Identifcation Of Cells For Spinal-Cord Repair

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Identifcation Of Cells For Spinal-Cord Repair Could Lead To

Nonsurgical Treatment For Injuries

22 Jul 2008

http://www.medicalnewstoday.com/articles/115757.php

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.

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Article adapted by Medical News Today from original press release.

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This study was supported by grants from the Swedish Research Council,

the Swedish Cancer Society, the Foundation for Strategic Research, the

Karolinska Institute, EuroStemCell and the and Dana Reeve

Foundation.