Marc Tessier-Lavigne
Training nerve cells to mend a damaged spine
A lab rat with an injured spinal cord may soon be able to run again. And with the lessons learned from that experiment, hopes have never been higher that researchers will one day be able to give mobility back to human victims, paralyzed because spinal cord injury prevents the brain from communicating with the body.
Leading the way in this research is Marc Tessier-Lavigne, a neuroscientist and head of the Center for Brain Development being established at the University of California-San Francisco.
Growing up in England and Belgium, where his father worked as a NATO civil servant, Tessier-Lavigne fell in love with mathematics but longed to connect its structural beauty to the practical world. Studies in philosophy and physiology sparked his interest in investigating the complex circuitry of the brain. "I was lured in by the hope of applying mathematical tools to biology and got captivated by the biology itself," he says.
Navigators. Twelve years ago, while doing research at Columbia University, Tessier-Lavigne uncovered clues to a key element of nervous system construction. He proved that axons, the long, tubelike carriers of messages from nerve cells to target cells, are guided to the targets by molecules called chemoattractants. "These chemicals are like signposts," Tessier-Lavigne says. "It really is like a sign that says, 'This way to San Francisco Airport,' and depending on who you are and where you want to go, you will decide whether or not to go that way."
In 1994, after transferring to UCSF, Tessier-Lavigne made another major find: identifying a family of chemoattractants he named netrins (after the Sanskrit word for guide) in the spinal cords of vertebrates. Tessier-Lavigne and other researchers now think that netrins can be used to coax healthy nerves into injured areas. At the University of Florida-Gainesville, for instance, scientists have induced nerve regeneration in the injured spinal cords of rats by grafting in cells that had been engineered to produce netrins. Further studies are ongoing to determine whether the netrins actually caused the nerve growth.
But bridging the gap isn't that simple. Other molecules present in the body, called chemorepellents, appear to prevent nerve regrowth. Scientists at McGill University are trying to outflank the repellents with a vaccine. Still, the success with netrins in animals shows "we are on the right track," Tessier-Lavigne says. How long until there's a cure in hand? "It depends on how forgiving nature is," he says. If the regenerating axons can find their own way back to the right targets, "it could be less than a decade." If scientists will have to intervene in guidance as well, it will take longer. Either way, Tessier-Lavigne says: "There is cause for optimism."
This story appears in the January 3, 2000 print edition of U.S. News & World Report.
advertisement
