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Stroke Patients Show Signs Of Recovery Following Stem Cell Trial




As one of the first ever trials to test the safety of stem cells as a treatment for stroke draws to a close, investigators report there appear to be no harmful side effects. Most patients have also shown modest improvements although it is too early to say if this is as a result of the treatment.

Updated interim results of the Pilot Investigation of Stem Cells in Stroke (PISCES) study, which is testing the safety and tolerability of injecting neural stem cells into the brains of ischemic stroke patients, were reported on Monday at the 22nd European Stroke Conference in London.

The stem cell trial started in 2010, with one stroke patient, an elderly Scotsman who was injected with ReN001 cells developed by ReNeuron Group plc, at the trial center at Southern General Hospital in Glasgow, UK.

By 2012, there were six patients on the small trial, and an early set of results presented at an international conference showed that five of the six patients were showing some improvement and there had been no adverse side effects.

Clare Walton, Research Communications Officer at the UK's Stroke Association says they are very excited about the results of the trial, but "we are currently at the beginning of a very long road and significant further development is needed before stem cell therapy can be regarded as a possible treatment." Concerns About Stem Cell Therapy Stem cells are undifferentiated precursor cells that can become virtually any cell of the body. Some stem cells are taken from adult cells like skin cells and reprogrammed, others are taken from embryos or fetuses. Embryonic stem cells are considered the "gold standard" of stem cells, but are controversial because of where they come from.

The ReN001 treatment uses a stem cell line that originated some ten years ago from the tissue of a 12-week fetus.

In theory, stem cells hold a lot of promise as regenerative treatments. The idea is where tissue is damaged, such as in a stroke, doctors should be able to inject stem cells to regenerate new tissue in its place.

But in practice, it is not easy to develop effective and safe stem cell therapies.

One of the safety concerns with stem cell therapies is that the stem cells will grow out of control and form tumors rather like cancer. Another is rejection or an adverse reaction by the patient's immune system. No Cell-Related or Immunological Adverse Effects However, at the conference in London this week, head trial investigator Keith Muir, a professor at the University of Glasgow, reported that data from the first nine patients on the PISCES trial show no "cell-related or immunological" adverse side effects.

While the main aim of the phase I trial is to evaluate the safety and tolerability of the ReN001 treatment, to help with the design of future clinical trials, the patients have also undergone tests of movement and brain function that will show if there are any reductions in their disability.

Muir reported that most patients have shown some "modest reductions in neurological impairment" and improvement in ability to carry out everyday tasks.

However, it is still too early to say whether these improvements are a result of the treatment or some other effect.

Two more patients have joined the trial since this latest data was collected. The phase I trial is now drawing to a close, and the team expects to publish full and final results next year. Phase II Trial Expected to Start By End of the Year Encouraged by the results, the team is preparing for a phase II trial, to test the effectiveness of the stem cell therapy in stroke patients, and expect to submit an application to the UK authorities in July. If they get the go-ahead, the trial could start before the end of the year.

Muir says in a statement that they are pleased and encouraged by the data from the PISCES study, "the data to date identify no safety issues with the ReN001 treatment - which is the primary focus of this Phase I trial."

"The evidence of functional improvement requires further investigation in a suitably designed Phase II efficacy study and we look forward to being a principal clinical site in that study when it commences," he adds.

The phase II controlled trial will take place at several centers. At first it will include 20 patients, all of whom will have suffered a recent stroke.

Michael Hunt, Chief Executive Officer of ReNeuron, says that as long as the required short-term follow ups confirm the good safety profile achieved so far in the phase I trial, they should be able to move "confidently" into the phase II trial later this year.

Before the phase II trial can go ahead, the company must seek final regulatory and ethical approvals. They have to submit data from the phase I trial, including results of three months of follow up on the patients who received the final dose of stem cells. Half of Stroke Survivors Suffer Permanent Disability Among developed nations, stroke is the third biggest cause of death and the single largest cause of adult disability.

Most strokes are of the ischemic type, caused by a blockage (such as a blood clot) to blood flow in the brain. Starved of oxygen, brain cells in the affected area die.

The other, less common, type of stroke is hemorrhagic stroke, which results from a bleed in the brain.

Because strokes damage brain tissue, around half of stroke survivors suffer permanent disability. In the UK estimates suggest the cost of caring for these patients amounts to some 5 billion or more. In the US this figure is around $70 billion. About a quarter of long term hospital beds are taken up by stroke patients.

Currently the only way to treat stroke with a chance of success is to give patients a clot-busting agent within hours of the stroke. Apart from that, the only treatment is rehabilitation to help patients manage their disabilities.

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