Stem cell therapy to prevent heart attacks

The use of stem cell therapy to prevent heart attacks is explored in a Comment published in this week's edition of The Lancet.

Professor Harald Arnesen and colleagues from the Ullevål University Hospital, Oslo, Norway looked at studies published to date on the relatively new technique of using of autologous cells derived from bone marrow cells (BMC) to strengthen cardiac function. Autologous cells are sourced from the patient they are used to treat. The authors refer to a trial done in 2002 in which such cells were administered into the heart with encouraging results.

The authors say: “The results of this and several other small uncontrolled studies with the same method were encouraging. However, three randomised trials that tested therapy with BMC were negative for the primary endpoint, improvement in left ventricular ejection-fraction (LVEF).”

A trial of 204 patients (REPAIR-AMI) is also discussed by the Comment authors. Half of these patients were randomised to receive an intracoronary infusion of BMC, or placebo. LVEF increased slightly in the placebo group (47% to 50%) and slightly more in the BMC group (47% to 54%). Despite this modest difference, there was a significant reduction in clinical events in the BMC group compared to placebo – namely that the combined risk of death, heart attack or revascularisation fell by nearly half. Investigators involved in REPAIR-AMI concluded that the results warranted large-scale trials to study effects of BMC infusion on morbidity and mortality.

The authors are concerned about this, because they feel that the methods for measurement of LVEF in REPAIR-AMI were not ideal, and that the positive clinical effect in that trial was driven by poor outcome in the placebo group.

They conclude: “Further research will hopefully develop cell-based treatments that can improve prognosis and quality of life for patients with cardiac diseases. However, because only a small treatment effect has been obtained with inaccurate methods, and because there is reason to question the safety of the placebo procedure in REPAIR-AMI, we think it is inappropriate to invite a large number of patients to participate in new studies based on the methods used in that investigation.”