A study in Nature Medicine, by the Memorial Sloan-Kettering Cancer Centre Team, has reported the successful treatment of mice with Parkinson's disease using 'therapeutic cloning', giving hope that one day a similar treatment could treat people with the condition.
In an important 'proof of concept' study for using genetically-matched stem cell to replace diseased tissue, the mice were treated with dopamine-producing neurons derived from their own cells, which replaced the missing nerve cells affected in Parkinson's.
The team, including Viviane Tabar, initially created a Parkinson's like disease in mice using chemicals to destroy their brain cells. They then took normal cells from the tails of the mice, removing the nucleus of the cell and transferred it to a mouse egg cell that had had its own nucleus removed. This effectively cloned the mouse cells, and after a few days embryonic stem cells (ES cells) were harvested from the resulting embryos.
ES cells can grow into any cell in the body, and the team developed the cells into dopamine-producing neurons. In Parkinson's disease, dopamine-producing nerve cells in the brain, which allow regulated function and movement of muscles, either die or malfunction. When the dopamine-producing cells were injected into the brains of the mice with Parkinson's, they showed signs of recovery over the next 11 weeks of the study.
The procedure was found to be much more effective in mice when using the mouse's own cloned cells, than when using cells cloned from another mouse. Dr Tabar emphasised how difficult the procedure was, but also said that the results, 'demonstrated what we suspected all along - that genetically matched tissue works better'. The fact that the cells were cloned from the mouse they were re-introduced to prevented rejection by the immune system.
Dr Kieran Breen, director of research and development at the Parkinson's Disease Society said, 'this is an exciting development, as for the first time, we can see that it may be possible to create a person's own embryonic stem cells to potentially treat their Parkinson's'.
Lorenz Studer, who led the research team, warned that it was too early to say whether the technique could be applied to humans, but allowed that it was 'proof of concept'. Human ES cell lines have not yet been created by the cloning method used in the study. As existing human ES cell lines are in short supply, the number of patients that potentially could be treated should a therapy be developed, would be limited at present.
Sources and References
Therapeutic cloning used to treat brain disease