Axons Regenerated In Adult Nerve Pathways In Rats

December 18, 1997

CLEVELAND, Ohio -- Neuroscientists from the Case Western Reserve University School of Medicine have shown that transplanted adult nerve cells can regenerate their axons in the adult rat brain's nerve fiber pathways, challenging long-held beliefs that this is impossible.

In their study, researchers found that nerve cells regenerated remarkably well and at relatively high rates of speed in 34 of 41 animals. Their paper is published in the December 18-25 issue of the journal Nature.

It is widely accepted that the adult mammalian central nervous system will not permit regeneration of nerve cell processes, called axons. In addition to physical or molecular barriers presented by scarring at a lesion site (such as a spinal cord injury), normal adult nerve pathways, which are insulated with white matter called the myelin sheath, are thought to be impenetrable to nerve regeneration. A 10-year old theory holds that the myelin sheath contains a type of cell which prohibits nerve regeneration.

Lead author Stephen J. A. Davies, a CWRU research associate, and colleagues removed dorsal root ganglion neurons from adult donor animals and then used a unique microtransplantation system to transplant them into the brain's nerve pathways of other adult animals. They witnessed rapid growth (1 millimeter per day) and saw that 80 percent of the cells were able to extend axon processes all the way into the brain's gray matter where they branched off in new directions, acting like normal nerve cells.

"These results were totally unexpected. There is a huge potential for regeneration in the adult white matter tracks of the central nervous system, at least with the nerve cells that we've used so far," said Jerry Silver, Ph.D., professor of neurosciences at CWRU and senior author of the study. "There's not a minimal potential. It's enormous."

The scientists believe that their method of transplantation played a key role in their results. Davies, a research associate in Silver's lab, developed the method, which introduces the nerve cells with little or no trauma to them or the host brain. The minimization of scarring may be important because the researchers found scar tissue around the transplanted cells in the study's seven animals that did not regenerate nerve cells. Within the scar tissue, they found a type of inhibitory molecule called chondroitin sulphate proteoglycan.

"In the failed transplants," said Davies, "every single regrowing axon had either stopped within the proteoglycan rich boundary or had actively turned away from the boundary and looped back into the transplant interior."

Silver said, "It gives great hope that regeneration might be possible, if we can learn how to breach the immediate vicinity of the lesion by building a bridge across that zone or breaking down the inhibitory scar molecules, we may get regeneration beyond what we ever dreamed possible."

Other authors on the study are M.T. Fitch, S.P. Memberg, and A.K. Hall of the Department of Neurosciences at CWRU's School of Medicine; and G. Raisman of the Norma and Sadi Lee Research Centre in the National Institute for Medical Research's Division of Neurobiology in London. Davies is also affiliated with this research center.

The research is funded by the International Spinal Research Trust, David Heumann Fund, Brumagin Memorial Fund, and the National Institutes of Health.
-end-


Case Western Reserve University

Related Nerve Cells Articles from Brightsurf:

Nerve cells let others "listen in"
How many ''listeners'' a nerve cell has in the brain is strictly regulated.

Nerve cells with energy saving program
Thanks to a metabolic adjustment, the cells can remain functional despite damage to the mitochondria.

Why developing nerve cells can take a wrong turn
Loss of ubiquitin-conjugating enzyme leads to impediment in growth of nerve cells / Link found between cellular machineries of protein degradation and regulation of the epigenetic landscape in human embryonic stem cells

Unique fingerprint: What makes nerve cells unmistakable?
Protein variations that result from the process of alternative splicing control the identity and function of nerve cells in the brain.

Ragweed compounds could protect nerve cells from Alzheimer's
As spring arrives in the northern hemisphere, many people are cursing ragweed, a primary culprit in seasonal allergies.

Fooling nerve cells into acting normal
In a new study, scientists at the University of Missouri have discovered that a neuron's own electrical signal, or voltage, can indicate whether the neuron is functioning normally.

How nerve cells control misfolded proteins
Researchers have identified a protein complex that marks misfolded proteins, stops them from interacting with other proteins in the cell and directs them towards disposal.

The development of brain stem cells into new nerve cells and why this can lead to cancer
Stem cells are true Jacks-of-all-trades of our bodies, as they can turn into the many different cell types of all organs.

Research confirms nerve cells made from skin cells are a valid lab model for studying disease
Researchers from the Salk Institute, along with collaborators at Stanford University and Baylor College of Medicine, have shown that cells from mice that have been induced to grow into nerve cells using a previously published method have molecular signatures matching neurons that developed naturally in the brain.

Bees can count with just four nerve cells in their brains
Bees can solve seemingly clever counting tasks with very small numbers of nerve cells in their brains, according to researchers at Queen Mary University of London.

Read More: Nerve Cells News and Nerve Cells Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.