Bone marrow-derived mesenchymal stem cells overexpressing MiR-21 efficiently repair myocardial damage in rats

Clinical Variables Influence the Ability of miR-101, miR-150, and miR-21 to Predict Ventricular Remodeling after ST-Elevation Myocardial Infarction

Left ventricle remodeling (LVR) after acute myocardial infarction (MI) leads to impairment of both systolic and diastolic function, a significant contributor to heart failure (HF). Despite extensive research in the field, predicting post-MI LVR and HF is still a challenge. Several circulant microRNAs have been proposed as LVR predictors; however, their clinical value is controversial. Here, we used real-time quantitative PCR to quantify the plasma levels of hsa-miR-101, hsa-miR-150, and hsa-miR-21 on the first day of hospital admission of MI patients with ST-elevation (STEMI). We analyzed their correlation to the patient's clinical and paraclinical variables and evaluated their ability to discriminate between post-MI LVR and non-LVR. We show that, despite being excellent MI discriminators, none of these microRNAs can distinguish between LVR and non-LVR patients. Furthermore, we found that diabetes mellitus (DM), Hb level, and the number of erythrocytes significantly influence all three plasma microRNA levels. This suggests that plasma microRNAs' diagnostic and prognostic value in STEMI patients should be reevaluated and interpreted in the context of associated pathologies.

Teriparatide Promotes Bone Marrow Mesenchymal Stem Cells (BMSCs) Proliferation and Differentiation via Down-Regulating miR-298

This study explored whether teriparatide promotes BMSCs proliferation and differentiation via downregulating miR-298 and provided a basis for bone repair. Based on the microarray analysis after teriparatide treatment, qRT-PCR verified the differentially expressed miRNAs and the osteogenic differentiation was assessed by transfection of miRNA overexpression plasmids and miRNA inhibitors. miRNA array analysis and qRT-PCR verification showed that miR-298 was significantly downregulated during teriparatide-induced BMSCs differentiation. miR-298 overexpression significantly inhibited ALP and OPN expression which was promoted by transfection of miR-298 inhibitor. miR-298 is a negative regulator of BMSCs differentiation induced by teriparatide. Dlx5 is the target of miR-298. Inhibition of DLX5 expression by miR-298 was involved in the osteogenic differentiation of BMSCs. In conclusion, miR-298 negatively regulates the differentiation of BMSCs induced by teriparatide by targeting DLX5, providing a possible therapeutic target for bone tissue repair and regeneration.

MicroRNAs-The Heart of Post-Myocardial Infarction Remodeling

Myocardial infarction (MI) is one of the most frequent cardiac emergencies, with significant potential for mortality. One of the major challenges of the post-MI healing response is that replacement fibrosis could lead to left ventricular remodeling (LVR) and heart failure (HF). This process involves canonical and non-canonical transforming growth factor-beta (TGF-β) signaling pathways translating into an intricate activation of cardiac fibroblasts and disproportionate collagen synthesis. Accumulating evidence has indicated that microRNAs (miRNAs) significantly contribute to the modulation of these signaling pathways. This review summarizes the recent updates regarding the molecular mechanisms underlying the role of the over 30 miRNAs involved in post-MI LVR. In addition, we compare the contradictory roles of several multifunctional miRNAs and highlight their potential use in pressure overload and ischemia-induced fibrosis. Finally, we discuss their attractive role as prognostic biomarkers for HF, highlighting the most relevant human trials involving these miRNAs.

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.

Non-Coding RNAs in Stem Cell Regulation and Cardiac Regeneration: Current Problems and Future Perspectives

Although advances in rapid revascularization strategies following acute myocardial infarction (AMI) have led to improved short and long-term outcomes, the associated loss of cardiomyocytes and the subsequent remodeling result in an impaired ventricular function that can lead to heart failure or death. The poor regenerative capacity of the myocardium and the current lack of effective regenerative therapies have driven stem cell research in search of a possible solution. One approach involves the delivery of stem cells to the site of injury in order to stimulate repair response. Although animal studies initially delivered promising results, the application of similar techniques in humans has been hampered by poor target site retention and oncogenic considerations. In response, several alternative strategies, including the use of non-coding RNAs (ncRNAs), have been introduced with the aim of activating and regulating stem cells or inducing stem cell status in resident cells. Circular RNAs (circRNAs) and microRNAs (miRNAs) are ncRNAs with pivotal functions in cell proliferation and differentiation, whose role in stem cell regulation and potential significance for the field of cardiac regeneration is the primary focus of this review. We also address the general advantages of ncRNAs as promising drivers of cardiac regeneration and potent stem cell regulators.

MicroRNA124 and microRNA21-5p regulate migration, proliferation and differentiation of rat bone marrow mesenchymal stem cells

Mesenchymal stem cells (MSCs) are multipotent stromal cells that can be a useful source of cells for the treatment of many diseases, including neurologic diseases. The curative effect of MSCs relies mostly on cell’s capacity of migration, proliferation and differentiation. MicroRNAs (miRNAs) are small non-coding RNAs that play important roles on regulating various cell behaviors. Here, we report that miRNA-124 (miR124) and miRNA-21-5p (miR21-5p) display different regulatory roles on migration, proliferation and neuron differentiation of MSCs. MiR124 was shown greatly promoting MSCs migration and neuronal differentiation. MiR21-5p could significantly enhance the proliferation and neuronal differentiation ability of MSCs. MiR124 and miR21-5p synergistically promote differentiation of MSCs into neurons. Collectively, miR124 and miR21-5p can functionally regulate cell migration, proliferation and neuronal differentiation of MSCs. Therefore, miR124 and miR21-5p may be promising tools to improve transplantation efficiency for neural injury.

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.

A methodological nine-step process to bioengineer heart muscle tissue

Research in the field of heart muscle tissue engineering is focused on the fabrication of heart muscle tissue which can be utilized to repair, replace and/or augment functionality of damaged and/or diseased tissue. In the simplest embodiment, bioengineering heart muscle tissue constructs involves culture of cardiomyocytes within natural or synthetic scaffolds. Functional integration of the cells with the scaffold and subsequent remodeling lead to the formation of 3D heart muscle tissue and physiological cues like mechanical stretch, electrical stimulation and perfusion are necessary to guide tissue maturation and development. Potential applications for bioengineered heart muscle include use as grafts to repair or replace damaged tissue, as models for basic research and as tools for high-throughput screening of pharmacological agents. In this article, we provide a methodological process to bioengineer functional 3D heart muscle tissue and discuss state of the art and potential challenges in each of the nine-step tissue fabrication process.

Cell Therapy Improves Cardiac Function in Anthracycline-Induced Cardiomyopathy Preclinical Models: A Systematic Review and Meta-Analysis

Although anthracycline (ANT)-based treatment strongly contributes to cancer survivorship, the use of these agents is limited by the risk of cardiotoxicity. For those patients who evolve to heart failure, myocardial regenerative approaches are of particular interest, and a growing body of preclinical studies has been investigating the use of cell therapy for ANT-induced cardiomyopathy (AIC). However, since animal models and modalities of cell therapy are highly heterogeneous between studies, the efficacy of cell therapy for AIC is not clear. Thus, we conducted a systematic review and meta-analysis of experimental studies reporting the use of cell therapy with mesenchymal stromal cells (MSC) or bone marrow mononuclear cells (BMMNC) in animal models of AIC with regard to global cardiac function. The Medline, EMBASE, and Web of Science databases were searched from inception to November 2019. Two reviewers independently extracted data on study quality and the results of left ventricular ejection fraction (LVEF) and fractional shortening (FS) obtained by echocardiography. The quality of outcomes was assessed using the Cochrane, Collaborative Approach to Meta-Analysis and Review of Animal Data from Experimental Studies (CAMARADES), and SYRCLE bias risk tools. Pooled random-effects modeling was used to calculate pooled mean differences (MD) and 95% confidence intervals (CIs). Twenty-two studies comprising 381 small animals (rabbits and rodents) were included. A pooled meta-analysis of all treatments showed that cell therapy increased LVEF by 9.87% (95% CI 7.25-12.50, P < 0.00001) and FS by 7.80% (95% CI 5.68-9.92, P < 0.00001) in small animals with AIC. Cell therapy with MSC/BMMNC is effective to mitigate the deleterious effects of ANT on cardiac function in preclinical models. Nevertheless, due to the small number of studies and considerable heterogeneity, future translational studies must be designed to diminish between-study discrepancies and increase similarity to the clinical landscape.

Genetic Engineering as a Strategy to Improve the Therapeutic Efficacy of Mesenchymal Stem/Stromal Cells in Regenerative Medicine

Mesenchymal stem/stromal cells (MSCs) have been widely studied in the field of regenerative medicine for applications in the treatment of several disease settings. The therapeutic potential of MSCs has been evaluated in studies in vitro and in vivo, especially based on their anti-inflammatory and pro-regenerative action, through the secretion of soluble mediators. In many cases, however, insufficient engraftment and limited beneficial effects of MSCs indicate the need of approaches to enhance their survival, migration and therapeutic potential. Genetic engineering emerges as a means to induce the expression of different proteins and soluble factors with a wide range of applications, such as growth factors, cytokines, chemokines, transcription factors, enzymes and microRNAs. Distinct strategies have been applied to induce genetic modifications with the goal to enhance the potential of MCSs. This review aims to contribute to the update of the different genetically engineered tools employed for MSCs modification, as well as the factors investigated in different fields in which genetically engineered MSCs have been tested.

Mesenchymal stem cells repair bone marrow damage of aging rats and regulate autophagy and aging genes

The current study investigated the role of mesenchymal stem cells (MSCs) in repairing senile bone marrow injury and the underlying mechanism. Adenoviral vectors expressing green fluorescent protein (GFP) were used to label MSCs. The level of malondialdehyde (MDA) and activity of superoxide dismutase (SOD) were detected by thiobarbituric acid (TBA) and xanthine oxidation (XTO) methods. The proportions of CD34, CD3⁺ cells, cell proliferation and apoptosis were determined by flow cytometry, Cell counting kit (CCK)-8 and comet assay. Tissues were stained by haematoxylin-eosin (HE) staining and their changes were observed under a transmission electron microscopy. Expression levels of age-related and autophagy-related genes were detected by RT-qPCR and Western Blot. MSCs were successfully implanted into the bone marrow of aging rats. We found that the SOD activity was increased and MDA content was reduced in MSCs group. The proportions of CD34 cells were significantly more in the MSCs group than those in the Model group, and bone marrow cell colony formation and cell viability were both greatly increased in MSCs group. The proportions of CD3⁺ cells and level of Vascular endothelial growth factor (VEGF) were increased significantly, while IL-6 level was reduced greatly in MSCs group. Moreover, the bone marrow tissues of the model group were severely damaged, but those of the MSCs group were significantly improved. In addition, MSCs were involved in regulation of aging-related genes and autophagy-related genes. In conclusion, our findings showed that MSCs can repair bone marrow damage in aging rats, and regulate aging- and autophagy-related genes and immune response. SIGNIFICANCE: This study investigated the role of MSCs in the repair of senile bone marrow injury and the underlying mechanism. The effects of MSCs on physiological and biochemical indicators, cell function, tissue structure differences and pathological changes in aging rats were studied. It was found that MSCs can repair bone marrow damage in aging rats. MSCs regulate aging and autophagy-related genes and its involvement in immune response. Our findings improve the understandings on the regulatory mechanism of MSCs and provide key evidence for the study of MSCs in bone marrow repair.

Epidermal growth factor stimulates exosomal microRNA-21 derived from mesenchymal stem cells to ameliorate aGVHD by modulating regulatory T cells

Regulatory T cells (Tregs), a subset of CD4⁺ T cells, may exert inhibitory effects on alloimmune responses including acute graft-versus-host disease (aGVHD), and several microRNAs are implicated in the pathophysiological process of GVHD. Therefore, we aimed in the present study to characterize the functional relevance of epidermal growth factor (EGF)-stimulated microRNA-21 (miR-21) in regulating bone marrow-derived mesenchymal stem cells (BMSCs) in a mouse model of aGVHD. We first isolated and cultured BMSCs and Tregs. Then, we examined effects of miR-21 knockdown or overexpression and EGF on cell activities of BMSCs and the expression of PTEN, Foxp3, AKT phosphorylation, and extent of c-jun phosphorylation by gain- and loss-of-function approaches. The results showed that miR-21 promoted the proliferation, invasion, and migration of BMSCs. Furthermore, miR-21 in BMSCs-derived exosomes inhibited PTEN, but enhanced AKT phosphorylation and Foxp3 expression in Tregs. In addition, EGF enhanced c-jun phosphorylation to elevate the miR-21 expression. Furthermore, EGF significantly increased the efficacy of BMSCs in a mouse model of aGVHD, manifesting in reduced IFN-γ expression and lesser organ damage. Moreover, EGF treatment promoted the Foxp3 expression of Tregs in BMSCs-treated aGVHD mice. Taken together, EGF induced the BMSCs-derived exosomal miR-21 expression, which enhanced Foxp3 expression in Tregs, thereby improving the therapeutic effect of BMSCs on aGVHD.

Genetical modification on adipose-derived stem cells facilitates facial nerve regeneration

Adipose-derived stem cells (ASCs) have a demonstrative therapeutic potential in aging-associated facial nerve regeneration, in which ASCs work as a source of Schwann cells therapy as an alternative to autologous nerve grafts. However, the transplantation of ASCs may induce local fibrosis, which causes inferior outcome. Here, we aimed to use genetic modification approaches to reduce the fibrogenic properties of ASCs to improve their therapeutic effects on facial nerve regeneration. Since procollagen-lysine 1, 2-oxoglutarate 5-dioxygenase 1 (PLOD1) is essential for hydroxylation of lysine residues in collagen telopeptides and for collagen pyridinoline cross-link formation during fibrosis, and since we found that ASCs expressed high levels of PLOD1, we depleted PLOD1 in ASCs by expression of either a short-hair interfering RNA for PLOD1 (shPLOD1) or a microRNA-449 (miR-449), the latter of which targets PLOD1 mRNA to suppress protein translation. Transplantation of either ASCs-shPLOD1 or ASCs-miR-449 or ASCs-control to repair a 6mm-gap in rat facial nerve was compared. Either ASCs-shPLOD1 or ASCs-miR-449 exhibited a better facial nerve function. Mechanistically, ASCs-shPLOD1 or ASCs-miR-449 significantly and similarly reduced the fibrosis in the injured region, likely through suppression of reactive oxygen species (ROS) and activation of myofibroblasts.

Inhibition of miR-21 alleviated cardiac perivascular fibrosis via repressing EndMT in T1DM

In type 1 and type 2 diabetes mellitus, increased cardiac fibrosis, stiffness and associated diastolic dysfunction may be the earliest pathological phenomena in diabetic cardiomyopathy. Endothelial-mesenchymal transition (EndMT) in endothelia cells (ECs) is a critical cellular phenomenon that increases cardiac fibroblasts (CFs) and cardiac fibrosis in diabetic hearts. The purpose of this paper is to explore the molecular mechanism of miR-21 regulating EndMT and cardiac perivascular fibrosis in diabetic cardiomyopathy. In vivo, hyperglycaemia up-regulated the mRNA level of miR-21, aggravated cardiac dysfunction and collagen deposition. The condition was recovered by inhibition of miR-21 following with improving cardiac function and decreasing collagen deposition. miR-21 inhibition decreased cardiac perivascular fibrosis by suppressing EndMT and up-regulating SMAD7 whereas activating p-SMAD2 and p-SMAD3. In vitro, high glucose (HG) up-regulated miR-21 and induced EndMT in ECs, which was decreased by inhibition of miR-21. A highly conserved binding site of NF-κB located in miR-21 5'-UTR was identified. In ECs, SMAD7 is directly regulated by miR-21. In conclusion, the pathway of NF-κB/miR-21/SMAD7 regulated the process of EndMT in T1DM, in diabetic cardiomyopathy, which may be regarded as a potential clinical therapeutic target for cardiac perivascular fibrosis.

Mesenchymal Stem Cell Therapy for Doxorubicin-Induced Cardiomyopathy: Potential Mechanisms, Governing Factors, and Implications of the Heart Stem Cell Debate

Over the past decades, researchers have reported several mechanisms for doxorubicin (DOX)-induced cardiomyopathy, including oxidative stress, inflammation, and apoptosis. Another mechanism that has been suggested is that DOX interferes with the cell cycle and induces oxidative stress in C-kit+ cells (commonly known as cardiac progenitor cells), reducing their regenerative capacity. Cardiac regeneration through enhancing the regenerative capacity of these cells or administration of other stem cells types has been the axis of several studies over the past 20 years. Several experiments revealed that local or systemic injections with mesenchymal stem cells (MSCs) were associated with significantly improved cardiac function, ameliorated inflammatory response, and reduced myocardial fibrosis. They also showed that several factors can affect the outcome of MSC treatment for DOX cardiomyopathy, including the MSC type, dose, route, and timing of administration. However, there is growing evidence that the C-kit+ cells do not have a cardiac regenerative potential in the adult mammalian heart. Similarly, the protective mechanisms of MSCs against DOX-induced cardiomyopathy are not likely to include direct differentiation into cardiomyocytes and probably occur through paracrine secretion, antioxidant and anti-inflammatory effects. Better understanding of the involved mechanisms and the factors governing the outcomes of MSCs therapy are essential before moving to clinical application in patients with DOX-induced cardiomyopathy.

Localized injection of miRNA-21-enriched extracellular vesicles effectively restores cardiac function after myocardial infarction

Myocardial infarction (MI), a main cause of heart failure, leads to irreversible cardiomyocytes loss and cardiac function impairment. Current clinical treatments for MI are largely ineffective as they mostly aim to alleviate symptoms rather than repairing the injured myocardium. Thus, development of more effective therapies is compelling. This study aims to investigate whether the extracellular vesicles (EVs) carrying specific anti-apoptotic miRNA can be efficiently internalized into myocardium to achieve desired therapeutic outcomes.

Methods: EVs were isolated from HEK293T cells overexpressing miRNA-21 (miR21-EVs) and identified. The RNase resistant rate of miR21-EVs was calculated by real-time PCR and compared with liposomes and polyethylenimine (PEI). Confocal laser scanning microscopy was used for visualizing the cellular internalization of miR21-EVs in primary cultured mouse neonatal cardiomyocytes (CMs), H9c2 rat cardiomyoblasts, and human umbilical vein endothelial cells (HUVECs). The effect of miR21-EVs on the expression of PDCD4, a pro-apoptotic protein that plays an important role in regulating myocardial apoptosis, was also evaluated in these three cell types by real-time PCR and Western blot analysis. In vivo, miR21-EVs was directly injected into the infarct zone following ligation of the left anterior descending of coronary artery in mice. The miR21-EVs distribution and blood vessel (capillary and arteriole) density were evaluated by immunofluorescence staining. Fluorescence in situ hybridization of miRNA-21 was also carried out to confirm the miR21-EVs distribution in vitro and in vivo. The protein level of PDCD4 in myocardium was assessed by immunohistochemical staining. The anti-apoptotic effect of miR21-EVs in cardiomyocytes and endothelial cells were measured using TUNEL staining. Four weeks after injection, the cardiac histological and functional recovery was evaluated by histochemistry staining and echocardiography, respectively.

Results: In contrast to liposomes and PEI, EVs significantly inhibited miRNA-21 degradation. MiR21-EVs efficiently delivered miRNA-21 into cardiomyocytes and endothelial cells within 4 hours. Exogenous miRNA-21 in turn significantly reduced PDCD4 expression and attenuated cell apoptosis in vitro. Consistently and importantly, in a preclinical MI animal model, miRNA-21-loaded EVs effectively sent miRNA-21 into cardiomyocytes and endothelial cells, drastically inhibited cell apoptosis and led to significant cardiac function improvement.

Conclusion: Our results suggest the cell-derived, genetically engineered EVs may be used therapeutically for the delivery of miRNAs for the rescue of MI and may benefit patients in the future.

Remote ischaemic preconditioning increases serum extracellular vesicle concentrations with altered micro-RNA signature in CABG patients

BACKGROUND

Remote ischaemic preconditioning (RIPC) can attenuate myocardial ischaemia/reperfusion injury but its underlying mechanisms remain largely unknown. Recently, extracellular vesicles (EVs) containing microRNAs (miRNAs) were shown to mediate distant intercellular communication that may be involved in cardioprotection. We tested the hypothesis that RIPC in anaesthetized patients undergoing coronary artery bypass (CABG) surgery results in the release of EVs from the ischaemic/reperfused arm into the blood stream harbouring cardioprotective miRNAs.

METHODS

In 58 patients randomised to RIPC (three 5/5 minutes episodes of left arm ischaemia/reperfusion by suprasystolic blood pressure cuff inflations/deflations) or Sham, a subprotocol comprising of parallel right radial artery and regional (left subclavian) venous blood sampling before (awake) and 5 and 60 minutes after RIPC/Sham during isoflurane/sufentanil anaesthesia could be completed. EVs were extracted by polymer-based precipitation methods, their concentrations measured, and their miRNA signature analysed.

RESULTS

Five minutes after RIPC, regional venous EV concentrations downstream from the cuff increased and arterial concentrations increased after 60 minutes (fold change [fc]: RIPC: 1.33 ± 0.5, Sham: 0.91 ± 0.31; P = 0.003 for interaction). Already 5 minutes after RIPC, expression of 26 miRNAs (threshold fc: 3.0, P < 0.05) isolated from EVs including the cardioprotective miR-21 had increased. RIPC also decreased postoperative Troponin I concentrations (AUC RIPC: 336 ng/mL × 72 hours ± 306 vs Sham: 713 ± 1013; P  =  0.041).

CONCLUSIONS

Remote ischaemic preconditioning increases serum EV concentrations, most likely by early EV release from the patients' left (RIPC) arm, alters their miRNA signature, and is associated with myocardial protection. Thus, an increased EV concentration with an altered miR-signature may mediate the RIPC effect.

Metformin Increases Proliferative Activity and Viability of Multipotent Stromal Stem Cells Isolated from Adipose Tissue Derived from Horses with Equine Metabolic Syndrome

In this study, we investigated the influence of metformin (MF) on proliferation and viability of adipose-derived stromal cells isolated from horses (EqASCs). We determined the effect of metformin on cell metabolism in terms of mitochondrial metabolism and oxidative status. Our purpose was to evaluate the metformin effect on cells derived from healthy horses (EqASCHE) and individuals affected by equine metabolic syndrome (EqASCEMS). The cells were treated with 0.5 μM MF for 72 h. The proliferative activity was evaluated based on the measurement of BrdU incorporation during DNA synthesis, as well as population doubling time rate (PDT) and distribution of EqASCs in the cell cycle. The influence of metformin on EqASC viability was determined in relation to apoptosis profile, mitochondrial membrane potential, oxidative stress markers and BAX/BCL-2 mRNA ratio. Further, we were interested in possibility of metformin affecting the Wnt3a signalling pathway and, thus, we determined mRNA and protein level of WNT3A and β-catenin. Finally, using a two-tailed RT-qPCR method, we investigated the expression of miR-16-5p, miR-21-5p, miR-29a-3p, miR-140-3p and miR-145-5p. Obtained results indicate pro-proliferative and anti-apoptotic effects of metformin on EqASCs. In this study, MF significantly improved proliferation of EqASCs, which manifested in increased synthesis of DNA and lowered PDT value. Additionally, metformin improved metabolism and viability of cells, which correlated with higher mitochondrial membrane potential, reduced apoptosis and increased WNT3A/β-catenin expression. Metformin modulates the miRNA expression differently in EqASCHE and EqASCEMS. Metformin may be used as a preconditioning agent which stimulates proliferative activity and viability of EqASCs.

MicroRNA-21 Overexpression Promotes the Neuroprotective Efficacy of Mesenchymal Stem Cells for Treatment of Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) has high morbidity and mortality, with no effective treatment at present. One possible therapeutic strategy involves the use of mesenchymal stem cells (MSCs), which have shown promise in experimental models and have great potential for treating nervous illnesses in humans. However, many deficiencies in MSC treatment still need to be addressed, including their poor survival rate post-transplantation. Previously, we reported that the microRNA-21 (miR-21) is downregulated in ICH patients' blood and brain tissue. In this study, we aimed to examine its role and therapeutic efficacy in ICH using miR-21-overexpressing MSCs. We found that this microRNA can enhance MSC survival and recovery of neurological function in ICH rats. Its mechanism of action involves reduced neuronal apoptosis. In addition, we demonstrated that miR-21 can be transported to neurons through exosomes derived from MSCs and that it can target transient receptor potential melastatin 7 (TRPM7) to alleviate neuronal injury following ICH. We also observed that the NF-κB pathway is involved in the regulation of miR-21 in neural cells. In conclusion, miR-21 significantly enhances the survival of MSCs in ICH, and miR-21-overexpressing MSCs clearly improved neurological function in ICH rats. Transplantation of miR-21-overexpressing MSCs may, therefore, provide an effective strategy for neuroprotection and treatment of cerebrovascular diseases.

LncRNA BISPR promotes the progression of thyroid papillary carcinoma by regulating miR-21-5p

Our study attempted to verify the effect of lncRNA BST2 interferon-stimulated positive regulator (BISPR) on cell viability, propagation and invasiveness of thyroid papillary carcinoma (TPC) and the interactive relationship between BISPR and miR-21-5p. Microarray analyzed the aberrant expression lncRNA BISPR in TPC. BISPR and miR-21-5p as well as B-cell lymphoma-2 (Bcl-2) expressions in TPC cells were determined by quantitative polymerase chain reaction (qRT-PCR) and Western blot. Cell counting kit-8 (CCK-8) assay, dual luciferase reporter assay, and transwell assay were conducted to manifest cell viability, propagation, and invasiveness of TPC cells. Flow cytometry was performed to determine the apoptosis and cell cycle of TPC cells. Mouse xenograft model was built to testify the effect of BISPR on tumor growth. BISPR in TPC tissues was over-expressed. BISPR knockdown restrained the propagation and invasiveness and enhanced the iodine uptake of TPC cells. The tumor-forming rate reduced after BISPR knockdown. In addition, miR-21-5p was lowly expressed in cancer tissues. BISPR promoted the development of TPC cells by inhibiting miR-21-5p expression. Bcl-2 was suppressed by miR-21-5p and sh-BISPR. BISPR, which was over-expressed in TPC, improved TPC cell viability, propagation, and invasiveness. MiR-21-5p was lowly expressed in TPC which inhibited Bcl-2 expression. BISPR stimulated propagation and invasiveness of TPC cells by depressing miR-21-5p.

Melatonin-mediated miR-526b-3p and miR-590-5p upregulation promotes chondrogenic differentiation of human mesenchymal stem cells

Bone marrow-derived mesenchymal stem cells (BMSCs), with inherent chondrogenic differentiation potential appear to be ideally suited for therapeutic use in cartilage regeneration. Accumulating evidence has demonstrated that melatonin can promote chondrogenic differentiation in human BMSCs. However, little is known about the mechanism. MicroRNAs (miRNAs) have been shown to regulate the differentiation of BMSCs, but their roles in melatonin-promoted chondrogenic differentiation have not been characterized. Here, we demonstrate that melatonin promoted chondrogenic differentiation of human BMSCs via upregulation of miR-526b-3p and miR-590-5p. Mechanistically, the elevated miR-526b-3p and miR-590-5p enhanced SMAD1 phosphorylation by targeting SMAD7. Additionally, administration of miR-526b-3p mimics or miR-590-5p mimics successfully promoted the chondrogenic differentiation of human BMSCs. Collectively, our study suggests that modification of BMSCs using melatonin or miRNA transduction could be an effective therapy for cartilage damage and degeneration.

Circadian MicroRNAs in Cardioprotection

The most dramatic feature of life on Earth is our adaptation to the cycle of day and night. Throughout evolutionary time, almost all living organisms developed a molecular clock linked to the light-dark cycles of the sun. In present time, we know that this molecular clock is crucial to maintain metabolic and physiological homeostasis. Indeed, a dysregulated molecular clockwork is a major contributing factor to many metabolic diseases. In fact, the time of onset of acute myocardial infarction exhibits a circadian periodicity and recent studies have found that the light regulated circadian rhythm protein Period 2 (PER2) elicits endogenous cardioprotection from ischemia. Manipulating the molecular clockwork may prove beneficial during myocardial ischemia in humans. MicroRNAs are small non-coding RNA molecules capable of silencing messenger RNA (mRNA) targets. MicroRNA dysregulation has been linked to cancer development, cardiovascular and neurological diseases, lipid metabolism, and impaired immunity. Therefore, microRNAs are gaining interest as putative novel disease biomarkers and therapeutic targets. To identify circadian microRNA-based cardioprotective pathways, a recent study evaluated transcriptional changes of PER2 dependent microRNAs during myocardial ischemia. Out of 352 most abundantly expressed microRNAs, miR-21 was amongst the top PER2 dependent microRNAs and was shown to mediate PER2 elicited cardioprotection. Further analysis suggested circadian entrainment via intense light therapy to be a potential strategy to enhance miR-21 activity in humans. In this review, we will focus on circadian microRNAs in the context of cardioprotection and will highlight new discoveries, which could lead to novel therapeutic concepts to treat myocardial ischemia.

Recent Progress in Stem Cell Modification for Cardiac Regeneration

During the past decades, stem cell-based therapy has acquired a promising role in regenerative medicine. The application of novel cell therapeutics for the treatment of cardiovascular diseases could potentially achieve the ambitious aim of effective cardiac regeneration. Despite the highly positive results from preclinical studies, data from phase I/II clinical trials are inconsistent and the improvement of cardiac remodeling and heart performance was found to be quite limited. The major issues which cardiac stem cell therapy is facing include inefficient cell delivery to the site of injury, accompanied by low cell retention and weak effectiveness of remaining stem cells in tissue regeneration. According to preclinical and clinical studies, various stem cells (adult stem cells, embryonic stem cells, and induced pluripotent stem cells) represent the most promising cell types so far. Beside the selection of the appropriate cell type, researchers have developed several strategies to produce “second-generation” stem cell products with improved regenerative capacity. Genetic and nongenetic modifications, chemical and physical preconditioning, and the application of biomaterials were found to significantly enhance the regenerative capacity of transplanted stem cells. In this review, we will give an overview of the recent developments in stem cell engineering with the goal to facilitate stem cell delivery and to promote their cardiac regenerative activity.

Thrombospondin-1 modified bone marrow mesenchymal stem cells (BMSCs) promote neurite outgrowth and functional recovery in rats with spinal cord injury

Stem cell therapies are currently gaining momentum in the treatment of spinal cord injury (SCI). However, unsatisfied intrinsic neurite growth capacity constitutes significant obstacles for injured spinal cord repair and ultimately results in neurological dysfunction. The present study assessed the efficacy of thrombospondin-1 (TSP-1), a neurite outgrowth-promoting molecule, modified bone marrow mesenchymal stem cells (BMSCs) on promoting neurite outgrowth in vitro and in vivo of Oxygen–Glucose Deprivation (OGD) treated motor neurons and SCI rat models. The present results demonstrated that the treatment of BMSCs+TSP-1 could promote the neurite length, neuronal survival, and functional recovery after SCI. Additionally, TSP-1 could activate transforming growth factor-β1 (TGF-β1) then induced the smad2 phosphorylation, and expedited the expression of GAP-43 to promote neurite outgrowth. The present study for the first time demonstrated that BMSCs+TSP-1 could promote neurite outgrowth and functional recovery after SCI partly through the TGF-β1/p-Samd2 pathway. The study provided a novel encouraging evidence for the potential treatment of BMSCs modification with TSP-1 in patients with SCI.