Monday, 24 May 2004
Rats with spinal cord injuries regained 70% of their normal walking function with a three-part treatment aimed at regrowing nerve cells, researchers have shown.
The U.S. and Brazilian scientists grafted nerve cells, injected the rats with a special messenger molecule and an antidepressant to produce their results, which were published in the latest issue of the journal Nature Medicine.
The researchers said that their approach could one day have implications for treating human paralysis.
“[The research produced results] far greater than what we’ve seen in anything else,” said the principal researcher, Dr Mary Bartlett Bunge, from the University of Miami School of Medicine
“It opens up a potential new avenue of treatment for human spinal cord injury,” said Bunge, who declined to speculate when human trials might be attempted.
The spinal cord carries messages between the brain and the muscles through a network of nerve cells. When injury severs the network, chemical signals prevent those nerves from regrowing, resulting in paralysis.
So, regrowing nerve cells and reconnecting them has been the Holy Grail of spinal cord research.
The Miami study involved hundreds of animals with crushing injuries to the thoracic region of the spinal cord, which mainly causes loss of control of the legs.
The researchers transplanted cells known as Schwann cells from the peripheral nerves, where regeneration does occur, to create a bridge across the damaged area of the spinal cord and promote the growth of axons, the nerve fibres that transmit messages. Those cells also make the protective myelin sheath that insulates nerve fibres.
A triple approach
In earlier research, such grafts promoted the growth of new nerve fibres across and through the damaged areas of the spinal cord. But they stopped growing too soon.
So the researchers combined the grafts with two other treatments: injections of cyclic AMP, a messenger molecule that guides the nerve cells to grow their connecting fibres, and the antidepressant rolipram, which prevents the breakdown of cyclic AMP.
“The cyclic AMP hangs around longer and can be more effective,” Bunge said.
After eight weeks, the rats that did not receive the treatment could occasionally take a halting step but could not take one step after another, Bunge said.
Those that received the treatment had regained 70% of their walking function, “a striking improvement”, Bunge said. They could step consistently, and had better fine motor control and coordination.
“The hind limbs knew what the fore limbs were doing,” said Bunge.
The triple-treated animals also had more tissue in their spinal cords than those without the treatment, suggesting it had stopped the secondary tissue loss that normally occurs after a spinal cord injury, Bunge said.
And the triple-treated rats had a 500% increase in nerve fibres in the graft area, she said.
Commenting, Dr Naomi Kleitman, a program director for spinal cord injury research at the National Institute of Neurological Disorders and Stroke, said:
“Each of the pieces of the strategy have been hailed as ‘promising’ in earlier reports, but the behavioral effects were not huge. With the right combination, the sum is now proving to be much greater than the parts.”
Spinal injury and sport, Health Minutes News Radio 18 Aug 2003
Spinal cord injury, The Health Report Radio National 4 Dec 2000
Real hope for spinal cord injury, News in Science 27 Oct 1999
Health & Medical . Environment & Nature . Space & Astronomy . Ancient Worlds . Innovation & Technology . Archives