The method uses a combination of transplantation and gene therapy. For the transplantation, the researchers implanted nerve cells cultured in vitro. The cells originated from the nerves between the ribs where they could be missed. Following the transplantation gene therapy has to further stimulate the growth and recovery of the damaged nerve cells. This is done by means of growth stimulating molecules. These neurotrophic factors are naturally present during, for example, the recovery of nerves following a deep cut in the finger. Normally they are not present in large enough quantities in the spinal cord. Over the next few years the researchers will try to improve their therapy. PhD student Bas Blits will continue his research (with sponsorship from the Netherlands Organisation for Scientific Research) at the University of Miami, where he will also attempt to implant stem cells instead of the used nerve cells from the fore rib.
The researchers attempted to repair three sorts of spinal cord damage in rats. The first, the dorsal, partial hemisection is comparable to a knife stab in the back in humans. The two most important neural tracts for voluntary movement are severed. In both humans and rats the result is a paralysed lower body. In rats the result is partially paralysed rear legs. After therapy the rat's walking improved. It appeared that one of the two neural tracts slowly recovered.
The second spinal cord lesion examined by the researchers was the complete transection at the height of the eighth vertebra. The spinal cord is completely severed, comparable in humans to a spinal cord lesion after a violent knife stab in the rib area. Also, this type results in paralysis in the lower part of the body. After the therapy the rat could make some movement with his hind limbs. The scientists are still trying to clarify this because anatomical investigation demonstrated that there was no recovery of the spinal cord lesion.
The third type of damage was ventral root avulsion. In this model the outgoing nerve fibre is torn lose from the spinal cord, for example during a serious motorbike accident. This damage often results in the dying of the affected motor neurones. These are large nerve cells which control movement. After the administration of growth stimulating substances, it appeared that the motor neurones did not die but neither did they regenerate and recover.
For further information please contact Bas Blits (Department of Neuroregeneration, Netherlands Institute for Brain Research (NIH) and from March 2002 onwards at The Miami Project to Cure Paralysis, University of Miami, United States), tel. +31 (0)20 5665512 (direct line) or +31 (0)20 5665500 (reception), fax +31 (0)20 6961006, e-mail: firstname.lastname@example.org
The defence of the doctoral thesis will take place on 26 February 2002 at the Free University of Amsterdam (VU). Mr Blits' supervisors are Prof. Joost Verhaagen (NIH/VU) and Prof. Dick F. Swaab (NIH/University of Amsterdam).
The research was funded by the Netherlands Organisation for Scientific Research (NWO).