord we can achieve a progressive recovery of motor function,” said Martin Marsala, MD, UCSD professor of anesthesiology. “This could some day prove to be an effective treatment for patients suffering from the same kind of ischemia-induced paralysis.”
For this study, nine of 16 rats with induced spinal cord ischemia were injected with human spinal stem cells 21 days after paralysis. The other seven were injected with a medium that contained no stem cells. The recovery of motor function was evaluated in 7?day intervals, showing a progressive recovery of ambulatory functions in the rats that received stem cells.
Three of the nine rats injected with hSSCs returned to walking at 6 weeks, and three others had improved mobility in all lower extremity joints. All nine animals grafted with hSSCs achieved significantly better motor scores than those in the control group, and showed a consistent presence of transplanted cells in the spinal area. In all the rats grafted with the stem cells, the majority of transplanted human spinal stem cells survived and became mature neurons, according to Marsala. A second study was conducted over a 3-month period with similar results.
It is important to note the difference between spinal cord ischemia and spinal cord trauma. In the ischemia model no mechanical damage has occurred to the spinal cord as could be the case in a diving or car accident. This research aims to replace lost neurons by grafting new spinal stem cells, which repopulates the pool of degenerated neurons.
Marsala is currently testing the human stem cell therapy for safety and efficacy in other animal models, and hopes to move to clinical trials in humans by 2008.
Illustration: MicroSoft clipart.
PR Newswire (05/30/07)
UCSD News (05/31/07)
Biology News (05/31/07)
United Press International (05/31/07)
Best Syndication (06/01/07)
Medical News Today (06/06/07)