Stroke stem cell trial extended

The world’s first clinical trial of brain stem cells to treat stroke has recorded no adverse effects to date, BBC News has reported. The BBC website reports that research using stem cells to treat strokes “is set to move to its next phase” after independent assessors approved continuation of the trial of the experimental treatment. So far the therapy has been tested on three patients left disabled by strokes.

The ongoing PISCES study (Pilot Investigation of Stem Cells in Stroke) is being performed by the University of Glasgow in collaboration with a company called ReNeuron. It has been given independent clearance to progress by the Data Safety Monitoring Board, and will now test higher doses of a stem cell therapy called ReN001 in a further nine patients. The PISCES study is a phase I trial that is intended primarily to test the safety and tolerability of ReN001 rather than how effectively it repairs stroke damage.

If the results of this next phase are positive, researchers will design and perform further trials looking at the effectiveness of the treatment.

What exactly is a stroke?

A stroke is a serious medical condition that occurs when blood supply to the brain is disrupted, leading to the loss or reduction of brain functions. There are two types of stroke. Ischaemic stroke is when blood supply to the brain is cut off due to a blockage and haemorrhagic stroke is where there is a leakage of blood in the brain due to a blood vessel bursting. Approximately 80% of strokes are ischaemic strokes.

The disruption of the blood supply to the brain can starve brain cells of oxygen, causing them to die. It is not uncommon to see large areas of dead and damaged tissue when brain scans are performed on people who have had a stroke. Depending on the part of the brain affected, people who have had a stroke may experience difficulty with speech and language, orientation and movement, or memory. These problems can be permanent or temporary.

Annually in England and Wales, 130,000 people experience a stroke, and there are 60,000 deaths due to stroke. Stroke is the leading cause of adult disability.

How might stem cells help?

Stem cells have the ability to form different specialised cell types and to renew themselves to form further new stem cells. There is currently a great deal of medical research looking at the potential for stem cells to repair damaged tissue and fight disease. This is based on the idea that stem cells could be used to produce appropriate cells to repair or replace the damaged tissue.

In this particular instance it is thought that introducing neural stem cells into the brains of patients who have been affected by strokes might repair the damage seen and improve mental and physical functioning. The neural stem cells used in this study (ReN001) have been found to be effective in initial tests of pre-clinical models, although they will need to undergo further assessment to confirm whether or not they are effective in humans.

What did the trial look at?

This was an initial safety test of using ReN001 neural stem cells in three patients who had been left disabled after an ischaemic stroke. The three different patients had either been treated three, six or nine months prior to this follow-up assessment. Rather than testing how effectively the stem cells might improve their disability this phase 1 trial was designed to look at whether use of the experimental treatment was safe and tolerable. This type of safety trial is intended to precede tests of effectiveness. As such, treatments are often applied at low dosages and in small numbers of people.

Following this stage in the phase I trial it is reported that higher doses of ReN001 will be given to a further nine patients, so that the safety and tolerability of ReN001 can be assessed further.

What results did it have?

Laboratory safety tests, neurological examinations and tests of brain function (movement, sensation and cognition) have been conducted and have found that the ReN001 treatment is safe and well-tolerated at the initial dose. It is worth bearing in mind that these positive results are only from three patients given low-dose treatment, so they may not be typical of the results that would be seen if larger groups of patients were tested.

What happens next?

The Data Safety Monitoring Board has reviewed the data from the first three patients and has allowed the phase I trial to continue. ReN001 will now be given at a higher dose. The company involved in the trial, ReNeuron, expects that a further three patients will be treated this year, and the remaining six patients in 2012. Depending on the results of this trial, they will then proceed with further trials.

What are the signs of a stroke?

The symptoms of stroke can vary from person to person but they usually begin suddenly. There are key warning signs that could signal that someone has had a stroke:

• Face. Their face may have fallen on one side. The person may not be able to smile, or their mouth or eye may have drooped.
• Arms. A person with suspected stroke may not be able to raise both arms and keep them there because of arm weakness or numbness.
• Speech. Their speech may be slurred.

If you suspect that you or someone else is having a stroke, you must phone 999 immediately and ask for an ambulance.

Read our Stroke: Act F.A.S.T. section for further information.