Public release date: 14-Feb-2012
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Contact: Jennifer Beal
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Wiley-Blackwell

Stem cell therapy moderately improves heart function after a heart attack, according to a systematic review published in The Cochrane Library. But the researchers behind the review say larger clinical trials are needed to establish whether this benefit translates to a longer life.

In a heart attack, the blood supply to parts of the heart is cut off by a blocked artery, causing damage to the heart tissue. The cells in the affected area start to die. This is called necrosis and in the days and weeks that follow, the necrotic area may grow, eventually leaving a large part of the heart unable to contract and increasing the risk of further heart problems. Stem cell therapy uses cells from the patient's own bone marrow to try to repair and reduce this damage. Currently, the treatment is only available in facilities with links to scientific research.

The authors of the review drew together all the available evidence to ask whether adult bone marrow stem cells can effectively prevent and repair the damage caused by a heart attack. In 2008, a Cochrane review of 13 stem cell therapy clinical trials addressed the same question, but the new review adds 20 more recent trials, drawing its conclusions from all 33. By incorporating longer follow up, the later trials provide a better indication of the effects of the therapy several years after treatment.

The total number of patients involved in trials was 1,765. All had already undergone angioplasty, a conventional treatment that uses a balloon to open the blocked artery and reintroduce the blood supply. The review's findings suggest that stem cell therapy using bone marrow-derived stem cells (BMSCs) can produce a moderate long-term improvement in heart function, which is sustained for up to five years. However, there was not enough data to reach firm conclusions about improvements in survival rates.

"This new treatment may lead to moderate improvement in heart function over standard treatments," said lead author of the study, Enca Martin-Rendon, of the Stem Cell Research laboratory, NHS Blood and Transplant at the John Radcliffe Hospital in Oxford, UK. "Stem cell therapy may also reduce the number of patients who later die or suffer from heart failure, but currently there is a lack of statistically significant evidence based on the small number of patients treated so far."

It is still too early to formulate guidelines for standard practice, according to the review. The authors say further work is required to establish standard methods, including cell dosage, timing of cell transplantation and methods to measure heart function. "The studies were hard to compare because they used so many different methods," said Martin-Rendon. "Larger trials with standardised treatment procedures would help us to know whether this treatment is really effective.

Recently, the task force of the European Society of Cardiology for Stem Cells and Cardiac Repair received funding from the European Union Seventh Framework Programme for Research and Innovation (EU FP7-BAMI) to start such a trial. Principal Investigator for the BAMI trial, and co-author of this Cochrane review, Anthony Mathur, said, ''The BAMI trial will be the largest stem cell therapy trial in patients who have suffered heart attacks and will test whether this treatment prolongs the life of these patients."

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Read more:
Stem cell treatments improve heart function after heart attack

A promising stem cell therapy approach could soon provide a way to regenerate heart muscle damaged by heart attacks.

Researchers at Cedars-Sinai Heart Institute and The Johns Hopkins University harvested stem cells from the hearts of 17 heart attack patients and after prepping the cells, infused them back into the patients' hearts. Their study is published in the current issue of The Lancet.

The patients received the stem cell infusions about three months after their heart attacks.

Researchers found that six months after treatment, patients had significantly less scarring of the heart muscle and also showed a considerable increase the amount of healthy heart muscle, compared to eight post-heart attack patients studied who did not receive the stem cell infusions. One year after, scar size was reduced by about 50 percent.

"The damaged tissue of the heart was replaced by what looks like healthy myocardium," said Dr. Peter Johnston, a study co-author and an assistant professor of medicine at The Johns Hopkins University School of Medicine. "It's functioning better than the damaged myocardium in the control subjects, and there's evidence it's starting to contract and generate electrical signals the way healthy heart tissue does."

While this research is an early study designed to demonstrate that this stem cell therapy is safe, cardiologists say it's an approach that could potentially benefit millions of people who have suffered heart attacks. Damage to the heart muscle is permanent and irreparable, and little can be done to compensate for loss of heart function.

"In the U.S., six million patients have heart failure, and the vast majority have it because of a prior heart attack," said Johnston.

The damaged scar tissue that results from a heart attack diminishes heart function, which can ultimately lead to enlargement of the heart.

At best, Johnston said, there are measures doctors can try to reduce or compensate for the damage, but in many cases, heart failure ultimately sets in, often requiring mechanical support or a transplant.

"This type of therapy can save people's lives and reduce the chances of developing heart failure," he said.

Cardiac Regeneration A Promising Field

Other researchers have also had positive early results in experiments with stem cell therapy using different types of cells, including bone marrow cells and a combination of bone marrow and heart cells.

"It's exciting that studies using a number of different cell types are yielding similar results," said Dr. Joshua Hare, professor of cardiology and director of the University of Miami Interdisciplinary Stem Cell Institute.

The next steps, he said, include determining what the optimal cell types are and how much of the cells are needed to regenerate damaged tissue.

"We also need to move to larger clinical trials and measure whether patients are improving clinically and exhibiting a better quality of life after the therapy."

In an accompanying comment, Drs. Chung-Wah Siu amd Hung-Fat Tse of the University of Hong Kong wrote that given the promising results of these studies, health care providers will hopefully recognize the benefits that cardiac regeneration can offer.

And Hare added that someday, this type of regeneration can possibly offer hope to others who suffered other types of organ damage.

"This stategy might work in other organs," he said. "Maybe this can work in the brain, perhaps for people who had strokes."

Excerpt from:
Stem Cells May Help Regenerate Heart Muscle

A promising stem cell therapy approach could soon provide a way to regenerate heart muscle damaged by heart attacks.

Researchers at Cedars-Sinai Heart Institute and The Johns Hopkins University harvested stem cells from the hearts of 17 heart attack patients and after prepping the cells, infused them back into the patients' hearts. Their study is published in the current issue of The Lancet.

The patients received the stem cell infusions about three months after their heart attacks.

Researchers found that six months after treatment, patients had significantly less scarring of the heart muscle and also showed a considerable increase the amount of healthy heart muscle, compared to eight post-heart attack patients studied who did not receive the stem cell infusions. One year after, scar size was reduced by about 50 percent.

"The damaged tissue of the heart was replaced by what looks like healthy myocardium," said Dr. Peter Johnston, a study co-author and an assistant professor of medicine at The Johns Hopkins University School of Medicine. "It's functioning better than the damaged myocardium in the control subjects, and there's evidence it's starting to contract and generate electrical signals the way healthy heart tissue does."

While this research is an early study designed to demonstrate that this stem cell therapy is safe, cardiologists say it's an approach that could potentially benefit millions of people who have suffered heart attacks. Damage to the heart muscle is permanent and irreparable, and little can be done to compensate for loss of heart function.

"In the U.S., six million patients have heart failure, and the vast majority have it because of a prior heart attack," said Johnston.

The damaged scar tissue that results from a heart attack diminishes heart function, which can ultimately lead to enlargement of the heart.

At best, Johnston said, there are measures doctors can try to reduce or compensate for the damage, but in many cases, heart failure ultimately sets in, often requiring mechanical support or a transplant.

"This type of therapy can save people's lives and reduce the chances of developing heart failure," he said.

Cardiac Regeneration A Promising Field

Other researchers have also had positive early results in experiments with stem cell therapy using different types of cells, including bone marrow cells and a combination of bone marrow and heart cells.

"It's exciting that studies using a number of different cell types are yielding similar results," said Dr. Joshua Hare, professor of cardiology and director of the University of Miami Interdisciplinary Stem Cell Institute.

The next steps, he said, include determining what the optimal cell types are and how much of the cells are needed to regenerate damaged tissue.

"We also need to move to larger clinical trials and measure whether patients are improving clinically and exhibiting a better quality of life after the therapy."

In an accompanying comment, Drs. Chung-Wah Siu amd Hung-Fat Tse of the University of Hong Kong wrote that given the promising results of these studies, health care providers will hopefully recognize the benefits that cardiac regeneration can offer.

And Hare added that someday, this type of regeneration can possibly offer hope to others who suffered other types of organ damage.

"This stategy might work in other organs," he said. "Maybe this can work in the brain, perhaps for people who had strokes."

See the article here:
Stem Cells May Help Regenerate Heart Muscle