Cardiac repair with intramyocardial injection of allogeneic mesenchymal stem cells after myocardial infarction

Cellular stress and epigenetic regulation in adult stem cells

Stem cells are a unique class of cells that possess the ability to differentiate and self-renew, enabling them to repair and replenish tissues. To protect and maintain the potential of stem cells, the cells and the environment surrounding these cells (stem cell niche) are highly responsive and tightly regulated. However, various stresses can affect the stem cells and their niches. These stresses are both systemic and cellular and can arise from intrinsic or extrinsic factors which would have strong implications on overall aging and certain disease states. Therefore, understanding the breadth of drivers, namely epigenetic alterations, involved in cellular stress is important for the development of interventions aimed at maintaining healthy stem cells and tissue homeostasis. In this review, we summarize published findings of epigenetic responses to replicative, oxidative, mechanical, and inflammatory stress on various types of adult stem cells.

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.

Stem cell therapy for heart failure in the clinics: new perspectives in the era of precision medicine and artificial intelligence

Stem/progenitor cells have been widely evaluated as a promising therapeutic option for heart failure (HF). Numerous clinical trials with stem/progenitor cell-based therapy (SCT) for HF have demonstrated encouraging results, but not without limitations or discrepancies. Recent technological advancements in multiomics, bioinformatics, precision medicine, artificial intelligence (AI), and machine learning (ML) provide new approaches and insights for stem cell research and therapeutic development. Integration of these new technologies into stem/progenitor cell therapy for HF may help address: 1) the technical challenges to obtain reliable and high-quality therapeutic precursor cells, 2) the discrepancies between preclinical and clinical studies, and 3) the personalized selection of optimal therapeutic cell types/populations for individual patients in the context of precision medicine. This review summarizes the current status of SCT for HF in clinics and provides new perspectives on the development of computation-aided SCT in the era of precision medicine and AI/ML.

Allogeneic Mesenchymal Stem Cells After In Vivo Transplantation: A Review

Autologous mesenchymal stem cells (MSCs) are ideal for tissue regeneration because of their ability to circumvent host rejection, but their procurement and processing present logistical and time-sensitive challenges. Allogeneic MSCs provide an alternative cell-based therapy capable of positively affecting all human organ systems, and can be readily available. Extensive research has been conducted in the treatment of autoimmune, degenerative, and inflammatory diseases with such stem cells, and has demonstrated predominantly safe outcomes with minimal complications. Nevertheless, continued clinical trials are necessary to ascertain optimal harvest and transplant techniques.

The therapeutic efficacy and clinical translation of mesenchymal stem cell-derived exosomes in cardiovascular diseases

Exosomes, mainly derived from mesenchymal stem cells, provide a good reference for cardiac function repair and clinical application in cardiac and vascular diseases by regulating cardiomyocyte viability, inflammatory levels, angiogenesis, and ventricular remodeling after a heart injury. This review presents the cardioprotective efficacy of mesenchymal stem cell-originated exosomes and explores the underlying molecular mechanisms. Furthermore, we expound on several efficient approaches to transporting exosomes into the heart in clinical application and comment on the advantages and disadvantages of each method.

Combination human umbilical cord perivascular and endothelial colony forming cell therapy for ischemic cardiac injury

Cell-based therapeutics are promising interventions to repair ischemic cardiac tissue. However, no single cell type has yet been found to be both specialized and versatile enough to heal the heart. The synergistic effects of two regenerative cell types including endothelial colony forming cells (ECFC) and first-trimester human umbilical cord perivascular cells (FTM HUCPVC) with endothelial cell and pericyte properties respectively, on angiogenic and regenerative properties were tested in a rat model of myocardial infarction (MI), in vitro tube formation and Matrigel plug assay. The combination of FTM HUCPVCs and ECFCs synergistically reduced fibrosis and cardiomyocyte apoptosis, while promoting favorable cardiac remodeling and contractility. These effects were in part mediated by ANGPT2, PDGF-β, and VEGF-C. PDGF-β signaling-dependent synergistic effects on angiogenesis were also observed in vitro and in vivo. FTM HUCPVCs and ECFCs represent a cell combination therapy for promoting and sustaining vascularization following ischemic cardiac injury.

Tailoring the Microarchitectures of 3D Printed Bone-like Scaffolds for Tissue Engineering Applications

Material extrusion (MEX), commonly referred to as fused deposition modeling (FDM) or fused filament fabrication (FFF), is a versatile and cost-effective technique to fabricate suitable scaffolds for tissue engineering. Driven by a computer-aided design input, specific patterns can be easily collected in an extremely reproducible and repeatable process. Referring to possible skeletal affections, 3D-printed scaffolds can support tissue regeneration of large bone defects with complex geometries, an open major clinical challenge. In this study, polylactic acid scaffolds were printed resembling trabecular bone microarchitecture in order to deal with morphologically biomimetic features to potentially enhance the biological outcome. Three models with different pore sizes (i.e., 500, 600, and 700 µm) were prepared and evaluated by means of micro-computed tomography. The biological assessment was carried out seeding SAOS-2 cells, a bone-like cell model, on the scaffolds, which showed excellent biocompatibility, bioactivity, and osteoinductivity. The model with larger pores, characterized by improved osteoconductive properties and protein adsorption rate, was further investigated as a potential platform for bone-tissue engineering, evaluating the paracrine activity of human mesenchymal stem cells. The reported findings demonstrate that the designed microarchitecture, better mimicking the natural bone extracellular matrix, favors a greater bioactivity and can be thus regarded as an interesting option for bone-tissue engineering.

Fibrin-Enriched Cardiac Extracellular Matrix Hydrogel Promotes In Vitro Angiogenesis

Angiogenesis is essential for cardiac repair after myocardial infarction. Promoting angiogenesis has been demonstrated as an effective approach for myocardial infarction treatment. Several different strategies for inducing myocardial angiogenesis have been explored, including exogenous delivery of angiogenic genes, proteins, microRNAs, cells, and extracellular vesicles. Various types of injectable hydrogels have been investigated for cardiac tissue repair. One of the most promising injectable hydrogels in cardiac regeneration is a cardiac extracellular matrix hydrogel that is derived from decellularized porcine myocardium. It can be delivered minimally invasively via transendocardial delivery. The safety and efficacy of cardiac extracellular matrix hydrogels have been shown in small and large animal myocardial infarction models as well as clinical trials. The main mechanisms underlying the therapeutic benefits of cardiac extracellular matrix hydrogels have been elucidated and involved in the modulation of the immune response, downregulation of pathways related to heart failure progression and fibrosis, upregulation of genes important for cardiac muscle contraction, and enhancing cardiomyocyte differentiation and maturation from stem cells. However, no potent capillary network formation induced by cardiac extracellular matrix hydrogels has been reported. In this study, we tested the feasibility of incorporating a fibrin matrix into cardiac extracellular matrix hydrogels to improve the angiogenic properties of the hydrogel. Our in vitro results demonstrate that fibrin-enriched cardiac extracellular matrix hydrogels can induce robust endothelial cell tube formation from human umbilical vein endothelial cells and promote the sprouting of human mesenchymal stem cell spheroids. The obtained information from this study is very critical toward the future in vivo evaluation of fibrin-enriched cardiac extracellular matrix hydrogels in promoting myocardial angiogenesis.

Simultaneous late-gadolinium enhancement and T1 mapping of fibrosis and a novel cell-based combination therapy in hypertensive mice

Fibrosis is a hallmark of chronic hypertension and disrupts the viability of human bone marrow-derived mesenchymal stromal cells (BM-MSCs) post-transplantation. This study thus, determined whether the anti-fibrotic drug, serelaxin (RLX), could enhance the therapeutic effects of BM-MSCs or BM-MSC-derived exosomes (BM-MSC-EXO) in hypertensive mice. Left ventricular (LV) fibrosis in particular was assessed using conventional histological staining and non-invasive cardiac magnetic resonance imaging (CMRI). CMRI was employed using a novel magnetisation prepared 2 rapid acquisition gradient echo (MP2RAGE) sequence to simultaneously perform late gadolinium enhancement imaging and T1 mapping. Adult male C57BL/6 mice were uninephrectomised, received deoxycorticosterone acetate and saline to drink (1 K/DOCA/salt) for 21 days, whilst control mice were given normal drinking water for the same time-period. On day 14 post-injury, subgroups of 1 K/DOCA/salt-hypertensive mice were treated with RLX alone or in combination with BM-MSCs or BM-MSC-EXO; or the mineralocorticoid receptor antagonist, spironolactone. At day 21 post-injury, LV and kidney histopathology was assessed, whilst LV fibrosis and function were additionally analysed by CMRI and echocardiography. 1 K/DOCA/salt-hypertensive mice developed kidney tubular injury, inflammation, fibrosis, and more moderate LV hypertrophy, fibrosis and diastolic dysfunction. RLX and BM-MSCs combined provided optimal protection against these pathologies and significantly reduced picrosirius red-stained organ fibrosis and MP2RAGE analysis of LV fibrosis. A significant correlation between MP2RAGE analysis and histologically-stained interstitial LV fibrosis was detected. It was concluded that the MP2RAGE sequence enhanced the non-invasive CMRI detection of LV fibrosis. Furthermore, combining RLX and BM-MSCs may represent a promising treatment option for hypertensive cardiorenal syndrome.

Rutin and quercetagetin enhance the regeneration potential of young and aging bone marrow-derived mesenchymal stem cells in the rat infarcted myocardium

Myocardial infarction (MI) damages cardiomyocytes permanently and compromises cardiac function. Mesenchymal stem cells (MSCs) with the potential to differentiate into multiple lineages are considered as one of the best options for the treatment of MI. However, aging affects their regeneration capability. With age, reactive oxygen species (ROS) accumulate in cells ultimately causing cell death. To successfully utilize these stem cells in clinic, novel strategies to improve their functional capability should be explored. In this study, we aimed to enhance the cardiac regeneration potential of bone marrow MSCs derived from aging rats by treating them with antioxidants, rutin or quercetagetin in separate in vivo experiments. Oxidative stress was induced by treating MSCs of young and aging rats with different concentrations of H₂O₂ which resulted in an increase in the ROS level. MSCs were treated with rutin or quercetagetin at varying concentrations and exposed to H₂O₂. It was observed that both antioxidants significantly (P < 0.001) suppressed H₂O₂-induced intracellular ROS accumulation in a dose-dependent manner. An optimized concentration of 10 µM rutin or quercetagetin was used for the in vivo experiments. MI models were developed in aging rats by ligation of left anterior descending artery and treated MSCs were transplanted in the MI models. Echocardiography was performed after 2 and 4 weeks of cell transplantation to evaluate the functional status of the infarcted heart and histological analysis was performed after 4 weeks to assess cardiac regeneration. Significant improvement was observed in cardiac parameters including LVEF% (P < 0.001), LVFS% (P < 0.01 and P < 0.001), LVIDd (P < 0.01 and P < 0.001), LVIDs (P < 0.001), LVEDV (P < 0.001) and LVESV (P < 0.001) in the treated young as well as aging MSCs. It is concluded from these findings that rutin and quercetagetin treatment enhance the regeneration efficiency of young and aging MSCs in vivo. These antioxidants can be effectively utilized to improve cellular therapy for myocardial infarction by suppressing ROS production.

Hyperthermia-stimulated tonsil-mesenchymal stromal cells suppress hematological cancer cells through downregulation of IL-6

There are contradictory reports on the use of mesenchymal stromal cells (MSCs) in cancer therapy. Variable outcomes have been associated with several factors including cancer pathology, experimental procedure, MSC source tissue, and individual genetic differences. It is also known that MSCs exert their therapeutic effects with various paracrine factors released from these cells. The profiles of the factors released from MSCs are altered by heat shock, hypoxia, oxidative stress, starvation or various agents such as inflammatory cytokines, and their therapeutic potential is affected. In this study, the antitumor potential of conditioned media (CM), which contains paracrine factors, of mild hyperthermia-stimulated mesenchymal stromal cells derived from lymphoid organ tonsil tissue (T-MSC) was investigated in comparison with CM obtained from T-MSCs grew under normal culture conditions. CM was obtained from T-MSCs that were successfully isolated from palatine tonsil tissue and characterized. The cytotoxic effect of CM on the growth of hematological cancer cell lines at different concentrations (1:1 and 1:2) was demonstrated by methylthiazoldiphenyl-tetrazolium bromide analysis. In addition, the apoptotic effect of T-MSC-CM treatment was evaluated on the cancer cells using Annexin-V/PI detection method by flow cytometry. The pro/anti-apoptotic and cytokine-related gene expressions were also analyzed by real-time polymerase chain reaction post T-MSC-CM treatment. In conclusion, we demonstrated that the factors released from hyperthermia-stimulated T-MSCs induced apoptosis in hematological cancer cell lines in a dose-dependent manner. Importantly, our results at the transcriptional level support that the factors and cytokines released from hyperthermia-stimulated T-MSC may exert antitumoral effects in cancer cells by downregulation of IL-6 that promotes tumorigenesis. These findings reveal that T-MSC-CM can be a powerful cell-free therapeutical strategy for cancer therapy.

Human Mesenchymal Stem Cell Secretome Driven T Cell Immunomodulation Is IL-10 Dependent

The Human Mesenchymal Stem Cell (hMSC) secretome has pleiotropic effects underpinning its therapeutic potential. hMSC serum-free conditioned media (SFCM) contains a variety of cytokines, with previous studies linking a changed secretome composition to physoxia. The Jurkat T cell model allowed the efficacy of SFCM vs. serum-free media (SFM) in the suppression of immunological aspects, including proliferation and polarisation, to be explored. Cell growth in SFM was higher [(21% O2 = 5.3 × 105 ± 1.8 × 104 cells/mL) and (2% O2 = 5.1 × 105 ± 3.0 × 104 cells/mL)], compared to SFCM [(21% O2 = 2.4 × 105 ± 2.5 × 104 cells/mL) and (2% O2 = 2.2 × 105 ± 5.8 × 103 cells/mL)]. SFM supported IL-2 release following activation [(21% O2 = 5305 ± 211 pg/mL) and (2% O2 = 5347 ± 327 pg/mL)] whereas SFCM suppressed IL-2 secretion [(21% O2 = 2461 ± 178 pg/mL) and (2% O2 = 1625 ± 159 pg/mL)]. Anti-inflammatory cytokines, namely IL-4, IL-10, and IL-13, which we previously confirmed as components of hMSC SFCM, were tested. IL-10 neutralisation in SFCM restored proliferation in both oxygen environments (SFM/SFCM+antiIL-10 ~1-fold increase). Conversely, IL-4/IL-13 neutralisation showed no proliferation restoration [(SFM/SFM+antiIL-4 ~2-fold decrease), and (SFM/SFCM+antiIL-13 ~2-fold decrease)]. Present findings indicate IL-10 played an immunosuppressive role by reducing IL-2 secretion. Identification of immunosuppressive components of the hMSC secretome and a mechanistic understanding of their action allow for the advancement and refinement of potential future cell-free therapies.

Differentiation Capacity of Bone Marrow-Derived Rat Mesenchymal Stem Cells from DsRed and Cre Transgenic Cre/loxP Models

Cre/loxP recombination is a well-established technique increasingly used for modifying DNA both in vitro and in vivo. Nucleotide alterations can be edited in the genomes of mammalian cells, and genetic switches can be designed to target the expression or excision of a gene in any tissue at any time in animal models. In this study, we propose a system which worked via the Cre/loxP switch gene and DsRed/emGFP dual-color fluorescence imaging. Mesenchymal stem cells (MSCs) can be used to regenerate damaged tissue because of their differentiation capacity. Although previous studies have presented evidence of fusion of transplanted MSCs with recipient cells, the possibility of fusion in such cases remains debated. Moreover, the effects and biological implications of the fusion of MSCs at the tissue and organ level have not yet been elucidated. Thus, the method for determining this issue is significant and the models we proposed can illustrate the question. However, the transgenic rats exhibited growth slower than that of wild-type rats over several weeks. The effects on the stemness, proliferation, cell cycle, and differentiation ability of bone marrow–derived rat MSCs (BM-rMSCs) from the models were examined to ensure our design was appropriate for the in vivo application. We demonstrated that MSC surface markers were maintained in DsRed and Cre transgenic rMSCs (DsRed-rMSCs and Cre-rMSCs, respectively). A WST-8 assay revealed decreased proliferative activity in these DsRed-rMSCs and Cre-rMSCs; this result was validated through cell counting. Furthermore, cell cycle analysis indicated a decrease in the proportion of G1-phase cells and a concomitant increase in the proportion of S-phase cells. The levels of cell cycle–related proteins also decreased in the DsRed-rMSCs and Cre-rMSCs, implying decelerated phase transition. However, the BM-rMSCs collected from the transgenic rats did not exhibit altered adipogenesis, osteogenesis, or chondrogenesis. The specific markers of these types of differentiation were upregulated after induction. Therefore, BM-rMSCs from DsRed and Cre transgenic models can be used to investigate the behavior of MSCs and related mechanisms. Such application may further the development of stem cell therapy for tissue damage and other diseases.

Myocardial infarction from a tissue engineering and regenerative medicine point of view: A comprehensive review on models and treatments

In the modern world, myocardial infarction is one of the most common cardiovascular diseases, which are responsible for around 18 million deaths every year or almost 32% of all deaths. Due to the detrimental effects of COVID-19 on the cardiovascular system, this rate is expected to increase in the coming years. Although there has been some progress in myocardial infarction treatment, translating pre-clinical findings to the clinic remains a major challenge. One reason for this is the lack of reliable and human representative healthy and fibrotic cardiac tissue models that can be used to understand the fundamentals of ischemic/reperfusion injury caused by myocardial infarction and to test new drugs and therapeutic strategies. In this review, we first present an overview of the anatomy of the heart and the pathophysiology of myocardial infarction, and then discuss the recent developments on pre-clinical infarct models, focusing mainly on the engineered three-dimensional cardiac ischemic/reperfusion injury and fibrosis models developed using different engineering methods such as organoids, microfluidic devices, and bioprinted constructs. We also present the benefits and limitations of emerging and promising regenerative therapy treatments for myocardial infarction such as cell therapies, extracellular vesicles, and cardiac patches. This review aims to overview recent advances in three-dimensional engineered infarct models and current regenerative therapeutic options, which can be used as a guide for developing new models and treatment strategies.

Injectable selenium-containing polymeric hydrogel formulation for effective treatment of myocardial infarction

Myocardial infarction (MI) is a serious threat to people’s life and health, which is significantly hindered by effective treatment formulations. Interestingly, our recent endeavour of designing selenium-containing polymeric hydrogel has been experimentally proved to be helpful in combating inflammatory responses and treating MI. The design was inspired by selenium with anti-inflammatory and anti-fibrosis activities, and the formulation could also serve as a support of myocardial tissue upon the failure of this function. In details, an injectable selenium-containing polymeric hydrogel, namely, poly[di-(1-hydroxylyndecyl) selenide/polypropylene glycol/polyethylene glycol urethane] [poly(DH-SE/PEG/PPG urethane)], was synthesised by combining a thermosensitive PPG block, DH-Se (which has oxidation-reduction properties), and hydrophilic PEG segments. Based on the established mouse model of MI, this formulation was experimentally validated to effectively promote the recovery of cardiac function. At the same time, we confirmed by enzyme-linked immunosorbent assay, Masson staining and Western blotting that this formulation could inhibit inflammation and fibrosis, so as to significantly improve left ventricular remodelling. In summary, a selenium-containing polymeric hydrogel formulation analysed in the current study could be a promising therapeutic formulation, which can provide new strategies towards the effective treatment of myocardial infarction or even other inflammatory diseases.

Dynamic Culture of Mesenchymal Stromal/Stem Cell Spheroids and Secretion of Paracrine Factors

In recent years, conditioned medium (CM) obtained from the culture of mesenchymal stromal/stem cells (MSCs) has been shown to effectively promote tissue repair and modulate the immune response in vitro and in different animal models, with potential for application in regenerative medicine. Using CM offers multiple advantages over the implantation of MSCs themselves: 1) simpler storage, transport, and preservation requirements, 2) avoidance of the inherent risks of cell transplantation, and 3) potential application as a ready-to-go biologic product. For these reasons, a large amount of MSCs research has focused on the characterization of the obtained CM, including soluble trophic factors and vesicles, preconditioning strategies for enhancing paracrine secretion, such as hypoxia, a three-dimensional (3D) environment, and biochemical stimuli, and potential clinical applications. In vitro preconditioning strategies can increase the viability, proliferation, and paracrine properties of MSCs and therefore improve the therapeutic potential of the cells and their derived products. Specifically, dynamic cultivation conditions, such as fluid flow and 3D aggregate culture, substantially impact cellular behaviour. Increased levels of growth factors and cytokines were observed in 3D cultures of MSC grown on orbital or rotatory shaking platforms, in stirred systems, such as spinner flasks or stirred tank reactors, and in microgravity bioreactors. However, only a few studies have established dynamic culture conditions and protocols for 3D aggregate cultivation of MSCs as a scalable and reproducible strategy for CM production. This review summarizes significant advances into the upstream processing, mainly the dynamic generation and cultivation of MSC aggregates, for de CM manufacture and focuses on the standardization of the soluble factor production.

Bone marrow mesenchymal stem cells alleviate the formation of pathological scars in rats

Introduction

Methods

Results

Conclusions

Human umbilical cord mesenchymal stem cell-derived extracellular vesicles loaded with miR-223 ameliorate myocardial infarction through P53/S100A9 axis

Mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) have been proposed as a promising strategy for myocardial infarction (MI). This study aims to explore the mechanism of human umbilical cord MSCs (hucMSCs)-derived EVs loaded with miR-223 on MI. Inflammation, cell biological functions, and fibrosis in vitro were measured. Furthermore, MI rat models were established to verify the role of EVs-miR-223 in vivo. The binding relationship between miR-223 and P53 was confirmed. ChIP assay was utilized to observe the combination of P53 and S100A9. The suppressed fibrosis of cardiomyocytes occurred with cells overexpressing miR-223. MiR-223 contributed to the angiogenesis of HUVECs. P53 was a target gene of miR-223. In vivo, miR-223 relieved myocardial fibrosis and inflammation infiltration, and promoted the angiogenesis in MI rats. HucMSC-derived EVs loaded with miR-223 mitigates MI and promotes myocardial repair through the P53/S100A9 axis, manifesting the underlying therapy values of hucMSC-derived EVs loaded with miR-223 in MI.

Optimal Delivery Route of Mesenchymal Stem Cells for Cardiac Repair: The Path to Good Clinical Practice

Research has shown that mesenchymal stem cells (MSCs) could be a promising therapy for treating progressive heart disease. However, translation into clinics efficiently and successfully has proven to be much more complicated. Many questions remain for optimizing treatment. Application method influences destiny of MSCs and afterwards impacts results of procedure, yet there is no general agreement about most suitable method of MSC delivery in the clinical setting. Herein, we explain principle of most-frequent MSCs delivery techniques in cardiology. This chapter summarizes crucial translational obstacles of clinical employment of MSCs for cardiac repair when analysed trough a prism of latest research centred on different techniques of MSCs application.

Adipose-Derived Stem Cells-Derived Exosomes with High Amounts of Circ_0001747 Alleviate Hypoxia/Reoxygenation-Induced Injury in Myocardial Cells by Targeting MiR-199b-3p/MCL1 Axis

Recent studies demonstrated that circular RNAs play important roles in exosome-mediated cardio-protective effects after acute myocardial infarction (AMI). A previous study reported that circ_0001747 level is down-regulated in mouse hypoxia/reoxygenation (H/R) injury model. However, its biological role and working mechanism in AMI remain largely unknown.Exosomes were isolated from the culture supernatant of adipose-derived stem cells (ADSCs) using an ExoQuick precipitation kit. We treated mouse myocardial cells HL-1 with H/R to explore the role of exosomal circ_0001747 in AMI pathology. Cell viability, proliferation, apoptosis, and inflammation were analyzed by Cell Counting Kit-8 assay, 5-ethynyl-2'-deoxyuridine assay, flow cytometry, and enzyme-linked immunosorbent assay. Dual-luciferase reporter assay and RNA immunoprecipitation assay were conducted to confirm the interaction between microRNA-199b-3p (miR-199b-3p) and circ_0001747 or MCL1 apoptosis regulator, BCL2 family member (MCL1).H/R-induced HL-1 dysfunction was attenuated by the incubation of exosomes derived from ADSCs, especially the exosomes with high amounts of circ_0001747. Circ_0001747 directly targeted miR-199b-3p in HL-1 cells. miR-199b-3p overexpression partly overturned exosomal circ_0001747-mediated protective effects in H/R-induced HL-1 cells. MCL1 was a direct target of miR-199b-3p in HL-1 cells. miR-199b-3p silencing alleviated H/R-induced damage in HL-1 cells partly by up-regulating MCL1. Circ_0001747 can elevate the messenger RNA and protein levels of MCL1 by sequestering miR-199b-3p.Overall, these results indicated that ADSCs-derived exosomes with high amounts of circ_0001747 attenuated H/R-induced HL-1 dysfunction partly by targeting miR-199b-3p/MCL1 signaling.

Pre-conditioning Strategies for Mesenchymal Stromal/Stem Cells in Inflammatory Conditions of Livestock Species

Mesenchymal stem/stromal cells (MSCs) therapy has been a cornerstone of regenerative medicine in humans and animals since their identification in 1968. MSCs can interact and modulate the activity of practically all cellular components of the immune response, either through cell-cell contact or paracrine secretion of soluble mediators, which makes them an attractive alternative to conventional therapies for the treatment of chronic inflammatory and immune-mediated diseases. Many of the mechanisms described as necessary for MSCs to modulate the immune/inflammatory response appear to be dependent on the animal species and source. Although there is evidence demonstrating an in vitro immunomodulatory effect of MSCs, there are disparate results between the beneficial effect of MSCs in preclinical models and their actual use in clinical diseases. This discordance might be due to cells' limited survival or impaired function in the inflammatory environment after transplantation. This limited efficacy may be due to several factors, including the small amount of MSCs inoculated, MSC administration late in the course of the disease, low MSC survival rates in vivo, cryopreservation and thawing effects, and impaired MSC potency/biological activity. Multiple physical and chemical pre-conditioning strategies can enhance the survival rate and potency of MSCs; this paper focuses on hypoxic conditions, with inflammatory cytokines, or with different pattern recognition receptor ligands. These different pre-conditioning strategies can modify MSCs metabolism, gene expression, proliferation, and survivability after transplantation.

Mesenchymal Stem Cell (MSCs) Therapy for Ischemic Heart Disease: A Promising Frontier

Although tremendous progress has been made in conventional treatment for ischemic heart disease, it still remains a major cause of death and disability. Cell-based therapeutics holds an exciting frontier of research for complete cardiac recuperation. The capacity of diverse stem and progenitor cells to stimulate cardiac renewal has been analysed, with promising results in both pre-clinical and clinical trials. Mesenchymal stem cells have been ascertained to have regenerative ability via a variety of mechanisms, including differentiation from the mesoderm lineage, immunomodulatory properties, and paracrine effects. Also, their availability, maintenance, and ability to replenish endogenous stem cell niches have rendered them suitable for front-line research. This review schemes to outline the use of mesenchymal stem cell therapeutics for ischemic heart disease, their characteristics, the potent mechanisms of mesenchymal stem cell-based heart regeneration, and highlight preclinical data. Additionally, we discuss the results of the clinical trials to date as well as ongoing clinical trials on ischemic heart disease.

MSC Pretreatment for Improved Transplantation Viability Results in Improved Ventricular Function in Infarcted Hearts

Many clinical studies utilizing MSCs (mesenchymal stem cells, mesenchymal stromal cells, or multipotential stromal cells) are underway in multiple clinical settings; however, the ideal approach to prepare these cells in vitro and to deliver them to injury sites in vivo with maximal effectiveness remains a challenge. Here, pretreating MSCs with agents that block the apoptotic pathways were compared with untreated MSCs. The treatment effects were evaluated in the myocardial infarct setting following direct injection, and physiological parameters were examined at 4 weeks post-infarct in a rat permanent ligation model. The prosurvival treated MSCs were detected in the hearts in greater abundance at 1 week and 4 weeks than the untreated MSCs. The untreated MSCs improved ejection fraction in infarcted hearts from 61% to 77% and the prosurvival treated MSCs further improved ejection fraction to 83% of normal. The untreated MSCs improved fractional shortening in the infarcted heart from 52% to 68%, and the prosurvival treated MSCs further improved fractional shortening to 77% of normal. Further improvements in survival of the MSC dose seems possible. Thus, pretreating MSCs for improved in vivo survival has implications for MSC-based cardiac therapies and in other indications where improved cell survival may improve effectiveness.

Transport viable heart tissue at physiological temperature yielded higher human cardiomyocytes compared to the conventional temperature

This study investigated the optimum transport condition for heart tissue to recover single-cell cardiomyocytes for future in-vitro or in-vivo studies. The heart tissues were obtained from removing excessive myocardium discharged during the repair surgery of an excessive right atrial hypertrophy due to a congenital disease. The transportation temperature studied was the most used temperature (4 °C) or the conventional condition, compared to a physiological temperature(37 °C). The heart tissues were transported from the operating theatre to the lab maintained less than 30 min consistently. Single-cell isolation was enzymatically and mechanically performed using collagenase-V (160 U/mg) and proteinase-XXIV (7-14 U/mg) following the previously described protocol. The impact of temperature differences was observed by the density of cells harvested per mg tissue, cell viability, and the senescence signals, identified by the p21, p53 and caspase-9 mRNA expressions. Results the heart tissue transported at 37 °C yielded significantly higher viable cell density (p < 0.01) yielded viable cells significantly higher density (p < 0.01) than the 4 °C; 2,335 ± 849 cells per mg tissue, and 732 ± 425 cells per mg tissue, respectively. The percentage of viable cells in both groups showed no difference. Although the 37 °C group expressed the apoptosis genes such as p21, p53 and caspase9 by 2.5-, 5.41-, 5-fold respectively (p > 0.05). Nonetheless, the Nk×2.5 and MHC genes were expressed 1,7- and 3.56-fold higher than the 4 °C. and the c-Kit+ expression was 17.56-fold, however, statistically insignificant. Conclusion When needed for single-cell isolation, a heart tissue transported at 37 °C yielded higher cell density per mg tissue compared to at 4 °C, while other indicators of gene expressions for apoptosis, cardiac structural proteins, cardiac progenitor cells showed no difference. Further investigations of the isolated cells at different temperature conditions towards their proliferation and differentiation capacities in a 3-D scaffold would be essential.

OUP accepted manuscript

Background

Left ventricular hypertrophy and heart failure with preserved ejection fraction (HFpEF) are primary manifestations of the cardiorenal syndrome in patients with chronic kidney disease (CKD). Therapies that improve morbidity and mortality in HFpEF are lacking. Cell-based therapies promote cardiac repair in ischemic and non-ischemic cardiomyopathies. We hypothesized that cell-based therapy ameliorates CKD-induced HFpEF.

Methods and Results

Yorkshire pigs (n = 26) underwent 5/6 embolization-mediated nephrectomy. CKD was confirmed by increased creatinine and decreased glomerular filtration rate (GFR). Mean arterial pressure (MAP) was not different between groups from baseline to 4 weeks. HFpEF was evident at 4 weeks by increased LV mass, relative wall thickening, end-diastolic pressure, and end-diastolic pressure-volume relationship, with no change in ejection fraction (EF). Four weeks post-embolization, allogeneic (allo) bone marrow-derived mesenchymal stem cells (MSC; 1 × 10⁷ cells), allo-kidney-derived stem cells (KSC; 1 × 10⁷ cells), allo-cell combination therapy (ACCT; MSC + KSC; 1:1 ratio; total = 1 × 10⁷ cells), or placebo (Plasma-Lyte) was delivered via intra-renal artery. Eight weeks post-treatment, there was a significant increase in MAP in the placebo group (21.89 ± 6.05 mmHg) compared to the ACCT group. GFR significantly improved in the ACCT group. EF, relative wall thickness, and LV mass did not differ between groups at 12 weeks. EDPVR improved in the ACCT group, indicating decreased ventricular stiffness.

Conclusions

Intra-renal artery allogeneic cell therapy was safe in a CKD swine model manifesting the characteristics of HFpEF. The beneficial effect on renal function and ventricular compliance in the ACCT group supports further research of cell therapy for cardiorenal syndrome.

Engineering pro-angiogenic biomaterials via chemoselective extracellular vesicle immobilization

Nanoscale extracellular vesicles (EVs) represent a unique cellular derivative that reflect the therapeutic potential of mesenchymal stem cells (MSCs) toward tissue engineering and injury repair without the logistical and safety concerns of utilizing living cells. However, upon systemic administration in vivo,EVs undergo rapid clearance and typically lack controlled targeted delivery, thus reducing their effectiveness in therapeutic regenerative therapies. Here, we describe a strategy that enables long-term in vivo spatial EV retention by chemoselective immobilization of metabolically incoporated azido ligand-bearing EVs (azido-EVs) within a dibenzocyclooctyne-modified collagen hydrogel. MSC-derived azido-EVs exhibit comparable morphological and functional properties as their non-labeled EV counterparts and, when immobilized within collagen hydrogel implants via click chemistry, they elicited more robust host cell infiltration, angiogenic and immunoregulatory responses including vascular ingrowth and macrophage recruitment compared to ten times the higher dose required by non-immobilized EVs. We envision this technology will enable a wide range of applications to spatially promote vascularization and host integration relevant to tissue engineering and regenerative medicine applications.

Identification of alpha-enolase as a potential immunogenic molecule during allogeneic transplantation of human adipose-derived mesenchymal stromal cells

BACKGROUND AIMS

Given their low immunogenicity, immunoregulatory effects and multiple differentiation capacity, mesenchymal stromal cells (MSCs) have the potential to be used for "off-the-shelf" cell therapy to treat various diseases. However, the allorejection of MSCs indicates that they are not fully immune-privileged. In this study, the authors investigated the immunogenicity of human adipose-derived MSCs (Ad-MSCs) and identified potential immunogenic molecules.

METHODS

To evaluate the immunogenicity of human Ad-MSCs in vivo, cells were transplanted into humanized mice (hu-mice), then T-cell infiltration and clearance of human Ad-MSCs were observed by immunofluorescence and bioluminescence imaging. One-way mixed lymphocyte reaction and flow cytometry were performed to evaluate the immunogenicity of human Ad-MSCs in vitro. High-throughput T-cell receptor (TCR) repertoire sequencing and mass spectrometry were applied to identified potential immunogenic molecules.

RESULTS

The authors observed that allogeneic Ad-MSCs recruited human T cells and caused faster clearance in hu-mice than non-humanized NOD.Cg-Prkdcscid IL2rgtm1Wjl/SzJ (NSG) mice. The proliferation and activation of T cells were significantly enhanced during in vitro co-culture with human Ad-MSCs. In addition, the level of HLA-II expression on human Ad-MSCs was dramatically increased after co-culture with human peripheral blood mononuclear cells (PBMCs). High-throughput sequencing was applied to analyze the TCR repertoire of the Ad-MSC-recruited T cells to identify dominant TCR CDR3 sequences. Using synthesized TCR CDR3 peptides, the authors identified several potential immunogenic candidates, including alpha-enolase (ENO1). The ENO1 expression level of Ad-MSCs significantly increased after co-culture with PBMCs, whereas ENO1 inhibitor (ENOblock) treatment decreased the expression level of ENO1 and Ad-MSC-induced proliferation of T cells.

CONCLUSIONS

The authors' findings improve the understanding of the immunogenicity of human Ad-MSCs and provide a theoretical basis for the safe clinical application of allogeneic MSC therapy.

The Functions of LncRNA H19 in the Heart

Cardiovascular diseases (CVDs) are major causes of morbidity and mortality worldwide. Great effort has been put into exploring early diagnostic biomarkers and innovative therapeutic strategies for preventing CVD progression over the last two decades. Long non-coding RNAs (lncRNAs) have been identified as novel regulators in cardiac development and cardiac pathogenesis. For example, lncRNA H19 (H19), also known as a fetal gene abundant in adult heart and skeletal muscles and evolutionarily conserved in humans and mice, has a regulatory role in aortic aneurysm, myocardial hypertrophy, extracellular matrix reconstitution, and coronary artery diseases. Yet, the exact function of H19 in the heart remains unknown. This review summarises the functions of H19 in the heart and discusses the challenges and possible strategies of H19 research for cardiovascular disease.

MSC-derived immunomodulatory extracellular matrix functionalized electrospun fibers for mitigating foreign-body reaction and tendon adhesion

Adhesion formation during tendon healing remains a severe problem in clinical practice. Multiple factors contribute to postoperative adhesion formation, and macrophage-driven inflammation is thought to be greatly involved in this process. We hypothesize that reducing macrophage-mediated inflammation in the injured tendon by regulating M1 to M2 macrophage polarization may effectively inhibit adhesion formation. Here, we developed an acellular immunomodulatory biomaterial consisting of an electrospun polycaprolactone/silk fibroin (PCL/SF) composite fibrous scaffold functionalized with mesenchymal stem cell (MSC)-derived extracellular matrix (ECM). To enhance the immunoregulatory potential of MSCs, we performed inflammatory licensing with IFN-γ to obtain immunomodulatory ECM (iECM). Proteomic analyses of MSCs and their secreted ECM components from different culture conditions revealed the MSC-ECM molecular signatures and the potential mechanism of ECM immunoregulation. Then, the immunoregulatory potential of the iECM-modified scaffold was evaluated in vitro and in vivo. Relative to the PCL/SF fibrous scaffold, the iECM-functionalized scaffold facilitated M2 macrophage polarization and inhibited the expression of multiple cytokines (IL-1β, IL-6, CXCL11, IL-10, IL-1R2, and TGF-β1) in vitro, strongly suggesting the immunosuppressive ability of iECM derived from inflammatory licensed MSCs. Consistent with the in vitro findings, the results of rat subcutaneous implantation indicated that a markedly lower foreign-body reaction (FBR) was obtained in the PCL/SF-iECM group than in the other groups, as evidenced by thinner fibrotic capsule formation, less type I collagen production and more M2-type macrophage polarization. In the rat Achilles tendon injury model, the PCL/SF-iECM scaffold greatly mitigated tendon adhesion with clear sheath space formation between the tendon and the scaffold. These data highlight the immunomodulatory potential of iECM-functionalized fibrous scaffolds to attenuate FBR by modulating M2 macrophage polarization, thereby preventing tendon adhesion. STATEMENT OF SIGNIFICANCE: Electrospun PCL/SF fibrous scaffolds functionalized with ECM secreted by MSCs stimulated by inflammatory factor IFN-γ was developed that combined physical barrier and immunomodulatory functions to prevent tendon adhesion formation. PCL/SF micro-nanoscale bimodal fibrous scaffolds prepared by emulsion electrospinning possess high porosity and a large pore size beneficial for nutrient transport to promote intrinsic healing; moreover, surface modification with immunomodulatory ECM (iECM) mitigates the FBR of fibrous scaffolds to prevent tendon adhesion. The iECM-functionalized electrospun scaffolds exhibit powerful immunomodulatory potency in vitro and in vivo. Moreover, the iECM-modified scaffolds, as an anti-adhesion physical barrier with immunomodulatory ability, have an excellent performance in a rat Achilles tendon adhesion model. MSC secretome-based therapeutics, as an acellular regenerative medicine strategy, are expected to be applied to other inflammatory diseases due to its strong immunoregulatory potential.

3D bioprinting of stem cell-laden cardiac patch: A promising alternative for myocardial repair

Stem cell-laden three-dimensional (3D) bioprinted cardiac patches offer an alternative and promising therapeutic and regenerative approach for ischemic cardiomyopathy by reversing scar formation and promoting myocardial regeneration. Numerous studies have reported using either multipotent or pluripotent stem cells or their combination for 3D bioprinting of a cardiac patch with the sole aim of restoring cardiac function by faithfully rejuvenating the cardiomyocytes and associated vasculatures that are lost to myocardial infarction. While many studies have demonstrated success in mimicking cardiomyocytes' behavior, improving cardiac function and providing new hope for regenerating heart post-myocardial infarction, some others have reported contradicting data in apparent ways. Nonetheless, all investigators in the field are speed racing toward determining a potential strategy to effectively treat losses due to myocardial infarction. This review discusses various types of candidate stem cells that possess cardiac regenerative potential, elucidating their applications and limitations. We also brief the challenges of and an update on the implementation of the state-of-the-art 3D bioprinting approach to fabricate cardiac patches and highlight different strategies to implement vascularization and augment cardiac functional properties with respect to electrophysiological similarities to native tissue.

Role of miRNA-324-5p-Modified Adipose-Derived Stem Cells in Post-Myocardial Infarction Repair

Background and Objectives

To seek out the role of mircoRNA (miR)-324-5p-modified adipose-derived stem cells (ADSCs) in post-myocardial infarction (MI) myocardial repair.

Methods and Results

Rat ADSCs were cultivated and then identified by morphologic observation, osteogenesis and adipogenesis induction assays and flow cytometry. Afterwards, ADSCs were modified by miR-324-5p lentiviral vector, with ADSC proliferation and migration measured. Then, rat MI model was established, which was treated by ADSCs or miR-324-5p-modified ADSCs. Subsequently, the function of miR-324-5p-modified ADSCs in myocardial repair of MI rats was assessed through functional assays. Next, the binding relation of miR-324-5p and Toll-interacting protein (TOLLIP) was validated. Eventually, functional rescue assay of TOLLIP was performed to verify the role of TOLLIP in MI. First, rat ADSCs were harvested. Overexpressed miR-324-5p improved ADSC viability. ADSC transplantation moderately enhanced cardiac function of MI rats, reduced enzyme levels and decreased infarct size and apoptosis; while miR-324-5p-modified ADSCs could better promote post-MI repair. Mechanically, miR-324-5p targeted TOLLIP in myocardial tissues. Moreover, TOLLIP overexpression debilitated the promotive role of miR-324-5p-modified ADSCs in post-MI repair in rats.

Conclusions

miR-324-5p-modified ADSCs evidently strengthened post-MI myocardial repair by targeting TOLLIP in myocardial tissues.

In vivo Cell Tracking Using Non-invasive Imaging of Iron Oxide-Based Particles with Particular Relevance for Stem Cell-Based Treatments of Neurological and Cardiac Disease

Stem cell-based therapeutics is a rapidly developing field associated with a number of clinical challenges. One such challenge lies in the implementation of methods to track stem cells and stem cell-derived cells in experimental animal models and in the living patient. Here, we provide an overview of cell tracking in the context of cardiac and neurological disease, focusing on the use of iron oxide-based particles (IOPs) visualized in vivo using magnetic resonance imaging (MRI). We discuss the types of IOPs available for such tracking, their advantages and limitations, approaches for labeling cells with IOPs, biological interactions and effects of IOPs at the molecular and cellular levels, and MRI-based and associated approaches for in vivo and histological visualization. We conclude with reviews of the literature on IOP-based cell tracking in cardiac and neurological disease, covering both preclinical and clinical studies.

Dynamic nanoassembly-based drug delivery system (DNDDS): Learning from nature

Dynamic nanoassembly-based drug delivery system (DNDDS) has evolved from being a mere curiosity to emerging as a promising strategy for high-performance diagnosis and/or therapy of various diseases. However, dynamic nano-bio interaction between DNDDS and biological systems remains poorly understood, which can be critical for precise spatiotemporal and functional control of DNDDS in vivo. To deepen the understanding for fine control over DNDDS, we aim to explore natural systems as the root of inspiration for researchers from various fields. This review highlights ingenious designs, nano-bio interactions, and controllable functionalities of state-of-the-art DNDDS under endogenous or exogenous stimuli, by learning from nature at the molecular, subcellular, and cellular levels. Furthermore, the assembly strategies and response mechanisms of tailor-made DNDDS based on the characteristics of various diseased microenvironments are intensively discussed. Finally, the current challenges and future perspectives of DNDDS are briefly commented.

Genetically-Modified Stem Cell in Regenerative Medicine and Cancer Therapy; A New Era

Recently, genetic engineering by various strategies to stimulate gene expression in a specific and controllable mode is a speedily growing therapeutic approach. Genetic modification of human stem or progenitor cells, such as embryonic stem cells (ESCs), neural progenitor cells (NPCs), mesenchymal stem/stromal cells (MSCs), and hematopoietic stem cells (HSCs) for direct delivery of specific therapeutic molecules or genes has been evidenced as an opportune plan in the context of regenerative medicine due to their supported viability, proliferative features, and metabolic qualities. On the other hand, a large number of studies have investigated the efficacy of modified stem cells in cancer therapy using cells from various sources, disparate transfection means for gene delivery, different transfected yields, and wide variability of tumor models. Accordingly, cell-based gene therapy holds substantial aptitude for the treatment of human malignancy as it could relieve signs or even cure cancer succeeding expression of therapeutic or suicide transgene products; however, there exist inconsistent results in this regard. Herein, we deliver a brief overview of stem cell potential to use in cancer therapy and regenerative medicine and importantly discuss stem cells based gene delivery competencies to stimulate tissue repair and replacement in concomitant with their potential to use as an anti-cancer therapeutic strategy, focusing on the last two decades in vivo studies.

In vitro and in vivo study on angiogenesis of porcine induced pluripotent stem cell-derived endothelial cells

Pluripotent stem cells (PSCs) are a promising source of endothelial cells (ECs) for the treatment of cardiovascular diseases. Since clinical application of embryo stem cells (ESCs) involves issues of medical ethics and risk of immune rejection, induced pluripotent stem cells (iPSCs) will facilitate cell transplantation therapy for the cardiovascular diseases. Swine is identified as an ideal large-animal model for human, because of its similar organ size and physiological characteristics. However, there are very few studies on EC differentiation of porcine iPSCs (piPSCs). In recent study, we provided an efficient protocol to differentiate piPSCs into ECs with the purity of 19.76% CD31 positive cells within 16 days. Passaging of these cells yielded a nearly pure population, which also expressed other endothelial markers such as CD144, eNOS and vWF. Besides, these cells exhibited functions of ECs such as uptake of low-density lipoprotein and formation of tubes in vitro or blood vessels in vivo. Our study successfully obtained ECs from piPSCs via a feeder- and serum-free monolayer system and demonstrated their angiogenic function in vivo and in vitro. piPSC-ECs derivation is not only potential for the autologous cell transplantation and cardiovascular drug screening, but also for the mechanistic studies on EC differentiation and endothelial dysfunction.

Nonequilibrium Dynamics of Magnetic Nanoparticles with Applications in Biomedicine

Magnetic nanoparticles are currently the focus of investigation for a wide range of biomedical applications that fall into the categories of imaging, sensing, and therapeutics. A deep understanding of nanoparticle magnetization dynamics is fundamental to optimization and further development of these applications. Here, a summary of theoretical models of nanoparticle dynamics is presented, and computational nonequilibrium models are outlined, which currently represent the most sophisticated methods for modeling nanoparticle dynamics. Nanoparticle magnetization response is explored in depth; the effect of applied field amplitude, as well as nanoparticle size, on the resulting rotation mechanism and timescale is investigated. Two applications in biomedicine, magnetic particle imaging and magnetic fluid hyperthermia, are highlighted.

Biological Aspects and Clinical Applications of Mesenchymal Stem Cells: Key Features You Need to be Aware of

Mesenchymal Stem Cells (MSCs), a form of adult stem cells, are known to have a selfrenewing property and the potential to specialize into a multitude of cells and tissues such as adipocytes, cartilage cells, and fibroblasts. MSCs can migrate and home to the desired target zone where inflammation is present. The unique characteristics of MSCs in repairing, differentiation, regeneration, and the high capacity of immune modulation have attracted tremendous attention for exerting them in clinical purposes, as they contribute to the tissue regeneration process and anti-tumor activity. The MSCs-based treatment has demonstrated remarkable applicability towards various diseases such as heart and bone malignancies, and cancer cells. Importantly, genetically engineered MSCs, as a stateof- the-art therapeutic approach, could address some clinical hurdles by systemic secretion of cytokines and other agents with a short half-life and high toxicity. Therefore, understanding the biological aspects and the characteristics of MSCs is an imperative issue of concern. Herein, we provide an overview of the therapeutic application and the biological features of MSCs against different inflammatory diseases and cancer cells. We further shed light on MSCs' physiological interaction, such as migration, homing, and tissue repairing mechanisms in different healthy and inflamed tissues.

A Phase II study of autologous mesenchymal stromal cells and c-kit positive cardiac cells, alone or in combination, in patients with ischaemic heart failure: the CCTRN CONCERT-HF trial

AIMS

CONCERT-HF is an NHLBI-sponsored, double-blind, placebo-controlled, Phase II trial designed to determine whether treatment with autologous bone marrow-derived mesenchymal stromal cells (MSCs) and c-kit positive cardiac cells (CPCs), given alone or in combination, is feasible, safe, and beneficial in patients with heart failure (HF) caused by ischaemic cardiomyopathy.

METHODS AND RESULTS

Patients were randomized (1:1:1:1) to transendocardial injection of MSCs combined with CPCs, MSCs alone, CPCs alone, or placebo, and followed for 12 months. Seven centres enrolled 125 participants with left ventricular ejection fraction of 28.6 ± 6.1% and scar size 19.4 ± 5.8%, in New York Heart Association class II or III. The proportion of major adverse cardiac events (MACE) was significantly decreased by CPCs alone (-22% vs. placebo, P = 0.043). Quality of life (Minnesota Living with Heart Failure Questionnaire score) was significantly improved by MSCs alone (P = 0.050) and MSCs + CPCs (P = 0.023) vs. placebo. Left ventricular ejection fraction, left ventricular volumes, scar size, 6-min walking distance, and peak oxygen consumption did not differ significantly among groups.

CONCLUSIONS

This is the first multicentre trial assessing CPCs and a combination of two cell types from different tissues in HF patients. The results show that treatment is safe and feasible. Even with maximal guideline-directed therapy, both CPCs and MSCs were associated with improved clinical outcomes (MACE and quality of life, respectively) in ischaemic HF without affecting left ventricular function or structure, suggesting possible systemic or paracrine cellular mechanisms. Combining MSCs with CPCs was associated with improvement in both these outcomes. These results suggest potential important beneficial effects of CPCs and MSCs and support further investigation in HF patients.

Cardiac Cell Therapy for Heart Repair: Should the Cells Be Left Out?

Cardiovascular disease (CVD) is still the leading cause of death worldwide. Coronary artery occlusion, or myocardial infarction (MI) causes massive loss of cardiomyocytes. The ischemia area is eventually replaced by a fibrotic scar. From the mechanical dysfunctions of the scar in electronic transduction, contraction and compliance, pathological cardiac dilation and heart failure develops. Once end-stage heart failure occurs, the only option is to perform heart transplantation. The sequential changes are termed cardiac remodeling, and are due to the lack of endogenous regenerative actions in the adult human heart. Regenerative medicine and biomedical engineering strategies have been pursued to repair the damaged heart and to restore normal cardiac function. Such strategies include both cellular and acellular products, in combination with biomaterials. In addition, substantial progress has been made to elucidate the molecular and cellular mechanisms underlying heart repair and regeneration. In this review, we summarize and discuss current therapeutic approaches for cardiac repair and provide a perspective on novel strategies that holding potential opportunities for future research and clinical translation.

Injectable GelMA Cryogel Microspheres for Modularized Cell Delivery and Potential Vascularized Bone Regeneration

Cell therapeutics hold tremendous regenerative potential and the therapeutic effect depends on the effective delivery of cells. However, current cell delivery carriers with unsuitable cytocompatibility and topological structure demonstrate poor cell viability during injection. Therefore, porous shape-memory cryogel microspheres (CMS) are prepared from methacrylated gelatin (GelMA) by combining an emulsion technique with gradient-cooling cryogelation. Pore sizes of the CMS are adjusted via the gradient-cooling procedure, with the optimized pore size (15.5 ± 6.0 µm) being achieved on the 30-min gradient-cooled variant (CMS-30). Unlike hydrogel microspheres (HMS), CMS promotes human bone marrow stromal cell (hBMSC) and human umbilical vein endothelial cell (HUVEC) adhesion, proliferated with high levels of stemness for 7 d, and protects cells during the injection process using a 26G syringe needle. Moreover, CMS-30 enhances the osteogenic differentiation of hBMSCs in osteoinductive media. CMS can serve as building blocks for delivering multiple cell types. Here, hBMSC-loaded and HUVEC-loaded CMS-30, mixed at a 1:1 ratio, are injected subcutaneously into nude mice for 2 months. Results show the development of vascularized bone-like tissue with high levels of OCN and CD31. These findings indicate that GelMA CMS of a certain pore size can effectively deliver multiple cells to achieve functional tissue regeneration.

Polymer Cell Surface Coating Enhances Mesenchymal Stem Cell Retention and Cardiac Protection

Mesenchymal stem cell (MSC) therapy has been widely tested in clinical trials to promote healing post-myocardial infarction. However, low cell retention and the need for a large donor cell number in human studies remain a key challenge for clinical translation. Natural biomaterials such as gelatin are ideally suited as scaffolds to deliver and enhance cell engraftment after transplantation. A potential drawback of MSC encapsulation in the hydrogel is that the bulky matrix may limit their biological function and interaction with the surrounding tissue microenvironment that conveys important injury signals. To overcome this limitation, we adopted a gelatin methacrylate (gelMA) cell-coating technique that photocross-links gelatin on the individual cell surface at the nanoscale. The present study investigated the cardiac protection of gelMA coated, hypoxia preconditioned MSCs (gelMA-MSCs) in a murine myocardial infarction (MI) model. We demonstrate that the direct injection of gelMA-MSC results in significantly higher myocardial engraftment 7 days after MI compared to uncoated MSCs. GelMA-MSC further amplified MSC benefits resulting in enhanced cardioprotection as measured by cardiac function, scar size, and angiogenesis. Improved MSC cardiac retention also led to a greater cardiac immunomodulatory function after injury. Taken together, this study demonstrated the efficacy of gelMA-MSCs in treating cardiac injury with a promising potential to reduce the need for donor MSCs through enhanced myocardial engraftment.

Mesenchymal Stem Cells Pretreatment With Stromal-Derived Factor-1 Alpha Augments Cardiac Function and Angiogenesis in Infarcted Myocardium

BACKGROUND

Stem cell therapy is among the novel approaches for the treatment of post-myocardial infarction cardiomyopathy. This study aims to compare the effect of stromal-derived factor 1 α (SDF1α), mesenchymal stem cells (MSCs) in combination with the lentiviral production of vascular endothelial growth factor (VEGF) on infarct area, vascularization and eventually cardiac function in a rat model of myocardial infarction (MI).

METHODS

The influence of SDf1α on MSCs survival was investigated. MSCs were transduced via a lentiviral vector containing VEGF. After that, the effect of mesenchymal stem cell transfection of VEGF-A165 and SDf1α preconditioning on cardiac function and scar size was investigated in five groups of MI rat models. The MSC survival, cardiac function, scar size, angiogenesis, and lymphocyte count were assessed 72 hours and 6 weeks after cell transplantation.

RESULTS

SDF1α decreased the lactate dehydrogenase release in MSCs significantly. Also, the number of viable cells in the SDF1α-pretreated group was meaningfully more than the control. The left ventricular systolic function significantly enhanced in groups with ^p240MSC, ^SDF1αMSC, and ^VEGF-A165MSC in comparison to the control group.

CONCLUSIONS

These findings suggest that SDF1α pretreatment and overexpressing VEGF in MSCs could augment the MSCs' survival in the infarcted myocardium, reduce the scar size, and improve the cardiac systolic function.

Role of prostaglandin E2 in allogeneic mesenchymal stem cell therapy for cardiac repair

Ischemic heart disease is among the primary causes of cardiovascular-related deaths worldwide. Conventional treatments including surgical interventions and medical therapies aid in preventing further damage to heart muscle but are unable to provide a permanent solution. In recent years, stem cell therapy has emerged as an attractive alternative to restore damaged myocardium after myocardial injury. Allogeneic (donor-derived) mesenchymal stem cells (MSCs) have shown great promise in preclinical and clinical studies, making them the most widely accepted candidates for cardiac cell therapy. MSCs promote cardiac repair by modulating host immune system and secreting various soluble factors, of which prostaglandin E2 (PGE2) is an important one. PGE2 plays a significant role in regulating cardiac remodeling following myocardial injury. In this review, we provide an overview of allogeneic MSCs as candidates for myocardial regeneration with a focus on the role of the PGE2/cyclooxygenase-2 (COX2) pathway in mediating these effects.

Combination Therapy of Killing Diseases by Injectable Hydrogels: From Concept to Medical Applications

The complexity of hard-to-treat diseases strongly undermines the therapeutic potential of available treatment options. Therefore, a paradigm shift from monotherapy toward combination therapy has been observed in clinical research to improve the efficiency of available treatment options. The advantages of combination therapy include the possibility of synchronous alteration of different biological pathways, reducing the required effective therapeutic dose, reducing drug resistance, and lowering the overall costs of treatment. The tunable physical properties, excellent biocompatibility, facile preparation, and ease of administration with minimal invasiveness of injectable hydrogels (IHs) have made them excellent candidates to solve the clinical and pharmacological limitations of present systems for multitherapy by direct delivery of therapeutic payloads and improving therapeutic responses through the formation of depots containing drugs, genes, cells, or a combination of them in the body after a single injection. In this review, currently available methods for the design and fabrication of IHs are systematically discussed in the first section. Next, as a step toward establishing IHs for future multimodal synergistic therapies, recent advances in cancer combination therapy, wound healing, and tissue engineering are addressed in detail in the following sections. Finally, opportunities and challenges associated with IHs for multitherapy are listed and further discussed.

The Potential Properties of Natural Compounds in Cardiac Stem Cell Activation: Their Role in Myocardial Regeneration

Cardiovascular diseases (CVDs), which include congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, and many other cardiac disorders, cause about 30% of deaths globally; representing one of the main health problems worldwide. Among CVDs, ischemic heart diseases (IHDs) are one of the major causes of morbidity and mortality in the world. The onset of IHDs is essentially due to an unbalance between the metabolic demands of the myocardium and its supply of oxygen and nutrients, coupled with a low regenerative capacity of the heart, which leads to great cardiomyocyte (CM) loss; promoting heart failure (HF) and myocardial infarction (MI). To date, the first strategy recommended to avoid IHDs is prevention in order to reduce the underlying risk factors. In the management of IHDs, traditional therapeutic options are widely used to improve symptoms, attenuate adverse cardiac remodeling, and reduce early mortality rate. However, there are no available treatments that aim to improve cardiac performance by replacing the irreversible damaged cardiomyocytes (CMs). Currently, heart transplantation is the only treatment being carried out for irreversibly damaged CMs. Hence, the discovery of new therapeutic options seems to be necessary. Interestingly, recent experimental evidence suggests that regenerative stem cell medicine could be a useful therapeutic approach to counteract cardiac damage and promote tissue regeneration. To this end, researchers are tasked with answering one main question: how can myocardial regeneration be stimulated? In this regard, natural compounds from plant extracts seem to play a particularly promising role. The present review will summarize the recent advances in our knowledge of stem cell therapy in the management of CVDs; focusing on the main properties and potential mechanisms of natural compounds in stimulating and activating stem cells for myocardial regeneration.