Stem cell treatment for acute myocardial infarction.

BACKGROUND: Stem cell therapy offers a promising approach to the regeneration of damaged vascular and cardiac tissue after myocardial infarction (MI). This has resulted in multiple randomised controlled trials (RCTs) worldwide.

OBJECTIVES: To critically evaluate evidence from RCTs on the effectiveness of adult bone marrow-derived stem cells (BMSC) to treat acute MI.

SEARCH STRATEGY: MEDLINE (1950 to August 2007), EMBASE (1974 to August 2007), The Cochrane Library (Issue 3 2007), and CINAHL (1982 to August 2007) were searched. In addition LILACS, KOREAMED, INMED, Current Controlled Trials Register, the UK National Research Register and other handsearching was undertaken to August 2007.

SELECTION CRITERIA: RCTs comparing autologous stem/progenitor cells with no autologous stem/progenitor cells in patients diagnosed with acute myocardial infarction (AMI) were eligible.

DATA COLLECTION AND ANALYSIS: Two reviewers independently screened all references, assessed trial quality and extracted data. Meta-analyses using a random-effects model were conducted and heterogeneity was explored using sub-group analyses.

MAIN RESULTS: Thirteen RCTs (811 participants) were included. There were insufficient events on clinical outcomes like mortality to draw clear conclusions. Stem/progenitor cell treatment does not appear to be associated with an increase in adverse events but again the data do not allow clear conclusions. Left ventricular ejection fraction (LVEF) was the outcome with most results and there was marked heterogeneity between trials. There was however a consistent pattern indicating that BMSC treatment generally improves short-term LVEF, with similar trends for left ventricular end systolic and end diastolic volumes (LVESV and LVEDV), infarct size or cardiac wall motion. There was a positive correlation between cell dose infused and the effect on LVEF measured by magnetic resonance imaging.

AUTHORS' CONCLUSIONS: The results of this systematic review suggest that there is little evidence to assess the clinical effects of this treatment. Larger trials using optimal dosing and more reliable, patient-centred outcomes are required. Several trials are ongoing but is unclear whether these will overcome the limitations of the current evidence base.