Fifteen years may seem like plenty of time to realise this dream, but there are so many contingencies that even he admits this may be optimistic. “It assumes that all our clinical trials go smoothly, that industry takes up the technology – and that ‘stem cell tourism’ doesn’t set us back,” he said.
It’s not difficult to understand why people resort to stem cell tourism – going abroad, usually to countries such as India and China, to receive private, unregulated stem cell therapies (however experimental) to treat incurable conditions such as Parkinson’s or multiple sclerosis. There has been much hype surrounding stem cells and, with nothing to lose, isn’t it worth at least trying one of these treatments? The trouble is that they are based on very limited – if any – evidence and have the potential “to go pear-shaped”, said Barker. This could damage public – and, more importantly, regulators’ – confidence in the field and lead to inappropriate restrictions on legitimate research.
The idea of cell transplants to treat Parkinson’s is not new. One of the key characteristics of the disease, which affects around one in 800 people by the time they are elderly, is the death of dopamine-producing cells in the brain. Finding a way to replace these cells could, in theory, lead to dramatic improvements in the patient’s health.
An adult typically has around half a million dopamine cells in the substantia nigra on each side of the brain. When half of these cells have died, the patient will begin showing symptoms, which include a resting tremor, slowness of movement and rigidity. “One of the reasons Parkinson’s disease is so attractive for cell therapies,” explained Barker, “is that it is a tractable problem. If we can get just 100,000 proper nigral dopamine cells in there, it should make a difference.”
Ever since the 1980s, scientists have been trialling ways of replacing dopamine cells with cells taken from aborted fetuses – a practice which, aside from ethical concerns, is not practical on a scale needed to treat the hundreds of thousands of patients in the UK alone.
The trials had mixed success. In some, patients continued to see improvements over 15 years; however, in others, the treatment not only failed, but patients suffered side effects. In part, this was due to an inconsistency in protocols, for example the age of participants, the clinical techniques used for cell delivery and the number of cells transplanted.
Now, with funding from the European Union, Barker and collaborators in Europe have developed a protocol that is more likely to provide safe, consistent and clinically effective benefits for patients. He is leading a trial in Europe to use fetal cells to treat patients, with the aim of “putting cell therapies for Parkinson’s disease back on the map.”
If the trial is successful, by 2018 the researchers hope to begin trialling the use of dopamine cells derived from embryonic stem cells through a new collaboration with teams across Europe, the USA and Japan. (The collaborators in Japan hope to conduct a similar trial using induced pluripotent stem cells – the patients’ own skin cells, reprogrammed to become stem cells.)
Reproduced courtesy of the University of Cambridge
Image:
Taking a shot
Credit: The District