Experimental muscle-cell 'patches' may hold promise for failing hearts
Patching the heart with sheets of patients' own cells might improve symptoms in some cases of severe heart failure, an early study suggests.
Japanese researchers harvested tissue from patients' thigh muscles to grow sheets of cells that were then affixed to patients' hearts during surgery.
The main point of the study was to evaluate the safety and feasibility of the procedure. But the research team also found that a year after the surgery, some patients had improvements in their exercise capacity and heart function.
The results must now be confirmed with more research and larger studies, Dr Yoshiki Sawa of Osaka University Graduate School of Medicine and colleagues write in the Journal of the American Heart Association.
Nearly 6 million people in the United States have heart failure, according to the Centers for Disease Control and Prevention (CDC). The condition occurs when the heart can't pump enough blood to the body.
Treatment for heart failure ranges from a combination of diet changes, medications and physical activity to surgery. In the 27 patients in this new study, traditional treatments for heart failure hadn't worked.
The patients had class II or III heart failure, which typically means everyday activities left them tired, with heart palpitations and shortness of breath.
Researchers extracted cells from a small piece of muscle taken from each patient's thigh. They grew these cells in culture, testing for signaling molecules that indicate the likely presence of skeletal muscle stem cells in the mix. Then they grew the cultured cells into small, thin sheets.
After surgery to apply the patch, patients were watched at the hospital for complications and discharged about 50 to 60 days later. None of them showed complications related to the surgery.
The researchers note that in previous studies, when stem cells were injected into the heart - rather than applied as a patch - some patients developed dangerous heart rhythms. In the new study, three patients had irregular heart rhythms after the cell sheets were implanted, but those rhythms were not life threatening and were present before their surgeries.
A year after surgery, 96 percent of patients were alive. About 84 percent were alive three years after surgery.
People with heart failure caused by an enlarged or weakened chamber of the heart - known as dilated cardiomyopathy - did not seem to improve as much after the surgery as people whose condition was caused narrowed blood vessels - known as ischemic cardiomyopathy.
On average, people with ischemic cardiomyopathy improved from class III heart failure before the surgery to class II a year later. Additionally, during tests to see how far patients could walk in six minutes, the group with ischemic cardiomyopathy went from an average of 416 meters before the procedure to an average of 484 meters one year later .
They also improved on a number of other measures, including a blood test that shows how well the heart is working.
The researchers did not compare the patches to other treatments such as surgery to bypass a poorly functioning blood vessel.
Dr Eiran Gorodeski, a cardiologist at the Cleveland Clinic and a expert on heart failure, pointed out that all the patients were taking medications for their heart failure.
"They are being treated with other things," he told Reuters Health. "It’s hard to know without a control group if the cells are why these patients got better."
Larger clinical trials that include a control or comparison group need to be performed, said Gorodeski, who wasn't involved in the new study.
"I’m willing to buy in that this approach is feasible and safe," he said.
Gorodeski says if the sheets of cells work, it may be due to their hormones sending signals to the heart to repair itself.
He noted that stem cell therapy for heart failure is not approved by the Food and Drug Administration.
"For now, treatment with stem cells remain firmly in the experimental realm," said Gorodeski. "There are intriguing and early signals that they may work, but we don’t have a slam dunk yet."