Stem cells could repair Parkinson's damage
"Stem cells can be used to heal the damage in the brain caused by Parkinson's disease," BBC News reports following the results of new Swedish research in rats.
This study saw researchers transplant stem cells into rats' brains. These cells then developed into dopamine-producing brain cells.
Parkinson's disease is a neurological condition associated with the loss of dopamine-producing brain cells. This leads to the symptoms characteristic of the condition, such as tremor, stiff, rigid muscles, and slow movements.
Parkinson's is currently treated with medication that attempts to compensate for the loss of these cells, but it cannot replace them.
This new research demonstrated it may be possible to use stem cell-derived dopamine nerve cells to treat the condition, giving long-term functional results.
Up to six months after the cells were grafted into the brains of the rats, brain scans and functional tests showed the transplanted cells had proliferated and matured, reinnervated the brain tissue, and were producing dopamine.
The next step would to be to try to follow on from this research with clinical trials in humans.
Where did the story come from?
The study was carried out by researchers from Lund University in Sweden and other research institutions in France.
The research and individual authors received various sources of financial support, including the European Community's 7th Framework Programme.
The study was published in the peer-reviewed journal, Cell Stem Cell on an open access basis, so it is free to read online.
Both BBC News and ITV News gave a good representation of the research.
What kind of research was this?
In this laboratory study, researchers aimed to produce dopamine neurones (nerve cells) from human embryonic stem cells and graft these into a rat model of Parkinson's disease. They wanted to see if this had the potential to be used as a treatment for the disease.
Parkinson's is a neurological disease with an unknown cause, which sees a loss of the nerve cells in the brain that produce the chemical dopamine.
Loss of dopamine causes the three classic Parkinson's symptoms of tremor, stiff, rigid muscles and slow movements, as well as a range of other effects, including dementia and depression. There is no cure, and current drugs aim to try to control symptoms by treating this dopamine imbalance.
Human embryonic stem cells have the potential to develop into any type of cell in the body. Using these stem cells to replace dopamine nerve cells seems a promising area for research, and this study is the first step in investigating whether this type of treatment could one day be possible.
What did the research involve?
The researchers developed dopamine nerve cells from human embryonic stem cells (hESC) in the laboratory.
They then needed to see whether these cells would survive and function in the long term when grafted into brain tissue.
They transplanted these hESC-derived dopamine neurones into a rat model of Parkinson's disease, where the rats' brains were injected with a toxin to stop dopamine production.
The researchers followed the rats for six months after the cells were transplanted into their brains, carrying out various brain scans and tissue examinations to see how the cells had developed and were functioning.
They then carried out a behavioural test in the rats to see whether the transplanted cells had caused a recovery of their motor function (movement).
What were the basic results?
One to five months after the hESC-derived dopamine neurones had been grafted into the brains of the rats, MRI scans showed the transplanted cells had increased in volume, indicating that they were proliferating and maturing.
Further imaging was carried out using PET scans to detect a radiolabeled chemical marker that targets dopamine receptors.
Before grafting, the brains of the Parkinson's rats demonstrated a high level of binding of this chemical to the dopamine receptors, indicating that dopamine was lacking and that this marker was taking dopamine's place in the receptors.
Five months after grafting, binding of this chemical was reduced to normal levels, which indicated there was an active release of dopamine from the transplanted cells and dopamine was therefore now binding to these receptors.
Examination of the rats' brain tissue confirmed these imaging findings, showing that the tissue was rich in dopamine neurones and that the transplanted cells had reinnervated the brain tissue.
The behavioural test also gave positive results, indicating that the transplanted hESC-derived dopamine neurones led to functional motor recovery in the rats.
How did the researchers interpret the results?
The researchers concluded they have "performed a comprehensive preclinical validation of hESC-derived [dopamine] neurons that fully supports their functional efficacy and capacity for long-distance, target-specific reinnervation, predictive of their therapeutic potential".
Conclusion
This is promising early-stage research that demonstrates it is possible to manufacture dopamine-producing nerve cells from human embryonic stem cells in the laboratory.
The cells were then transplanted into a rat model of Parkinson's disease (the rats were given a toxin that destroyed their dopamine-producing cells).
Up to six months after the cell transplant, brain scans and functional tests showed that the transplanted cells had proliferated and matured, reinnervated the brain tissue, and were producing dopamine.
The next step is to follow on from this research with the first clinical trials in humans. The researchers say they hope they will be ready for the first clinical trial in about three years' time.
But there are several technical obstacles that need to be overcome first. Although the results indicate the transplanted cells were functioning well in the rat model at five months, as the researchers say, it is important to verify that these functional effects are robust and stable over significantly longer time periods.
Also, the rat brain is much smaller than the human brain. It would therefore need to be demonstrated that the transplanted cells have the capacity to grow nerve fibres that can reinnervate distances relevant to the size of the human brain.
This research holds promise for a future stem cell treatment that could restore the dopamine-producing nerve cells lost in people with Parkinson's disease. The next stages in this research are awaited eagerly.
