Bone marrow converted into rare brain tissue
Adult stem cells from bone marrow have been successfully converted into a type of brain tissue lacking in multiple sclerosis sufferers for the first time, Australian scientists have announced.
Researchers at St Vincent's Hospital in Sydney told a press conference on Tuesday they had used stem cells from bone marrow to create the white matter-forming cells in the brain - offering the potential to eliminate some of the effects of multiple sclerosis (MS) and other similar brain diseases.
"These are early days, but it is an important piece of the puzzle," said Professor Bruce Brew, a neurologist who led the study. "The data are preliminary but convincing."
The group harvested stem cells from the bone marrow of mice and humans, then inserted them into the brains of mice with a disease that closely resembles MS in humans. They found that the stem cells changed into several different kinds of cells: most importantly, many converted into cells called oligodendrocytes, which manufacture 'white matter'.
Brains are made up of white matter and grey matter regions: white matter handles communication between brain cells, as well as transmission of impulses to the rest of the body. White matter contains bundles of nerve fibres sheathed in a white fatty insulating protein called myelin.
The neurones of MS sufferers are low in myelin, and messages don't travel as effectively between them - causing many of the disabilities associated with the disease. Scientists hope that boosting oligodendrocyte numbers in the brain of MS sufferers might reverse the loss of myelin.
But the experiments suggest only areas of fresh damage might be treatable. In the mice tested, the damage appeared to trigger the stem cells to turn into oligodendrocytes. If the process can be repeated in humans, only those diagnosed with MS - but where the disease has not advanced greatly - are likely to benefit.
"One scenario which is reasonably likely is the patient with MS in some years to come who will be stable in their deficit [of white matter cells], the result of a white matter damage in the past," Brew told reporters.
"They would then have their own stem cells isolated from bone marrow. These would then be cultured, and injected either intravenously or be introduced into the area, if it was large enough in the brain, to repair some of that damage," he said.
"It means that deficits will be minimised, physically and mentally," Brew added. "There is no guarantee that deficits will be able to be completely reversed, but there is a very good likelihood that in years to come that deficits - as a result of white matter damage in MS patients - will be able to be treated, at least partially."
Until now, scientists had been unable to produce oligodendrocytes, although other groups have successfully created neurones from stem cells. Brew has presented early data on the research at two recent scientific symposiums in Sydney, and the work is being submitted to the European Journal of Neuroscience for publication.
Bone marrow cells can migrate
In related research published in today's issue of the journal, Proceedings of the National Academy of Sciences, American researchers have found stem cells from transplanted bone marrow ended up in the brains of the transplant recipients.
Studying the brains of four deceased females who had received a bone marrow transplant from a male donor, the researchers at the National Institutes of Health in Bethesda, Maryland, USA, isolated brain cells that contained Y chromosomes. Y chromosomes only appear in male cells.
This suggests that adult human bone marrow cells have the capacity to find their into the brain and convert into neurones.
Earlier studies had suggested bone marrow stem cells could develop into neurones when inserted in the brain. This is the first time that this has been seen in patients of bone marrow transplants, suggesting the cells can migrate to the brain and convert on their own.