Wednesday November 17 2010
Strokes are usually diagnosed by studying images of the brain
In a world first, a British man has had stem cells injected into his brain to repair the damage caused by stroke. Many newspapers reported this clinical trial, which is designed to test the safety of a new therapy for stroke damage.
The main purpose of this early experimental trial is to test the safety of a new stem cell therapy for the treatment of ischaemic stroke.
The stroke survivor reported in the newspapers was the first to receive the therapy in the trial and, should it pass review in a month’s time, another 11 stroke survivors will be given the treatment. The patients will be followed for at least two years. The researchers will also evaluate the treatment’s effectiveness and whether it has any affect on function and disability after stroke.
As reported, this is a world first and a newsworthy development. The stem cell treatment’s effectiveness at reversing the damage caused by stroke will probably not be known for some time.
What is the aim of the trial?
This is the world’s first fully regulated clinical trial of neural stem cell therapy for disabled stroke patients. Called the Pilot Investigation of Stem Cells in Stroke (PISCES), it is an early (stage 1) trial, designed primarily to test the safety of this particular type of stem cell therapy. The new treatment will therefore be given in a different range of doses in a small number of people who have survived ischaemic strokes.
The new therapy uses a neural stem cell line generated in the laboratory, and produced by ReNeuron, a company specialising in stem cell therapies. The stem cells in this initial clinical trial are taken from existing cell banks. The company says there will be no need to create new cell lines for subsequent trials or for use, since all such cells can be expanded from the existing cell banks.
ReNeuron says this particular type of stem cell therapy, called ReN001, has been shown to reverse functional deficits associated with stroke disability in animal models. It also says ‘extensive pre-clinical testing’ indicates the therapy is safe.
What does the trial involve?
The PISCES trial involves 12 patients being given the stem cell therapy between 6 and 24 months after their stroke. The treatment is a simple surgical procedure in which stem cells are injected into the brain under local anaesthetic. Patients in the trial will be monitored for at least two years, with longer follow-up procedures in place afterwards. Doctors and scientists at the Division of Clinical Neurosciences at the University of Glasgow and at the Stroke Treatment Centre, Glasgow General Hospital are carrying out the trial.
The first patient in this trial has been given the stem cell therapy. Doctors reported that the surgery was successful and the patient was discharged after two days. A full safety review of his progress will take place next month. If this is satisfactory, the rest of this first cohort of patients will also be treated. If the treatment is found to be safe, the company says it will initiate further trials, focusing on particular stroke patients who are expected to most benefit from the therapy.
Has the media coverage been accurate?
In general, the media coverage has been accurate. The Daily Express’ photo of an injection into the arm was misleading because in this specific trial the cells were transplanted directly into the patient’s brain.
How does this affect you?
This is an early stage trial to test the safety of stem cell therapy in disabled stroke patients. As yet, little is known about the effectiveness of this type of therapy in stroke survivors. It will probably take several years before more is known about whether the therapy is effective in reversing any of the physical and functional deficits after stroke.
For anyone suspected of having a stroke, it is crucial to get to hospital as quickly as possible. The earlier treatment of stroke is carried out, the less the likelihood of lasting disability.
What is ischaemic stroke?
A stroke is a serious medical condition that occurs when the blood supply to part of the brain is cut off. Like all organs, the brain needs the oxygen and nutrients provided by blood to function properly. If the supply of blood is restricted or stopped, brain cells begin to die. This can lead to brain damage and possibly death.
About 150,000 people in the UK suffer a stroke each year. The majority of these are ischaemic strokes, caused by a blockage of blood flow in the brain (as opposed to a haemorrhagic stroke, caused by bleeding in the brain). About 50% of stroke survivors are left with permanent disabilities as a result of the damaged brain tissue caused by stroke.
Most people who have a stroke will be treated with aspirin or other medications to thin the blood when they arrive in hospital. It is possible for patients in the first three hours of ischaemic stroke to be treated with anti-clotting drugs to dissolve the clot causing the blockage (thrombolysis). However, this is possible in only a small proportion of patients due to uncertainty of the time of onset of stroke, or delays in reaching hospital or confirming that the stroke is ischaemic (there must be confirmation there is no bleeding in the brain).
Stroke survivors are managed with other drug treatments to control risk factors for stroke (e.g. blood pressure and cholesterol medications) and receive specialised physiotherapy and rehabilitation to alleviate the disabilities caused by stroke.
What are stem cells?
The human body is made up of billions of cells, of which there are at least 200 distinct cell types, such as liver cells and skin cells. These specialised, mature cells all derive from a common ‘ancestor’ – stem cells.
Stem cells are ‘primitive’, undifferentiated cells that have the ability to develop into specialised types of cells that make up the organs and tissues of the human body. They can also repair tissue, dividing without limit to replenish other cells.
There are several different types of stem cells. Some, called 'pluripotent’ cells, can give rise to any cell type except those in the placenta. Cells taken from embryos are pluripotent cells. ‘Multipotent’ cells, can give rise to other cell types but are limited to specific organ systems. Multipotent cells are found in foetal and some adult tissue. The stem cells used in the current trial are in this latter category.
What is stem cell therapy?
Cell death and degeneration is the cause of many major disorders, such as stroke, Alzheimer’s and heart disease. Stem cell therapy aims to replace dead or non-functioning cells with stem cells that can then develop into healthy, functioning cells of the equivalent cell type. The aim of stem cell therapy in stroke patients, for example, is to develop healthy cells that replace the dead brain cells and restore function.
Certain types of stem cell therapy have been in existence for decades. The most common type of stem cell therapy is the transplantation of bone marrow cells in leukaemia patients. Less well-known treatments using mature (non-stem) cells include the transplantation of insulin-producing cells for the treatment of type 1 diabetes.
Most existing cell therapy relies on transplanting healthy mature cells taken from the patient’s own body or from donated tissue. However, mature cells do not have the ability to regenerate themselves and cannot be grown on large-scale in the laboratory. Stem cells offer the potential to overcome these difficulties. They can be grown in the laboratory and retain the ability to differentiate into the particular specialised cell type required.