ACC: Stem Cells Improve Outcomes in Ischemic HF

CHICAGO -- Autologous bone marrow stem cell injections into the heart appeared to improve outcomes in heart failure from ischemic dilated cardiomyopathy, a phase IIb trial showed.

Ixmyelocel-T injection reduced by a relative 37% the primary composite efficacy endpoint rate of all-cause death, cardiovascular-related hospitalization, and unplanned clinic visits for independently-adjudicated acute decompensated HF at 12 months compared with double-blind bone marrow aspiration and placebo injection (rate 49% versus 38%, P=0.0344).

The effect was driven driven by both cardiac mortality and cardiac admissions, Timothy Henry, MD, of Cedars-Sinai Heart Institute in Los Angeles, and colleagues reported here at the American College of Cardiology meeting.

The procedure was also safer than placebo, with serious adverse events in 53% of patients who got the treatment versus 75% in the placebo group (P=0.0197).

"Ixmyelocel-T could be a cell therapy option for patients with NYHA class III/IV ischaemic congestive heart failure who have exhausted optimised medical therapy," they wrote in a paper released simultaneously online in The Lancet.

The trial was larger than most such prior stem cell trials, but with 126 participants was "still rather small," so the findings would have to be replicated in larger trials, John Jarcho, MD, of Brigham and Women's Hospital in Boston and a deputy editor for the New England Journal of Medicine, noted as a discussant at the late-breaking clinical trial session press conference.

The ixCELL-DCM trial included patients with NYHA class III or IV symptomatic heart failure from ischemic dilated cardiomyopathy and reduced left ventricular ejection fraction (35% or less), an automatic implantable cardioverter defibrillator, and who were ineligible for revascularization procedures.

The stem cell treatment to which they were randomized 1:1 was produced by selectively expanding certain types of bone marrow mononuclear cells for each patient (CD90+ mesenchymal stem cells and CD45+ CD14+ auto-fluorescent+ activated macrophages).

But the trial showed no benefit of the treatment on ejection fraction or functional capacity, raising the question of how did it improve outcome, Jarcho added.

Steven Houser, PhD, a cardiac myocyte researcher at Temple University in Philadelphia and president-elect of the American Heart Association, suggested a potential mechanism in an interview with MedPage Today.

"The cells that appear to be having some modest impact in patients with damaged hearts do so in all likelihood by what's called a paracrine effect -- they secrete things into the damaged area that help make new blood vessels and modify the scar formation in the heart," he said. "I don't think there's any evidence in this new trial that they figured out how to make new heart muscle cells, which is the ultimate goal of stem therapy. It's another small step in the right direction."

And there are plenty of other steps yet ahead on the way to the clinic, Houser cautioned.

"In my view it's unclear what cell we should use or if we should use cells at all. Maybe we should use cell products. There's a new evolving field in ... exosomes, small particles secreted by cells," he added. "We're still quite a ways away from having something that truly can regenerate the heart."

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