Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers find molecule that inhibits regrowth of spinal nerve cells

12.07.2005


A molecule that helps the body’s motor nerve cells grow along proper paths during embryonic development also plays a major role in inhibiting spinal-cord neurons from regenerating after injury, researchers at UT Southwestern Medical Center have found. In cultured cells, the researchers found that a component of myelin – a substance that normally insulates and stabilizes long nerve fibers in adult vertebrates – chemically blocks the ability of nerve cells to grow through myelin that is released when the spinal cord is damaged. While other myelin components also block nerve growth, a component called ephrin-B3 inhibits such activity as well or better than that of other known blocking agents combined, UT Southwestern researchers report in an upcoming issue of the Proceedings of the National Academy of Sciences.



"I believe that to the extent that overcoming myelin-based inhibition is going to provide some sort of functional recovery for spinal cord injury patients, understanding ephrins is a major step forward," said Dr. Luis Parada, senior author on the paper and director of the Center for Developmental Biology and the Kent Waldrep Center for Basic Research on Nerve Growth and Regeneration at UT Southwestern. A mixture of molecules and proteins, myelin insulates nerve fibers and impedes them from having contact with other nerve cells. After a spinal-cord injury, myelin is released into the tissues. Not only does myelin encourage the growth of scars – called glial scars – which physically block nerve cells from regrowing in the damaged area, but components of myelin also chemically prevent nerve cells from regrowing there as well.

Considerable research has been done in the past 10 years to identify elements in myelin that chemically inhibit the regeneration of nerve cells, Dr. Parada said. Three individual components – the molecules Nogo, MAG and OMgp – have been shown to do so in isolation. Developmental biologists at UT Southwestern have been studying how ephrin-B3 helps control how and where nerve fibers grow during early development. They previously showed that the molecule throws up "fences" that repel developing nerves and guide them along the pathways to their appropriate connections to muscles.


In 2002 Dr. Mark Henkemeyer, associate professor in the Center for Developmental Biology and of cell biology and one of the authors of the PNAS study, found that such a "fence" is erected specifically down the middle of the cortical spinal tract, which is damaged during spinal-cord injury.

In the current study, Dr. Parada and his colleagues asked: What is this molecule, whose normal function is to be repellent during embryonic development, doing in the mature system?

"To our surprise, we found that ephrin-B3, which normally is present as a ’wall’ down the middle of adult spinal cords, also is found in very high levels in adult myelin," said Dr. Parada.

The researchers knew from previous work that ephrin-B3 interacts with receptors on neurons in the cortical spinal cord. So, in the lab, led by the study’s lead author Dr. M. Douglas Benson, a postdoctoral research fellow, they cultured neurons together with isolated ephrin-B3 and confirmed that the molecule activated the neuron’s receptors. They then cultured normal myelin together with the neurons and got the same results.

However, when they cultured neurons with myelin from which the ephrin-B3 had been removed, the receptors were not activated. The findings suggest that there is much more to be learned about myelin-based inhibition, Dr. Parada said. "We firmly believe that ephrin-B3 is an important, functional, relevant component of myelin, although there may be other elements that are left to be discovered," he said.

Dr. Parada added that several factors must be overcome before spinal-cord regeneration and recovery from injury can occur in a meaningful way for patients.

"We have to figure out how to dissolve the glial scars or impede their formation," he said. "We also need to get mature neurons to be better at growing, similar to the way they do during embryonic development. And finally, we have to remove myelin-based inhibition. If and when we achieve those three things, then we’ll have robust regeneration of injured nerves."

Other Center for Developmental Biology researchers involved with the study were Dr. Mark Lush, postdoctoral research fellow, and Dr. Q. Richard Lu, assistant professor. Dr. Mario Romero, assistant professor of neurology, also contributed.

Amanda Siegfried | EurekAlert!
Further information:
http://www.utsouthwestern.edu

More articles from Life Sciences:

nachricht Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>