Research suggest brain cells may come back after damage from multiple sclerosis

Posted by Brie Zeltner August 05, 2008 15:43PM

Brain cells in areas targeted by multiple sclerosis may regenerate - often years after the initial injury, according to research by a team of Cleveland Clinic neuroscientists.

The finding, published online today, lends further support for the concept of adult neurogenesis -- that the human brain can regenerate itself, and in the case of MS, is working to repair itself.

Multiple sclerosis is a chronic disease in which the immune system begins to attack the fatty protective barrier around nerve fibers in the central nervous system. When that area, known as the myelin, is destroyed, the impulses traveling along those pathways from the brain or spinal cord can be slowed, distorted, or cut off completely if the nerve itself is injured.

The researchers examined the brains of nine multiple sclerosis patients who donated their organs after death in the hopes of furthering research on the disease,

"The brain is continuously trying to replace what has been destroyed -- not just myelin, but also neurons," said Bruce Trapp, one of the lead authors on the paper and chair of neurosciences at the Lerner Research Institute.

Trapp think the biggest impact of the paper will be just that -- that there is evidence of the neurogenesis in this area of the brain. Many scientists have resisted the increasing amount of evidence that shows regeneration of neurons in other areas of the brain, like the hippocampus, because of a long-held belief that the brain cannot regenerate. In short, you're stuck with what you've got.

"It's a controversial area, and it's something that's very difficult to prove," said Trapp.

Trapp and his team went looking for old MS lesions in the brains they examined, and wanted to know what happened to the neurons in those areas. They weren't surprised that many of them were destroyed, probably as "bystanders" when the myelin was attacked.

"But then we were shocked when we saw areas of old lesions, and these lesions can be decades old, that had very high concentrations of neurons," Trapp said. In one quarter of the lesions they looked at, there was a 72 percent increase in density of interneurons, which are the neurons that communicate locally.

The question of whether a motor neuron, which communicates over a long distance, could regenerate is still an unanswered question.

Trapp's team was able to count the neurons because the white matter is relatively neuron-poor compared to the rest of the brain. They were also able to show that the neurons had made connections to each other through synapses.

But, Trapp doesn't know if the neurons he saw were capable of communicating with one another or were functional.