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Autologous cardiosphere-derived cells (CDCs) were the first therapeutic modality to demonstrate myocardial regeneration with a decrease in scar size and an increase in viable, functional tissue. Widespread applicability of autologous CDC therapy is limited by the need for patient-specific myocardial biopsy, cell processing, and quality control, resulting in delays to therapy and inherent logistical and economic constraints. Preclinical data had demonstrated equivalent efficiency of allogeneic to autologous CDCs. The ALLogeneic Heart STem Cells to Achieve Myocardial Regeneration (ALLSTAR) trial is a multicenter randomized, double-blind, placebo-controlled phase 1/2 safety and efficacy trial of intracoronary delivery of allogeneic CDCs (CAP-1002) in patients with myocardial infarction (MI) and ischemic left ventricular dysfunction. The phase 1 safety cohort enrolled 14 patients in an open-label, nonrandomized, dose-escalation safety trial. The phase 2 trial is a doubleblind, randomized, placebo-controlled trial that will compare intracoronary CDCs to placebo in a 2:1 allocation and will enroll up to 120 patients. The primary endpoint for both phases is safety at 1 month. For phase 2, the primary efficacy endpoint is relative change from baseline in infarct size at 12 months, as assessed by magnetic resonance imaging. The ALLSTAR trial employs a “seamless” WOVE 1 design that enables continuous enrollment from phase 1 to phase 2 and will evaluate the safety of intracoronary administration of allogeneic CDCs and its efficacy in decreasing infarct size in post-MI patients.

An increasing number of patients have refractory angina despite optimal medical therapy and are without further revascularization options. Preclinical studies indicate that human CD34 + stem cells can stimulate new blood vessel formation in ischemic myocardium, improving perfusion and function. In ACT34-CMI ( N = 167), patients treated with autologous CD34 + stem cells had improvements in angina and exercise time at 6 and 12 months compared to placebo; however, the longer-term effects of this treatment are unknown. ACT34 was a phase II randomized, double-blind, placebo-controlled clinical trial comparing placebo, low dose (1 × 10 5 CD34/kg body weight), and high dose (5 × 10 5 CD34/kg) using intramyocardial delivery into the ischemic zone following NOGA ® mapping. To obtain longer-term safety and efficacy in these patients, we compiled data of major adverse cardiac events (MACE; death, myocardial infarction, acute coronary syndrome, or heart failure hospitalization) up to 24 months as well as angina and quality of life assessments in patients who consented for 24-month follow-up. A total of 167 patients with class III–IV refractory angina were randomized and completed the injection procedure. The low-dose-treated patients had a significant reduction in angina frequency ( p = 0.02, 0.035) and improvements in exercise tolerance testing (ETT) time ( p = 0.014, 0.017) compared to the placebo group at 6 and 12 months. At 24 months, patients treated with both low-and high-dose CD34 + cells had significant reduction in angina frequency ( p = 0.03). At 24 months, there were a total of seven deaths (12.5%) in the control group versus one (1.8%) in the low-dose and two (3.6%) in the high-dose ( p = 0.08) groups. At 2 years, MACE occurred at a rate of 33.9%, 21.8%, and 16.2% in control, low-, and high-dose patients, respectively ( p = 0.08). Autologous CD34 + cell therapy was associated with persistent improvement in angina at 2 years and a trend for reduction in mortality in no-option patients with refractory angina.

In the current study, we sought to identify bone marrow-derived mononuclear cell (BM-MNC) subpopulations associated with a combined improvement in left ventricular ejection fraction (LVEF), left ventricular end-systolic volume (LVESV), and maximal oxygen consumption (VO 2 max) in patients with chronic ischemic cardiomyopathy 6 months after receiving transendocardial injections of autologous BM-MNCs or placebo. For this prospectively planned analysis, we conducted an embedded cohort study comprising 78 patients from the FOCUS-Cardiovascular Cell Therapy Research Network (CCTRN) trial. Baseline BM-MNC immunophenotypes and progenitor cell activity were determined by flow cytometry and colony-forming assays, respectively. Previously stable patients who demonstrated improvement in LVEF, LVESV, and VO 2 max during the 6-month course of the FOCUS-CCTRN study (group 1, n = 17) were compared to those who showed no change or worsened in one to three of these endpoints (group 2, n = 61) and to a subset of patients from group 2 who declined in all three functional endpoints (group 2A, n = 11). Group 1 had higher frequencies of B-cell and CXCR4 + BM-MNC subpopulations at study baseline than group 2 or 2A. Furthermore, patients in group 1 had fewer endothelial colony-forming cells and monocytes/macrophages in their bone marrow than those in group 2A. To our knowledge, this is the first study to show that in patients with ischemic cardiomyopathy, certain bone marrow-derived cell subsets are associated with improvement in LVEF, LVESV, and VO 2 max at 6 months. These results suggest that the presence of both progenitor and immune cell populations in the bone marrow may influence the natural history of chronic ischemic cardiomyopathy—even in stable patients. Thus, it may be important to consider the bone marrow composition and associated regenerative capacity of patients when assigning them to treatment groups and evaluating the results of cell therapy trials.