A nose job for the spinal cord
Putting some pig in the middle of a severed spinal cord may be a means of enhancing repair of central nervous system injuries. Long-thought unthinkable, new data reported in this issue Nature Biotechnology (Vol 18, No. 9, September 2000) suggest that cells from the snout of pigs engineered to avoid immunological responses can enhance the repair of, and restore function to, severed spinal cords in mice.
Any attempts to transplant organs from one species to another encounter problems with immune rejection of the foreign antigens on the donor organ. Jeffery Kocsis and his colleagues have got around this by engineering pig cells to express a protein-human complement inhibitory protein (hCD59)-that suppresses immune rejection responses. They found their donor cells by looking in a most unusual location-the snout of a pig. This is a relatively accessible source of useful quantities of nerve fiber-ensheathing cells: olfactory ensheathing cells (OECs) and Schwann cells.
When transplanted into rats that had had their spinal cords severed, engineered pig cells facilitated regeneration of rat nerves, formed new myelin (the substance the insulates nerve fibers), and restored the relay of nerve signals up and down the severed spinal cords of 7 of 10 treated rats. Nerve fiber growth occurred at a typical rate of 1mm/day, and the regenerated nerves actually conducted impulses faster than normal nerves.
The authors speculate that transformed pig cells could soon be used for the same purpose in humans-to regenerate spinal cord nerves without eliciting immunological rejection. However, the study is still preliminary and many question marks remain over the safety of xenotransplants for humans, given concerns with the potential transmission of infectious viral agents.
Dr. Jeffery D. Kocsis
Yale University School of Medicine
Neuroscience Research Center (127A)
West Haven, CT 06516
Telephone #: 203.937.3802
Fax #: 203.937.3801
Contact (news & views)
Professor Lars Olson
Department of Neuroscience
Division for Development, Growth Factors and Transplantation
Berzelius väg 1, Solna
Karolinska Institutet, 171 77 Stockholm, Sweden
Tel: +46 8 08-728 70 50
(C) Nature Biotechnology press release.
Message posted by: Trevor M. D'Souza