Researchers devising new treatment of spinal cord injuries

September 19th, 2008 - 4:26 pm ICT by IANS  

Washington, Sep 19 (IANS) Two groups of scientists are working on a new method to heal spinal cord injuries that may enable paralysis victims to make a recovery.The research by scientists from medical colleges of the Universities of Rochester and Colorado focuses on a major support cell in the central nervous system (CNS) called astrocytes.

When nerve fibres are injured in the spinal cord, their severed ends fail to regenerate and reconnect with the nervous system circuitry beyond the site of the injury.

During early development, astrocytes are highly supportive of nerve fibre growth, and scientists believe that if properly directed, these cells could play a key role in regenerating damaged nerves in the spinal cord.

The Rochester team, comprising biomedical geneticists Chris Proschel, Margot Mayer-Proschel and Mark Noble, rather than transplanting naive stem cells, adopted an approach of pre-differentiating stem cells into better defined populations of brain cells, reports Eurekalert.

These are then selected for their ability to promote recovery. Here glial restricted precursor (GRP) cells - a population of stem cells that can give rise to several different types of brain cell - were induced to make two different astrocyte sub-types, using different growth factors that promote cell formation during normal development.

Although these astrocytes are made from the same stem cell population, they apparently have very distinct characteristics and functions.

“These studies are particularly exciting in addressing two of the most significant challenges to the field of stem cell medicine - defining the optimal cell for repair and identifying means by which inadequately characterised stem cell approaches may actually cause harm,” said Noble, co-director of the New State Centre of Research Excellence in Spinal Cord Injury, a primary funder of the research.

Colorado research team comprising Stephen Davies and Jeannette Davies, transplanted the two types of astrocytes into the injured spinal cords of rats and found dramatically different outcomes.

One type of astrocyte was remarkably effective at promoting nerve regeneration and functional recovery, with transplanted animals showing very high levels of new cell growth and survival, as well as recovery of limb function.

However, the other type of astrocyte not only failed to promote nerve fibre regeneration or functional recovery but also caused neuropathic pain, a severe side effect that was not seen in rats treated with the beneficial astrocytes.

“To our knowledge, this is the first time that two distinct sub-types of astrocytic support cells generated, from a common stem cell-like precursor have been shown to have robustly different effects when transplanted into the injured adult nervous system,” said Mayer-Proschel.

“However by using the right astrocytes to repair spinal cord injuries we can have all the gains without the pain, while these other cell types appear to provide the opposite - pain but no gain,” said Stephen Davies.

These findings were published in the online version of Journal of Biology.

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