Delayed administration of allogeneic cardiac stem cell therapy for acute myocardial infarction could ameliorate adverse remodeling: experimental study in swine

Induced Pluripotent Stem Cell-Derived Cardiomyocytes Therapy for Ischemic Heart Disease in Animal Model: A Meta-Analysis

Ischemic heart disease (IHD) poses a significant challenge in cardiovascular health, with current treatments showing limited success. Induced pluripotent derived-cardiomyocyte (iPSC-CM) therapy within regenerative medicine offers potential for IHD patients, although its clinical impacts remain uncertain. This study utilizes meta-analysis to assess iPSC-CM outcomes in terms of efficacy and safety in IHD animal model studies. A meta-analysis encompassing PUBMED, ScienceDirect, Web of Science, and the Cochrane Library databases, from inception until October 2023, investigated iPSC therapy effects on cardiac function and safety outcomes. Among 51 eligible studies involving 1012 animals, despite substantial heterogeneity, the iPSC-CM transplantation improved left ventricular ejection fraction (LVEF) by 8.23% (95% CI, 7.15 to 9.32%; p < 0.001) compared to control groups. Additionally, cell-based treatment reduced the left ventricle fibrosis area and showed a tendency to reduce left ventricular end-systolic volume (LVESV) and end-diastolic volume (LVEDV). No significant differences emerged in mortality and arrhythmia risk between iPSC-CM treatment and control groups. In conclusion, this meta-analysis indicates iPSC-CM therapy's promise as a safe and beneficial intervention for enhancing heart function in IHD. However, due to observed heterogeneity, the efficacy of this treatment must be further explored through large randomized controlled trials based on rigorous research design.

Cardiac Progenitor Cell Exosomal miR-935 Protects against Oxidative Stress

Oxidative stress-induced myocardial apoptosis and necrosis are critically involved in ischemic infarction, and several sources of extracellular vesicles appear to be enriched in therapeutic activities. The central objective was to identify and validate the differential exosome miRNA repertoire in human cardiac progenitor cells (CPC). CPC exosomes were first analyzed by LC-MS/MS and compared by RNAseq with exomes of human mesenchymal stromal cells and human fibroblasts to define their differential exosome miRNA repertoire (exo-miRSEL). Proteomics demonstrated a highly significant representation of cardiovascular development functions and angiogenesis in CPC exosomes, and RNAseq analysis yielded about 350 different miRNAs; among the exo-miRSEL population, miR-935 was confirmed as the miRNA most significantly up-regulated; interestingly, miR-935 was also found to be preferentially expressed in mouse primary cardiac Bmi1+high CPC, a population highly enriched in progenitors. Furthermore, it was found that transfection of an miR-935 antagomiR combined with oxidative stress treatment provoked a significant increment both in apoptotic and necrotic populations, whereas transfection of a miR-935 mimic did not modify the response. Conclusion. miR-935 is a highly differentially expressed miRNA in exo-miRSEL, and its expression reduction promotes oxidative stress-associated apoptosis. MiR-935, together with other exosomal miRNA members, could counteract oxidative stress-related apoptosis, at least in CPC surroundings.

Recapitulating porcine cardiac development in vitro: from expanded potential stem cell to embryo culture models

Domestic pigs (Sus scrofa) share many genetic, anatomical, and physiological traits with humans and therefore constitute an excellent preclinical animal model. Fundamental understanding of the cellular and molecular processes governing early porcine cardiogenesis is critical for developing advanced porcine models used for the study of heart diseases and new regenerative therapies. Here, we provide a detailed characterization of porcine cardiogenesis based on fetal porcine hearts at various developmental stages and cardiac cells derived from porcine expanded pluripotent stem cells (pEPSCs), i.e., stem cells having the potential to give rise to both embryonic and extraembryonic tissue. We notably demonstrate for the first time that pEPSCs can differentiate into cardiovascular progenitor cells (CPCs), functional cardiomyocytes (CMs), epicardial cells and epicardial-derived cells (EPDCs) in vitro. Furthermore, we present an enhanced system for whole-embryo culture which allows continuous ex utero development of porcine post-implantation embryos from the cardiac crescent stage (ED14) up to the cardiac looping (ED17) stage. These new techniques provide a versatile platform for studying porcine cardiac development and disease modeling.

Transcriptome Profile Reveals Differences between Remote and Ischemic Myocardium after Acute Myocardial Infarction in a Swine Model

Acute myocardial infarction (AMI) is the consequence of an acute interruption of myocardial blood flow delimiting an area with ischemic necrosis. The loss of cardiomyocytes initiates cardiac remodeling in the myocardium, leading to molecular changes in an attempt to recover myocardial function. The purpose of this study was to unravel the differences in the molecular profile between ischemic and remote myocardium after AMI in an experimental model. To mimic human myocardial infarction, healthy pigs were subjected to occlusion of the mid-left anterior descending coronary artery, and myocardial tissue was collected from ischemic and remote zones for omics techniques. Comparative transcriptome analysis of both areas was accurately validated by proteomic analysis, resulting in mitochondrion-related biological processes being the most impaired mechanisms in the infarcted area. Moreover, Immune system process-related genes were up-regulated in the remote tissue, mainly due to the increase of neutrophil migration in this area. These results provide valuable information regarding differentially expressed genes and their biological functions between ischemic and remote myocardium after AMI, which could be useful for establishing therapeutic targets for the development of new treatments.

Intracoronary Administration of Microencapsulated HGF in a Reperfused Myocardial Infarction Swine Model

Therapy microencapsulation allows minimally invasive, safe, and effective administration. Hepatocyte growth factor (HGF) has angiogenic, anti-inflammatory, anti-apoptotic, and anti-fibrotic properties. Our objective was to evaluate the cardiac safety and effectiveness of intracoronary (IC) administration of HGF-loaded extended release microspheres in an acute myocardial infarction (AMI) swine model. An IC infusion of 5 × 106 HGF-loaded microspheres (MS+HGF, n = 7), 5 × 106 placebo microspheres (MS, n = 7), or saline (SAL, n = 7) was performed two days after AMI. TIMI flow and Troponin I (TnI) values were assessed pre- and post-treatment. Cardiac function was evaluated with magnetic resonance imaging (cMR) before injection and at 10 weeks. Plasma cytokines were determined to evaluate the inflammatory profile and hearts were subjected to histopathological evaluation. Post-treatment coronary flow was impaired in five animals (MS+HGF and MS group) without significant increases in TnI. One animal (MS group) died during treatment. There were no significant differences between groups in cMR parameters at any time (p > 0.05). No statistically significant changes were found between groups neither in cytokines nor in histological analyses. The IC administration of 5 × 106 HGF-loaded-microspheres 48 h post-AMI did not improve cardiac function, nor did it decrease inflammation or cardiac fibrosis in this experimental setting.

Intrapericardial cardiosphere-derived cells hinder epicardial dense scar expansion and promote electrical homogeneity in a porcine post-infarction model

The arrhythmic substrate of ventricular tachycardias in many structural heart diseases is located in the epicardium, often resulting in poor outcomes with currently available therapies. Cardiosphere-derived cells (CDCs) have been shown to modify myocardial scarring. A total of 19 Large White pigs were infarcted by occlusion of the mid-left anterior descending coronary artery for 150 min. Baseline cardiac magnetic resonance (CMR) imaging with late gadolinium enhancement sequences was obtained 4 weeks post-infarction and pigs were randomized to a treatment group (intrapericardial administration of 300,000 allogeneic CDCs/kg), (n = 10) and to a control group (n = 9). A second CMR and high-density endocardial electroanatomical mapping were performed at 16 weeks post-infarction. After the electrophysiological study, pigs were sacrificed and epicardial optical mapping and histological studies of the heterogeneous tissue of the endocardial and epicardial scars were performed. In comparison with control conditions, intrapericardial CDCs reduced the growth of epicardial dense scar and epicardial electrical heterogeneity. The relative differences in conduction velocity and action potential duration between healthy myocardium and heterogeneous tissue were significantly smaller in the CDC-treated group than in the control group. The lower electrical heterogeneity coincides with heterogeneous tissue with less fibrosis, better cardiomyocyte viability, and a greater quantity and better polarity of connexin 43. At the endocardial level, no differences were detected between groups. Intrapericardial CDCs produce anatomical and functional changes in the epicardial arrhythmic substrate, which could have an anti-arrhythmic effect.

Intrapericardial Administration of Secretomes from Menstrual Blood-Derived Mesenchymal Stromal Cells: Effects on Immune-Related Genes in a Porcine Model of Myocardial Infarction

Acute myocardial infarction (AMI) is a manifestation of ischemic heart disease where the immune system plays an important role in the re-establishment of homeostasis. We hypothesize that the anti-inflammatory activity of secretomes from menstrual blood-derived mesenchymal stromal cells (S-MenSCs) and IFNγ/TNFα-primed MenSCs (S-MenSCs*) may be considered a therapeutic option for the treatment of AMI. To assess this hypothesis, we have evaluated the effect of S-MenSCs and S-MenSCs* on cardiac function parameters and the involvement of immune-related genes using a porcine model of AMI. Twelve pigs were randomly divided into three biogroups: AMI/Placebo, AMI/S-MenSCs, and AMI/S-MenSCs*. AMI models were generated using a closed chest coronary occlusion-reperfusion procedure and, after 72 h, the different treatments were intrapericardially administered. Cardiac function parameters were monitored by magnetic resonance imaging before and 7 days post-therapy. Transcriptomic analyses in the infarcted tissue identified 571 transcripts associated with the Gene Ontology term Immune response, of which 57 were differentially expressed when different biogroups were compared. Moreover, a prediction of the interactions between differentially expressed genes (DEGs) and miRNAs from secretomes revealed that some DEGs in the infarction area, such as STAT3, IGFR1, or BCL6 could be targeted by previously identified miRNAs in secretomes from MenSCs. In conclusion, the intrapericardial administration of secretome early after infarction has a significant impact on the expression of immune-related genes in the infarcted myocardium. This confirms the immunomodulatory potential of intrapericardially delivered secretomes and opens new therapeutic perspectives in myocardial infarction treatment.

Efficacy of Stem Cell Therapy in Large Animal Models of Ischemic Cardiomyopathies: A Systematic Review and Meta-Analysis

Stem-cell therapy provides a promising strategy for patients with ischemic heart disease. In recent years, numerous studies related to this therapeutic approach were performed; however, the results were often heterogeneous and contradictory. For this reason, we conducted a systematic review and meta-analysis of trials, reporting the use of stem-cell treatment against acute or chronic ischemic cardiomyopathies in large animal models with regard to Left Ventricular Ejection Fraction (LVEF). The defined research strategy was applied to the PubMed database to identify relevant studies published from January 2011 to July 2021. A random-effect meta-analysis was performed on LVEF mean data at follow-up between control and stem-cell-treated animals. In order to improve the definition of the effect measure and to analyze the factors that could influence the outcomes, a subgroup comparison was conducted. Sixty-six studies (n = 1183 animals) satisfied our inclusion criteria. Ischemia/reperfusion infarction was performed in 37 studies, and chronic occlusion in 29 studies; moreover, 58 studies were on a pig animal model. The meta-analysis showed that cell therapy increased LVEF by 7.41% (95% Confidence Interval 6.23−8.59%; p < 0.001) at follow-up, with significative heterogeneity and high inconsistency (I2 = 82%, p < 0.001). By subgroup comparison, the follow-up after 31−60 days (p = 0.025), the late cell injection (>7 days, p = 0.005) and the route of cellular delivery by surgical treatment (p < 0.001) were significant predictors of LVEF improvement. This meta-analysis showed that stem-cell therapy may improve heart function in large animal models and that the swine specie is confirmed as a relevant animal model in the cardiovascular field. Due to the significative heterogeneity and high inconsistency, future translational studies should be designed to take into account the evidenced predictors to allow for the reduction of the number of animals used.

Comparative proteomic analysis of nuclear and cytoplasmic compartments in human cardiac progenitor cells

Clinical trials evaluating cardiac progenitor cells (CPC) demonstrated feasibility and safety, but no clear functional benefits. Therefore a deeper understanding of CPC biology is warranted to inform strategies capable to enhance their therapeutic potential. Here we have defined, using a label-free proteomic approach, the differential cytoplasmic and nuclear compartments of human CPC (hCPC). Global analysis of cytoplasmic repertoire in hCPC suggested an important hypoxia response capacity and active collagen metabolism. In addition, comparative analysis of the nuclear protein compartment identified a significant regulation of a small number of proteins in hCPC versus human mesenchymal stem cells (hMSC). Two proteins significantly upregulated in the hCPC nuclear compartment, IL1A and IMP3, showed also a parallel increase in mRNA expression in hCPC versus hMSC, and were studied further. IL1A, subjected to an important post-transcriptional regulation, was demonstrated to act as a dual-function cytokine with a plausible role in apoptosis regulation. The knockdown of the mRNA binding protein (IMP3) did not negatively impact hCPC viability, but reduced their proliferation and migration capacity. Analysis of a panel of putative candidate genes identified HMGA2 and PTPRF as IMP3 targets in hCPC. Therefore, they are potentially involved in hCPC proliferation/migration regulation.

The epicardial delivery of cardiosphere derived cells or their extracellular vesicles is safe but of limited value in experimental infarction

The epicardial administration of therapeutics via the pericardial sac offers an attractive route, since it is minimally invasive and carries no risks of coronary embolization. The aim of this study was to assess viability, safety and effectiveness of cardiosphere-derived cells (CDCs), their extracellular vesicles (EVs) or placebo administered via a mini-thoracotomy 72 h after experimental infarction in swine. The epicardial administration was completed successfully in all cases in a surgery time (knife-to-skin) below 30 min. No significant differences between groups were found in cardiac function parameters evaluated using magnetic resonance imaging before therapy and at the end of the study, despite a trend towards improved function in CDC-treated animals. Moreover, infarct size at 10 weeks was smaller in treated animals, albeit not significantly. Arrhythmia inducibility did not differ between groups. Pathological examination showed no differences, nor were there any pericardial adhesions evidenced in any case 10 weeks after surgery. These results show that the epicardial delivery of CDCs or their EVs is safe and technically easy 3 days after experimental myocardial infarction in swine, but it does not appear to have any beneficial effect on cardiac function. Our results do not support clinical translation of these therapies as implemented in this work.

Intrapericardial Delivery of APA-Microcapsules as Promising Stem Cell Therapy Carriers in an Experimental Acute Myocardial Infarction Model

The administration of cardiosphere-derived cells (CDCs) after acute myocardial infarction (AMI) is very promising. CDC encapsulation in alginate-poly-l-lysine-alginate (APA) could increase cell survival and adherence. The intrapericardial (IP) approach potentially achieves high concentrations of the therapeutic agent in the infarcted area. We aimed to evaluate IP therapy using a saline vehicle as a control (CON), a dose of 30 × 106 CDCs (CDCs) or APA microcapsules containing 30 × 106 CDCs (APA-CDCs) at 72 h in a porcine AMI model. Magnetic resonance imaging (MRI) was used to determine the left ventricular ejection fraction (LVEF), infarct size (IS), and indexed end diastolic and systolic volumes (EDVi; ESVi) pre- and 10 weeks post-injection. Programmed electrical stimulation (PES) was performed to test arrhythmia inducibility before euthanasia. Histopathological analysis was carried out afterwards. The IP infusion was successful in all animals. At 10 weeks, MRI revealed significantly higher LVEF in the APA-CDC group compared with CON. No significant differences were observed among groups in IS, EDVi, ESVi, PES and histopathological analyses. In conclusion, the IP injection of CDCs (microencapsulated or not) was feasible and safe 72 h post-AMI in the porcine model. Moreover, CDCs APA encapsulation could have a beneficial effect on cardiac function, reflected by a higher LVEF at 10 weeks.

Intracoronary Delivery of Porcine Cardiac Progenitor Cells Overexpressing IGF-1 and HGF in a Pig Model of Sub-Acute Myocardial Infarction

Human cardiac progenitor cells (hCPC) are considered a good candidate in cell therapy for ischemic heart disease, demonstrating capacity to improve functional recovery after myocardial infarction (MI), both in small and large preclinical animal models. However, improvements are required in terms of cell engraftment and efficacy. Based on previously published reports, insulin-growth factor 1 (IGF-1) and hepatocyte growth factor (HGF) have demonstrated substantial cardioprotective, repair and regeneration activities, so they are good candidates to be evaluated in large animal model of MI. We have validated porcine cardiac progenitor cells (pCPC) and lentiviral vectors to overexpress IGF-1 (co-expressing eGFP) and HGF (co-expressing mCherry). pCPC were transduced and IGF1-eGFP^pos and HGF-mCherry^pos populations were purified by cell sorting and further expanded. Overexpression of IGF-1 has a limited impact on pCPC expression profile, whereas results indicated that pCPC-HGF-mCherry cultures could be counter selecting high expresser cells. In addition, pCPC-IGF1-eGFP showed a higher cardiogenic response, evaluated in co-cultures with decellularized extracellular matrix, compared with native pCPC or pCPC-HGF-mCherry. In vivo intracoronary co-administration of pCPC-IGF1-eGFP and pCPC-HFG-mCherry (1:1; 40 × 10⁶/animal), one week after the induction of an MI model in swine, revealed no significant improvement in cardiac function.

The Intrapericardial Delivery of Extracellular Vesicles from Cardiosphere-Derived Cells Stimulates M2 Polarization during the Acute Phase of Porcine Myocardial Infarction

Acute myocardial infarction triggers a strong inflammatory response in the affected cardiac tissue. New therapeutic tools based on stem cell therapy may modulate the unbalanced inflammation in the damaged cardiac tissue, contributing to the resolution of this pathological condition. The main goal of this study was to analyze the immunomodulatory effects of cardiosphere-derived cells (CDCs) and their extracellular vesicles (EV-CDCs), delivered by intrapericardial administration in a clinically relevant animal model, during the initial pro-inflammatory phase of an induced myocardial infarction. This effect was assessed in peripheral blood and pericardial fluid leukocytes from infarcted animals. Additionally, cardiac functional parameters, troponin I, hematological and biochemical components were also analyzed to characterize myocardial infarction-induced changes, as well as the safety aspects of these procedures. Our preclinical study demonstrated a successful myocardial infarction induction in all animals, without any reported adverse effect related to the intrapericardial administration of CDCs or EV-CDCs. Significant changes were observed in biochemical and immunological parameters after myocardial infarction. The analysis of peripheral blood leukocytes revealed an increase of M2 monocytes in the EV-CDCs group, while no differences were reported in other lymphocyte subsets. Moreover, arginase-1 (M2-differentiation marker) was significantly increased in pericardial fluids 24 h after EV-CDCs administration. In summary, we demonstrate that, in our experimental conditions, intrapericardially administered EV-CDCs have an immunomodulatory effect on monocyte polarization, showing a beneficial effect for counteracting an unbalanced inflammatory reaction in the acute phase of myocardial infarction. These M2 monocytes have been defined as “pro-regenerative cells” with a pro-angiogenic and anti-inflammatory activity.

Delivery of cardiovascular progenitors with biomimetic microcarriers reduces adverse ventricular remodeling in a rat model of chronic myocardial infarction

Despite tremendous progress in cell-based therapies for heart repair, many challenges still exist. To enhance the therapeutic potential of cell therapy one approach is the combination of cells with biomaterial delivery vehicles. Here, we developed a biomimetic and biodegradable micro-platform based on polymeric microparticles (MPs) capable of maximizing the therapeutic potential of cardiac progenitor cells (CPCs) and explored its efficacy in a rat model of chronic myocardial infarction. The transplantation of CPCs adhered to MPs within the infarcted myocardial microenvironment improved the long-term engraftment of transplanted cells for up to one month. Furthermore, the enhancement of cardiac cellular retention correlated with an increase in functional recovery. In consonance, better tissue remodeling and vasculogenesis were observed in the animals treated with cells attached to MPs, which presented smaller infarct size, thicker right ventricular free wall, fewer deposition of periostin and greater density of vessels than animals treated with CPCs alone. Finally, we were able to show that part of this beneficial effect was mediated by CPC-derived extracellular vesicles (EVs). Taken together, these findings indicate that the biomimetic microcarriers support stem cell survival and increase cardiac function in chronic myocardial infarction through modulation of cardiac remodeling, vasculogenesis and CPCs-EVs mediated therapeutic effects. The biomimetic microcarriers provide a solution for biomaterial-assisted CPC delivery to the heart. STATEMENT OF SIGNIFICANCE: In this study, we evaluate the possibility of using a biomimetic and biodegradable micro-platform to improve cardiovascular progenitor therapy. The strategy reported herein serves as an injectable scaffold for adherent cells due to their excellent injectability through cardiac catheters, capacity for biomimetic three-dimensional stem cell support and controllable biodegradability. In a rat model of chronic myocardial infarction, the biomimetic microcarriers improved cardiac function, reduced chronic cardiac remodeling and increased vasculogenesis through the paracrine signaling of CPCs. We have also shown that extracellular vesicles derived from CPCs cultured on biomimetic substrates display antifibrotic effects, playing an important role in the therapeutic effects of our tissue-engineered approach. Therefore, biomimetic microcarriers represent a promising and effective strategy for biomaterial-assisted CPC delivery to the heart.

Intracoronary Administration of Allogeneic Cardiosphere-Derived Cells Immediately Prior to Reperfusion in Pigs With Acute Myocardial Infarction Reduces Infarct Size and Attenuates Adverse Cardiac Remodeling

BACKGROUND

Allogeneic cardiosphere-derived cells (CDCs) exert cardioprotective effects when administered intracoronarily after reperfusion in animal models of acute myocardial infarction (AMI). The "no-reflow" phenomenon develops rapidly post-reperfusion and may undermine the efficacy of cell therapy, due to poor cell delivery in areas of microvascular obstruction (MVO). We hypothesized that CDC-induced cardioprotection would be enhanced by cell administration prior to reperfusion, when microvasculature is still relatively intact, to facilitate widespread cell delivery within the ischemic area.

METHODS AND RESULTS

We studied 81 farm pigs; 55 completed the specified protocols. A dose-optimization study in infarcted pigs demonstrated that the doses of 5 million and 10 million CDCs are the maximum safe doses that can be administered intracoronarily at 5 minutes prior to and at 5 minutes post-reperfusion, respectively, without aggravating MVO. Quantification of acute cell retention by polymerase chain reaction demonstrated that cell delivery prior to reperfusion resulted in higher cardiac cell retention compared to delivery post-reperfusion. We then performed a randomized, placebo-controlled study to assess the long-term efficacy of intracoronary infusion of 5 million allogeneic CDCs, delivered at 5 minutes prior to reperfusion, in a porcine model of AMI. The CDC therapy resulted in decreased scar size, improved regional systolic function, and attenuation of adverse cardiac remodeling (manifested as preserved global systolic function, preserved end-systolic volume, and decreased interstitial fibrosis) compared to placebo at 30 days post-MI.

CONCLUSIONS

Dose-optimized intracoronary infusion of allogeneic CDCs prior to reperfusion in a porcine model of AMI is feasible, safe and confers long-term benefits.

Plasmatic Membrane Expression of Adhesion Molecules in Human Cardiac Progenitor/Stem Cells Might Explain Their Superior Cell Engraftment after Cell Transplantation

Human bone marrow mesenchymal stem cells (BM-MSCs) and cardiac progenitor/stem cells (CPCs) have been extensively studied as a potential therapeutic treatment for myocardial infarction (MI). Previous reports suggest that lower doses of CPCs are needed to improve cardiac function relative to their bone marrow counterparts. Here, we confirmed this observations and investigated the surface protein expression profile that might explain this effect. Myocardial infarction was performed in nude rats by permanent ligation of the left coronary artery. Cardiac function and infarct size before and after cell transplantation were evaluated by echocardiography and morphometry, respectively. The CPC and BM-MSC receptome were analyzed by proteomic analysis of biotin-labeled surface proteins. Rats transplanted with CPCs showed a greater improvement in cardiac function after MI than those transplanted with BM-MSCs, and this was associated with a smaller infarct size. Analysis of the receptome of CPCs and BM-MSCs showed that gene ontology biological processes and KEGG pathways associated with adhesion mechanisms were upregulated in CPCs compared with BM-MSCs. Moreover, the membrane protein interactome in CPCs showed a strong relationship with biological processes related to cell adhesion whereas the BM-MSCs interactome was more related to immune regulation processes. We conclude that the stronger capacity of CPCs over BM-MSCs to engraft in the infarcted area is likely linked to a more pronounced cell adhesion expression program.

Anesthesia Protocols used to Create Ischemia Reperfusion Myocardial Infarcts in Swine

The porcine ischemia-reperfusion model is one of the most commonly used for cardiology research and for testing interventions for myocardial regeneration. In creating ischemic reperfusion injury, the anesthetic protocol is important for assuring hemodynamic stability of the animal during the induction of the experimental lesion and may affect its postoperative survival. This paper reviews the many drugs and anesthetic protocols used in recent studies involving porcine models of ischemiareperfusion injury. The paper also summarizes the most important characteristics of some commonly used anesthetic drugs. Literature was selected for inclusion in this review if the authors described the anesthetic protocol used and also reported the mortality rate attributed to the creation of the model. This information is an important consideration because the anesthetic protocol can influence hemodynamic stability during the experimental induction of an acute myocardial infarction, thereby impacting the survival rate and affecting the number of animals needed for each study.

Safety and efficacy of cell therapies in pediatric heart disease: a systematic review and meta-analysis

BACKGROUND

Adult clinical trials have reported safety and the therapeutic potential of stem cells for cardiac disease. These observations have now translated to the pediatric arena. We conducted a meta-analysis to assess safety and efficacy of cell-based therapies in animal and human studies of pediatric heart disease.

METHODS AND RESULTS

A literature search was conducted to examine the effects of cell-based therapies on: (i) safety and (ii) cardiac function. In total, 18 pre-clinical and 13 human studies were included. Pre-clinical: right ventricular dysfunction was the most common animal model (80%). Cardiac-derived (28%) and umbilical cord blood (24%) cells were delivered intravenously (36%) or intramyocardially (35%). Mortality was similar between cell-based and control groups (OR 0.94; 95% CI 0.05, 17.41). Cell-based treatments preserved ejection fraction by 6.9% (p < 0.01), while intramyocardial at a dose of 1-10 M cells/kg optimized ejection fraction. Clinical: single ventricle physiology was the most common cardiac disease (n = 9). Cardiac tissue was a frequent cell source, dosed from 3.0 × 105 to 2.4 × 107 cells/kg. A decrease in adverse events occurred in the cell-based cohort (OR 0.17, p < 0.01). Administration of cell-based therapies improved ejection fraction (MD 4.84; 95% CI 1.62, 8.07; p < 0.01).

CONCLUSIONS

In this meta-analysis, cell-based therapies were safe and improved specific measures of cardiac function. Implications from this review may provide methodologic recommendations (source, dose, route, timing) for future clinical trials. Of note, many of the results described in this study pattern those seen in adult stem cell reviews and meta-analyses.

The Immunomodulatory Signature of Extracellular Vesicles From Cardiosphere-Derived Cells: A Proteomic and miRNA Profiling

Experimental data demonstrated that the regenerative potential and immunomodulatory capacity of cardiosphere-derived cells (CDCs) is mediated by paracrine mechanisms. In this process, extracellular vesicles derived from CDCs (EV-CDCs) are key mediators of their therapeutic effect. Considering the future applicability of these vesicles in human diseases, an accurate preclinical-to-clinical translation is needed, as well as an exhaustive molecular characterization of animal-derived therapeutic products. Based on that, the main goal of this study was to perform a comprehensive characterization of proteins and miRNAs in extracellular vesicles from porcine CDCs as a clinically relevant animal model. The analysis was performed by identification and quantification of proteins and miRNA expression profiles. Our results revealed the presence of clusters of immune-related and cardiac-related molecular biomarkers in EV-CDCs. Additionally, considering that priming stem cells with inflammatory stimuli may increase the therapeutic potential of released vesicles, here we studied the dynamic changes that occur in the extracellular vesicles from IFNγ-primed CDCs. These analyses detected statistically significant changes in several miRNAs and proteins. Notably, the increase in interleukin 6 (IL6) protein, as well as the increase in mir-125b (that targets IL6 receptor) was especially relevant. These results suggest a potential involvement of EV-CDCs in the regulation of the IL6/IL6R axis, with implications in inflammatory-mediated diseases.

Microencapsulated Insulin-Like Growth Factor-1 therapy improves cardiac function and reduces fibrosis in a porcine acute myocardial infarction model

Insulin-like growth factor-1 (IGF-1) has demonstrated beneficial effects after myocardial infarction (MI). Microencapsulation of IGF-1 could potentially improve results. We aimed to test the effect of an intracoronary (IC) infusion of microencapsulated IGF-1 in a swine acute MI model. For that purpose IC injection of a 10 ml solution of 5 × 106 IGF-1 loaded microspheres (MSPs) (n = 8, IGF-1 MSPs), 5 × 106 unloaded MSPs (n = 9; MSPs) or saline (n = 7; CON) was performed 48 hours post-MI. Left ventricular ejection fraction (LVEF), indexed ventricular volumes and infarct size (IS) were determined by cardiac magnetic resonance at pre-injection and 10 weeks. Animals were euthanized at 10 weeks, and myocardial fibrosis and vascular density were analysed. End-study LVEF was significantly greater in IGF-1 MSPs compared to MSPs and CON, while ventricular volumes exhibited no significant differences between groups. IS decreased over time in all groups. Collagen volume fraction on the infarct area was significantly reduced in IGF-1 MSPs compared to CON and MSPs. Vascular density analysis of infarct and border zones showed no significant differences between groups. In conclusion, the IC injection of 5 × 106 IGF-1 loaded MSPs in a porcine acute MI model successfully improves cardiac function and limits myocardial fibrosis, which could be clinically relevant.

Pentoxifylline alleviated cardiac injury via modulating the cardiac expression of lncRNA-00654-miR-133a-SOX5 mRNA in the rat model of ischemia-reperfusion

Pentoxifylline (PTX) protects from many cardiovascular complications. It plays a critical role in stem cell proliferation and differentiation. Here, the effect of PTX administration on cardiac ischemia and dysfunction was explored. PTX in 3 doses (20, 30, and 40 mg/kg), was administered in vivo 5 min before a 45 min occlusion of the left anterior descending artery, followed by a 120 min reperfusion in male Wistar rats. The left ventricular end-diastolic pressure and dP/dt_max were assessed. Blood and cardiac tissue samples were collected for measuring the levels of cardiac enzymes and the expression of lncRNA-00654-miR-133a-SOX5. Samples of left ventricles were collected and processed for light microscopic, immunohistochemical staining for c-kit (a marker for cardiac progenitor cells) and transmission electron microscopic examination. PTX administration showed improvements in cardiac function tests, enzymes, and myocytes. Microscopic features showed minimal cardiac edema, hemorrhage, cellular inflammatory infiltration and fibrosis in addition to increased c-kit + cells in cardiac tissue samples. Notably, this treatment also produced a dose-dependent decrease in lncRNA-00654 with an increase in SOX5 mRNA and miRNA-133a-3p expressions. In conclusion, PTX has the potential to alleviate cardiac injury and increase the number of c-kit + cells following ischemia-reperfusion in the rat model via modulation of lncRNA-00654 and miR-133a-SOX5 mRNA expressions.

Bioreactor-based 3D human myocardial ischemia/reperfusion in vitro model: a novel tool to unveil key paracrine factors upon acute myocardial infarction

During acute myocardial infarction (AMI), Ischemia/Reperfusion (I/R) injury causes cardiomyocyte (CM) death and loss of tissue function, making AMI one of the major causes of death worldwide. Cell-based in vitro models of I/R injury have been increasingly used as a complementary approach to preclinical research. However, most approaches use murine cells in 2D culture setups, which are not able to recapitulate human cellular physiology, as well as nutrient and gas gradients occurring in the myocardium. In this work we established a novel human in vitro model of myocardial I/R injury using CMs derived from human induced pluripotent stem cells (hiPSC-CMs), which were cultured as 3D aggregates in stirred tank bioreactors. We were able to recapitulate important hallmarks of AMI, including loss of CM viability with disruption of cellular ultrastructure, increased angiogenic potential, and secretion of key proangiogenic and proinflammatory cytokines. Conditioned medium was further used to probe human cardiac progenitor cells (hCPCs) response to paracrine cues from injured hiPSC-CMs through quantitative whole proteome analysis (SWATH-MS). I/R injury hiPSC-CM conditioned media incubation caused upregulation of hCPC proteins associated with migration, proliferation, paracrine signaling, and stress response-related pathways, when compared to the control media incubation. Our results indicate that the model developed herein can serve as a novel tool to interrogate mechanisms of action of human cardiac populations upon AMI.

Safety and Efficacy of Intracoronary Infusion of Allogeneic Human Cardiac Stem Cells in Patients With ST-Segment Elevation Myocardial Infarction and Left Ventricular Dysfunction

RATIONALE

Allogeneic cardiac stem cells (AlloCSC-01) have shown protective, immunoregulatory, and regenerative properties with a robust safety profile in large animal models of heart disease.

OBJECTIVE

To investigate the safety and feasibility of early administration of AlloCSC-01 in patients with ST-segment-elevation myocardial infarction.

METHODS AND RESULTS

CAREMI (Safety and Efficacy of Intracoronary Infusion of Allogeneic Human Cardiac Stem Cells in Patients With STEMI and Left Ventricular Dysfunction) was a phase I/II multicenter, randomized, double-blind, placebo-controlled trial in patients with ST-segment-elevation myocardial infarction, left ventricular ejection fraction ≤45%, and infarct size ≥25% of left ventricular mass by cardiac magnetic resonance, who were randomized (2:1) to receive AlloCSC-01 or placebo through the intracoronary route at days 5 to 7. The primary end point was safety and included all-cause death and major adverse cardiac events at 30 days (all-cause death, reinfarction, hospitalization because of heart failure, sustained ventricular tachycardia, ventricular fibrillation, and stroke). Secondary safety end points included major adverse cardiac events at 6 and 12 months, adverse events, and immunologic surveillance. Secondary exploratory efficacy end points were changes in infarct size (percentage of left ventricular mass) and indices of ventricular remodeling by magnetic resonance at 12 months. Forty-nine patients were included (92% male, 55±11 years), 33 randomized to AlloCSC-01 and 16 to placebo. No deaths or major adverse cardiac events were reported at 12 months. One severe adverse events in each group was considered possibly related to study treatment (allergic dermatitis and rash). AlloCSC-01 elicited low levels of donor-specific antibodies in 2 patients. No immune-related adverse events were found, and no differences between groups were observed in magnetic resonance-based efficacy parameters at 12 months. The estimated treatment effect of AlloCSC-01 on the absolute change from baseline in infarct size was -2.3% (95% confidence interval, -6.5% to 1.9%).

CONCLUSIONS

AlloCSC-01 can be safely administered in ST-segment-elevation myocardial infarction patients with left ventricular dysfunction early after revascularization. Low immunogenicity and absence of immune-mediated events will facilitate adequately powered studies to demonstrate their clinical efficacy in this setting.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov . Unique identifier: NCT02439398.

Dose-dependent improvement of cardiac function in a swine model of acute myocardial infarction after intracoronary administration of allogeneic heart-derived cells

BACKGROUND

Allogeneic cardiac-derived progenitor cells (CPC) without immunosuppression could provide an effective ancillary therapy to improve cardiac function in reperfused myocardial infarction. We set out to perform a comprehensive preclinical feasibility and safety evaluation of porcine CPC (pCPC) in the infarcted porcine model, analyzing biodistribution and mid-term efficacy, as well as safety in healthy non-infarcted swine.

METHODS

The expression profile of several pCPC isolates was compared with humans using both FACS and RT-qPCR. ELISA was used to compare the functional secretome. One week after infarction, female swine received an intracoronary (IC) infusion of vehicle (CON), 25 × 10⁶ pCPC (25 M), or 50 × 10⁶ pCPC (50 M). Animals were followed up for 10 weeks using serial cardiac magnetic resonance imaging to assess functional and structural remodeling (left ventricular ejection fraction (LVEF), systolic and diastolic volumes, and myocardial salvage index). Statistical comparisons were performed using Kruskal-Wallis and Mann-Whitney U tests. Biodistribution analysis of ¹⁸F-FDG-labeled pCPC was also performed 4 h after infarction in a different subset of animals.

RESULTS

Phenotypic and functional characterization of pCPC revealed a gene expression profile comparable to their human counterparts as well as preliminary functional equivalence. Left ventricular functional and structural remodeling showed significantly increased LVEF 10 weeks after IC administration of 50 M pCPC, associated to the recovery of left ventricular volumes that returned to pre-infarction values (LVEF at 10 weeks was 42.1 ± 10.0% in CON, 46.5 ± 7.4% in 25 M, and 50.2 ± 4.9% in 50 M, p < 0.05). Infarct remodeling was also improved following pCPC infusion with a significantly higher myocardial salvage index in both treated groups (0.35 ± 0.20 in CON; 0.61 ± 0.20, p = 0.04, in 25 M; and 0.63 ± 0.17, p = 0.01, in 50 M). Biodistribution studies demonstrated cardiac tropism 4 h after IC administration, with substantial myocardial retention of pCPC-associated tracer activity (18% of labeled cells in the heart), and no obstruction of coronary flow, indicating their suitability as a cell therapy product.

CONCLUSIONS

IC administration of allogeneic pCPC at 1 week after acute myocardial infarction is feasible, safe, and associated with marked structural and functional benefit. The robust cardiac tropism of pCPC and the paracrine effects on left ventricle post-infarction remodeling established the preclinical bases for the CAREMI clinical trial (NCT02439398).

Human cardiac progenitor cell activation and regeneration mechanisms: exploring a novel myocardial ischemia/reperfusion in vitro model

BACKGROUND

Numerous studies from different labs around the world report human cardiac progenitor cells (hCPCs) as having a role in myocardial repair upon ischemia/reperfusion (I/R) injury, mainly through auto/paracrine signaling. Even though these cell populations are already being investigated in cell transplantation-based clinical trials, the mechanisms underlying their response are still poorly understood.

METHODS

To further investigate hCPC regenerative process, we established the first in vitro human heterotypic model of myocardial I/R injury using hCPCs and human-induced pluripotent cell-derived cardiomyocytes (hiPSC-CMs). The co-culture model was established using transwell inserts and evaluated in both ischemia and reperfusion phases regarding secretion of key cytokines, hiPSC-CM viability, and hCPC proliferation. hCPC proteome in response to I/R was further characterized using advanced liquid chromatography mass spectrometry tools.

RESULTS

This model recapitulates hallmarks of I/R, namely hiPSC-CM death upon insult, protective effect of hCPCs on hiPSC-CM viability (37.6% higher vs hiPSC-CM mono-culture), and hCPC proliferation (approximately threefold increase vs hCPCs mono-culture), emphasizing the importance of paracrine communication between these two populations. In particular, in co-culture supernatant upon injury, we report higher angiogenic functionality as well as a significant increase in the CXCL6 secretion rate, suggesting an important role of this chemokine in myocardial regeneration. hCPC whole proteome analysis allowed us to propose new pathways in the hCPC-mediated regenerative process, including cell cycle regulation, proliferation through EGF signaling, and reactive oxygen species detoxification.

CONCLUSION

This work contributes with new insights into hCPC biology in response to I/R, and the model established constitutes an important tool to study the molecular mechanisms involved in the myocardial regenerative process.

Meshes in a mess: Mesenchymal stem cell-based therapies for soft tissue reinforcement

Surgical meshes are frequently used for the treatment of abdominal hernias, pelvic organ prolapse, and stress urinary incontinence. Though these meshes are designed for tissue reinforcement, many complications have been reported. Both differentiated cell- and mesenchymal stem cell-based therapies have become attractive tools to improve their biocompatibility and tissue integration, minimizing adverse inflammatory reactions. However, current studies are highly heterogeneous, making it difficult to establish comparisons between cell types or cell coating methodologies. Moreover, only a few studies have been performed in clinically relevant animal models, leading to contradictory results. Finally, a thorough understanding of the biological mechanisms of mesenchymal stem cells in the context of foreign body reaction is lacking. This review aims to summarize in vitro and in vivo studies involving the use of differentiated and mesenchymal stem cells in combination with surgical meshes. According to preclinical and clinical studies and considering the therapeutic potential of mesenchymal stem cells, it is expected that these cells will become valuable tools in the treatment of pathologies requiring tissue reinforcement. STATEMENT OF SIGNIFICANCE: The implantation of surgical meshes is the standard procedure to reinforce tissue defects such as hernias. However, an adverse inflammatory response secondary to this implantation is frequently observed, leading to a strong discomfort and chronic pain in the patients. In many cases, an additional surgical intervention is needed to remove the mesh. Both differentiated cell- and stem cell-based therapies have become attractive tools to improve biocompatibility and tissue integration, minimizing adverse inflammatory reactions. However, current studies are incredibly heterogeneous and it is difficult to establish a comparison between cell types or cell coating methodologies. This review aims to summarize in vitro and in vivo studies where differentiated and stem cells have been combined with surgical meshes.

Human cardiac stem cells inhibit lymphocyte proliferation through paracrine mechanisms that correlate with indoleamine 2,3-dioxygenase induction and activity

Transplantation of allogeneic human cardiac/stem progenitor cells (hCSCs) is currently being tested in several phase I/II clinical trials as a novel and promising therapy for restoration of myocardial tissue function in acute myocardial infarction (AMI) patients. Previous findings demonstrate that these cells have an immune suppressive profile interacting with different populations from the immune system, resulting in overall attenuation of myocardial inflammation. However, transplanted hCSCs are still recognized and cleared from the injured site, impairing long retention times in the tissue that could translate into a higher clinical benefit.In this work, through modeling allogeneic hCSC/T lymphocyte interaction in vitro by direct contact, transwell inserts, and hCSC conditioned medium, our results demonstrate that hCSCs exert an immune-suppressive effect on T lymphocyte proliferation not only through the previously described cell contact-dependent programmed cell death-1 (PD1)/programmed death ligand-1 (PDL-1) axis but also through a paracrine mechanism associated with indoleamine 2,3-dioxygenase (IDO) enzyme-mediated tryptophan metabolism. Such findings constitute a step forward in better understanding the mechanisms of action of transplanted hCSCs in allogeneic settings.

Cardiosphere-Derived Cells and Ischemic Heart Failure

After a myocardial infarction, heart tissue becomes irreversibly damaged, leading to scar formation and inevitably ischemic heart failure. Of the many available interventions after a myocardial infarction, such as percutaneous intervention or pharmacological optimization, none can reverse the ischemic insult on the heart and restore cardiac function. Thus, the only available cure for patients with scarred myocardium is allogeneic heart transplantation, which comes with extensive costs, risks, and complications. However, multiple studies have shown that the heart is, in fact, not an end-stage organ and that there are endogenous mechanisms in place that have the potential to spark regeneration. Stem cell therapy has emerged as a potential tool to tap into and activate this endogenous framework. Particularly promising are stem cells derived from cardiac tissue itself, referred to as cardiosphere-derived cells (CDCs). CDCs can be extracted and isolated from the patient's myocardium and then administered by intramyocardial injection or intracoronary infusion. After early success in the animal model, multiple clinical trials have demonstrated the safety and efficacy of autologous CDC therapy in humans. Clinical trials with allogeneic CDCs showed early promising results and pose a potential "off-the-shelf" therapy for patients in the acute setting after a myocardial infarction. The mechanism responsible for CDC-induced cardiac regeneration seems to be a combination of triggering native cardiomyocyte proliferation and recruitment of endogenous progenitor cells, which most prominently occurs via paracrine effects. A further understanding of the mediators involved in paracrine signaling can help with the development of a stem cell-free therapy, with all the benefits and none of the associated complications.

Rationale and Design of a Clinical Trial to Evaluate the Safety and Efficacy of Intracoronary Infusion of Allogeneic Human Cardiac Stem Cells in Patients With Acute Myocardial Infarction and Left Ventricular Dysfunction

Rationale:

Stem cell therapy has increased the therapeutic armamentarium in the fight against ischemic heart disease and heart failure. The administration of exogenous stem cells has been investigated in patients suffering an acute myocardial infarction, with the final aim of salvaging jeopardized myocardium and preventing left ventricular adverse remodeling and functional deterioration. However, phase I and II clinical trials with autologous and first-generation stem cells have yielded inconsistent benefits and mixed results.

Objective:

In the search for new and more efficient cellular regenerative products, interesting cardioprotective, immunoregulatory, and cardioregenerative properties have been demonstrated for human cardiac stem cells. On the other hand, allogeneic cells show several advantages over autologous sources: they can be produced in large quantities, easily administered off-the-shelf early after an acute myocardial infarction, comply with stringent criteria for product homogeneity, potency, and quality control, and may exhibit a distinctive immunologic behavior.

Methods and Results:

With a promising preclinical background, CAREMI (Cardiac Stem Cells in Patients With Acute Myocardial Infarction) has been designed as a double-blind, 2:1 randomized, controlled, and multicenter clinical trial that will evaluate the safety, feasibility, and efficacy of intracoronary delivery of allogeneic human cardiac stem cell in 55 patients with large acute myocardial infarction, left ventricular dysfunction, and at high risk of developing heart failure.

Conclusions:

This phase I/II clinical trial represents a novel experience in humans with allogeneic cardiac stem cell in a rigorously imaging-based selected group of acute myocardial infarction patients, with detailed safety immunologic assessments and magnetic resonance imaging–based efficacy end points.

Clinical Trial Registration:

URL: http://www.clinicaltrials.gov . Unique identifier: NCT02439398.

Autologous and allogeneic cardiac stem cell therapy for cardiovascular diseases

Stem cell therapy is one of the most promising therapeutic innovations to help restore cardiac structure and function after ischemic insults to the heart. However, phase I and II clinical trials with autologous "first-generation stem cells" have yielded inconsistent results in ischemic cardiomyopathy patients and have not produced the definitive evidence for their broad clinical application. Recently, new cell types such as cardiac stem cells (CSC) and new allogeneic sources have attracted the attention of researchers given their inherent biological, clinical and logistic advantages. Preclinical evidence and emerging clinical data show that exogenous CSC produce a range of protein-based factors that have a powerful cardioprotective effect in the ischemic myocardium, immunoregulatory properties that promote angiogenesis and reduce scar formation, and are able to activate endogenous CSC which multiply and differentiate into cardiomyocytes and microvasculature. Furthermore, allogeneic CSC can be produced in large quantities beforehand and can be administered "off-the-shelf" early during the acute phase of myocardial ischemia. The distinctive immunological behavior of allogeneic CSC and their interaction with the host immune system is supposed to produce immunomodulatory beneficial effects in the short-term, preventing long-term side-effects after their rejection. Preclinical studies have shown highly promising results with allogeneic CSC, and clinical trials are already ongoing. Finally, unraveling questions about the biology and physiology of CSC, the characterization of their secretome, the conduction of larger clinical trials with autologous CSC, the definitive evidence on the safety and efficacy of allogeneic CSC in humans and the possibility of repeated administrations or combinations with other cell types and soluble factors will pave the road for further developments with CSC, that will undoubtedly determine the future of cardiovascular regenerative medicine in human beings.

Non-invasive in vivo imaging of cardiac stem/progenitor cell biodistribution and retention after intracoronary and intramyocardial delivery in a swine model of chronic ischemia reperfusion injury

Background

The safety and efficacy of cardiac stem/progenitor cells (CSC) have been demonstrated in previous preclinical and clinical assays for heart failure. However, their optimal delivery route to the ischemic heart has not yet been assessed. This study was designed to determine by a non-invasive imaging technique (PET/CT) the biodistribution and acute retention of allogeneic pig CSC implanted by two different delivery routes, intracoronary (IC) and intramyocardial (IM), in a swine preclinical model of chronic ischemia–reperfusion.

Methods

Ischemia–reperfusion was induced in six Goettingen hybrid minipigs by 90 min coronary artery occlusion followed by reperfusion. Thirty days later, animals were allocated to receive IC (n = 3) or NOGA^®-guided IM injection (n = 3) of 50 million of ¹⁸F-FDG/GFP-labeled allogeneic pig CSC. Acute retention was quantified by PET/CT 4 h after injection and cell engraftment assessed by immunohistochemical quantification of GFP⁺ cells three days post-injection.

Results

Biodistribution of ¹⁸F-FDG-labeled CSC was clearly visualized by PET/CT imaging and quantified. No statistical differences in acute cell retention (percentage of injected dose, %ID) were found in the heart when cells were administered by NOGA^®-guided IM (13.4 ± 3.4%ID) or IC injections (17.4 ± 4.1%ID). Interestingly, engrafted CSC were histologically detected only after IM injection.

Conclusion

PET/CT imaging of ¹⁸F-FDG-labeled CSC allows quantifying biodistribution and acute retention of implanted cells in a clinically relevant pig model of chronic myocardial infarction. Similar levels of acute retention are achieved when cells are IM or IC administered. However, acute cell retention does not correlate with cell engraftment, which is improved by IM injection.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-017-1157-0) contains supplementary material, which is available to authorized users.

Comparison of mesenchymal stem cells and leukocytes from Large White and Göttingen Minipigs: Clues for stem cell-based immunomodulatory therapies

The mesenchymal stem cells (MSCs) are one of the most promising cell types for human and veterinary use and their therapeutic effect is associated with their immunomodulatory properties. Farm animal models, such as pigs, have become a valuable tool to evaluate the safety and efficacy of adoptively transferred MSCs in the setting of veterinary medicine. In order to evaluate the immunomodulatory effect of stem cell-based therapies in porcine breeds, a deep analysis and comparison of MSCs and leukocyte subsets are absolutely necessary. Here we provide a detailed analysis of bone-marrow derived MSCs and leukocyte subsets from Large White pigs and Göttingen Minipigs. Significant differences were observed between the two pig breeds in terms of T cell subsets that need to be considered for immune monitoring of stem cell-based therapies.

Cardiac Stem Cell Treatment in Myocardial Infarction: A Systematic Review and Meta-Analysis of Preclinical Studies

RATIONALE

Cardiac stem cells (CSC) therapy has been clinically introduced for cardiac repair after myocardial infarction (MI). To date, there has been no systematic overview and meta-analysis of studies using CSC therapy for MI.

OBJECTIVE

Here, we used meta-analysis to establish the overall effect of CSCs in preclinical studies and assessed translational differences between and within large and small animals in the CSC therapy field. In addition, we explored the effect of CSC type and other clinically relevant parameters on functional outcome to better predict and design future (pre)clinical studies using CSCs for MI.

METHODS AND RESULTS

A systematic search was performed, yielding 80 studies. We determined the overall effect of CSC therapy on left ventricular ejection fraction and performed meta-regression to investigate clinically relevant parameters. We also assessed the quality of included studies and possible bias. The overall effect observed in CSC-treated animals was 10.7% (95% confidence interval 9.4-12.1; P<0.001) improvement in ejection fraction compared with placebo controls. Interestingly, CSC therapy had a greater effect in small animals compared with large animals (P<0.001). Meta-regression indicated that cell type was a significant predictor for ejection fraction improvement in small animals. Minor publication bias was observed in small animal studies.

CONCLUSIONS

CSC treatment resulted in significant improvement of ejection fraction in preclinical animal models of MI compared with placebo. There was a reduction in the magnitude of effect in large compared with small animal models. Although different CSC types have overlapping culture characteristics, we observed a significant difference in their effect in post-MI animal studies.

Allogeneic cardiosphere-derived cells for myocardial regeneration: current progress and recent results

Early-phase clinical testing of autologous cardiosphere-derived cells (CDCs) has yielded intriguing results, consistent with therapeutic myocardial regeneration. However, autologous therapy is associated with significant technical, timing, economic and logistic constraints, prompting researchers to explore the potential of allogeneic CDC therapy. CDCs exhibit a favorable immunologic antigenic profile and are hypoimmunogenic in vitro. Preclinical studies in immunologically mismatched animals demonstrate that allogeneic CDC transplantation without immunosuppression is safe and produces sustained functional and structural benefits through stimulation of endogenous regenerative pathways. Currently, allogeneic human CDCs are being tested clinically in the ALLSTAR and DYNAMIC trials. Potential establishment of clinical safety and efficacy of allogeneic CDCs combined with generation of highly standardized, ‘off-the-shelf’ allogeneic cellular products would facilitate broad clinical adoption of cell therapy.

Test-retest repeatability of myocardial blood flow and infarct size using ¹¹C-acetate micro-PET imaging in mice

PURPOSE

Global and regional responses of absolute myocardial blood flow index (iMBF) are used as surrogate markers to assess response to therapies in coronary artery disease. In this study, we assessed the test-retest repeatability of iMBF imaging, and the accuracy of infarct sizing in mice using (11)C-acetate PET.

METHODS

(11)C-Acetate cardiac PET images were acquired in healthy controls, endothelial nitric oxide synthase (eNOS) knockout transgenic mice, and mice after myocardial infarction (MI) to estimate global and regional iMBF, and myocardial infarct size compared to (18)F-FDG PET and ex-vivo histology results.

RESULTS

Global test-retest iMBF values had good coefficients of repeatability (CR) in healthy mice, eNOS knockout mice and normally perfused regions in MI mice (CR = 1.6, 2.0 and 1.5 mL/min/g, respectively). Infarct size measured on (11)C-acetate iMBF images was also repeatable (CR = 17 %) and showed a good correlation with the infarct sizes found on (18)F-FDG PET and histopathology (r (2) > 0.77; p < 0.05).

CONCLUSION

(11)C-Acetate micro-PET assessment of iMBF and infarct size is repeatable and suitable for serial investigation of coronary artery disease progression and therapy.