Heart tissue death, light micrograph

Heart attacks can damage the muscle cells (shown here) that keep the organ beating.Credit: Steve Gschmeissner/Science Photo Library

The US National Heart, Lung, and Blood Institute (NHLBI) has paused a clinical trial using stem cells to treat heart failure after questions were raised about the validity of the science behind it.

The institute made the decision “out of an abundance of caution to ensure the study continues to meet the highest standards for participant safety and scientific integrity”, it said in a statement released on 29 October.

The trial was based on research done by cardiologist Piero Anversa at New York Medical College in Valhalla, and later at Harvard University Medical School and Brigham and Women's Hospital in Boston, Massachusetts. In 2002, he and his colleagues suggested that a type of stem cell in the heart, called c-kit cells, could regenerate damaged heart muscle1. The NHLBI study gave people with chronic heart failure infusions of c-kit cells or combinations of c-kit cells and bone-marrow stem cells. It launched in 2015, with the goal of enrolling 144 participants; so far, 125 patients have signed up.

Doubts about Anversa’s work arose in the early 2000s after other researchers failed to replicate his findings and questioned whether cardiac stem cells existed2,3,4.

Anversa, who moved to Harvard Medical School and Brigham and Women's Hospital in Boston, Massachusetts in 2007, closed his lab there in 2015. In 2017, Partners HealthCare System — which runs Brigham and Women’s Hospital — paid the US government US$10 million as part of a settlement over accusations that Anversa’s team had submitted fraudulent data to obtain federal funds.

Earlier this month, the hospital and Harvard called on journal editors to retract 31 of Anversa’s papers, after their investigations found that they contained data that had been manipulated or fabricated.

Anversa could not immediately be reached for comment.

The NHLBI says that the decision to halt the study was due to concerns about Anversa’s animal studies, and not due to any data generated by the trial itself. The agency says that it does not think that the trial has compromised patient safety.