The use of intramyocardial mesenchymal precursor cells (MPC) to promote cardiac recovery is fast losing favour with new evidence showing the cell therapy does not improve temporary weaning from left ventricular assist devices (LVAD).
The multicentre US study comprised 159 patients with end-stage heart failure randomised to receive either an intramyocardial injection of MPCs or placebo at the time of their LVAD implant.
Patients were assessed for successful temporary weaning from full to minimal LVAD support at 2, 4 and 6 months and followed out to 12 months or heart transplant.
The study found there was no significant difference in successful weaning rates between the groups (61% with MPC versus 58% in controls; p=0.55).
Left ventricular ejection fraction, 6-minute walk distance and quality of life scores were similar in both groups as were rates of serious adverse events (70.9 v 78.7 per 100 patient-months; p=0.63) and mortality (9.4% v 11.3%; p=0.68).
An editorial published in JAMA said the findings were ‘yet another example of a negative study in a largely disappointing body of cell-based research’.
“The original hypothesis was that stem cells would engraft in the myocardium and replace damaged cardiomyocytes. However, the weight of the evidence to date indicates that any clinical benefit resulting from stem cell therapy for heart failure with reduced ejection fraction has been small and inconsistent.”
It noted the lack of evidence had not stopped stem cell therapy being offered to patients with heart failure in the US.
It called for the FDA to consider regulatory action for such unauthorised activities and questioned whether funding bodies should continue to invest research dollars in stem cell therapy.
“Based on the unimpressive results to date, it will be even more important to be parsimonious about investments in stem cell therapy for heart failure unless new ideas and novel approaches open fresh avenues for potential success,” concluded the commentary by JAMA deputy editor, cardiologist Dr Gregory Curfman.
However Associate Professor James Chong, head of the Cardiac Regeneration Laboratory at Westmead Institute for Medical Research said the negative findings should not tarnish all stem cell and cardiac regenerative therapies
He told the limbic the US study was small but well-designed with robust primary and secondary endpoints and safety endpoints.
“And the fact that it was negative in my mind is not a big deal. We need to publish studies like this. I personally don’t think it is an unexpected result.”
He said it was important to remember that there was no single generic stem cell and the new wave of pluripotent stem cells along with other cardiac regenerative techniques such as tissue engineering, exosome therapies and mRNAs were still to come.
“Fast forward another 20-30 years and who knows where we will be?”
He added that such therapies were purely in the research setting, in the context of well-designed and reportable clinical trials. Unscrupulous practitioners should not be charging patients for such therapies.