Sunday, July 20, 2008

Stem Cells Identified for Spinal-Cord Repair

A researcher at MIT’s Picower Institute for Learning and Memory has pinpointed stem cells within the spinal cord that, if persuaded to differentiate into more healing cells and fewer scarring cells following an injury, may lead to a new, non-surgical treatment for debilitating spinal-cord injuries.

The work, reported in the July issue of the journal PLoS (Public Library of Science) Biology, is by Konstantinos Meletis, a postdoctoral fellow at the Picower Institute, and colleagues at the Karolinska Institute in Sweden. Their results could lead to drugs that might restore some degree of mobility to the 30,000 people worldwide afflicted each year with spinal-cord injuries.

In a developing embryo, stem cells differentiate into all the specialized tissues of the body. In adults, stem cells act as a repair system, replenishing specialized cells, but also maintaining the normal turnover of regenerative organs such as blood, skin or intestinal tissues.

The tiny number of stem cells in the adult spinal cord proliferate slowly or rarely, and fail to promote regeneration on their own. But recent experiments show that these same cells, grown in the lab and returned to the injury site, can restore some function in paralyzed rodents and primates.

The researchers at MIT and the Karolinska Institute found that neural stem cells in the adult spinal cord are limited to a layer of cube- or column-shaped, cilia-covered cells called ependymal cells. These cells make up the thin membrane lining the inner-brain ventricles and the connecting central column of the spinal cord.

“We have been able to genetically mark this neural stem cell population and then follow their behavior,” Meletis said. “We find that these cells proliferate upon spinal cord injury, migrate toward the injury site and differentiate over several months.”

The study uncovers the molecular mechanism underlying the tantalizing results of the rodent and primate and goes one step further: By identifying for the first time where this subpopulation of cells is found, they pave a path toward manipulating them with drugs to boost their inborn ability to repair damaged nerve cells.

“The ependymal cells’ ability to turn into several different cell types upon injury makes them very interesting from an intervention aspect: Imagine if we could regulate the behavior of this stem cell population to repair damaged nerve cells,” Meletis said.

Upon injury, ependymal cells proliferate and migrate to the injured area, producing a mass of scar-forming cells, plus fewer cells called oligodendrocytes. The oligodendrocytes restore the myelin, or coating, on nerve cells’ long, slender, electrical impulse-carrying projections called axons. Myelin is like the layer of plastic insulation on an electrical wire; without it, nerve cells don’t function properly.

“The limited functional recovery typically associated with central nervous system injuries is in part due to the failure of severed axons to regrow and reconnect with their target cells in the peripheral nervous system that extends to our arms, hands, legs and feet,” Meletis said. “The function of axons that remain intact after injury in humans is often compromised without insulating sheaths of myelin.”

If scientists could genetically manipulate ependymal cells to produce more myelin and less scar tissue after a spinal cord injury, they could potentially avoid or reverse many of the debilitating effects of this type of injury, the researchers said.

Provided by MIT

Labels: , , , , , , ,

Read the Full Post!

Thursday, July 17, 2008

Allen Institute Releases Spinal Cord Map

Spinal cord injuries have long baffled doctors. Now the Allen Institute for Brain Science is doing for spinal research what they did for brain science - providing the first comprehensive road map of a mouse's spine.

"It's a groundbreaking project that tells us where each gene in the genome is turned on in cells in the spinal cord," Dr. Allan Jones, Allen Institute's Chief Scientific Officer, said in a news conference Thursday. "This is very important because the genes ultimately contribute to the specific biochemistry of a particular cell."

Jones says because mice share many of the same genes with humans, the implications are far-reaching.

"Researchers working on things like spinal muscular atrophy, degenerative disease like MS and Lou Gerhig's disease or ALS , also people who suffer from spinal cord injuries," he said.

The first 2,000 genes are available online now, with the full map of 20,000 genes to be completed by the end of the year. All the information is free to scientists and the public.

"It's sort of a virtual microscope that scientists can come and zoom in," said Jones. "It's like having the microscope slide right there in front of them."

"The comprehensive map of the genes of the spinal cord will be an incredible resource for scientists and researchers studying how the spinal cord is altered in disease or an injury, and more importantly it's going to give hope to really millions of Americans who suffer from spinal cord diseases and disorders," Sen. Patty Murray said at the news conference.

Said each day, 1,000 scientists have been accessing the Allen Brain Atlas Project, which went live in December of 2004 and was completed in 2006.

"Researchers have been using this to support all aspects of brain research," said Jones. "Just some examples: Alzheimer's, autism, bipolar, Down syndrome, Fragile X mental retardation, epilepsy, alcoholism, obesity, Parkinson's disease, sleep, hearing, memory, and more."

In December, Marine Corporal Jerold Mason was paralyzed in a car crash. These days he's grateful for the small things, like being able to listen to his I-Pod.

"It like takes you away from the stress. I will always use music to do that," he said.

Mason can now control his I-Pod with a straw. This one small step is inspiring him.

"Allows me to think of times when I did have the use of my arms, my legs and you know it makes me want to push harder," he said.

Thanks to the spinal cord map, researchers will be able to push harder, as well.

"It's all undiscovered new stuff. So they're a bit like a kid in a candy store in terms of the new data in the excitement of looking at it," said Jones.

Microsoft co-founder Paul Allen started the mapping project with $100 million in seed money. It's now grown to include other private, as well as public, funding.


Labels: ,

Read the Full Post!