Long-Term Outcome of Combined (Percutaneous Intramyocardial and Intracoronary) Application of Autologous Bone Marrow Mononuclear Cells Post Myocardial Infarction: The 5-Year MYSTAR Study

Intravenously delivered mesenchymal stem cells prevent microvascular obstruction formation after myocardial ischemia/reperfusion injury

Microvascular obstruction (MVO) after primary percutaneous coronary intervention (pPCI) is identified as an independent risk factor for poor prognosis in patients with acute myocardial infarction (AMI). The inflammatory response induced by ischemia and reperfusion (I/R) injury is considered one of the main mechanisms of MVO. Mesenchymal stem cells (MSCs) are a unique stromal cell type that confers an immunomodulatory effect in cardiac disease. The present study aimed to investigate whether immediate intravenous delivery of MSCs could be used as a potential therapeutic method to attenuate MVO formation. A cardiac catheterization-induced porcine model of myocardial I/R injury was established, and allograft MSCs were immediately delivered intravenously. Cardiac magnetic resonance (CMR) imaging was performed on days 2 and 7 after the operation to determine the infarct area, MVO, and cardiac function. The pigs with allograft MSCs showed decreased MVO and infarct size, as well as an improved left ventricular ejection fraction (LVEF). Histological analysis revealed decreased myocyte area, fibrosis, and inflammatory cell infiltration in the peri-infarct zone of pigs with allograft MSCs. Moreover, the concentrations of interleukin-1β (IL-1β), interleukin-6 (IL-6) and C-reactive protein (CRP) in the serum were reduced in the allograft MSC group compared to the control group. Flow cytometry indicated decreased natural killer (NK) cells in the peripheral blood and ischemic heart tissue in the pigs with allograft MSCs. In summary, allograft MSCs delivered intravenously and immediately after myocardial I/R injury can attenuate MVO formation in a porcine model through a decline in the number of NK cells in the myocardium.

Rationale and design of a prospective, randomised study of retrograde application of bone marrow aspirate concentrate (BMAC) through coronary sinus in patients with congestive heart failure of ischemic etiology (the RETRO study)

Background

Heart failure (HF) is a major chronic illness and results in high morbidity and mortality. The most frequent cause of HF with reduced ejection fraction (HFREF) is coronary artery disease (CAD). Although revascularisation of ischemic myocardium lead to improvements in myocardial contractility and systolic function, it cannnot restore the viability of the already necrotic myocardium.

Methods/design

The aim of our prospective randomised study is to assess the efficacy of the retrograde application of non-selected bone marrow autologous cells concentrate (BMAC) in patients with HFREF of ischemic aetiology. The evaluated preparation is concentrated BMAC, obtained using Harvest SmartPReP2 (Harvest Technologies, Plymouth, MA, USA). The study population will be a total of 40 patients with established CAD, systolic dysfunction with LV EF of ≤40% and HF in the NYHA class 3. Patients have been on standard HF therapy for 3 months and in a stabilised state for at least 1 month, before enrolling in the clinical study. Patients will be randomised 1:1 to either retrograde BMAC administration via coronary sinus or standard HF therapy. The primary end-points (left ventricular end-systolic and end-diastolic diameters [LVESd/EDd] and volumes [LVESV/EDV] and left ventricular ejection fraction [LV EF]) will be assessed by magnetic resonance imaging. The follow-up period will be 12 month.

Discussion

The application of bone marrow stem cells into affected areas of the myocardium seems to be a promising treatment of ischemic cardiomyopathy.

The Harvest BMAC contains the entire population of nuclear cells from bone marrow aspirates together with platelets. The presence of both platelets and additional granulocytes can have a positive effect on the neovascularisation potential of the resulting concentrate. Our assumption is that retrograde administration on non-selected BMAC via coronary sinus, due to the content of platelets and growth factors, might improve left ventricular function and parameters compared to standard HF therapy. Furthermore, it will be associated with improved exercise tolerance in the six-minute corridor walk test and an improvement in the life quality of patients without increasing the incidence of severe ventricular arrythmias.

Trial registration

(ClinicalTrials.gov; https://clinicaltrials.gov; NCT03372954).

Therapeutic effects of adipose derived fresh stromal vascular fraction-containing stem cells versus cultured adipose derived mesenchymal stem cells on rescuing heart function in rat after acute myocardial infarction

We tested the hypothesis that adipose-derived fresh stromal vascular fraction (SVF) is non-inferior to conventional adipose-derived mesenchymal stem cell (ADMSC) therapy for improving left-ventricular ejection fraction (LVEF) in rat after acute myocardial infarction (AMI). Male-adult SD rats (n = 48) were categorized into group 1 (sham control), AMI, AMI + ADMSCs (1.2 × 10⁶) cells] and AMI + SVF (1.2 × 10⁶) cells]. Flow cytometric and qPCR analyses showed that the expressions of surface biomarkers for endothelial progenitor cells, and cardiac-stem cells were significantly higher in the SVF population than in the ADMSC population, whereas MSCs showed a reversed pattern between these two groups (all P < 0.001). By day-42 after AMI, LVEF was highest in SC, lowest in AMI, and significantly higher in AMI + SVF than in AMI + ADMSCs (P < 0.0001). Protein expression indicating angiogenesis, anti-inflammatory/anti-apoptotic, mitochondrial/bioenergy-integrity and antifibrotic biomarkers showed an identical pattern, whereas protein expressions for inflammatory, apoptotic and pressure-overload/heart failure biomarkers exhibited an opposite pattern to LVEF among the four groups (all P < 0.001). Histopathology displayed that LV infarction/fibrotic area/collagen-deposition areas, cellular expressions of DNA-damage, and inflammatory biomarkers exhibited an opposite pattern, whereas cellular expressions of endothelial/gap-junction biomarkers showed an identical pattern to LVEF among the four groups (all P < 0.0001). Cellular expression of angiogenesis biomarkers significantly and progressively increased from groups 1 to 4 (all P < 0.0001). In conclusion, SVF may be better than ADMSC at improving LVEF in rat after AMI.