Study sheds light on stem cell therapy best time to helping survivors of heart attack
A research network led by a Mayo Clinic found that administration of stem cells from bone marrow, one or two weeks after a heart attack, did not improve cardiac function of patients. This is the first study to systematically examine the timing and method of administration of stem cells and provides key information in the field of cell therapy.
The results were presented at the meeting of the Scientific Sessions 2011 of the American Heart Association in Orlando, Florida. Also, be published in the Journal of the American Medical Association (JAMA).
“Some data suggest that stem cell therapy is useful when administered within the first week after heart attack,” said Dr. Robert Simari, Mayo Clinic cardiologist and chairman of the Cardiovascular Cell Therapy Research Network (Research Network on Cardiovascular Cell Therapy, CCTRN). The network comprises five clinics, and others funded by the National Heart, Lung and Blood Institute, part of the National Institutes of Health. “Our study helps to identify the time limit in which the stem cell therapy is helpful. We now know that this therapy should not be more than two or three weeks after a heart attack. Although not dangerous, finding no benefit of therapy on cardiac function after six months.”
From July 2008 to February 2011, 87 people with heart attack and left ventricular dysfunction, moderate to severe received a placebo or their own stem cells derived from mononuclear bone marrow. The study, called LateTIME, developed a standardized method to process stem cells from bone marrow mononuclear and was the first trial of its kind to offer a uniform dose to each participant.
The scientists assessed the functioning of the heart through a cardiac MRI to measure the ejection fraction or percentage of blood ejected by the left ventricle with each contraction. No significant differences in cardiac function between the results of the baseline and six months later, or the group of stem cells from bone marrow mononuclear (from 48.7 percent to 49.2 percent) nor in the placebo group (from 45.3 percent to 48.8 percent).
Dr. Simari said that previous studies suggest that stem cell therapy benefits most patients with serious heart attack. Scientists were interested in studying the period of two to three weeks, because many people with serious heart attacks are not good enough or stable to get cell just after the event. “Many need life support or other support systems, so we thought that as soon study was not the best way to evaluate the benefit to the sickest patients,” says Dr. Simari.
The study involves LateTIME a lesson for people who have suffered heart attacks and plan to travel abroad to undergo a stem cell transplant. “We would like to suggest to those people who do not seek treatment outside the United States with therapies whose efficacy has not been proven,” says Dr. Simari. Scientists believe that two or three weeks after a heart attack, the heart may be less responsive to such therapy or the power of stem cells decreases the person at that time.
Dr. Jay Traverse, lead study author and cardiologist at the Minneapolis Heart Institute at Abbott Northwestern Hospital, notes that patients will receive medical monitoring for two years in the study LateTIME.
“Over time, still could be found other benefits of stem cell therapy,” says Dr. Traverse. “It was observed that patients receiving cell therapy had fewer adverse events such as the placement of defibrillators or need for repeat revascularization than those receiving placebo, which is consistent with the observations of some European trials. This therapy could offer hidden safety measures that reduce adverse events and that is something that merits close monitoring.”
The study is one of three LateTIME cardiac stem cell trials conducted by the CCTRN. The other essays explore the effectiveness of stem cell therapy administered between three and seven days after a heart attack and utility of stem cell therapy in people with chronic heart failure.
The research was funded by the National Heart, Lung and Blood Institute and supported in part by the facilities Molecular and Cellular Therapeutics, University of Minnesota and Cell Processing Facility of the Baylor School of Medicine.