The following are key points to remember about this consensus statement from the Task Force of the European Society of Cardiology concerning the clinical investigation of the use of autologous adult stem cells for the treatment of acute myocardial infarction (AMI) and heart failure (HF):

1. The largest phase II trial of autologous, unfractionated cell therapy in acute myocardial infarction (AMI) (N Engl J Med, 2006) revealed a 2.5% increase in EF compared with the control group. The BAMI (effect of intracoronary reinfusion of bone marrow-derived mononuclear cells on all-cause mortality in AMI) trial is currently recruiting patients to determine effects of intracoronary bone marrow-derived mononuclear cells on clinical outcomes.
2. In attempts to improve cell therapy results, more specific cell types (i.e., mesenchymal stem cells, cardiac progenitor cells) or ex vivo modified cells have been tested in small trials; however, effects on cardiac function have been modest. Trials examining combinations of specific cell types are underway.
3. Cell retention in the heart is a major problem following cell administration. Potential strategies to improve retention include: a) adjunctive biomimetic materials with stem cells designed to enhance viability and engraftment; b) preconditioning of the heart tissue with shock wave treatment or transfer of genes that promote stem cell retention; and c) repetitive cell treatment.
4. “Off the shelf” allogeneic cell lines may serve as a much more practical approach to cell therapy. In a small study, allogeneic mesenchymal cells appeared as safe as autologous cells—larger trials are underway.
5. Although several systematic reviews/meta-analyses have suggested that cell therapy is beneficial, these methods are controversial and large-scale, blinded clinical trials are necessary to determine efficacy of cell therapy.
6. Patient populations that may receive the most benefit from cell therapy include those with ischemic HF/dilated cardiomyopathy. AMI may not be an optimal therapeutic target, as primary percutaneous coronary intervention for ST-segment elevation MI is widely utilized with consequent low rates of mortality and recurrent events.
7. Considering the lack of full understanding of cell-based therapies, there is ethical debate regarding whether clinical trials should proceed. This task force suggests that clinical trials should proceed given initial promising results—as long as patient safety is at the forefront of trial design.
8. Increased regulatory hurdles as well as complexity and cost of clinical trials have hampered progress in this field. Further regulatory refinement is needed to promote feasibility of widespread multicenter trials.
9. The ongoing BAMI trial is a phase III trial with 2-year follow-up that should provide a definitive answer regarding clinical benefits of cell therapy in AMI. Recruitment should be completed in October 2017.

Keywords: Acute Coronary Syndrome, Adult Stem Cells, Biomimetic Materials, Bone Marrow Cells, Cardiomyopathy, Dilated, Cell- and Tissue-Based Therapy, Heart Failure, Mesenchymal Stem Cells, Myocardial Infarction, Myocardial Ischemia, Percutaneous Coronary Intervention, Primary Prevention, Stem Cell Research

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