For 15 years, scientists have put various stem cells into seriously ill patients’ hearts in hopes of regenerating injured muscle and boosting heart function. A new mouse study may finally debunk the idea behind the controversial procedure, showing the beneficial effects of two types of cell therapy are caused not by the rejuvenating properties of stem cells, but by the body’s wound-healing response — which can also be triggered by injecting dead cells or a chemical into the heart.
The discovery will have to be repeated and investigated in human tissue, but the emergence of a likely explanation for how heart cell therapy can have modest benefits comes after years of hype, hope and disagreement about stem cells’ potential to heal broken hearts. Experimental therapies have been tested in hundreds of patients with heart disease, even as doubts have grown about the underlying scientific rationale. The idea that the cells could regenerate the heart was intuitively attractive and captured a field searching for therapies to offer desperate patients, and many scientists started companies to try to commercialize different cell types. The new work provides a long-awaited explanation — one that some outside scientists argued does not support more trials with the cells.
“It’s sort of an ‘Aha!’ feeling,” said Christine Mummery, a developmental biologist at the Netherlands’ Leiden University Medical Center not involved in the study. “My personal view is that we’ve done so many of these studies, particularly for the heart, I think it would be a waste of time starting up any new ones. Whether or not the old ones should be continued — I call it expensive homeopathy."