Mesenchymal stem cell therapy: A promising cell-based therapy for treatment of myocardial infarction

Long non-coding RNA muscleblind like splicing regulator 1 antisense RNA 1 (LncRNA MBNL1-AS1) promotes the progression of acute myocardial infarction by regulating the microRNA-132-3p/SRY-related high-mobility-group box 4 (SOX4) axis

Long non-coding RNA muscleblind like splicing regulator 1 antisense RNA 1 (LncRNA MBNL1-AS1) exerts vital role in various physiological processes. However, its functions in acute myocardial infarction (AMI) are not elucidated. AMI model was constructed using Wistar rats and it was found that LncRNA MBNL1-AS1 was upregulated in AMI model according to the quantitative real-time polymerase chain reaction (qRT-PCR) results. The left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP) and maximum rate of rise/fall of left ventricle pressure (±dp/dt max) were detected through hemodynamics test, which showed that knockdown of MBNL1-AS1 improved cardiac function in AMI model. Next, the myocardial infarction area was estimated by triphenyltetrazole chloride (TTC) staining, and the levels of cardiac troponin I (cTn-I) and creatine kinase-MB (CK-MB) were detected by enzyme-linked immunosorbent assay (ELISA) kit. The results revealed that silencing MBLN1-AS1 alleviated myocardial injury in AMI model. Additionally, MBNL1-AS1 knockdown inhibited apoptosis of myocardial cells and reduced the expression of apoptotic proteins. According to DIANA database and luciferase reporter assay, miR-132-3p was the direct target of MBNL1-AS1 and was negatively regulated by MBNL1-AS1. Furthermore, Targetscan database predicted that SRY-related high-mobility-group box 4 (SOX4) was the direct target of miR-132-3p and was regulated by MBNL1-AS1 through miR-132-3p. Moreover, overexpression of SOX4 partially eliminated effects of MBNL1-AS1 on myocardial cells. In conclusion, this investigation for the first time revealed that LncRNA MBNL1-AS1 was the potential target for treating AMI and expounded the underlying mechanisms of it.

Chitosan for biomedical applications, promising antidiabetic drug delivery system, and new diabetes mellitus treatment based on stem cell

Since chitosan's excellent pharmacokinetic and chemical properties, it is an attractive and promising carbohydrate biopolymer in biomedical applications. Chitosan's beneficial function in the defense and propagation of pancreatic β cells, reducing hyperglycemia, and avoiding diabetes mellitus associated with impaired lipid metabolism has been demonstrated in several studies. Additionally, chitosan has also been used in various nanocarriers to deliver various antidiabetic drugs to reduce glucose levels. Herein, the first to provide the currently available potential benefits of chitosan in diabetes mellitus treatment focuses on chitosan-based nanocarriers for oral administration of various antidiabetic drugs nasal and subcutaneous passages. Moreover, chitosan is used to activate and deliver stem cells and differentiate them into cells similar to pancreatic beta cells as a new type of treatment for type one diabetes mellitus. The results of this review will be helpful in the development of promising treatments and better control of diabetes mellitus.

Engineering Cardiac Small Extracellular Vesicle-Derived Vehicles with Thin-Film Hydration for Customized microRNA Loading

Cell therapies for myocardial infarction, including cardiac ckit+ progenitor cell (CPC) therapies, have been promising, with clinical trials underway. Recently, paracrine signaling, specifically through small extracellular vesicle (sEV) release, was implicated in cell-based cardiac repair. sEVs carry cardioprotective cargo, including microRNA (miRNA), within a complex membrane and improve cardiac outcomes similar to that of their parent cells. However, miRNA loading efficiency is low, and sEV yield and cargo composition vary with parent cell conditions, minimizing sEV potency. Synthetic mimics allow for cargo-loading control but consist of much simpler membranes, often suffering from high immunogenicity and poor stability. Here, we aim to combine the benefits of sEVs and synthetic mimics to develop sEV-like vesicles (ELVs) with customized cargo loading. We developed a modified thin-film hydration (TFH) mechanism to engineer ELVs from CPC-derived sEVs with pro-angiogenic miR-126 encapsulated. Characterization shows miR-126+ ELVs are similar in size and structure to sEVs. Upon administration to cardiac endothelial cells (CECs), ELV uptake is similar to sEVs too. Further, when functionally validated with a CEC tube formation assay, ELVs significantly improve tube formation parameters compared to sEVs. This study shows TFH-ELVs synthesized from sEVs allow for select miRNA loading and can improve in vitro cardiac outcomes.

Evaluation of an Injectable Hydrogel Based on Hyaluronic Acid-chitosan/β-glycerophosphate-loaded Mesenchymal Stem Cells in Enhancing the Therapeutic Efficacy of Myocardial Infarction

Myocardial infarction (MI), which is due to cardiac dysfunction, results in morbidity and mortality. Moreover, the cellular activity of transplanted mesenchymal stem cells (MSCs)generally limits their therapeutic efficacy in the treatment of MI. Here, inject able hyaluronic acid-chitosan/β-glycerophosphate (HA-CS/β-GP) hydrogel-loaded MSCs were prepared, after which their effects on the treatment of MI were investigated. The synthesized HA-CS/β-GP hydrogels exhibited swelling ratio (SR), an in vitro degradation value, and a gelatin time of 82.19 ± 4.1, 88.18% ± 2.4%, and 9 s, respectively. Further, rheological studies revealed that the elastic modulus of the HA-CS/β-GP hydrogels was ≥230 Pa, exhibiting large elastic to viscous modulus ratio, which indicated their mechanical strength. Furthermore, the in vitro 3T3 cell and MSC culture studies confirmed the good biocompatibility of the HA-CS and HA-CS/β-GP hydrogels. The implantation of the synthesized hydrogels in the mouse MI model considerably improved the therapeutic effect of the MSCs (enhanced cardiac function, reduced cardiomyocyte apoptosis, and increased vascularization) for the first time. The innovative synergistic strategy of combining injectable HA-CS and HA-CS/β-GP hydro gels with MSCs might be suitable for the effective treatment of cardiac morbidity due to MIs. This article is protected by copyright. All rights reserved.

Mesenchymal Stem Cell Exosomes in the Treatment of Myocardial Infarction: a Systematic Review of Preclinical In Vivo Studies

Several prior studies have highlighted the promise of mesenchymal stem cells (MSCs) as tools for treating myocardial infarction (MI) patients. While MSCs were initially thought to mediate post-MI repair through differentiation and replacement of injured cells, they are now thought to function by releasing exosomes carrying important cargos which can prevent apoptosis and facilitate revascularization in the context of MI. Herein, we comprehensively survey prior preclinical studies examining MSC-derived exosomes (MSC-Exos) utility for the repair of MI-related tissue injury. In total, 24 relevant studies were identified in the PubMed, Web of Science, Embase, and Cochrane Library databases as per the PRISMA guidelines. In most studies, exosome-treated rodents exhibited improved cardiac function and angiogenesis together with decreased apoptotic cell death. MSC-Exos thus offer beneficial therapeutic efficacy when treating MI injury. However, further work will be necessary to standardize experimental preclinical models and to validate these results. This systematic review provides a comprehensive overview of previous preclinical studies on the utility of exosomes derived from mesenchymal stem cells (MSCs) in the repair of myocardial infarction (MI) injury.

Cell sheet formation enhances the therapeutic effects of human umbilical cord mesenchymal stem cells on myocardial infarction as a bioactive material

Stem cell-based therapy has been used to treat ischaemic heart diseases for two decades. However, optimal cell types and transplantation methods remain unclear. This study evaluated the therapeutic effects of human umbilical cord mesenchymal stem cell (hUCMSC) sheet on myocardial infarction (MI).

METHODS

hUCMSCs expressing luciferase were generated by lentiviral transduction for in vivo bio-luminescent imaging tracking of cells. We applied a temperature-responsive cell culture surface-based method to form the hUCMSC sheet. Cell retention was evaluated using an in vivo bio-luminescent imaging tracking system. Unbiased transcriptional profiling of infarcted hearts and further immunohistochemical assessment of monocyte and macrophage subtypes were used to determine the mechanisms underlying the therapeutic effects of the hUCMSC sheet. Echocardiography and pathological analyses of heart sections were performed to evaluate cardiac function, angiogenesis and left ventricular remodelling.

RESULTS

When transplanted to the infarcted mouse hearts, hUCMSC sheet significantly improved the retention and survival compared with cell suspension. At the early stage of MI, hUCMSC sheet modulated inflammation by decreasing Mcp1-positive monocytes and CD68-positive macrophages and increasing Cx3cr1-positive non-classical macrophages, preserving the cardiomyocytes from acute injury. Moreover, the extracellular matrix produced by hUCMSC sheet then served as bioactive scaffold for the host cells to graft and generate new epicardial tissue, providing mechanical support and routes for revascularsation. These effects of hUCMSC sheet treatment significantly improved the cardiac function at days 7 and 28 post-MI.

CONCLUSIONS

hUCMSC sheet formation dramatically improved the biological functions of hUCMSCs, mitigating adverse post-MI remodelling by modulating the inflammatory response and providing bioactive scaffold upon transplantation into the heart.

TRANSLATIONAL PERSPECTIVE

Due to its excellent availability as well as superior local cellular retention and survival, allogenic transplantation of hUCMSC sheets can more effectively acquire the biological functions of hUCMSCs, such as modulating inflammation and enhancing angiogenesis. Moreover, the hUCMSC sheet method allows the transfer of an intact extracellular matrix without introducing exogenous or synthetic biomaterial, further improving its clinical applicability.

Efficacy and Safety of mesenchymal stem cell therapy in patients with acute myocardial infarction: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND OBJECTIVES

The adjuvant treatment of stem cell therapy for acute myocardial infarction (AMI) has been studied in multiple clinical trials, but many questions remain to be addressed, such as efficacy, safety, identification of the optimal cell type, tractable route of delivery, transplant dosage, and transplant timing. The current meta-analysis aimed to explore the issues of mesenchymal stem cells (MSCs) transplantation in patients with AMI based on published randomized controlled trials (RCTs) and guide the design of subsequent clinical trials of MSCs therapy for AMI.

METHODS

The Cochrane Library, PubMed, EMBASE databases were searched for relevant clinical trials from January 1, 2000, to January 23, 2021. Results from RCTs involving MSCs transplantation for the treatment of AMI were identified. According to the Cochrane systematic review method, the literature quality, including studies, was evaluated and valid data was extracted. RevMan 5.3 and Stata 15.1 software were used for Meta-analysis.

RESULTS

After a literature search and detailed evaluation, 9 randomized controlled trials enrolling 460 patients were included in the quantitative analysis. Pooled analyses indicated that MSCs therapy was associated with a significantly greater improvement in overall left ventricular ejection fraction (LVEF), and the effect was maintained for up to 24 months. No significant difference in favor of MSCs treatment in left ventricular (LV) volume and in the risk of rehospitalization as a result of heart failure (HF) was noted, compared with the controls. For transplantation dose, the LVEF of patients accepting a MSCs dose of 107-108 cells was significantly increased by 2.62% (95% CI 1.54 to 3.70; P < 0.00001; I2 =0%), but this increase was insignificant in the subgroup that accepted an MSCs dose of < 107 cells (1.65% in LVEF, 95% CI, 0.03 to 3.27; P =0.05; I2 =75%) or >108 cells (4.65% in LVEF, 95% CI, -4.55 to 13.48; P =0.32; I2 =95%), compared with the controls. For transplantation timing, a significant improvement of LVEF of 3.18% was achieved in the group of patients accepting a MSCs infusion within 2 to 14 days Percutaneous coronary intervention (PCI) (95% CI, 2.89 to 3.47; P <0.00001; I2 = 0). There was no association between MSCs therapy and major adverse events.

CONCLUSION

Results from our systematic review suggest that MSCs therapy for patients with AMI appears to be safe and might induce a significant increase in LVEF with a limited impact on LV volume and rehospitalization caused by HF. The effect was maintained for up to 24 months. MSCs dose of 107-108 cells was more likely to achieve better clinical endpoints than <107 or >108 cells. The optimal time window for cell transplantation might be within 2-14 days after PCI. This meta-analysis was registered with PROSPERO, number CRD 42021241104.

Impact of Diabetes Mellitus on the Potential of Autologous Stem Cells and Stem Cell-Derived Microvesicles to Repair the Ischemic Heart

Ischemic heart disease remains the leading cause of morbidity and mortality worldwide. Despite the advances in medical management and catheter-based therapy, mortality remains high, as does the risk of developing heart failure. Regenerative therapies have been widely used as an alternative option to repair the damaged heart mainly because of their paracrine-related beneficial effects. Although cell-based therapy has been demonstrated as feasible and safe, randomized controlled trials and meta-analyses show little consistent benefit from treatments with adult-derived stem cells. Mounting evidence from our group and others supports that cardiovascular risk factors and comorbidities impair stem cell potential thus hampering their autologous use. This review aims to better understand the influence of diabetes on stem cell potential. For this purpose, we will first discuss the most recent advances in the mechanistic understanding of the effects of diabetes on stem cell phenotype, function, and molecular fingerprint to further elaborate on diabetes-induced alterations in stem cell extracellular vesicle profile. Although we acknowledge that multiple sources of stem or progenitor cells are used for regenerative purposes, we will focus on bone marrow hematopoietic stem/progenitor cells, mesenchymal stem cells residing in the bone marrow, and adipose tissue and briefly discuss endothelial colony-forming cells.

Deciphering the in vivo Dynamic Proteomics of Mesenchymal Stem Cells in Critical Limb Ischemia

Objective

Regenerative therapy using mesenchymal stem cells (MSC) is a promising therapeutic method for critical limb ischemia (CLI). To understand how the cells are involved in the regenerative process of limb ischemia locally, we proposed a metabolic protein labeling method to label cell proteomes in situ and then decipher the proteome dynamics of MSCs in ischemic hind limb.

Methods and Results

In this study, we overexpressed mutant methionyl-tRNA synthetase (MetRS), which could utilize azidonorleucine (ANL) instead of methionine (Met) during protein synthesis in MSCs. Fluorescent non-canonical amino-acid tagging (FUNCAT) was performed to detect the utilization of ANL in mutant MSCs. Mice with hindlimb ischemia (HLI) or Sham surgery were treated with MetRS^mut MSCs or PBS, followed by i.p. administration of ANL at days 0, 2 6, and 13 after surgery. FUNCAT was also performed in hindlimb tissue sections to demonstrate the incorporation of ANL in transplanted cells in situ. At days 1, 3, 7, and 14 after the surgery, laser doppler imaging were performed to detect the blood reperfusion of ischemic limbs. Ischemic tissues were also collected at these four time points for histological analysis including HE staining and vessel staining, and processed for click reaction based protein enrichment followed by mass spectrometry and bioinformatics analysis. The MetRS^mut MSCs showed strong green signal in cell culture and in HLI muscles as well, indicating efficient incorporation of ANL in nascent protein synthesis. By 14 days post-treatment, MSCs significantly increased blood reperfusion and vessel density, while reducing inflammation in HLI model compared to PBS. Proteins enriched by click reaction were distinctive in the HLI group vs. the Sham group. 34, 31, 49, and 26 proteins were significantly up-regulated whereas 28, 32, 62, and 27 proteins were significantly down-regulated in HLI vs. Sham at days 1, 3, 7, and 14, respectively. The differentially expressed proteins were more pronounced in the pathways of apoptosis and energy metabolism.

Conclusion

In conclusion, mutant MetRS allows efficient and specific identification of dynamic cell proteomics in situ, which reflect the functions and adaptive changes of MSCs that may be leveraged to understand and improve stem cell therapy in critical limb ischemia.

Programmed cell death in stem cell-based therapy: Mechanisms and clinical applications

Stem cell-based therapy raises hopes for a better approach to promoting tissue repair and functional recovery. However, transplanted stem cells show a high death percentage, creating challenges to successful transplantation and prognosis. Thus, it is necessary to investigate the mechanisms underlying stem cell death, such as apoptotic cascade activation, excessive autophagy, inflammatory response, reactive oxygen species, excitotoxicity, and ischemia/hypoxia. Targeting the molecular pathways involved may be an efficient strategy to enhance stem cell viability and maximize transplantation success. Notably, a more complex network of cell death receives more attention than one crucial pathway in determining stem cell fate, highlighting the challenges in exploring mechanisms and therapeutic targets. In this review, we focus on programmed cell death in transplanted stem cells. We also discuss some promising strategies and challenges in promoting survival for further study.

Cyclic Strain and Electrical Co-stimulation Improve Neural Differentiation of Marrow-Derived Mesenchymal Stem Cells

The current study investigated the combinatorial effect of cyclic strain and electrical stimulation on neural differentiation potential of rat bone marrow-derived mesenchymal stem cells (BMSCs) under epidermal growth factor (EGF) and fibroblast growth factor 2 (FGF2) inductions in vitro. We developed a prototype device which can provide cyclic strain and electrical signal synchronously. Using this system, we demonstrated that cyclic strain and electrical co-stimulation promote the differentiation of BMCSs into neural cells with more branches and longer neurites than strain or electrical stimulation alone. Strain and electrical co-stimulation can also induce a higher expression of neural markers in terms of transcription and protein level. Neurotrophic factors and the intracellular cyclic AMP (cAMP) are also upregulated with co-stimulation. Importantly, the co-stimulation further enhances the calcium influx of neural differentiated BMSCs when responding to acetylcholine and potassium chloride (KCl). Finally, the phosphorylation of extracellular-signal-regulated kinase (ERK) 1 and 2 and protein kinase B (AKT) was elevated under co-stimulation treatment. The present work suggests a synergistic effect of the combination of cyclic strain and electrical stimulation on BMSC neuronal differentiation and provides an alternative approach to physically manipulate stem cell differentiation into mature and functional neural cells in vitro.

The Current Dilemma and Breakthrough of Stem Cell Therapy in Ischemic Heart Disease

Ischemic heart disease (IHD) is the leading cause of mortality worldwide. Stem cell transplantation has become a promising approach for the treatment of IHD in recent decades. It is generally recognized that preclinical cell-based therapy is effective and have yielded encouraging results, which involves preventing or reducing myocardial cell death, inhibiting scar formation, promoting angiogenesis, and improving cardiac function. However, clinical studies have not yet achieved a desired outcome, even multiple clinical studies showing paradoxical results. Besides, many fundamental puzzles remain to be resolved, for example, what is the optimal delivery timing and approach? Additionally, limited cell engraftment and survival, challenging cell fate monitoring, and not fully understood functional mechanisms are defined hurdles to clinical translation. Here we review some of the current dilemmas in stem cell-based therapy for IHD, along with our efforts and opinions on these key issues.

Adipose-Derived Mesenchymal Stem Cells-Derived Exosomes Carry MicroRNA-671 to Alleviate Myocardial Infarction Through Inactivating the TGFBR2/Smad2 Axis

Mesenchymal stem cells (MSCs) and their derived extracellular vesicles have been reported as promising tools for the management of heart disease. The aim of this study was to explore the function of adipose-derived MSCs (adMSCs)-derived exosomes (Exo) in the progression of myocardial infarction (MI) and the molecules involved. Mouse cardiomyocytes were treated with oxygen-glucose deprivation (OGD) to mimic an MI condition in vitro. The adMSCs-derived Exo were identified and administrated into the OGD-treated cardiomyocytes, and then the viability and apoptosis of cells, and the secretion of fibrosis- and inflammation-related cytokines in cells were determined. Differentially expressed microRNAs (miRNAs) in cells after Exo treatment were screened using a microarray analysis. The downstream molecules regulated by miR-671 were explored through bioinformatic analysis. Involvements of miR-671 and transforming growth factor beta receptor 2 (TGFBR2) in the exosome-mediated events were confirmed by rescue experiments. A murine model with MI was induced and treated with Exo for functional experiments in vivo. Compared to phosphate-buffered saline treatment, the Exo treatment significantly enhanced viability while reduced apoptosis of cardiomyocytes, and in reduced myocardial fibrosis and inflammation both in vitro and in vivo. miR-671 was significantly upregulated in cells after Exo treatment. Downregulation of miR-671 blocked the protective functions of Exo. miR-671 targeted TGFBR2 and suppressed phosphorylation of Smad2. Artificial downregulation of TGFBR2 enhanced viability of the OGD-treated cardiomyocytes. This study suggested that adMSC-derived exosomal miR-671 directly targets TGFBR2 and reduces Smad2 phosphorylation to alleviate MI-like symptoms both in vivo and in vitro.

Cellular Senescence Affects Cardiac Regeneration and Repair in Ischemic Heart Disease

Ischemic heart disease (IHD) is defined as a syndrome of ischemic cardiomyopathy. Myogenesis and angiogenesis in the ischemic myocardium are important for cardiomyocyte (CM) survival, improving cardiac function and decreasing the progression of heart failure after IHD. Cellular senescence is a state of permanent irreversible cell cycle arrest caused by stress that results in a decline in cellular functions, such as proliferation, migration, homing, and differentiation. In addition, senescent cells produce the senescence-associated secretory phenotype (SASP), which affects the tissue microenvironment and surrounding cells by secreting proinflammatory cytokines, chemokines, growth factors, and extracellular matrix degradation proteins. The accumulation of cardiovascular-related senescent cells, including vascular endothelial cells (VECs), vascular smooth muscle cells (VSMCs), CMs and progenitor cells, is an important risk factor of cardiovascular diseases, such as vascular aging, atherosclerotic plaque formation, myocardial infarction (MI) and ventricular remodeling. This review summarizes the processes of angiogenesis, myogenesis and cellular senescence after IHD. In addition, this review focuses on the relationship between cellular senescence and cardiovascular disease and the mechanism of cellular senescence. Finally, we discuss a potential therapeutic strategy for MI targeting senescent cells.

The Application of Mesenchymal Stromal Cells and Their Homing Capabilities to Regenerate the Intervertebral Disc

Chronic low back pain (LBP) remains a challenging condition to treat, and especially to cure. If conservative treatment approaches fail, the current “gold standard” for intervertebral disc degeneration (IDD)-provoked back pain is spinal fusion. However, due to its invasive and destructive nature, the focus of orthopedic research related to the intervertebral disc (IVD) has shifted more towards cell-based therapeutic approaches. They aim to reduce or even reverse the degenerative cascade by mimicking the human body’s physiological healing system. The implementation of progenitor and/or stem cells and, in particular, the delivery of mesenchymal stromal cells (MSCs) has revealed significant potential to cure the degenerated/injured IVD. Over the past decade, many research groups have invested efforts to find ways to utilize these cells as efficiently and sustainably as possible. This narrative literature review presents a summary of achievements made with the application of MSCs for the regeneration of the IVD in recent years, including their preclinical and clinical applications. Moreover, this review presents state-of-the-art strategies on how the homing capabilities of MSCs can be utilized to repair damaged or degenerated IVDs, as well as their current limitations and future perspectives.

NGF nanoparticles enhance the potency of transplanted human umbilical cord mesenchymal stem cells for myocardial repair

In this study, we investigated whether human umbilical cord mesenchymal stem cell (hUCMSC) fibrin patches loaded with nerve growth factor (NGF) poly(lactic-co-glycolic acid) (PLGA) nanoparticles could enhance the therapeutic potency of hUCMSCs for myocardial infarction (MI). In vitro, NGF significantly improved the proliferation of hUCMSCs and mitigated cytotoxicity and apoptosis under hypoxic injury. NGF also promoted the paracrine effects of hUCMSCs on angiogenesis and cardiomyocyte protection. The tyrosine kinase A (TrkA) and phosphoinositide 3-kinase (PI3K)-serine/threonine protein kinase (Akt) signaling pathways in hUCMSCs were involved in the NGF-induced protection. NGF PLGA nanoparticles continued to release NGF for at least 1 mo and also exerted a protective effect on hUCMSCs, the same with free NGF. In vivo, we treated MI mice with nothing (MI group), a cell-free fibrin patch with blank PLGA nanoparticles (MI + OP group), a cell-free fibrin patch with NGF nanoparticles (MI + NGF group), and hUCMSC fibrin patches with blank PLGA nanoparticles (MI + MSC group) or NGF PLGA nanoparticles (MSC + NGF group). Among these groups, the MSC + NGF group exhibited the best cardiac contractile function, the smallest infarct size, and the thickest ventricular wall. The application of NGF PLGA nanoparticles significantly improved the retention of transplanted hUCMSCs and enhanced their ability to reduce myocardial apoptosis and promote angiogenesis in the mouse heart after MI. These findings demonstrate the promising therapeutic potential of hUCMSC fibrin cardiac patches loaded with NGF PLGA nanoparticles.NEW & NOTEWORTHY NGF PLGA nanoparticles can exert a protective effect on hUCMSCs and promote the paracrine effects of hUCMSCs on angiogenesis and cardiomyocyte protection through TrkA-PI3K/Akt signaling pathway, the same with free NGF. The application of NGF PLGA nanoparticles in the hUCMSC fibrin cardiac patches can significantly improve the retention of transplanted hUCMSCs and enhance their ability to reduce myocardial apoptosis and promote angiogenesis in the mouse heart after MI.

Bifunctional Labeling of Rabbit Mesenchymal Stem Cells for MR Imaging and Fluorescence Microscopy

PURPOSE

Longitudinal imaging studies are important in the translational process of stem cell-based therapies. Small animal imaging models are widely available and practical but insufficiently depict important morphologic detail. In contrary, large animal models are logistically challenging and costly but offer greater imaging quality. In order to combine the advantages of both, we developed an intermediate-sized rabbit animal model for cartilage imaging studies.

PROCEDURES

Rabbit mesenchymal stem cells (rMSC) were isolated as primary cultures from the bone marrow of New Zealand white rabbits. rMSC were subsequentially transduced lentivirally with eGFP and magnetically labeled with the iron oxide ferucarbotran. eGFP expression was evaluated by flow cytometry and iron uptake was analyzed by isotope dilution mass spectrometry and Prussian blue staining. Fluorescence microscopy of eGFP-transduced rMSC was performed. Viability and induction of apoptosis were assessed by XTT and caspase-3/-7 measurements. The chondrogenic potential of labeled cells was quantified by glycosaminoglycan contents in TGF-β3 induced pellet cultures. Labeled and unlabeled cells underwent magnetic resonance imaging (MRI) at 1.5 T before and after differentiation using T1-, T2-, and T2*-weighted pulse sequences. Relaxation rates were calculated. rMSCs were implanted in fibrin clots in osteochondral defects of cadaveric rabbit knees and imaged by 7 T MRI. T2* maps were calculated. Statistical analyses were performed using multiple regression models.

RESULTS

Efficiency of lentiviral transduction was greater than 90 %. Fluorescence signal was dose dependent. Cellular iron uptake was significant for all concentrations (p < 0.05) and dose dependent (3.3-56.5 pg Fe/cell). Labeled rMSC showed a strong, dose-dependent contrast on all MR pulse sequences and a significant decrease in T2 and T2* relaxation rates. Compared with non-transduced or unlabeled controls, there were no adverse effects on cell viability, rate of apoptosis, or chondrogenic differentiation. MRI of labeled rMSCs in osteochondral defects showed a significant signal of the transplant with additional high-resolution anatomical information.

CONCLUSIONS

This intermediate-sized rabbit model and its bifunctional labeling technique allow for improved depiction of anatomic detail for noninvasive in vivo rMSC tracking with MRI and for immunohistological correlation by fluorescence microscopy.

Enhancing the Therapeutic Potential of Mesenchymal Stem Cells with Light-Emitting Diode: Implications and Molecular Mechanisms

This study evaluated the effects of light-emitting diode (LED) on mesenchymal stem cells (MSCs). An electronic search was conducted in PubMed/MEDLINE, Scopus, and Web of Science database for articles published from 1980 to February 2020. Ten articles met the search criteria and were included in this review. The risk of bias was evaluated to report quality, safety, and environmental standards. MSCs were derived from adipose tissue, bone marrow, dental pulp, gingiva, and umbilical cord. Protocols for cellular irradiation used red and blue light spectrum with variations of the parameters. The LED has been shown to induce greater cellular viability, proliferation, differentiation, and secretion of growth factors. The set of information available leads to proposing a complex signaling cascade for the action of photobiomodulation, including angiogenic factors, singlet oxygen, mitogen-activated protein kinase/extracellular signal-regulated protein kinase, Janus kinase/signal transducer, and reactive oxygen species. In conclusion, although our results suggest that LED can boost MSCs, a nonuniformity in the experimental protocol, bias, and the limited number of studies reduces the power of systematic review. Further research is essential to find the optimal LED irradiation parameters to boost MSCs function and evaluate its impact in the clinical setting.

The emerging therapeutic role of mesenchymal stem cells in anthracycline-induced cardiotoxicity

Mesenchymal stem cell (MSC)-based tissue regeneration therapy has been extensively investigated for cardiac regeneration over the past two decades. Numerous animal and clinical investigations demonstrated the efficacy of various types of MSCs towards myocardial protection and restoration against anthracycline-induced cardiotoxicity (AIC). It has been established that local or systemic administration of MSCs considerably improved the cardiac function, while ameliorating inflammatory responses and myocardial fibrosis. Several factors influence the outcomes of MSC treatment for AIC, including MSC types, dosages, and routes and duration of administration. In this review, we discuss the recent (from 2015 to 2020) experimental and clinical research on the preventive and regeneration efficacy of different types of MSCs (with or without supporting agents) against AIC, as well as the key factors responsible for MSC-mediated cardiac repair. In addition, challenges and future perspectives of MSC-based cardiac regeneration therapy are also outlined.

Therapeutic Potential of Umbilical Cord Stem Cells for Liver Regeneration

The liver is a vital organ for life and the only internal organ that is capable of natural regeneration. Although the liver has high regeneration capacity, excessive hepatocyte death can lead to liver failure. Various factors can lead to liver damage including drug abuse, some natural products, alcohol, hepatitis, and autoimmunity. Some models for studying liver injury are APAP-based model, Fas ligand (FasL), D-galactosamine/endotoxin (Gal/ET), Concanavalin A, and carbon tetrachloride-based models. The regeneration of the liver can be carried out using umbilical cord blood stem cells which have various advantages over other stem cell types used in liver transplantation. UCB-derived stem cells lack tumorigenicity, have karyotype stability and high immunomodulatory, low risk of graft versus host disease (GVHD), low risk of transmitting somatic mutations or viral infections, and low immunogenicity. They are readily available and their collection is safe and painless. This review focuses on recent development and modern trends in the use of umbilical cord stem cells for the regeneration of liver fibrosis.

ELABELA ameliorates hypoxic/ischemic-induced bone mesenchymal stem cell apoptosis via alleviation of mitochondrial dysfunction and activation of PI3K/AKT and ERK1/2 pathways

Background

Mesenchymal stem cells (MSCs) have exerted their brilliant potential to promote heart repair following myocardial infarction. However, low survival rate of MSCs after transplantation due to harsh conditions with hypoxic and ischemic stress limits their therapeutic efficiency in treating cardiac dysfunction. ELABELA (ELA) serves as a peptide hormone which has been proved to facilitate cell growth, survival, and pluripotency in human embryonic stem cells. Although ELA works as an endogenous ligand of a G protein-coupled receptor APJ (Apelin receptor, APLNR), whether APJ is an essential signal for the function of ELA remains elusive. The effect of ELA on apoptosis of MSCs is still vague.

Objective

We studied the role of ELABELA (ELA) treatment on the anti-apoptosis of MSCs in hypoxic/ischemic (H/I) conditions which mimic the impaired myocardial microenvironment and explored the possible mechanisms in vitro.

Methods

MSCs were obtained from donated rats weighing between 80~120 g. MSCs were exposed to serum-free and hypoxic (1% O₂) environments for 24 h, which mimics hypoxic/ischemic damage in vivo, using serum-containing normoxic conditions (20% O₂) as a negative control. MSCs that were exposed to H/I injury with ELA processing were treated by 5 μM of ELA. Cell viability and apoptosis of MSCs were evaluated by CCK8 and flow cytometry, respectively. Mitochondrial function of MSCs was also assessed according to mitochondrial membrane potential (MMP) and ATP content. The protein expression of key kinases of the PI3K/AKT and ERK1/2 signaling pathways involving t-AKT, p-AKT, t-ERK1/2, and p-ERK1/2, as well as apoptosis-related protein expression of Bcl-2, Bax, and cleaved Caspase 3, were monitored by Western blot.

Results

We found that ELA treatment of H/I-induced MSCs improved overall cell viability, enhanced Bcl/Bax expression, and decreased Caspase 3 activity. ELA inhibited H/I-induced mitochondrial dysfunction by increasing ATP concentration and suppressing the loss of mitochondrial transmembrane potential. However, this anti-apoptotic property of ELA was restrained in APJ-silenced MSCs. Additionally, ELA treatment induced the phosphorylation of AKT and ERK, while the blockade of PI3K/AKT and ERK1/2 pathways with respective inhibitors, LY294002 and U0126, suppressed the action of ELA.

Conclusion

ELA positively affected on the survival of MSCs and exhibited anti-apoptotic characteristics when exposed to hypoxic/ischemic condition in vitro. Also, the function of ELA was correlated with the APJ receptor, reduced mitochondrial damage, and activation of the PI3K/AKT and ERK1/2 signal axes.

USP7, negatively regulated by miR-409-5p, aggravates hypoxia-induced cardiomyocyte injury

Hypoxia-induced apoptosis is linked to the pathogenesis of myocardial infarction (MI) and heart failure. Ubiquitin-specific peptidase 7 (USP7) is related to catabolic/pro-apoptotic signaling. However, its role in cardiomyocyte injury is unclear. In this study, we aimed to investigate the role and the underlying regulatory mechanism of USP7 in MI. H9c2 cardiomyocytes were cultured in hypoxia to establish an in vitro model of myocardial hypoxic/ischemic injury. Sprague-Dawley (SD) rats were used to establish animal models with MI. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot assays were performed to evaluate the expression levels of miR-409-5p, USP7, and p53, respectively. After USP7 and miR-409-5p were selectively regulated in H9c2 cells, the inflammatory response, apoptosis, and cell viability were detected by ELISA, flow cytometry, and MTT assay, respectively. The interaction between USP7 and miR-409-5p was determined by bioinformatics analysis, qRT-PCR, Western blot, and dual-luciferase reporter assay. LVEF, LVIDd, and LVIDs of rats after MI were also measured. USP7 expression was markedly elevated while miR-409-5p expression was significantly down-regulated in H9c2 cells under hypoxic culture. Augmentation of USP7 expression led to a dramatic promotion of hypoxia-induced apoptosis of cardiomyocytes, accompanied by an increase in the secretion of the cytokines IL-1β, TNF-α, and IL-6. Myocardial injury markers LDH, cTnI, and CK-MB expressions were also increased. Besides, overexpression of USP7 aggravated left ventricular remodeling and decreased left ventricular function of the rats. Conversely, the up-regulation of miR-409-5p expression protected H9c2 cells from apoptosis and inhibited the release of cytokines and myocardial injury. Left ventricular remodeling and left ventricular function were also improved by miR-409-5p overexpression. Furthermore, USP7 was identified as a target of miR-409-5p and the overexpression of miR-409-5p reversed the effects of USP7 on H9c2 cells. USP7 exacerbates myocardial ischemic injury by promoting inflammation and apoptosis of cardiomyocytes, and the up-regulation of its expression is partly caused by the down-regulation of miR-409-5p expression.

Recent Development in Therapeutic Cardiac Patches

For the past decades, heart diseases remain the leading cause of death worldwide. In the adult mammalian heart, damaged cardiomyocytes will be replaced by non-contractile fibrotic scar tissues due to the poor regenerative ability of heart, causing heart failure subsequently. The development of tissue engineering has launched a new medical innovation for heart regeneration. As one of the most outstanding technology, cardiac patches hold the potential to restore cardiac function clinically. Consisted of two components: therapeutic ingredients and substrate scaffolds, the fabrication of cardiac patches requires both advanced bioactive molecules and biomaterials. In this review, we will present the most state-of-the-art cardiac patches and analysis their compositional details. The therapeutic ingredients will be discussed from cell sources to bioactive molecules. In the meanwhile, the recent advances to obtain scaffold biomaterials will be highlighted, including synthetic and natural materials. Also, we have focused on the challenges and potential strategies to fabricate clinically applicable cardiac patches.

Comparative Effect of MSC Secretome to MSC Co-culture on Cardiomyocyte Gene Expression Under Hypoxic Conditions in vitro

Introduction

Despite major leaps in regenerative medicine, the regeneration of cardiomyocytes after ischemic conditions remains to elucidate. It is crucial to understand hypoxia induced cellular mechanisms to provide advanced treatment options, including the use of stem cell paracrine factors for myocardial regeneration.

Materials and Methods

In this study, the regenerative potential of hypoxic human cardiomyocytes (group Hyp-CMC) in vitro was evaluated when co-cultured with human bone-marrow derived MSC (group Hyp-CMC-MSC) or stimulated with the secretome of MSC (group Hyp-CMC-S_MSC). The secretome of normoxic MSC and CMC, and the hypoxic CMC was analyzed with a cytokine panel. Gene expression changes of HIF-1α, proliferation marker Ki-67 and cytokinesis marker RhoA over different reoxygenation time periods of 4, 8, 24, 48, and 72 h were analyzed in comparison to normoxic CMC and MSC. Further, the proinflammatory cytokine IL-18 protein expression change, metabolic activity and proliferation was assessed in all experimental setups.

Results and Conclusion

HIF-1α was persistently overexpressed in Hyp-CMC-S_MSC as compared to Hyp-CMC (except at 72 h). Hyp-CMC-MSC showed a weaker HIF-1α expression than Hyp-CMC-S_MSC in most tested time points, except after 8 h. The Ki-67 expression showed the strongest upregulation in Hyp-CMC after 24 and 48 h incubation, then returned to baseline level, while a temporary increase in Ki-67 expression in Hyp-CMC-MSC at 4 and 8 h and at 48 h in Hyp-CMC-S_MSC could be observed. RhoA was increased in normoxic MSCs and in Hyp-CMC-S_MSC over time, but not in Hyp-CMC-MSC. A temporary increase in IL-18 protein expression was detected in Hyp-CMC-SMSC and Hyp-CMC. Our study demonstrates timely dynamic changes in expression of different ischemia and regeneration-related genes of CMCs, depending from the culture condition, with stronger expression of HIF-1α, RhoA and IL-18 if the hypoxic CMC were subjected to the secretome of MSCs.

Photoluminescent oxygen-release microspheres to image the oxygen release process in vivo

Cell therapy is a promising strategy to treat ischemic diseases, but the efficacy is limited due to high rate of cell death under low oxygen environment of the ischemic tissues. Sustained release of oxygen to continuously oxygenate the transplanted cells may augment cell survival and improve therapeutic efficacy. We have shown previously that oxygen released from oxygen-release microspheres stimulated cell survival in ischemic tissue [1]. To understand how oxygen is released in vivo and duration of release, it is attractive to image the process of oxygen release. Herein, we have developed photoluminenscent oxygen-release microspheres where the in vivo oxygen release can be non-invasively and real-time monitored by an In Vivo Imaging System (IVIS). In the oxygen-release microspheres, a complex of polyvinylpyrrolidone, H₂O₂ and a fluorescent drug hypericin (HYP) was used as core, and poly(N-isopropylacrylamide-co-acrylate-oligolactide-co-hydroxyethyl methacrylate-co-N-acryloxysuccinimide) conjugated with catalase was used as shell. To distinguish fluorescent signal change for different oxygen release kinetics, the microspheres with various release profiles were developed by using the shell with different degradation rates. In vitro, the fluorescent intensity gradually decreased during the 21-day oxygen release period, consistent with oxygen release kinetics. The released oxygen significantly augmented mesenchymal stem cell (MSC) survival under hypoxic condition. In vivo, the oxygen release rate was faster. The fluorescent signal can be detected for 17 days for the microspheres with the slowest oxygen release kinetics. The implanted microspheres did not induce substantial inflammation. The above results demonstrate that the developed microspheres have potential to monitor the in vivo oxygen release.

Three-dimensional scaffold-free microtissues engineered for cardiac repair

Cardiovascular diseases, including myocardial infarction (MI), persist as the leading cause of mortality and morbidity worldwide. The limited regenerative capacity of the myocardium presents significant challenges specifically for the treatment of MI and, subsequently, heart failure (HF). Traditional therapeutic approaches mainly rely on limiting the induced damage or the stress on the remaining viable myocardium through pharmacological regulation of remodeling mechanisms, rather than replacement or regeneration of the injured tissue. The emerging alternative regenerative medicine-based approaches have focused on restoring the damaged myocardial tissue with newly engineered functional and bioinspired tissue units. Cardiac regenerative medicine approaches can be broadly categorized into three groups: cell-based therapies, scaffold-based cardiac tissue engineering, and scaffold-free cardiac tissue engineering. Despite significant advancements, however, the clinical translation of these approaches has been critically hindered by two key obstacles for successful structural and functional replacement of the damaged myocardium, namely: poor engraftment of engineered tissue into the damaged cardiac muscle and weak electromechanical coupling of transplanted cells with the native tissue. To that end, the integration of micro- and nanoscale technologies along with recent advancements in stem cell technologies have opened new avenues for engineering of structurally mature and highly functional scaffold-based (SB-CMTs) and scaffold-free cardiac microtissues (SF-CMTs) with enhanced cellular organization and electromechanical coupling for the treatment of MI and HF. In this review article, we will present the state-of-the-art approaches and recent advancements in the engineering of SF-CMTs for myocardial repair.

Biomaterials Loaded with Growth Factors/Cytokines and Stem Cells for Cardiac Tissue Regeneration

Myocardial infarction causes cardiac tissue damage and the release of damage-associated molecular patterns leads to activation of the immune system, production of inflammatory mediators, and migration of various cells to the site of infarction. This complex response further aggravates tissue damage by generating oxidative stress, but it eventually heals the infarction site with the formation of fibrotic tissue and left ventricle remodeling. However, the limited self-renewal capability of cardiomyocytes cannot support sufficient cardiac tissue regeneration after extensive myocardial injury, thus, leading to an irreversible decline in heart function. Approaches to improve cardiac tissue regeneration include transplantation of stem cells and delivery of inflammation modulatory and wound healing factors. Nevertheless, the harsh environment at the site of infarction, which consists of, but is not limited to, oxidative stress, hypoxia, and deficiency of nutrients, is detrimental to stem cell survival and the bioactivity of the delivered factors. The use of biomaterials represents a unique and innovative approach for protecting the loaded factors from degradation, decreasing side effects by reducing the used dosage, and increasing the retention and survival rate of the loaded cells. Biomaterials with loaded stem cells and immunomodulating and tissue-regenerating factors can be used to ameliorate inflammation, improve angiogenesis, reduce fibrosis, and generate functional cardiac tissue. In this review, we discuss recent findings in the utilization of biomaterials to enhance cytokine/growth factor and stem cell therapy for cardiac tissue regeneration in small animals with myocardial infarction.

Hydrogel-Based Localized Nonviral Gene Delivery in Regenerative Medicine Approaches-An Overview

Hydrogel-based nonviral gene delivery constitutes a powerful strategy in various regenerative medicine scenarios, as those concerning the treatment of musculoskeletal, cardiovascular, or neural tissues disorders as well as wound healing. By a minimally invasive administration, these systems can provide a spatially and temporarily defined supply of specific gene sequences into the target tissue cells that are overexpressing or silencing the original gene, which can promote natural repairing mechanisms to achieve the desired effect. In the present work, we provide an overview of the most avant-garde approaches using various hydrogels systems for controlled delivery of therapeutic nucleic acid molecules in different regenerative medicine approaches.

Effect of Conditioned Medium from Human Umbilical Cord-Derived Mesenchymal Stromal Cells on Rejuvenation of Nucleus Pulposus Derived Stem/Progenitor Cells from Degenerated Intervertebral Disc

Background and Objectives

Mesenchymal stromal cells (MSCs)-based treatment for degeneration of intervertebral disc (IVD) has been proposed recently. We here addressed whether MSC secreted factors can rejuvenate nucleus pulposus-derived stem/progenitor cells from degenerated disc (D-NPSCs) in vitro.

Methods and Results

We analyzed the expression of MSCs and NP cell specific surface markers, pluripotency related genes, multilineage potential and cell proliferative capacity of D-NPSCs upon incubation with the conditioned medium which was collected from the umbilical cord derived MSCs (UCMSCs). Our results indicated that the conditioned medium restore the stemness of D-NPSCs by up-regulating the expression level of CD29 and CD105, pluripotency related genes OCT4 and Nanog, and NP progenitor marker Tie2. The increased stemness was accompanied by promoted cell proliferative capacity and improved osteogenic and chondrogenic differentiation potential.

Conclusions

Our findings suggested that the UCMSCs derived conditioned medium might be used to rejuvenate the degenerated NP stem/progenitor cells.

Upregulating MicroRNA-203 Alleviates Myocardial Remodeling and Cell Apoptosis Through Downregulating Protein Tyrosine Phosphatase 1B in Rats With Myocardial Infarction

Myocardial infarction (MI) is one of cardiovascular diseases with high incidence and mortality. MicroRNAs, as posttranscriptional regulators of genes, are involved in many diseases, including cardiovascular diseases. The aim of the present study was to determine whether miR-203 was functional in MI therapy and how it worked. Left anterior descending artery ligation and hypoxia/reoxygenation (H/R) treatment were, respectively, performed to obtain MI rats and hypoxia-injured H9c2 cells. Western blot and quantitative real-time polymerase chain reaction were used to determine protein levels and messenger RNA of relevant genes, respectively. Lentivirus-mediated overexpression of miR-203 was performed to study the miR-203 functions on left ventricular remodeling, infarct size, and cardiomyocyte apoptosis. Compared with the sham group, miR-203 levels were significantly decreased in MI and H/R groups. However, overexpressing miR-203 greatly improved the cardiac function, reduced infarct size in rats after MI and weakened infarction-induced apoptosis by increasing Bcl-2 and reducing decreasing Bax, cleaved caspase-3, and cleaved caspase-9. In addition, Protein tyrosine phosphatase 1B (PTP1B) was proved as a target of miR-203 in cardiomyocytes, and it was negatively regulated by miR-203. Further experiments indicated that PTP1B overexpression could remarkably inhibit miR-203-mediated antiapoptosis of cardiomyocytes and alleviate protective effects of miR-203 on mitochondria after H/R treatment. Altogether, miR-203 prevented infarction-induced apoptosis by regulating PTP1B, including reducing proapoptosis proteins, inactivating caspase pathway, and protecting mitochondria. In conclusion, miR-203 had abilities to alleviate MI-caused injury on myocardium tissues and reduce mitochondria-mediated apoptosis, which might be a potential target used for MI therapy.

Hypoxia-challenged MSC-derived exosomes deliver miR-210 to attenuate post-infarction cardiac apoptosis

BACKGROUND

Myocardial infarction (MI) is a major cause of death worldwide. Although percutaneous coronary intervention and coronary artery bypass grafting can prolong life, cardiac damage persists. In particular, cardiomyocytes have no regenerative capacity. Mesenchymal stem cells (MSCs) are attractive candidates for the treatment of MI. The manner by which MSCs exert a beneficial effect upon injured cells is a source of continued study.

METHODS

After the isolation and identification of exosomes from MSCs, the expression of miR-210 was determined by microarray chip. Subsequently, gain- and loss-function approaches were conducted to detect the role of exosomes and exosomal-miR-210 in cell proliferation and apoptosis of cardiomyocytes, as well as the MI in vivo. Dual-Luciferase Report Gene System was used to demonstrate the target gene of miR-210.

RESULTS

We tested the hypothesis that MSC-derived exosomes transfer specific miRNA to protect cardiomyocytes from apoptotic cell death. Interestingly, direct cardiac injection of MSC exosomes reduced infarct size and improved heart function after coronary ligation. In vitro, the MSC exosomes enhanced cardiomyocyte survival to hypoxia. Confirmation of exosome uptake in myocytes was confirmed. Dual-luciferase reporter assay implicated miR-210 as a mediator of the therapeutic effect and AIFM3 as a downstream target. Treatment with miR-210 overexpressing MSC exosomes improved myocyte protection to both in vitro and in vivo stress. Furthermore, the endogenous and exogenous miR-210 had the same therapeutic effects.

CONCLUSION

These results demonstrated that the beneficial effects offered by MSC-exosomes transplantation after MI are at least partially because of excreted exosome containing mainly miR-210.

Exosomal miR-25-3p from mesenchymal stem cells alleviates myocardial infarction by targeting pro-apoptotic proteins and EZH2

Mesenchymal stem cell (MSC) therapy is a promising approach against myocardial infarction (MI). Studies have demonstrated that MSCs can communicate with other cells by secreting exosomes. In the present study, we aimed to identify exosomal microRNAs that might contribute to MSC-mediated cardioprotective effects. Primary cardiomyocytes were deprived of oxygen and glucose to mimic MI in vitro. For the animal model of MI, the left anterior descending artery was ligated for 1 h, followed by reperfusion for 12 h. MSC-derived exosomes were used to treat primary cardiomyocytes or mice. Cardioprotection-related microRNAs were determined, followed by target gene identification and functional studies with quantitative PCR, western blotting, MTT assay, flow cytometry assay, chromatin immunoprecipitation and dual-luciferase assay. We found that MSC co-culture reduced OGD-induced cardiomyocyte apoptosis and inflammatory responses. Cardioprotection was also observed upon treatment with MSC-derived exosomes in vitro and in vivo. In line with this, exosome uptake led to a significant increase in miR-25-3p in cardiomyocytes. Depletion of miR-25-3p in MSCs abolished the protective effects of exosomes. Mechanistically, miR-25-3p directly targeted the pro-apoptotic genes FASL and PTEN and reduced their protein levels. Moreover, miR-25-3p decreased the levels of EZH2 and H3K27me3, leading to derepression of the cardioprotective gene eNOS as well as the anti-inflammatory gene SOCS3. Inhibition of EZH2 or overexpression of miR-25-3p in cardiomyocytes was sufficient to confer cardioprotective effects in vitro and in vivo. We concluded that exosomal miR-25-3p from MSCs alleviated MI by targeting pro-apoptotic proteins and EZH2.

Growth Factor Gene-Modified Mesenchymal Stem Cells in Tissue Regeneration

There have been marked changes in the field of stem cell therapeutics in recent years, with many clinical trials having been conducted to date in an effort to treat myriad diseases. Mesenchymal stem cells (MSCs) are the cell type most frequently utilized in stem cell therapeutic and tissue regenerative strategies, and have been used with excellent safety to date. Unfortunately, these MSCs have limited ability to engraft and survive, reducing their clinical utility. MSCs are able to secrete growth factors that can support the regeneration of tissues, and engineering MSCs to express such growth factors can improve their survival, proliferation, differentiation, and tissue reconstructing abilities. As such, it is likely that such genetically modified MSCs may represent the next stage of regenerative therapy. Indeed, increasing volumes of preclinical research suggests that such modified MSCs expressing growth factors can effectively treat many forms of tissue damage. In the present review, we survey recent approaches to producing and utilizing growth factor gene-modified MSCs in the context of tissue repair and discuss its prospects for clinical application.

Silence of miR-32-5p promotes endothelial cell viability by targeting KLF2 and serves as a diagnostic biomarker of acute myocardial infarction

Background

MicroRNAs (miRNAs) have been investigated in various cardiovascular diseases. As a fatal disease, acute myocardial infarction (AMI) is a serious global health burden. The purpose of this study was to investigate the role of miR-32-5p in AMI patients and human umbilical vein endothelial cells (HUVECs) to explore novel diagnostic and therapeutic approaches for AMI.

Methods

A target prediction tool miRanda and the luciferase activity assay were used to confirm the interaction of miR-32-5p with Kruppel-like factor 2 (KLF2). Effect of miR-32-5p on HUVECs viability was examined using CCK-8 assay. Serum miR-32-5p expression was measured using quantitative Real-Time PCR, and its correlation with myocardial damage and endothelial injury markers and pro-inflammatory cytokines was assessed. Receiver operating characteristic (ROC) curves were used to evaluate the diagnostic value of miR-32-5p in AMI patients.

Results

miR-32-5p, as a direct regulator of KLF2, could suppress the cell proliferation of HUVECs. Serum miR-32-5p expression was elevated in AMI patients and positively correlated with the biomarker levels of myocardial damage and endothelial injury and pro-inflammatory cytokines. The area under the ROC curve for miR-32-5p was 0.949, indicating the relatively high diagnostic accuracy of miR-32-5p in AMI patients.

Conclusion

The data of this study revealed that the increased serum miR-32-5p expression serves as a candidate diagnostic biomarker of AMI, and that miR-32-5p may be involved in the myocardial damage, endothelial injury and inflammatory responses of AMI by targeting KLF2, indicating the potential of miR-32-5p as a diagnostic biomarker and molecular target to improve the treatment of AMI.

Donor MSCs release apoptotic bodies to improve myocardial infarction via autophagy regulation in recipient cells

Mesenchymal stem cell (MSC) transplantation has been widely applied as a potential therapeutic for multiple diseases. However, the underlying therapeutic mechanisms are not fully understood, especially the paradox between the low survival rate of transplanted cells and the beneficial therapeutic effects generated by these cells. Herein, in a myocardial infarction (MI) model, we found that transplanted MSCs released apoptotic bodies (ABs) to enhance angiogenesis and improve cardiac functional reclovery via regulating macroautophagy/autophagy in the recipient endothelial cells (ECs). Mechanistically, after local transplantation, MSCs underwent extensive apoptosis in the short term and released ABs, which were engulfed by the recipient ECs. Then, in the ECs, ABs activated lysosome functions and promoted the expression of TFEB (transcription factor EB), which is a master gene in lysosomal biogenesis and autophagy. Finally, the increase in TFEB enhanced autophagy-related gene expression in ECs and promoted angiogenesis and cardiac functional recovery after MI. Collectively, we found that apoptotic donor MSCs promote angiogenesis via regulating autophagy in the recipient ECs, unveiling the role of donor cell apoptosis in the therapeutic effects generated by cell transplantation. Abbreviations: 3-MA: 3-methyladenine; ABs: apoptotic bodies; BECN1: beclin 1; CASP3: caspase 3; CQ: chloroquine; ECs: endothelial cells; EVs: extracellular vesicles; LAMP1: lysosomal-associated membrane protein 1; LVEF: left ventricular ejection fraction; LVFS: left ventricular fractional shortening; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MI: myocardial infarction; MSC: mesenchymal stem cell; NO: nitric oxide; TFEB: transcription factor EB; TUNEL: TdT-mediated dUTP Nick-End Labeling.

Rosmarinic Acid Protects Adipose Tissue-Derived Mesenchymal Stem Cells in Nutrient-Deficient Conditions

One of the major challenges for stem cell therapy of ischemic organs is that the transplanted cells are confronted with nutrient deficiency and oxidative stress. Previous studies have indicated that pretreatment of stem cells with cytoprotective phytochemicals improves their therapeutic potential. This study was aimed to investigate whether rosmarinic acid can enhance survival of adipose tissue-derived stem cells (ASCs) in nutrient-deficient culture as an in vitro model of ischemia. The ASCs were isolated from subcutaneous adipose tissue of male adult Wistar rats and incubated for 24 h with rosmarinic acid in nutrient-deficient (glucose- and serum-deprived, GSD) culture medium. In a separate experiment, ASCs were pre-incubated for 4 h with rosmarinic acid and then exposed to GSD conditions for 24 h. The viability of ASCs was determined using thiazolyl blue tetrazolium bromide assays. The effect of rosmarinic acid on the cell cycle was evaluated using propidium iodide staining. GSD conditions significantly decreased the viability of ASCs and enhanced the generation of reactive oxygen species (ROS), lipid peroxidation, sub-G1 cell populations, and necrosis. Both pre-incubation and incubation of ASCs with 0.75~6 μM rosmarinic acid significantly increased cell viability in GSD conditions. Rosmarinic acid further decreased the level of ROS, lipid peroxidation, the percent of cells in sub-G1 stage, and necrosis in GSD conditions. These findings suggest that rosmarinic acid enhances survival of ASCs cultured in nutrient-deficient conditions through promoting antioxidant effects. Therefore, rosmarinic acid may help preserve ASCs survival after they are transplanted into ischemic organs.

mi R -15a/15b Cluster Modulates Survival of Mesenchymal Stem Cells to Improve Its Therapeutic Efficacy of Myocardial Infarction

Background

The poor viability of transplanted mesenchymal stem cells (MSCs) hampers their therapeutic efficacy for ischemic heart disease. MicroRNAs are involved in regulation of MSC survival and function. The present study was designed to investigate the molecular effects of miR‐15a/15b on MSC survival, focusing on the role of vascular endothelial growth factor receptor 2.

Methods and Results

We first harvested donor luc(Luciferase)‐MSCs (5×10⁵) isolated from the luciferase transgenic mice with FVB background. Luc‐MSCs were transfected with miR‐15a/15b mimics or inhibitors and cultured under oxygen glucose deprivation condition for 12 hours to mimics the harsh microenvironment in infarcted heart; they were subjected to MTT (3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2‐H‐tetrazolium bromide?Thiazolyl Blue Tetrazolium Bromide) assay, bioluminescence imaging, quantitative reverse transcription–polymerase chain reaction, transferase‐mediated deoxyuridine triphosphate–digoxigenin nick‐end labeling assay, and flow cytometry. Furthermore, the levels of vascular endothelial growth factor receptor 2, protein kinase B, p(Phosphorylate)‐protein kinase B, Bcl‐2, Bax, and caspase‐3 proteins were available by Western blotting assay. In vivo, acute myocardial infarction was induced in 24 mice by coronary ligation, with subsequent receipt of Luc‐MSCs, Luc‐MSCs+miR‐15a/15b inhibitors, or PBS treatment. The therapeutic procedure and treatment effects were tracked and assessed using bioluminescence imaging and echocardiographic measurement. Next, ex vivo imaging and immunohistochemistry were conducted to verify the distribution of MSCs. We demonstrated that miR‐15a/15b targeted vascular endothelial growth factor receptor 2 to modulate MSC survival, possibly via phosphatidylinositol 3‐kinase/protein kinase B signaling pathway, which was proved by bioluminescence imaging, immunohistochemistry analysis, and echocardiographic measurement.

Conclusions

Luc‐MSCs could be followed dynamically in vitro and in vivo by bioluminescence imaging, and the role of miR‐15a/b could be inferred from the loss of signals from luc‐MSCs. This finding may have practical clinical implications in miR‐15a/15b–modified MSC transplantation in treating myocardial infarction.

Free thiol groups on poly(aspartamide) based hydrogels facilitate tooth-derived progenitor cell proliferation and differentiation

Cell-based tissue reconstruction is an important field of regenerative medicine. Stem and progenitor cells derived from tooth-associated tissues have strong regeneration potential. However, their in vivo application requires the development of novel scaffolds that will provide a suitable three-dimensional (3D) environment allowing not only the survival of the cells but eliciting their proliferation and differentiation. Our aim was to study the viability and differentiation capacity of periodontal ligament cells (PDLCs) cultured on recently developed biocompatible and biodegradable poly(aspartamide) (PASP)-based hydrogels. Viability and behavior of PDLCs were investigated on PASP-based hydrogels possessing different chemical, physical and mechanical properties. Based on our previous results, the effect of thiol group density in the polymer matrix on cell viability, morphology and differentiation ability is in the focus of our article. The chemical composition and 3D structures of the hydrogels were determined by FT Raman spectroscopy and Scanning Electron Microscopy. Morphology of the cells was examined by phase contrast microscopy. To visualize cell growth and migration patterns through the hydrogels, two-photon microscopy were utilized. Cell viability analysis was performed according to a standardized protocol using WST-1 reagent. PDLCs were able to attach and grow on PASP-based hydrogels. An increase in gel stiffness enhanced adhesion and proliferation of the cells. However, the highest population of viable cells was observed on the PASP gels containing free thiol groups. The presence of thiol groups does not only enhance viability but also facilitates the osteogenic direction of the differentiating cells. These cell-gel structures seem to be highly promising for cell-based tissue reconstruction purposes in the field of regenerative medicine.

Combination therapies enhance immunoregulatory properties of MIAMI cells

Background

Mesenchymal stromal cells (MSCs), adult stromal cells most commonly isolated from bone marrow (BM), are being increasingly utilized in various therapeutic applications including tissue repair via immunomodulation, which is recognized as one of their most relevant mechanism of action. The promise of MSC-based therapies is somewhat hindered by their apparent modest clinical benefits, highlighting the need for approaches that would increase the efficacy of such therapies. Manipulation of cellular stress-response mechanism(s) such as autophagy, a catabolic stress-response mechanism, with small molecules prior to or during MSC injection could improve MSCs’ therapeutic efficacy. Unfortunately, limited information exists on how manipulation of autophagy affects MSCs’ response to inflammation and subsequent immunoregulatory properties.

Methods

In this study, we exposed BM-MSC precursor cells, “marrow-isolated adult multilineage inducible” (MIAMI) cells, to autophagy modulators tamoxifen (TX) or chloroquine (CQ), together with IFN-γ. Exposed cells then underwent RNA sequencing (RNAseq) to determine the effects of TX or CQ co-treatments on cellular response to IFN-γ at a molecular level. Furthermore, we evaluated their immunoregulatory capacity using activated CD4+ T cells by analyzing T cell activation marker CD25 and the percentage of proliferating T cells after co-culturing the cells with MIAMI cells treated or not with TX or CQ.

Results

RNAseq data indicate that the co-treatments alter both mRNA and protein levels of key genes responsible for MSCs’ immune-regulatory properties. Interestingly, TX and CQ also altered some of the microRNAs targeting such key genes. In addition, while IFN-γ treatment alone increased the surface expression of PD-L1 and secretion of IDO, this increase was further enhanced with TX. An improvement in MIAMI cells’ ability to decrease the activation and proliferation of T cells was also observed with TX, and to a lesser extent, CQ co-treatments.

Conclusion

Altogether, this work suggests that both TX and CQ have a potential to enhance MIAMI cells’ immunoregulatory properties. However, this enhancement is more pronounced with TX co-treatment.

Inhibition of lncRNA XIST Improves Myocardial I/R Injury by Targeting miR-133a through Inhibition of Autophagy and Regulation of SOCS2

The objective of this study was to investigate the role of lncRNA XIST and its relationship with miR-133a in myocardial I/R injury. H9C2 cells treated by hypoxia/reoxygenation (H/R) were used to establish an in vitro I/R model. The small interfering RNA (siRNA) for XIST and miR-133 mimics, inhibitor, and suppressor of cytokine signaling (SOCS2) recombinant plasmids were used to transfect the cells. Cell apoptosis was determined by flow cytometry analysis, and cell viability was used for 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide, Thiazolyl Blue Tetrazolium Bromide (MTT) assay. The dual-luciferase reporter assay was performed to confirm binding between XIST and miR-133a, as well as miR-133a and SOCS2. To inhibit or overexpress XIST, miR-133a, or SOCS2 in I/R mice, we used recombinant lentivirus vectors and adenovirus vectors for tail vein injection. The expression of XIST, miR-133a, and SOCS2 was determined by quantitative real-time PCR, and LC3 I/II and Beclin1 was determined by western blotting. The expression of XIST and SOCS2 was significantly upregulated, whereas the miR-133a level was remarkably downregulated in both H/R H9C2 cells and I/R mice myocardial tissues. In both H/R H9C2 cells and I/R mice, the inhibition of XIST led to decreased apoptosis and autophagy, and inhibition of miR-133a reversed these effects. Similarly, overexpression of miR-133a resulted in reduced apoptosis and autophagy, which were reversed by overexpression of SOCS2. The inhibition of XIST and overexpression of miR-133a also promote cell viability of H/R cells. The dual-luciferase reporter assay significantly showed that XIST directly targeted on miR-133a, and miR-133a directly targeted on SOCS2. The inhibition of XIST could improve myocardial I/R injury by regulation of the miR-133a/SOCS2 axis and inhibition of autophagy.

Mesenchymal Stem Cells for Regenerative Medicine

In recent decades, the biomedical applications of mesenchymal stem cells (MSCs) have attracted increasing attention. MSCs are easily extracted from the bone marrow, fat, and synovium, and differentiate into various cell lineages according to the requirements of specific biomedical applications. As MSCs do not express significant histocompatibility complexes and immune stimulating molecules, they are not detected by immune surveillance and do not lead to graft rejection after transplantation. These properties make them competent biomedical candidates, especially in tissue engineering. We present a brief overview of MSC extraction methods and subsequent potential for differentiation, and a comprehensive overview of their preclinical and clinical applications in regenerative medicine, and discuss future challenges.

Therapeutic effect of transplantation of human bone marrow‑derived mesenchymal stem cells on neuron regeneration in a rat model of middle cerebral artery occlusion

Human bone marrow-derived mesenchymal stromal cells (hBMSCs) have been revealed to be beneficial for the regeneration of tissues and cells in several diseases. The present study aimed to elucidate the mechanisms underlying the effect of hBMSC transplantation on neuron regeneration in a rat model of middle cerebral artery occlusion (MCAO). The hBMSCs were isolated, cultured and identified. A rat model of MCAO was induced via the modified Longa method. Neurological severity scores (NSS) were adopted for the evaluation of neuronal function in the model rats after cell transplantation. Next, the expression levels of nestin, β-III-tubulin (β-III-Tub), glial fibrillary acidic protein (GFAP), HNA and neuronal nuclear antigen (NeuN) were examined, as well as the positive expression rates of human neutrophil alloantigen (HNA), nestin, NeuN, β-III-Tub and GFAP. The NSS, as well as the mRNA and protein expression of nestin, decreased at the 1st, 2nd, 4 and 8th weeks, while the mRNA and protein expression of NeuN, β-III-Tub and GFAP increased with time. In addition, after treatment, the MCAO rats showed decreased NSS and mRNA and protein expression of nestin, but elevated mRNA and protein expression of NeuN, β-III-Tub and GFAP at the 2nd, 4 and 8th weeks, and decreased positive expression of HNA and nestin with enhanced expression of NeuN, β-III-Tub and GFAP. Therefore, the present findings demonstrated that hBMSC transplantation triggered the formation of nerve cells and enhanced neuronal function in a rat model of MCAO.

Main histological parameters to be evaluated in an experimental model of myocardial infarct treated by stem cells on pigs

Myocardial infarction has been carefully studied in numerous experimental models. Most of these models are based on electrophysiological and functional data, and pay less attention to histological discoveries. During the last decade, treatment using advanced therapies, mainly cell therapy, has prevailed from among all the options to be studied for treating myocardial infarction. In our study we wanted to show the fundamental histological parameters to be evaluated during the development of an infarction on an experimental model as well as treatment with mesenchymal stem cells derived from adipose tissue applied intra-lesionally. The fundamental parameters to study in infarcted tissue at the histological level are the cells involved in the inflammatory process (lymphocytes, macrophages and M2, neutrophils, mast cells and plasma cells), neovascularization processes (capillaries and arterioles) and cardiac cells (cardiomyocytes and Purkinje fibers). In our study, we used intramyocardial injection of mesenchymal stem cells into the myocardial infarction area 1 hour after arterial occlusion and allowed 1 month of evolution before analyzing the modifications on the normal tissue inflammatory infiltrate. Acute inflammation was shortened, leading to chronic inflammation with abundant plasma cells and mast cells and complete disappearance of neutrophils. Another benefit was an increase in the number of vessels formed. Cardiomyocytes and Purkinje fibers were better conserved, both from a structural and metabolic point of view, possibly leading to reduced morbidity in the long term. With this study we present the main histological aspects to be evaluated in future assays, complementing or explaining the electrophysiological and functional findings.

Mesenchymal Stem Cells Reduce Corneal Fibrosis and Inflammation via Extracellular Vesicle-Mediated Delivery of miRNA

Mesenchymal stem cells from corneal stromal stem cells (CSSC) prevent fibrotic scarring and stimulate regeneration of transparent stromal tissue after corneal wounding in mice. These effects rely on the ability of CSSC to block neutrophil infiltration into the damaged cornea. The current study investigated the hypothesis that tissue regeneration by CSSC is mediated by secreted extracellular vesicles (EVs). CSSC produced EVs 130-150 nm in diameter with surface proteins that include CD63, CD81, and CD9. EVs from CSSC reduced visual scarring in murine corneal wounds as effectively as did live cells, but EVs from human embryonic kidney (HEK)293T cells had no regenerative properties. CSSC EV treatment of wounds decreased expression of fibrotic genes Col3a1 and Acta2, blocked neutrophil infiltration, and restored normal tissue morphology. CSSC EVs labeled with carboxyfluorescein succinimidyl ester dye, rapidly fused with corneal epithelial and stromal cells in culture, transferring microRNA (miRNA) to the target cells. Knockdown of mRNA for Alix, a component of the endosomal sorting complex required for transport, using siRNA, resulted in an 85% reduction of miRNA in the secreted EVs. The EVs with reduced miRNA were ineffective at blocking corneal scarring. Furthermore, CSSC with reduced Alix expression also lost their regenerative function, suggesting EVs as an obligate component in the delivery of miRNA. The results of these studies support an essential role for extracellular vesicles in the process by which CSSC cells block scarring and initiate regeneration of transparent corneal tissue after wounding. EVs appear to serve as a delivery vehicle for miRNA, which affects the regenerative action. Stem Cells Translational Medicine 2019;8:1192-1201.

Novel Evidence of the Increase in Angiogenic Factor Plasma Levels after Lineage-Negative Stem/Progenitor Cell Intracoronary Infusion in Patients with Acute Myocardial Infarction

Cell therapy raises hope to reduce the harmful effects of acute myocardial ischemia. Stem and progenitor cells (SPCs) may be a valuable source of trophic factors. In this study, we assessed the plasma levels of selected trophic factors in patients undergoing application of autologous bone marrow (BM)-derived, lineage-negative (Lin^-) stem/progenitor cells into the coronary artery in the acute phase of myocardial infarction. The study group consisted of 15 patients with acute myocardial infarction (AMI) who underwent percutaneous revascularization and, afterwards, Lin^- stem/progenitor cell administration into the infarct-related artery. The control group consisted of 19 patients. BM Lin^- cells were isolated using immunomagnetic methods. Peripheral blood was collected on day 0, 2, 4, and 7 and after the first and third month to assess the concentration of selected trophic factors using multiplex fluorescent bead-based immunoassays. We found in the Lin^- group that several angiogenic trophic factors (vascular endothelial growth factor, Angiopoietin-1, basic fibroblast growth factor, platelet-derived growth factor-aa) plasma level significantly increased to the 4th day after myocardial infarction. In parallel, we noticed a tendency where the plasma levels of the brain-derived neurotrophic factor were increased in the Lin^- group. The obtained results suggest that the administered SPCs may be a valuable source of angiogenic trophic factors for damaged myocardium, although this observation requires further in-depth studies.

Cardioprotective effects of microRNA-18a on acute myocardial infarction by promoting cardiomyocyte autophagy and suppressing cellular senescence via brain derived neurotrophic factor

Background

The prevention of cardiovascular diseases is a matter of great concern, of which acute myocardial infarction (AMI) remains one of the leading causes of death resulting in high morbidity worldwide. Emerging evidence highlights the importance of microRNAs (miRNAs) as functional regulators in cardiovascular disease. In this study, an AMI rat model was established in order to investigate the effect of miR-18a on cardiomyocyte autophagy and senescence in AMI and the underlying mechanism.

Methods

In the present study, an AMI model was induced by ligating the anterior descending branch of left coronary artery in Wistar rats. Dual-luciferase reporter gene assay was introduced for exploration on the relationship between miR-18a and brain derived neurotrophic factor (BDNF). The gain- and loss-of-function experiments were performed to elucidate miR-18a and BDNF effects on cell autophagy and senescence in AMI by transfecting hypoxia-exposed H9c2 cells with miR-18a inhibitor or mimic, siRNA against BDNF, or hypoxia-exposed H9c2 cell treatment with an agonist of the Akt/mTOR axis (LM22B-10).

Results

Upregulation of miR-18a was found in AMI, while downregulation was present in BDNF to activate the Akt/mTOR axis. Compared with the miR-18a inhibitor group, the expression of p-Akt and p-mTOR increased and the number of senescent cells increased in the miR-18a inhibitor + LM22B-10 group, and the expression of Beclin1, LC3-II, p62 decreased and autophagy decreased (all p < 0.05). Furthermore, this could be rescued by knocking down BDNF or Akt/mTOR axis activation by LM22B-10.

Conclusion

All in all, downregulation of miR-18a could promote BDNF expression, which offers protection against AMI by inactivating the Akt/mTOR axis, highlighting a promising therapeutic strategy for AMI treatment.