Stem cell therapy study reports mixed results in heart failure patients

Despite failing to increase the amount of time between cardiac events, stem-cell injections into heart muscle may instead reduce heart attacks and strokes in some patients.

The DREAM-HF study was a multicentre, randomised controlled trial investigating the effectiveness of donor bone marrow-derived mesenchymal precursor stem cell (MPC) injections in treating heart failure. However, even though the administration of MPCs was safe, the treatment did not improve the heart's function in patients with chronic heart failure due to poor pump function. Although, it did reduce heart attacks and strokes, particularly in patients with inflammation.

Publishing the results in the Journal of the American College of Cardiology, study lead author from the Texas Heart Institute, Dr Emerson Perrin, said, 'The cells appear to work by reducing inflammation, increasing microvascular flow, and strengthening heart muscle. In large blood vessels throughout the body, the reduced inflammation resulting from the activation of MPCs may decrease plaque instability, which is what leads to heart attacks and strokes.'

Heart failure affects up to 64 million people worldwide. In this condition, heart pump function is weakened, leading to poor blood circulation. Patients experience symptoms such as difficulty breathing, fluid retention and heart rhythm abnormalities that can cause heart attacks.

Researchers analysed 537 participants with chronic heart failure due to poor pump function, 265 received the MPC therapy, while 272 received a placebo. All patients also received standard medical treatment throughout and were followed up after 30 months.

The study missed its primary endpoint, as the MPC therapy did not significantly reduce the number of times a patient required immediate medical treatment due to the signs or symptoms of heart failure.

However, the researchers did report that the MPC therapy group had a 58 percent reduction in the risk of heart attacks or strokes during follow-up. The researchers then focused on subgroups of patients and discovered that patients with inflammation had a 75 percent reduction in the risk of heart attacks or strokes.

But, as these results were not pre-specified primary endpoints, which were to increase the time between cardiac events, there is potential for bias and their significance remains unclear. Professor Roberto Bolli, chair in cardiology at the Jewish Hospital Heart and Lung Institute, Kentucky, who was not involved in the study, explained to USA Today the need for a follow-up study concentrating on patients with inflammation: 'If that trial confirms these results, that will be a major advance in cardiovascular medicine… We don't know of any other treatment that does that.'

However, Professor Paul Knoepfler from the University of California Davis School of Medicine, who was also not involved in the study, wrote an article in the Niche stating: 'Overall this is a negative study with perhaps helpful data to guide future studies of MPCs and similar cells.'