Mesenchymal stem cell transplantation after acute myocardial infarction: a meta-analysis of clinical trials

20 years of treating ischemic cardiomyopathy with mesenchymal stromal cells: a meta-analysis and systematic review

This meta-analysis and systematic review compiles comparative data from 2004 to 2024, investigating the safety and efficacy of mesenchymal stem/stromal cells (MSCs) derived from various tissues for the treatment of ischemic cardiomyopathy (ICM) and associated heart failure. In addition, this review highlights the limitations of these interventions and provides valuable insights for future therapeutic approaches. Relevant articles were retrieved from the PubMed® database using targeted keywords. Our inclusion criteria included clinical trials with patients over 18 years of age, case reports and pilot studies. Animal experiments, in vitro studies, correlational and longitudinal studies, and study designs and protocols were excluded. Forty-nine original articles resulted in follow-up reports of 45 trials. MSCs from bone marrow, umbilical cord and adipose tissue were moderately well tolerated. Of the 1408 participants who received MSCs, 33 trials (67.3%) reported the occurrence of death or serious adverse events. These events resulted in 80 deaths (52% of reported cases) following MSC administration. Importantly, 41.3% of these deaths (n = 33) were not considered to be related to the intervention itself, while 40% of these deaths had no reported cause. As the primary outcome, the mean increase in left ventricular ejection fraction (LVEF) from baseline was 5.75% (95% CI: 3.38% -8.11%, p < 0.0001, I2 = 90,9%) in the randomized controlled trials only (n = 24) within the treatment groups and 3.19% (95% CI: 1.63% to 4.75%, p < 0.0001, I2 = 74,17%) in the control groups after the intervention. When the above results were compared using the standardized mean difference (SDM), a significance in favor of the treatment group was also found (SDM = 0.41; 95% CI: 0.19-0.64, p < 0.001, I2 = 71%). Although improvements were also seen in the control groups, 33.3% (n = 15) of the studies showed no significant difference between the control and treatment groups. The 6-minute walking test (6MWT) and New York Heart Association (NYHA) class scores, used for assessing exercise tolerance and quality of life (QoL), respectively, further supported the improvements in the treatment group. These improvements were noted as 62.5% (n = 10) for the 6MWT and 54.5% (n = 12) for the NYHA class scores. According to the risk of bias analysis, 4 trials were of good quality (11.8%), 15 were of fair quality (44.1%), and 15 were of poor quality (44.1%). Major limitations of these studies included small sample size, diagnostic challenges/lack, uncertain cell dosage and potential bias in patient selection. Despite the ongoing debate surrounding cell administration for ICM, there are supporting signs of improved clinical and laboratory outcomes, as well as improved QoL in the MSC-treated groups. However, it is important to recognize the limitations of each study, highlighting the need for larger, controlled trials to validate these findings.

The Use of Hematopoietic Stem Cells for Heart Failure: A Systematic Review

The purpose of this review is to summarize the current understanding of the therapeutic effect of stem cell-based therapies, including hematopoietic stem cells, for the treatment of ischemic heart damage. Following PRISMA guidelines, we conducted electronic searches in MEDLINE, and EMBASE. We screened 592 studies, and included RCTs, observational studies, and cohort studies that examined the effect of hematopoietic stem cell therapy in adult patients with heart failure. Studies that involved pediatric patients, mesenchymal stem cell therapy, and non-heart failure (HF) studies were excluded from our review. Out of the 592 studies, 7 studies met our inclusion criteria. Overall, administration of hematopoietic stem cells (via intracoronary or myocardial infarct) led to positive cardiac outcomes such as improvements in pathological left-ventricular remodeling, perfusion following acute myocardial infarction, and NYHA symptom class. Additionally, combined death, rehospitalization for heart failure, and infarction were significantly lower in patients treated with bone marrow-derived hematopoietic stem cells. Our review demonstrates that hematopoietic stem cell administration can lead to positive cardiac outcomes for HF patients. Future studies should aim to increase female representation and non-ischemic HF patients.

REGENERATE-COBRA: A phase II randomized sham-controlled trial assessing the safety and efficacy of intracoronary administration of autologous bone marrow-derived cells in patients with refractory angina

AIMS

The REGENERATE-COBRA trial (NCT05711849) will assess the safety and efficacy of an intracoronary infusion of autologous bone marrow-derived mononuclear cells in refractory angina patients with no revascularization options who are symptomatic despite optimal medical and device therapy.

METHODS

REGENERATE-COBRA is a single site, blinded, randomized, sham-controlled, Phase II clinical trial enrolling 110 refractory angina patients with no revascularization options who are symptomatic despite optimal medical and device therapy. Patients will be randomized to either autologous bone marrow derived-mononuclear cells or a sham procedure. Patients in the cell-treated arm will undergo a bone marrow aspiration and an intracoronary infusion of autologous bone marrow derived-mononuclear cells. Patients in the control arm will undergo a sham bone marrow aspiration and a sham intracoronary infusion. The trial's primary endpoint is an improvement in Canadian Cardiovascular Society (CCS) angina class by 2 classes between baseline and 6 months. Secondary endpoints include change in: CCS class at 12 months, myocardial ischemic burden (as measured by perfusion imaging) at 6 months, quality of life at 6 and 12 months (as measured by EQ-5D-5L, EQ-5D-VAS and Seattle Angina Questionnaire), angina frequency at 6 and 12 months, total exercise time (as measured by a modified Bruce protocol) and major adverse cardiovascular events at 6 and 12 months.

CONCLUSIONS

This is the first trial to assess the safety and efficacy of an intracoronary infusion of autologous bone marrow-derived unfractionated mononuclear cells in symptomatic refractory angina patients who have exhausted conventional therapeutic options.

Therapeutic application of adipose-derived stromal vascular fraction in myocardial infarction

The insufficiency of natural regeneration processes in higher organisms, including humans, underlies myocardial infarction (MI), which is one of the main causes of disability and mortality in the population of developed countries. The solution to this problem lies in the field of revealing the mechanisms of regeneration and creating on this basis new technologies for stimulating endogenous regenerative processes or replacing lost parts of tissues and organs with transplanted cells. Of great interest is the use of the so-called stromal vascular fraction (SVF), derived from autologous adipose tissue. It is known that the main functions of SVF are angiogenetic, antiapoptotic, antifibrotic, immune regulation, anti-inflammatory, and trophic. This study presents data on the possibility of using SVF, targeted regulation of its properties and reparative potential, as well as the results of research studies on its use for the restoration of damaged ischemic tissue after MI.

Exploring Cutting-Edge Approaches to Potentiate Mesenchymal Stem Cell and Exosome Therapy for Myocardial Infarction

Cardiovascular diseases (CVDs) continue to be a significant global health concern. Many studies have reported promising outcomes from using MSCs and their secreted exosomes in managing various cardiovascular-related diseases like myocardial infarction (MI). MSCs and exosomes have demonstrated considerable potential in promoting regeneration and neovascularization, as well as exerting beneficial effects against apoptosis, remodeling, and inflammation in cases of myocardial infarction. Nonetheless, ensuring the durability and effectiveness of MSCs and exosomes following in vivo transplantation remains a significant concern. Recently, novel methods have emerged to improve their effectiveness and robustness, such as employing preconditioning statuses, modifying MSC and their exosomes, targeted drug delivery with exosomes, biomaterials, and combination therapy. Herein, we summarize the novel approaches that intensify the therapeutic application of MSC and their derived exosomes in treating MI.

Mesenchymal stromal cells for improvement of cardiac function following acute myocardial infarction: a matter of timing

Acute myocardial infarction (AMI) is the leading cause of cardiovascular death and remains the most common cause of heart failure. Reopening of the occluded artery, i.e., reperfusion, is the only way to save the myocardium. However, the expected benefits of reducing infarct size are disappointing due to the reperfusion paradox, which also induces specific cell death. These ischemia-reperfusion (I/R) lesions can account for up to 50% of final infarct size, a major determinant for both mortality and the risk of heart failure (morbidity). In this review, we provide a detailed description of the cell death and inflammation mechanisms as features of I/R injury and cardioprotective strategies such as ischemic postconditioning as well as their underlying mechanisms. Due to their biological properties, the use of mesenchymal stromal/stem cells (MSCs) has been considered a potential therapeutic approach in AMI. Despite promising results and evidence of safety in preclinical studies using MSCs, the effects reported in clinical trials are not conclusive and even inconsistent. These discrepancies were attributed to many parameters such as donor age, in vitro culture, and storage time as well as injection time window after AMI, which alter MSC therapeutic properties. In the context of AMI, future directions will be to generate MSCs with enhanced properties to limit cell death in myocardial tissue and thereby reduce infarct size and improve the healing phase to increase postinfarct myocardial performance.

Detailed role of mesenchymal stem cell (MSC)-derived exosome therapy in cardiac diseases

Coronary heart disease (CHD) continues to be the leading cause of morbidity and mortality. There are numerous therapeutic reperfusion methods, including thrombolytic therapy, primary percutaneous coronary intervention, and anti-remodeling drugs like angiotensin-converting enzyme inhibitors and beta-blockers. Despite this, there is no pharmacological treatment that can effectively stop cardiomyocyte death brought on by myocardial ischemia/reperfusion (I/R) injury. For the purpose of regenerating cardiac tissue, mesenchymal stem cell (MSC) therapy has recently gained more attention. The pleiotropic effects of MSCs are instead arbitrated by the secretion of soluble paracrine factors and are unrelated to their capacity for differentiation. One of these paracrine mediators is the extracellular vesicle known as an exosome. Exosomes deliver useful cargo to recipient cells from MSCs, including peptides, proteins, cytokines, lipids, miRNA, and mRNA molecules. Exosomes take part in intercellular communication processes and help tissues and organs that have been injured or are ill heal. Exosomes alone were found to be the cause of MSCs' therapeutic effects in a variety of animal models, according to studies. Here, we have focused on the recent development in the therapeutic capabilities of exosomal MSCs in cardiac diseases.

The bone mesenchymal stem cell-derived exosomal miR-146a-5p promotes diabetic wound healing in mice via macrophage M1/M2 polarization

A diabetic wound is a refractory disease that afflicts patients globally. MicroRNA-146a-5p (miR-146a-5p) is reported to represent a potential therapeutic target for diabetic wounds. However, microRNA easily degrades in the wound microenvironment. This study extracted bone marrow mesenchymal stem cell (BMSC)-derived exosomes (EXO). Electroporation technology was used to load miR-146a-5p into EXO (labeled as EXO-miR-146a). The endothelial cells (human umbilical vein endothelial cells [HUVECs]) and macrophages were cocultured in transwell chambers in the presence of high glucose. Cell proliferation, migration, and angiogenesis were measured with cell counting kit 8, scratch, and tube forming assays, respectively. Flow cytometry was introduced to validate the biomarker of macrophages and BMSCs. The expression level of macrophage polarization-related proteins and tumor necrosis factor receptor-associated factor 6 (TRAF6) was assessed with western blotting analysis. The full-thickness skin wound model was developed to verify the in vitro results. EXO-miR-146a promoted the proliferation, migration, and angiogenesis of HUVECs in the hyperglycemic state by suppressing the TRAF6 expression in vitro. Additionally, EXO-miR-146a treatment facilitated M2 but inhibited M1 macrophage polarization. Furthermore, EXO-miR-146a enhances reepithelialization, angiogenesis, and M2 macrophage polarization, thereby accelerating diabetic wound healing in vivo. The EXO-miR-146a facilitated M2 macrophage polarization, proliferation, migration, and angiogenesis of HUVECs through TRAF6, thereby ameliorating intractable diabetic wound healing. These results established the basis for using EXO to deliver drugs and revealed mediators for diabetic wound treatment.

PD-L1 and AKT Overexpressing Adipose-Derived Mesenchymal Stem Cells Enhance Myocardial Protection by Upregulating CD25+ T Cells in Acute Myocardial Infarction Rat Model

This study explores the synergistic impact of Programmed Death Ligand 1 (PD-L1) and Protein Kinase B (Akt) overexpression in adipose-derived mesenchymal stem cells (AdMSCs) for ameliorating cardiac dysfunction after myocardial infarction (MI). Post-MI adult Wistar rats were allocated into four groups: sham, MI, ADMSC treatment, and ADMSCs overexpressed with PD-L1 and Akt (AdMSC-PDL1-Akt) treatment. MI was induced via left anterior descending coronary artery ligation, followed by intramyocardial AdMSC injections. Over four weeks, cardiac functionality and structural integrity were assessed using pressure-volume analysis, infarct size measurement, and immunohistochemistry. AdMSC-PDL1-Akt exhibited enhanced resistance to reactive oxygen species (ROS) in vitro and ameliorated MI-induced contractile dysfunction in vivo by improving the end-systolic pressure-volume relationship and preload-recruitable stroke work, together with attenuating infarct size. Molecular analyses revealed substantial mitigation in caspase3 and nuclear factor-κB upregulation in MI hearts within the AdMSC-PDL1-Akt group. Mechanistically, AdMSC-PDL1-Akt fostered the differentiation of normal T cells into CD25+ regulatory T cells in vitro, aligning with in vivo upregulation of CD25 in AdMSC-PDL1-Akt-treated rats. Collectively, PD-L1 and Akt overexpression in AdMSCs bolsters resistance to ROS-mediated apoptosis in vitro and enhances myocardial protective efficacy against MI-induced dysfunction, potentially via T-cell modulation, underscoring a promising therapeutic strategy for myocardial ischemic injuries.

Spatiotemporal signaling underlies progressive vascular rarefaction in myocardial infarction

Therapeutic angiogenesis represents a promising avenue to revascularize the ischemic heart. Its limited success is partly due to our poor understanding of the cardiac stroma, specifically mural cells, and their response to ischemic injury. Here, we combine single-cell and positional transcriptomics to assess the behavior of mural cells within the healing heart. In response to myocardial infarction, mural cells adopt an altered state closely associated with the infarct and retain a distinct lineage from fibroblasts. This response is concurrent with vascular rarefaction and reduced vascular coverage by mural cells. Positional transcriptomics reveals that the infarcted heart is governed by regional-dependent and temporally regulated programs. While the remote zone acts as an important source of pro-angiogenic signals, the infarct zone is accentuated by chronic activation of anti-angiogenic, pro-fibrotic, and inflammatory cues. Together, our work unveils the spatiotemporal programs underlying cardiac repair and establishes an association between vascular deterioration and mural cell dysfunction.

Stem Cell-Based Therapy and Cell-Free Therapy as an Alternative Approach for Cardiac Regeneration

The World Health Organization reports that cardiovascular diseases (CVDs) represent 32% of all global deaths. The ineffectiveness of conventional therapies in CVDs encourages the development of novel, minimally invasive therapeutic strategies for the healing and regeneration of damaged tissue. The self-renewal capacity, multilineage differentiation, lack of immunogenicity, and immunosuppressive properties of mesenchymal stem cells (MSCs) make them a promising option for CVDs. However, growing evidence suggests that myocardial regeneration occurs through paracrine factors and extracellular vesicle (EV) secretion, rather than through differentiation into cardiomyocytes. Research shows that stem cells secrete or surface-shed into their culture media various cytokines, chemokines, growth factors, anti-inflammatory factors, and EVs, which constitute an MSC-conditioned medium (MSC-CM) or the secretome. The use of MSC-CM enhances cardiac repair through resident heart cell differentiation, proliferation, scar mass reduction, a decrease in infarct wall thickness, and cardiac function improvement comparable to MSCs without their side effects. This review highlights the limitations and benefits of therapies based on stem cells and their secretome as an innovative treatment of CVDs.

Effect of once versus twice intracoronary injection of allogeneic-derived mesenchymal stromal cells after acute myocardial infarction: BOOSTER-TAHA7 randomized clinical trial

BACKGROUND

Mesenchymal stromal cell (MSC) transplantation can improve the left ventricular ejection fraction (LVEF) after an acute myocardial infarction (AMI). Transplanted MSCs exert a paracrine effect, which might be augmented if repeated doses are administered. This study aimed to compare the effects of single versus double transplantation of Wharton's jelly MSCs (WJ-MSCs) on LVEF post-AMI.

METHODS

We conducted a single-blind, randomized, multicenter trial. After 3-7 days of an AMI treated successfully by primary PCI, 70 patients younger than 65 with LVEF < 40% on baseline echocardiography were randomized to receive conventional care, a single intracoronary infusion of WJ-MSCs, or a repeated infusion 10 days later. The primary endpoint was the 6-month LVEF improvement as per cardiac magnetic resonance (CMR) imaging.

RESULTS

The mean baseline EF measured by CMR was similar (~ 40%) in all three groups. By the end of the trial, while all patients experienced a rise in EF, the most significant change was seen in the repeated intervention group. Compared to the control group (n = 25), single MSC transplantation (n = 20) improved the EF by 4.54 ± 2%, and repeated intervention (n = 20) did so by 7.45 ± 2% when measured by CMR imaging (P < 0.001); when evaluated by echocardiography, these values were 6.71 ± 2.4 and 10.71 ± 2.5%, respectively (P < 0.001).

CONCLUSIONS

Intracoronary transplantation of WJ-MSCs 3-7 days after AMI in selected patients significantly improves LVEF, with the infusion of a booster dose 10 days later augmenting this effect.

TRIAL REGISTRATION

Trial registration: Iranian Registry of Clinical Trials, IRCT20201116049408N1. Retrospectively Registered 20 Nov. 2020, https://en.irct.ir/trial/52357.

Mesenchymal Stem Cell Therapy for a Better Prognosis of Heart Failure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Mesenchymal stem cell (MSC) therapy is a frequently used treatment option for achieving a better prognosis in patients with heart failure (HF). However, due to reported adverse effects, patients are often hesitant to consider this treatment. Consequently, the aim of this systemic review and meta-analysis is to further investigate the effects of MSCs on survival outcomes, hospital readmissions, and left ventricular ejection fraction (LVEF) in individuals with pre-existing HF. We systematically searched PubMed, Web of Science, Embase, and Cochrane Library to review studies published up until July 16, 2023. Risk ratios were generated using the extracted data for all the outcomes except LVEF. The mean difference was generated for LVEF. Sensitivity analysis was performed to investigate heterogeneity, and the risk of bias tool was used to assess the quality of the included studies. Fourteen randomized controlled trials were included in the meta-analysis. Pooled results revealed that the MSC therapy group did not significantly affect the outcomes of cardiovascular death, rehospitalization rate, myocardial infarction, recurrence of HF, and total death when compared to a control group. However, MSC therapy was significantly associated with an increased LVEF (RR = 3.35; 95% CI: 0.79-5.72; p = 0.010; I2 = 95%). Upon sensitivity analysis, MSC therapy was significantly associated with a decreased hospitalization rate (RR = 0.46; 95% CI: 0.34-0.64; p < 0.00001; I2 = 0%). MSC transplantation results in a significantly improved LVEF and rehospitalization rate.

The beneficial effects of mesenchymal stem cells and their exosomes on myocardial infarction and critical considerations for enhancing their efficacy

Mesenchymal stem cells (MSCs) are multipotent stromal cells with regenerative, anti-inflammatory, and immunomodulatory properties. MSCs and their exosomes significantly improved structural and functional alterations after myocardial infarction (MI) in preclinical studies and clinical trials. By reprograming intracellular signaling pathways, MSCs attenuate inflammatory response, oxidative stress, apoptosis, pyroptosis, and endoplasmic reticulum (ER) stress and improve angiogenesis, mitochondrial biogenesis, and myocardial remodeling after MI. MSC-derived exosomes contain a mixture of non-coding RNAs, growth factors, anti-inflammatory mediators, and anti-fibrotic factors. Although primary results from clinical trials were promising, greater efficacies can be achieved by controlling several modifiable factors. The optimum timing of transplantation, route of administration, origin of MSCs, number of doses, and number of cells per dose need to be further investigated by future studies. Newly, highly effective MSC delivery systems have been developed to improve the efficacy of MSCs and their exosomes. Moreover, MSCs can be more efficacious after being pretreated with non-coding RNAs, growth factors, anti-inflammatory or inflammatory mediators, and hypoxia. Similarly, viral vector-mediated overexpression of particular genes can augment the protective effects of MSCs on MI. Therefore, future clinical trials must consider these advances in preclinical studies to properly reflect the efficacy of MSCs or their exosomes for MI.

Pulsed Electromagnetic Fields Combined With Adipose-Derived Stem Cells Protect Ischemic Myocardium by Regulating miR-20a-5p/E2F1/p73 Signaling

Myocardial infarction (MI) is a serious threat to human health. Although monotherapy with pulsed electromagnetic fields (PEMFs) or adipose-derived stem cells (ADSCs) has been reported to have positive effect on the treatment of MI, a satisfactory outcome has not yet been achieved. In recent years, combination therapy has attracted widespread interest. Herein, we explored the synergistic therapeutic effect of combination therapy with PEMFs and ADSCs on MI and found that the combination of PEMFs and ADSCs effectively reduced infarct size, inhibited cardiomyocyte apoptosis and protected the cardiac function in mice with MI. In addition, bioinformatics analysis and RT-qPCR showed that the combination therapy could affect apoptosis by regulating the expression of miR-20a-5p. A dual-luciferase reporter gene assay also confirmed that the miR-20a-5p could target E2F transcription factor 1 (E2F1) and inhibit cardiomyocyte apoptosis by regulating the E2F1/p73 signaling pathway. Therefore, our study systematically demonstrated the effectiveness of combination therapy on the inhibition of cardiomyocyte apoptosis by regulating the miR-20a-5p/E2F1/p73 signaling pathway in mice with MI. Thus, our study underscored the effectiveness of the combination of PEMFs and ADSCs and identified miR-20a-5p as a promising therapeutic target for the treatment of MI in the future.

Bone Marrow Mesenchymal Stem Cells for Heart Failure Treatment: A Systematic Review and Meta-Analysis

AIM

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are the most well-studied and characterised stem cell types. This review was undertaken of the current available phase II/III randomised clinical trials (RCTs) that delivered BM-MSCs to treat patients with cardiomyopathy, and to assess their performance.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines were followed during the systematic review and meta-analysis. Eligible studies were reviewed, and their data charted. To assess the efficacy of BM-MSCs, the outcome was improvement in left ventricular ejection fraction (LVEF) and 6-minute walking distance (6MWD).

RESULTS

The pooled weighted mean difference (WMD) showed that BM-MSCs treatment improved the 6MWD by 27.86 m (95% CI 0.11-55.6 m) compared with the control groups. The pooled WMD showed that BM-MSCs treatment improved the LVEF by 6.37% (95% CI 5.48%-7.26%) compared with the control groups.

CONCLUSION

BM-MSCs treatment is an effective intervention for managing patients with heart failure, but it requires larger and more robust clinical trials to support its routine use in clinics.

Unlocking the Mysteries, Bridging the Gap, and Unveiling the Multifaceted Potential of Stem Cell Therapy for Cardiac Tissue Regeneration: A Narrative Review of Current Literature, Ethical Challenges, and Future Perspectives

Revolutionary advancements in regenerative medicine have brought stem cell therapy to the forefront, offering promising prospects for the regeneration of ischemic cardiac tissue. Yet, its full efficacy, safety, and role in treating ischemic heart disease (IHD) remain limited. This literature review explores the intricate mechanisms underlying stem cell therapy. Furthermore, we unravel the innovative approaches employed to bolster stem cell survival, enhance differentiation, and seamlessly integrate them within the ischemic cardiac tissue microenvironment. Our comprehensive analysis uncovers how stem cells enhance cell survival, promote angiogenesis, and modulate the immune response. Stem cell therapy harnesses a multifaceted mode of action, encompassing paracrine effects and direct cell replacement. As our review progresses, we underscore the imperative for standardized protocols, comprehensive preclinical and clinical studies, and careful regulatory considerations. Lastly, we explore the integration of tissue engineering and genetic modifications, envisioning a future where stem cell therapy reigns supreme in regenerative medicine.

Screening of the best time window for MSC transplantation to treat acute myocardial infarction with SDF-1α antibody-loaded targeted ultrasonic microbubbles: An in vivo study in miniswine

The present study aimed to screen the best time window for the transplantation of bone marrow mesenchymal stem cells (MSCs) after acute myocardial infarction (MI) through targeted ultrasound microbubbles loaded with SDF-1α antibody. Thirty-six MI miniswine were randomly divided into six experimental groups according to the duration after infarction (1 day, 3 days, 1 week, 2 weeks, 3 weeks, and 4 weeks after infarction). MSCs were labeled with BrdU and then injected through the coronary artery in the stem cell transplantation group to detect the number of transplanted MSCs at different time points after MI. Three miniswine were randomly selected as the control group (sham operation: open chest without ligation of the coronary artery). All SDF-1α groups and control groups were injected with a targeted microbubble ultrasound contrast agent. The values of the myocardial perfusion parameters (A, β, and A × β) were determined. A _T, β _T, and (A × β)_T varied with time and peaked 1 week after MI (P < 0.05). The number of transplanted stem cells in the myocardium through coronary injection of MSCs at 1 week was the greatest and consistent with the changing tendency of A _T, β _T, and (A × β)_T (r = 0.658, 0.778, 0.777, P < 0.05). β _T(X), (A × β)_T(X), and the number of transplanted stem cells was used to establish the regression equation as follows: Y = 36.11 + 17.601X; Y = 50.023 + 3.348X (R ² = 0.605, 0.604, P < 0.05). The best time window for transplanting stem cells was 1 week after MI. The myocardial perfusion parameters of the SDF-1α targeted contrast agent can be used to predict the number of transplanted stem cells in the myocardial tissue.

Understanding the impact of bioactive coating materials for human mesenchymal stromal cells and implications for manufacturing

Bioactive materials interact with cells and modulate their characteristics which enable the generation of cell-based products with desired specifications. However, their evaluation and impact are often overlooked when establishing a cell therapy manufacturing process. In this study, we investigated the role of different surfaces for tissue culture including, untreated polystyrene surface, uncoated Cyclic Olefin Polymer (COP) and COP coated with collagen and recombinant fibronectin. It was observed that human mesenchymal stromal cells (hMSCs) expanded on COP-coated plates with different bioactive materials resulted in improved cell growth kinetics compared to traditional polystyrene plates and non-coated COP plates. The doubling time obtained was 2.78 and 3.02 days for hMSC seeded in COP plates coated with collagen type I and recombinant fibronectin respectively, and 4.64 days for cells plated in standard polystyrene treated plates. Metabolite analysis reinforced the findings of the growth kinetic studies, specifically that cells cultured on COP plates coated with collagen I and fibronectin exhibited improved growth as evidenced by a higher lactate production rate (9.38 × 10⁵ and 9.67 × 10⁵ pmol/cell/day, respectively) compared to cells from the polystyrene group (5.86 × 10⁵ pmol/cell/day). This study demonstrated that COP is an effective alternative to polystyrene-treated plates when coated with bioactive materials such as collagen and fibronectin, however COP-treated plates without additional coatings were found not to be sufficient to support cell growth. These findings demonstrate the key role biomaterials play in the cell manufacturing process and the importance of optimising this selection.

Cardiac Reverse Remodeling in Ischemic Heart Disease with Novel Therapies for Heart Failure with Reduced Ejection Fraction

Despite the improvements in the treatment of coronary artery disease (CAD) and acute myocardial infarction (MI) over the past 20 years, ischemic heart disease (IHD) continues to be the most common cause of heart failure (HF). In clinical trials, over 70% of patients diagnosed with HF had IHD as the underlying cause. Furthermore, IHD predicts a worse outcome for patients with HF, leading to a substantial increase in late morbidity, mortality, and healthcare costs. In recent years, new pharmacological therapies have emerged for the treatment of HF, such as sodium-glucose cotransporter-2 inhibitors, angiotensin receptor-neprilysin inhibitors, selective cardiac myosin activators, and oral soluble guanylate cyclase stimulators, demonstrating clear or potential benefits in patients with HF with reduced ejection fraction. Interventional strategies such as cardiac resynchronization therapy, cardiac contractility modulation, or baroreflex activation therapy might provide additional therapeutic benefits by improving symptoms and promoting reverse remodeling. Furthermore, cardiac regenerative therapies such as stem cell transplantation could become a new therapeutic resource in the management of HF. By analyzing the existing data from the literature, this review aims to evaluate the impact of new HF therapies in patients with IHD in order to gain further insight into the best form of therapeutic management for this large proportion of HF patients.

Intravenous Infusion of Exosomes Derived from Human Adipose Tissue-Derived Stem Cells Promotes Angiogenesis and Muscle Regeneration: An Observational Study in a Murine Acute Limb Ischemia Model

INTRODUCTION

Recent studies have demonstrated that adipose tissue-derived stem cell (ADSC) transplantation could promote neoangiogenesis in various ischemic diseases. However, as whole cells, ADSCs have some disadvantages, such as shipping and storage issues, high costs, and controversies related to the fates of grafted cells in the recipients. Therefore, this study aimed to investigate the effects of intravenously infused exosomes purified from human ADSCs on ischemic disease in a murine hindlimb ischemia model.

METHODS

ADSCs were cultured in exosome-free medium for 48 h before the conditioned medium was collected for exosome isolation by ultracentrifugation. The murine ischemic hindlimb models were created by cutting and burning the hindlimb arteries. Exosomes were intravenously infused into murine models (ADSC-Exo group), with phosphate-buffered saline (PBS) used as a placebo (PBS group). Treatment efficacy was determined using a murine mobility assay (frequency of pedaling in water per 10 s), peripheral blood oxygen saturation (SpO₂ index), and the recovery of vascular circulation by trypan blue staining. The formation of blood vessels was shown by X-ray. Expression levels of genes related to angiogenesis and muscle tissue repair were quantified by quantitative reverse-transcription polymerase chain reaction. Finally, H&E staining was used to determine the histological structure of muscle in the treatment and placebo groups.

RESULTS

The rates of acute limb ischemia in the PBS and ADSC-Exo injection groups were 66% (9/16 mice) and 43% (6/14 mice), respectively. The mobility of the limbs 28 days after surgery was significantly different between the ADSC-Exo treatment group (41 ± 1 times/10 s) and the PBS group (24 ± 1 times/10 s; n = 3; p < 0.05). Peripheral blood oxygen saturation 21 days after treatment was 83.83% ± 2.02% in the PBS group and 83% ± 1.73% in the ADSC-Exo treatment group, and the difference was not statistically significant (n = 3, p > 0.05). On day 7 after treatment, the time required to stain the toes after trypan blue injection was 20.67 ± 12.5 s and 85 ± 7.09 s in the ADSC-Exo and PBS groups, respectively (n = 3, p < 0.05). On day 3 after the operation, the expression of genes promoting angiogenesis and muscle remodeling, such as Flk1, Vwf, Ang1, Tgfb1, Myod, and Myf5, was increased 4-8 times in the ADSC-Exo group compared with the PBS group. No mice in either group died during the experimental period.

CONCLUSIONS

These results revealed that intravenous infusion of human ADSC-derived exosomes is a safe and effective method to treat ischemic disease, especially hindlimb ischemia, by promoting angiogenesis and muscle regeneration.

Safety and efficacy of intracoronary artery administration of human bone marrow-derived mesenchymal stem cells in STEMI of Lee-Sung pigs—A preclinical study for supporting the feasibility of the OmniMSC-AMI phase I clinical trial

Background

This study tested whether early left intracoronary arterial (LAD) administration of human bone marrow-derived mesenchymal stem cells (hBMMSCs, called OmniMSCs) in acute ST-segment elevation myocardial infarction (STEMI) of Lee-Sung pigs induced by 90 min balloon-occluded LAD was safe and effective.

Methods and results

Young male Lee-Sung pigs were categorized into SC (sham-operated control, n = 3), AMI-B (STEMI + buffer/21 cc/administered at 90 min after STEMI, n = 6), and AMI-M [acute myocardial infarction (AMI) + hBMMSCs/1.5 × 107/administered at 90 min after STEMI, n = 6] groups. By 2 and 5 months after STEMI, the cardiac magnetic resonance imaging demonstrated that the muscle scar score (MSS) and abnormal cardiac muscle exercise score in the infarct region were significantly increased in the AMI-B than in the SC group that were significantly reversed in the AMI-M group, whereas the left ventricular ejection function by each month (from 1 to 5) displayed an opposite pattern of MSS among the groups (all p &lt; 0.001). By 5 months, histopathological findings of infarct and fibrosis areas and isolectin-B4 exhibited an identical pattern, whereas the cellular expressions of troponin-I/troponin-T/von Willebrand factor exhibited an opposite pattern of MSS among the groups (all p &lt; 0.001). The ST-segment resolution (&gt;80%) was significantly earlier (estimated after 6-h AMI) in the AMI-M group than in the AMI-B group (p &lt; 0.001). The protein expressions of inflammation (IL-1β/TNF-α/NF-κB)/oxidative stress (NOX-1/NOX-2/oxidized protein)/apoptosis (cleaved caspase-3/cleaved PARP)/DNA damage (γ-H2AX) displayed an identical pattern to MSS among the groups, whereas the protein expressions of angiogenesis factors (SDF-1α/VEGF) were significantly and progressively increased from SC, AMI-B, to AMI-M groups (all p &lt; 0.001).

Conclusion

Early intra-LAD transfusion of OmniMSC treatment effectively reduced the infarct size and preserved LV function in porcine STEMI.

Immunomodulation—a general review of the current state-of-the-art and new therapeutic strategies for targeting the immune system

In recent years, there has been a tremendous development of biotechnological, pharmacological, and medical techniques which can be implemented in the functional modulation of the immune system components. Immunomodulation has attracted much attention because it offers direct applications in both basic research and clinical therapy. Modulation of a non-adequate, amplified immune response enables to attenuate the clinical course of a disease and restore homeostasis. The potential targets to modulate immunity are as multiple as the components of the immune system, thus creating various possibilities for intervention. However, immunomodulation faces new challenges to design safer and more efficacious therapeutic compounds. This review offers a cross-sectional picture of the currently used and newest pharmacological interventions, genomic editing, and tools for regenerative medicine involving immunomodulation. We reviewed currently available experimental and clinical evidence to prove the efficiency, safety, and feasibility of immunomodulation in vitro and in vivo. We also reviewed the advantages and limitations of the described techniques. Despite its limitations, immunomodulation is considered as therapy itself or as an adjunct with promising results and developing potential.

In Search of the Holy Grail: Stem Cell Therapy as a Novel Treatment of Heart Failure with Preserved Ejection Fraction

Heart failure, a leading cause of hospitalizations and deaths, is a major clinical problem. In recent years, the increasing incidence of heart failure with preserved ejection fraction (HFpEF) has been observed. Despite extensive research, there is no efficient treatment for HFpEF available. However, a growing body of evidence suggests stem cell transplantation, due to its immunomodulatory effect, may decrease fibrosis and improve microcirculation and therefore, could be the first etiology-based therapy of the disease. In this review, we explain the complex pathogenesis of HFpEF, delineate the beneficial effects of stem cells in cardiovascular therapy, and summarize the current knowledge concerning cell therapy in diastolic dysfunction. Furthermore, we identify outstanding knowledge gaps that may indicate directions for future clinical studies.

Mechanotransduction of mesenchymal stem cells and hemodynamic implications

Mesenchymal stem cells (MSCs) possess the capacity for self-renewal and multipotency. The traditional approach to manipulating MSC's fate choice predominantly relies on biochemical stimulation. Accumulating evidence also suggests the role of physical input in MSCs differentiation. Therefore, investigating mechanotransduction at the molecular level and related to tissue-specific cell functions sheds light on the responses secondary to mechanical forces. In this review, a new frontier aiming to optimize the cultural parameters was illustrated, i.e. spatial boundary condition, which recapitulates in vivo physiology and facilitates the investigations of cellular behavior. The concept of mechanical memory was additionally addressed to appreciate how MSCs store imprints from previous culture niches. Besides, different types of forces as physical stimuli were of interest based on the association with the respective signaling pathways and the differentiation outcome. The downstream mechanoreceptors and their corresponding effects were further pinpointed. The cardiovascular system or immune system may share similar mechanisms of mechanosensing and mechanotransduction; for example, resident stem cells in a vascular wall and recruited MSCs in the bloodstream experience mechanical forces such as stretch and fluid shear stress. In addition, baroreceptors or mechanosensors of endothelial cells detect changes in blood flow, pass over signals induced by mechanical stimuli and eventually maintain arterial pressure at the physiological level. These mechanosensitive receptors transduce pressure variation and regulate endothelial barrier functions. The exact signal transduction is considered context dependent but still elusive. In this review, we summarized the current evidence of how mechanical stimuli impact MSCs commitment and the underlying mechanisms. Future perspectives are anticipated to focus on the application of cardiovascular bioengineering and regenerative medicine.

Human Bone Marrow-Derived Mesenchymal Stromal Cells Reduce the Severity of Experimental Necrotizing Enterocolitis in a Concentration-Dependent Manner

Necrotizing enterocolitis (NEC) is a devastating gut disease in preterm neonates. In NEC animal models, mesenchymal stromal cells (MSCs) administration has reduced the incidence and severity of NEC. We developed and characterized a novel mouse model of NEC to evaluate the effect of human bone marrow-derived MSCs (hBM-MSCs) in tissue regeneration and epithelial gut repair. NEC was induced in C57BL/6 mouse pups at postnatal days (PND) 3-6 by (A) gavage feeding term infant formula, (B) hypoxia/hypothermia, and (C) lipopolysaccharide. Intraperitoneal injections of PBS or two hBM-MSCs doses (0.5 × 10⁶ or 1 × 10⁶) were given on PND2. At PND 6, we harvested intestine samples from all groups. The NEC group showed an incidence of NEC of 50% compared with controls (p < 0.001). Severity of bowel damage was reduced by hBM-MSCs compared to the PBS-treated NEC group in a concentration-dependent manner, with hBM-MSCs (1 × 10⁶) inducing a NEC incidence reduction of up to 0% (p < 0.001). We showed that hBM-MSCs enhanced intestinal cell survival, preserving intestinal barrier integrity and decreasing mucosal inflammation and apoptosis. In conclusion, we established a novel NEC animal model and demonstrated that hBM-MSCs administration reduced the NEC incidence and severity in a concentration-dependent manner, enhancing intestinal barrier integrity.

Bone marrow mesenchymal stromal cell-derived small extracellular vesicles: A novel therapeutic agent in ischemic heart diseases

Myocardial injury is a major pathological factor that causes death in patients with heart diseases. In recent years, mesenchymal stromal cells (MSCs) have been generally used in treating many diseases in animal models and clinical trials. mesenchymal stromal cells have the ability to differentiate into osteocytes, adipocytes and chondrocytes. Thus, these cells are considered suitable for cardiac injury repair. However, mechanistic studies have shown that the secretomes of mesenchymal stromal cells, mainly small extracellular vesicles (sEVs), have better therapeutic effects than mesenchymal stromal cells themselves. In addition, small extracellular vesicles have easier quality control characteristics and better safety profiles. Therefore, mesenchymal stromal cell-small extracellular vesicles are emerging as novel therapeutic agents for damaged myocardial treatment. To date, many clinical trials and preclinical experimental results have demonstrated the beneficial effects of bone marrow-derived mesenchymal stromal cells (BMMSCs) and bone marrow-derived mesenchymal stromal cells-small extracellular vesicles on ischemic heart disease. However, the validation of therapeutic efficacy and the use of tissue engineering methods require an exacting scientific rigor and robustness. This review summarizes the current knowledge of bone marrow-derived mesenchymal stromal cells- or bone marrow-derived mesenchymal stromal cells-small extracellular vesicle-based therapy for cardiac injury and discusses critical scientific issues in the development of these therapeutic strategies.

c-kit+VEGFR-2+ Mesenchymal Stem Cells Differentiate into Cardiovascular Cells and Repair Infarcted Myocardium after Transplantation

Resent study suggests that c-kit⁺ cells in bone marrow-derived MSCs may differentiate toward cardiamyocytes. However, the properties of c-kit⁺ MSCs remain unclear. This study isolated c-kit⁺VEGFR-2⁺ cells from rat bone marrow-derived MSCs, and assessed potential of c-kit⁺VEGFR-2⁺ MSCs to differentiate towards cardiovascular cells and their efficiency of repairing the infarcted myocardium after transplantation. Gene expression profile of the cells was analyzed with RNA-sequencing. Potential of differentiation of the cells was determined after induction. Rat models of myocardial infarction were established by ligation of the left anterior descending coronary artery. The cells were treated with hypoxia and serum deprivation for four hours before transplantation. Improvement of cardiac function and repair of the infarcted myocardium were assessed at four weeks after transplantation. Gene expression profile revealed that c-kit⁺VEGFR-2⁺ MSCs expressed most smooth muscle-specific and myocardium-specific genes, while expression of endothelium-specific genes was upregulated significantly. After induction with VEGF or TGF-β for two weeks, the cells expressed CD31 and α-SMA respectively. At three weeks, BMP-2-induced cells expressed cTnT. After transplantation of the cells, cardiac function was improved, scar size of the infarcted myocardium was decreased, and angiogenesis and myocardial regeneration were enhanced significantly. Moreover, paracrine in the myocardium was increased after transplantation. These results suggest that c-kit⁺VEGFR-2⁺ MSCs have a potential of differentiation towards cardiovascular cells. Transplantation of c-kit⁺VEGFR-2⁺ MSCs is effective for repair of the infarcted myocardium. c-kit⁺VEGFR-2⁺ MSCs may be a reliable source for cell therapy of ischaemic diseases.

A Study on the Protective Effect of sRAGE-MSCs in a Rodent Reperfusion Model of Myocardial Infarction

Acute myocardial infarction (AMI) is one of the major leading causes of death in humans globally. Recently, increased levels of recruited macrophages and AGE-albumin were observed in the hearts of humans and animals with acute myocardial infarction. Thus, the purposes of this study were to investigate whether the elevated levels of AGE-albumin from activated macrophage cells are implicated in ischemia-induced cardiomyocyte death and to develop therapeutic strategies for AMI based on its underlying molecular mechanisms with respect to AGEs. The present study demonstrated that activated macrophages and AGE-albumin were observed in heart tissues obtained from humans and rats with AMI incidences. In the cellular model of AMI, it was found that increased expression of AGE-albumin was shown to be co-localized with macrophages, and the presence of AGE-albumin led to increased expression of RAGE through the mitogen-activated protein kinase pathway. After revealing cardiomyocyte apoptosis induced by toxicity of the AGE-RAGE system, sRAGE-secreting MSCs were generated using the CRISPR/Cas9 platform to investigate the therapeutic effects of sRAGE-MSCs in an AMI rat model. Gene-edited sRAGE-MSCs showed greater therapeutic effects against AMI pathogenesis in rat models compared to mock MSCs, and promising results of the functional improvement of stem cells could result in significant improvements in the clinical management of cardiovascular diseases.

Controlled Release of Encapsuled Stromal-Derived Factor 1α Improves Bone Marrow Mesenchymal Stromal Cells Migration

Stem cell treatment is a promising method of therapy for the group of patients whose conventional options for treatment have been limited or rejected. Stem cells have the potential to repair, replace, restore and regenerate cells. Moreover, their proliferation level is high. Owing to these features, they can be used in the treatment of numerous diseases, such as cancer, lung diseases or ischemic heart diseases. In recent years, stem cell therapy has greatly developed, shedding light on stromal-derived factor 1α (SDF-1α). SDF-1α is a mobilizing chemokine for application of endogenous stem cells to injury sites. Unfortunately, SDF-1α presented short-term results in stem cell treatment trials. Considering the tremendous benefits of this therapy, we developed biodegradable polymeric microspheres for the release of SDF-1α in a controlled and long-lasting manner. The microspheres were designed from poly(L-lactide/glycolide/trimethylene carbonate) (PLA/GA/TMC). The effect of controlled release of SDF-1α from microspheres was investigated on the migration level of bone marrow Mesenchymal Stromal Cells (bmMSCs) derived from a pig. The study showed that SDF-1α, released from the microspheres, is more efficient at attracting bmMSCs than SDF-1α alone. This may enable the controlled delivery of selected and labeled MSCs to the destination in the future.

Cell administration routes for heart failure: a comparative re-evaluation of the REGENERATE-DCM and REGENERATE-IHD trials

Aims: Given the logistical issues surrounding intramyocardial cell delivery, we sought to address the efficacy of the simpler, more accessible intracoronary route by re-evaluating REGENERATE-DCM and REGENERATE-IHD (autologous cell therapy trials for heart failure; n = 150). Methods: A retrospective statistical analysis was performed on the trials' combined data. The following end points were evaluated: left ventricular ejection fraction (LVEF), N-terminal pro brain natriuretic peptide concentration (NT-proBNP), New York Heart Association class (NYHA) and quality of life. Results: This demonstrated a new efficacy signal for intracoronary delivery, with significant benefits to: LVEF (3.7%; p = 0.01), NT-proBNP (median -76 pg/ml; p = 0.04), NYHA class (48% patients; p = 0.01) and quality of life (12 ± 19; p = 0.006). The improvements in LVEF, NYHA and quality of life scores remained significant compared to the control group. Conclusion: The efficacy and logistical simplicity of intracoronary delivery should be taken into consideration for future trials.

First-in-human pilot trial of combined intracoronary and intravenous mesenchymal stem cell therapy in acute myocardial infarction

Background

Acute ST-elevation myocardial infarction (STEMI) elicits a robust cardiomyocyte death and inflammatory responses despite timely revascularization.

Objectives

This phase 1, open-label, single-arm, first-in-human study aimed to assess the safety and efficacy of combined intracoronary (IC) and intravenous (IV) transplantation of umbilical cord-derived mesenchymal stem cells (UMSC01) for heart repair in STEMI patients with impaired left ventricular ejection fraction (LVEF 30-49%) following successful reperfusion by percutaneous coronary intervention.

Methods

Consenting patients received the first dose of UMSC01 through IC injection 4-5 days after STEMI followed by the second dose of UMSC01 via IV infusion 2 days later. The primary endpoint was occurrence of any treatment-related adverse events and the secondary endpoint was changes of serum biomarkers and heart function by cardiac magnetic resonance imaging during a 12-month follow-up period.

Results

Eight patients gave informed consents, of whom six completed the study. None of the subjects experienced treatment-related serious adverse events or major adverse cardiovascular events during IC or IV infusion of UMSC01 and during the follow-up period. The NT-proBNP level decreased (1362 ± 1801 vs. 109 ± 115 pg/mL, p = 0.0313), the LVEF increased (52.67 ± 12.75% vs. 62.47 ± 17.35%, p = 0.0246), and the wall motion score decreased (26.33 ± 5.57 vs. 22.33 ± 5.85, p = 0.0180) at the 12-month follow-up compared to the baseline values. The serial changes of LVEF were 0.67 ± 3.98, 8.09 ± 6.18, 9.04 ± 10.91, and 9.80 ± 7.56 at 1, 3, 6, and 12 months, respectively as compared to the baseline.

Conclusion

This pilot study shows that combined IC and IV transplantation of UMSC01 in STEMI patients with impaired LVEF appears to be safe, feasible, and potentially beneficial in improving heart function. Further phase 2 studies are required to explore the effectiveness of dual-route transplantation of UMSC01 in STEMI patients.

Transplantation of mesenchymal stem cells for prevention of acute myocardial infarction induced heart failure: study protocol of a phase III randomized clinical trial (Prevent-TAHA8)

Background

Results from recent clinical trials on bone marrow mononuclear cell (BM-MNC) transplantation show that this intervention can help reduce the incidence of heart failure (HF) after acute myocardial infarction (AMI). However, no study has evaluated the effect of the transplantation of mesenchymal stem cells (MSCs) on a clinical endpoint such as HF.

Methods

This single-blinded, randomized, multicenter trial aims to establish whether the intracoronary infusion of umbilical cord-derived Wharton’s jelly MSCs (WJ-MSCs) helps prevent HF development after AMI. The study will enroll 390 patients 3 to 7 days following AMI. Only patients aged below 65 years with impaired LV function (LVEF < 40%) will be included. They will be randomized (2:1 ratio) to either receive standard care or a single intracoronary infusion of 10⁷ WJ-MSCs. The primary outcome of this study is the assessment of HF development during long-term follow-up (3 years).

Discussion

Data will be collected until Nov 2024. Thereafter, the analysis will be conducted. Results are expected to be ready by Dec 2024. We will prepare and submit the related manuscript following the CONSORT guidelines. This study will help determine whether or not the infusion of intracoronary WJ-MSCs in patients with AMI will reduce the incidence of AMI-induced HF.

Trial registration

ClinicalTrials.gov NCT05043610, Registered on 14 September 2021 - retrospectively registered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06594-1.

Comparing the effect of bone marrow mono-nuclear cells with mesenchymal stem cells after acute myocardial infarction on improvement of left ventricular function: a meta-analysis of clinical trials

BACKGROUND

The effect of transplantation of bone-marrow mononuclear cells (BM-MNCs) and mesenchymal stem cells (MSCs) on ejection fraction (LVEF) has been studied in patients with acute myocardial infarction (AMI) in clinical trials. This raises the question that which type of cell may help improve LVEF better in AMI patients. No meta-analysis of clinical trials has yet addressed this question.

METHODS

Electronic databases were searched thoroughly to find eligible trials on the effects of transplantation of BM-MNCs and MSCs in patients with AMI. The primary outcome was improvement in LVEF. Data were synthesized using random-effects meta-analysis. For maximizing the credibility of subgroup analysis, we used the instrument for assessing the Credibility of Effect Modification of Analyses (ICEMAN) for meta-analyses.

RESULTS

A total of 36 trials (26 on BM-MNCs and 10 on MSCs) with 2489 patients (1466 were transplanted [1241 with BM-MNCs and 225 with MSCs] and 1023 as controls) were included. Both types of cells showed significant improvements in ejection fraction in short-term follow-up (BM-MNCs: WMD = 2.13%, 95% CI = 1.23 to 3.04, p < 0.001; MSCs: WMD = 3.71%, 95% CI = 2.32 to 5.09, p < 0.001), and according to ICEMAN criteria, MSCs are more effective. For selected population of patients who received stem cell transplantation in early course after AMI (less than 11 days), this effect was even more pronounced (BM-MNC: WMD = 3.07%, 95% CI = 1.97 to 4.17, p < 0.001, I² = 40.7%; MSCs: WMD = 5.65%, 95% CI = 3.47 to 7.84, p < 0.001, I² = 84.6%).

CONCLUSION

Our results showed that transplantation of MSCs after AMI might increase LVEF more than BM-MNCs; also, based on ICEMAN, there was likely effect modification between subgroups although uncertainty still remained.

Single vs. double intracoronary injection of mesenchymal stromal cell after acute myocardial infarction: the study protocol from a randomized clinical trial: BOOSTER-TAHA7 trial

Background

Meta-analysis from previous studies have shown that treatment with mesenchymal stromal cell (MCSs) may increase the left ventricular ejection fraction (LVEF) after acute myocardial infarction (AMI) by 3.84%, and the effect is greater in those who are not aged and have developed a reduced LVEF. However, it seems that MSC transplantation does its effect through an indirect paracrine effect, and direct differentiation to the cardiomyocytes does not occur. Therefore, it can be hypothesized that this paracrine effect would be augmented if repeated doses of MSC are transplanted. This study is conducted to compare single vs. double injection of MSCs.

Methods

This is a single-blind, randomized, multicenter trial aiming to determine whether intracoronary infusion of double doses of umbilical cord-derived Wharton’s jelly MSCs (WJ-MSCs) improves LVEF more after AMI compared to single administration. Sixty patients 3 to 7 days after AMI will be enrolled. The patients should be under 65 years old and have a severe impairment in LV function (LVEF < 40%). They will be randomized to three arms receiving single or double doses of intracoronary infusion of WJ-MSCs or placebo. The primary endpoint of this study is assessment of improvement in LVEF at 6-month post intervention as compared to the baseline.

Discussion

This investigation will help to determine whether infusion of booster (second) dose of intracoronary WJ-MSCs in patients with AMI will contribute to increasing its effect on the improvement of myocardial function.

Trial registration

Iranian Registry of Clinical Trials (www.IRCT.ir) IRCT20201116049408N1. Registered on November 26 2020