The results of this TIME (Transplantation In Myocardial Infarction Evaluation) trial were presented by Jay Traverse, MD of the Minneapolis Heart Institute Foundation Tuesday, today at the 2012 Scientific Sessions of the American Heart Association in Los Angeles.
The results of this trial mirror a previous, related study (LateTIME) which found that autologous bone marrow stem cell therapy given 2-3 weeks after a heart attack did not improve cardiac recovery. Both TIME and LateTIME were carried out by the Cardiovascular Cell Therapy Research Network (CCTRN).
TIME enrolled 120 volunteers (avg. age 57) between July 2008 and February 2011; the participants all had moderate to severe impairment in their left ventricle and had undergone coronary stent placement as treatment for the heart attack. The participants were randomly assigned to one of four groups: day 3 stem cell, day 3 placebo (inactive cells), day 7 stem cell, or day 7 placebo.
The CCTRN researchers developed a method of processing and purifying the stem cells from the bone marrow of each volunteer to ensure everyone received a uniform dose (150 million stem cells). These were adult stem cells, not human embryonic stem cells.
"The data presented by TIME do much to advance stem cell therapy research," said Jay Traverse, MD of the Minneapolis Heart Institute Foundation and Principal Investigator of this study. "While this study did not provide a demonstrated cardiac benefit after six months, we still learned a great deal. Together, TIME and Late TIME have shown that stem cell therapy is safe, and they have set a baseline in terms of quantity of stem cells, type of stem cells, and severity of heart attack."
Heart improvement was assessed six months after stem cell therapy by measuring the percentage of blood that gets pumped out of the left ventricle during each contraction (left-ventricular ejection fraction, or LVEF). The study found no significant differences between the change in LVEF readings at the six month follow-up in either the Day 3 or Day 7 stem cell groups compared with placebo or with each other; every group showed about a 3 percent improvement in LVEF. However, the researchers found that younger patients randomized to Day 7 had greater improvement in their LVEF compared to their placebo counterparts
"The lack of six-month improvement seen for TIME and, prior to that, LateTIME, does not mean stem cell therapy is not a viable post-heart attack strategy," said Traverse. "Because we have this data we can start to address some parameters; for example this therapy may work better in younger people, or maybe we need to use cells from healthy volunteers (allogeneic) since their cells may provide greater therapeutic benefit. There will also be upcoming studies using novel cell types which we look forward to using in future clinical trials."
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