Can stem cells can aid stroke recovery? Ongoing U.S. clinical study tests this. Strokes kill and maim. Each year, about 800,000 Americans and two million people in Japan, the U.S. and the major European countries combined, suffer a new or recurrent stroke. Each year, more than 137,000 Americans die from strokes. Stroke is the top fourth cause of deaths in the United States, claiming one in every 18 deaths.
In terms of costs, Americans paid US$73.7 billion in 2010 alone for stroke-related medical costs and disability. The number of strokes will rise by 25 percent in the next 20 years and costs will skyrocket to US$140 billion in 2030, the American Heart Association forecasts.
But beyond the figures, looking at the impact of strokes on individual lives is like looking down a long, dark tunnel. People who survive strokes suffer paralysis and impaired mobility. They have bladder and bowel problems, and problems swallowing and eating. They suffer memory loss, erratic behavior, depression and difficulty communicating, putting stress on their caregivers and loved ones. Lying immobile can cause pain in the joints and muscles, nerve pain and bed sores.
Currently, there’s only one drug therapy approved by the Food and Drug Administration for the treatment of ischemic stroke—or the type of stroke that makes up 80 percent of all strokes.
The drug, thrombolytic tPA, helps to dissolve the blood clot that impedes blood flow in the brain. But tPA must be administered several hours after a stroke has occurred in order to be effective.
Because this tiny window of opportunity is missed in most patients, only about five percent of stroke patients actually receive tPA treatment.
This sheer lack of effective therapies forces many patients who suffer from stroke to require extensive physical therapy. Or, they simply put up with the significant and maybe even permanent disability—and are forced to be sent for long-term institutional care or are cared for by a family member for the rest of their lives.
Stem cell therapy trial
It’s in the recovery where stem cell therapy has the potential to help.
A stroke happens when blood supply to the brain is blocked by a clot (ischaemic stroke) or when a blood vessel in the brain bursts, spilling blood into the spaces surrounding brain cells (haemorrhagic stroke). Walking, talking and thinking and other brain functions suffer when brain cells die because they no longer receive oxygen and nutrients from the blood or there’s sudden bleeding into or around the brain.
Right now, stem cells aren’t used as a matter for course for the treatment of stroke, but in many animal studies, fetal brain stem cells or stem cells from bone marrow and umbilical cord blood have been transplanted into animals that have had strokes—and have shown promising results.
Stem cell treatments being studies now involve using either embryonic or induced pluripotent stem cells (iPSCs) that would then specialize into the neural cells that have died in the affected area of the brain.
In several studies using animals, the new neural cells that developed from stem cells were able to move to the affected area, replace the dead cells, survive, connect to existing healthy cells and re-establish the damaged circuits of the brain. Or at least that’s what doctors used to think.
However the exact mechanism of how the stem cells work, the fact is, they’ve worked in animal studies. Which is why, in the past year or so, this approach has been tried in humans in a number of studies—some in Europe, and recently, two studies from a medical center in India reported in this year’s International Stoke Conference 2012 showed that stem cell injections helped stroke victims recover.
U.S. clinical trial
One clinical trial is now ongoing at the Georgia Health Sciences University.
The trial, being undertaken jointly by Dr. David Hess, the chairman of GHSU’s Department of Neurology and the biotechnology company Athersys Inc, involves stem cells derived from the bone marrow of healthy donors. These cells are then tested and processed in a way that allows them to be banked or stored in a most hospitals, where they can be given to patients without the need to match blood type.
Called MultiStem cells, the stem cell product line has been tested on mice and rats that suffered strokes, and has been shown to help the rodents recover.
Now, the ongoing trial is meant to test whether MultiStem cells can help humans recover from a severe stroke.
Most other ongoing trials involve using autologous stem cells taken from stroke patients themselves, then painstakingly grown and given back to them—a laborious, expensive and time-consuming process.
Because the MultiStem developed by Athersys are “ready-to-go,” they pose an advantage over the use of autologous stem cells, being cheaper, and quicker and less laborious to administer, according to Dr. Hess.
Also, the GHSU neuroscientist says, stroke patients tend to be older and their stem cells might not be as effective as the ones taken from the younger donors Athersys uses.
Unlike embryonic stem cells, the cells derived from bone marrow have a very low risk of spawning a tumor, and so far they shown few side effects, Dr. Hess also claims.
Now there’s a clinical trial to see whether the stem cells can provide a benefit in patients who haven’t seen much progress in a day or so after the stroke.
How the cells work
Originally, scientists thought the stem cells, injected intravenously, traveled to the site of injury in the brain and then formed new neurons and blood vessels.
But this turned out to be “naive,” Dr. Hess explains to the Augusta Chronicle, a Georgia local news site. Instead, the cells appear to migrate to other organs that are involved in forming immune system cells, such as the spleen.
The neurology professor surmises that the stem cells are actually working to dampen the immune response that causes inflammation in the brain and the release of toxic materials that further brain damage after a stroke.
“The immune system plays a deleterious role” in stroke, Dr. Hess says, so quieting the immune system should aid in recovery.
Second patient, huge grants
A massive stroke suffered in Feb. 2 has rendered his left arm useless, so Chris Woods, 45, of Tignall, Georgia., is taking part in the Athersys clinical trial while he recovers at the Medical College of Georgia Hospital. He’s the second patient to take part in the ongoing trial to test if the MultiStem cells will help him recover from his stroke.
Only a day before, Athersys announced in a news release that it received a total of US$3.6 million in grants to further advance its MultiStem product programs and cell therapy platform.
Of that amount, US$1.9 million came from the National Institute of Neurological Disorders and Stroke (NINDS) to develop MultiStem for the treatment of traumatic brain injury (TBI) under the SBIR Fast-Track grant.
Another US$1.2 million (EURO0.9 million) was given to Athersys’ subsidiary based in Belgium, ReGenesys BVBA, to develop cell therapy formulations and manufacturing capabilities further. That grant came from the Belgium’s Agency for Innovation by Science and Technology (IWT).
The remaining funds went to work in other areas, such as using MultiStem to treat chronic cardiovascular disease.
“These grant awards provide us with additional funding to support further development of MultiStem in specific therapeutic areas, as well as enhance our manufacturing platform,” says Dr. Gil Van Bokkelen, Athersys Chairman and CEO in the news release.
“Historically, we have been very successful at obtaining this type of funding, which reflects our commitment to outstanding science and technology development, and development of innovative new therapies,” he says.
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