Experimental Heart Failure Treatment Shows Promise
But experts caution that larger studies of combined treatment are needed
"Whether these findings can be reproduced, and whether there is any clinical benefit that will result from this approach, will require subsequent, well-designed clinical trials," said Fonarow.
The findings are based on 103 patients who'd developed chronic heart failure after a heart attack. Zeiher's team randomly assigned 81 patients to receive shock wave therapy; afterward, 42 of them received an infusion of bone marrow cells, while 39 were given a cell-free "placebo" infusion.
The remaining 21 patients received placebo shock wave therapy. (A cushion was placed over the chest so the ultrasound waves could not reach the heart.) They did, however, get a real infusion of bone marrow cells.
Four months later, patients who'd received the combination therapy were faring best: On average, the percentage of blood being pushed out of the heart's main pumping chamber ticked up 3 percent.
That's "modest," the researchers acknowledged, but it compared with no significant change in the other patients.
The combination-therapy group also had fewer heart-related "events," such as heart rhythm problems, hospitalization for heart failure, repeat heart attacks or strokes. There were 32 such complications among the 42 patients, versus 18 among the 21 patients who received only bone marrow cells.
Now, one of the big questions is whether the improved heart function fades with time, Zeiher said. Repeat treatments may be necessary.
"In principle," Zeiher said, "that can be very easily performed, because the procedure itself is rather simple and -- most importantly -- safe."
Marban agreed that, based on years of research experience, bone marrow cell therapy does seem to be safe.
It's not clear, though, exactly how it works. Early on, some researchers suggested that transplanted bone marrow cells actually generate new heart muscle. But studies since then have failed to show that's true.
The "best guess," Marban said, is that the bone marrow cells secrete certain growth factors that improve the heart's ability to contract.
Right now, the standard treatments for heart failure include medications that lighten the heart's workload and moderate exercise. But researchers are looking for new ways to improve the heart's pumping ability, or even regenerate the damaged muscle.
Marban and his colleagues are studying the use of heart stem cells -- primitive cells within the heart that are, in theory, capable of generating new heart muscle.
The current study was funded by Goethe University. Zeiher and a co-researcher are founders of a company, t2cure, focused on regenerative therapies for heart disease.