image:www..georgiapainphysicians.com
Megan Ogilvie
Health Reporter
A Toronto-led team of researchers has found a way to use stem cells derived from skin to treat spinal cord injuries in rats.
The finding lends promise to the idea that stem cells could one day be used to heal spinal cord injuries in humans, helping thousands of Canadians to walk again.
Injured rats injected with skin-derived stem cells regained mobility and had better walking co-ordination, according to the study published yesterday in the Journal of Neuroscience. The skin-derived stem cells, injected directly into the injured rats' spinal cords, were able to survive in their new location and set off a flurry of activity, helping to heal the cavity in the cord.
Freda Miller, a senior scientist at The Hospital for Sick Children and lead author of the study, said skin-derived stem cells have some advantages over other stem cell types. Scientists who use skin to generate stem cells do not need to use embryos, for example, and skin-derived stem cells can potentially be harvested from patients themselves, she said.
"You can imagine a scenario for people with spinal cord injuries, that maybe, just maybe, we could take a piece of their skin, grow the cells up and transplant them (the patient) with their own cells," she said. "You wouldn't have to give them immunosuppressive drugs. That's a tremendous clinical advantage if it comes true."
Miller and her colleagues from The Hospital for Sick Children and the University of British Columbia have been exploring the possibilities of using skin to derive stem cells since 2001.
Over the course of their research, the team found that skin-derived stem cells share characteristics with embryonic neural stem cells, which generate the nervous system. They also showed skin-derived stem cells can produce Schwann cells, a cell type that creates a good growth environment to repair injured central nervous system axons – the long nerve cell fibres that conduct electrical impulses between nerves – and that these Schwann cells put down myelin along the injured spinal cord. Like the insulation around an electrical cord, myelin wraps around nerves, creating a sheath that helps quickly conduct nerve impulses.
Miller said the next step was to see whether transplanting the Schwann cells directly into spinal cords would help treat injured rats.
To test their hypothesis, Miller and her team generated stem cells from the skin of rats and mice and forced them to differentiate into Schwann cells, which were then transplanted into the rats. After 12 weeks, the rats were able to walk better, with more co-ordination.
Miller said the cells thrived within the injured spinal cord. Before treatment, the injured rats had a cavity in their spinal cord, a result of their injury. But after treatment, Miller said the Schwann cells had created a bridge that spanned the cavity, and helped nerves grow through the bridge.
The next step is to see whether stem cells derived from human skin can produce similar results.
"We are highly encouraged," said Miller.
An Original artical from :
Embryonic stem cells (ESCs) have huge potential use for scientists because they have the ability to turn into many different forms of tissue. However, their use remains highly controversial.
Britain has allowed scientists to conduct embryonic stem cell experiments, but they could soon be banned by the European Union, and the US is still considering the issue.
New Scientist magazine reports that the US team harvested cells from human embryos at an early stage of development.
They then manipulated them in the laboratory to turn them into specialised cells that form myelin, the insulating layer than surrounds nerve fibres.
These cells were transplanted into paralysed rats with bruised spines.
After nine weeks, the rats fully regained the ability to walk.
Analysis of the rats' spinal cords showed that the cells had wrapped themselves around nerve cells and formed new myelin sheaths.
They also secreted substances that appeared to have stimulated the formation of new nerves.
Recent injuries
Dr Hans Keirstead and his team from the University of California at Irvine now plan to use the same technique to treat human patients who have sustained recent spinal cord injuries.
However, treating people who have been paralysed for years or suffer from degenerative nerve diseases will be far more difficult.
Scientists have tried using adult stem cells derived from bone marrow and nerve cells repair damaged spines.
But Thomas Okarma, of US biotech company Geron Corporation which funded the new research, believes only ESCs stand a real chance of success.
They are more versatile than adult stem cells, and, unlike them, can be mass-produced.
Mr Okarma said: 'At this moment, there is very little hard evidence that a bone marrow stem cell can turn into anything but blood or that a skin stem cell can become anything but skin.
