Mesenchymal stem cells overexpressing integrin-linked kinase attenuate cardiac fibroblast proliferation and collagen synthesis through paracrine actions

The Role of Stem Cells in the Treatment of Cardiovascular Diseases

Cardiovascular diseases (CVDs) are the leading cause of death and include several vascular and cardiac disorders, such as atherosclerosis, coronary artery disease, cardiomyopathies, and heart failure. Multiple treatment strategies exist for CVDs, but there is a need for regenerative treatment of damaged heart. Stem cells are a broad variety of cells with a great differentiation potential that have regenerative and immunomodulatory properties. Multiple studies have evaluated the efficacy of stem cells in CVDs, such as mesenchymal stem cells and induced pluripotent stem cell-derived cardiomyocytes. These studies have demonstrated that stem cells can improve the left ventricle ejection fraction, reduce fibrosis, and decrease infarct size. Other studies have investigated potential methods to improve the survival, engraftment, and functionality of stem cells in the treatment of CVDs. The aim of the present review is to summarize the current evidence on the role of stem cells in the treatment of CVDs, and how to improve their efficacy.

Stem cells for treatment of liver fibrosis/cirrhosis: clinical progress and therapeutic potential

Cost-effective treatment strategies for liver fibrosis or cirrhosis are limited. Many clinical trials of stem cells for liver disease shown that stem cells might be a potential therapeutic approach. This review will summarize the published clinical trials of stem cells for the treatment of liver fibrosis/cirrhosis and provide the latest overview of various cell sources, cell doses, and delivery methods. We also describe the limitations and strengths of various stem cells in clinical applications. Furthermore, to clarify how stem cells play a therapeutic role in liver fibrosis, we discuss the molecular mechanisms of stem cells for treatment of liver fibrosis, including liver regeneration, immunoregulation, resistance to injury, myofibroblast repression, and extracellular matrix degradation. We provide a perspective for the prospects of future clinical implementation of stem cells.

Emerging Trends in Mesenchymal Stem Cells Applications for Cardiac Regenerative Therapy: Current Status and Advances

Irreversible myocardium infarction is one of the leading causes of cardiovascular disease (CVD) related death and its quantum is expected to grow in coming years. Pharmacological intervention has been at the forefront to ameliorate injury-related morbidity and mortality. However, its outcomes are highly skewed. As an alternative, stem cell-based tissue engineering/regenerative medicine has been explored quite extensively to regenerate the damaged myocardium. The therapeutic modality that has been most widely studied both preclinically and clinically is based on adult multipotent mesenchymal stem cells (MSC) delivered to the injured heart. However, there is debate over the mechanistic therapeutic role of MSC in generating functional beating cardiomyocytes. This review intends to emphasize the role and use of MSC in cardiac regenerative therapy (CRT). We have elucidated in detail, the various aspects related to the history and progress of MSC use in cardiac tissue engineering and its multiple strategies to drive cardiomyogenesis. We have further discussed with a focus on the various therapeutic mechanism uncovered in recent times that has a significant role in ameliorating heart-related problems. We reviewed recent and advanced technologies using MSC to develop/create tissue construct for use in cardiac regenerative therapy. Finally, we have provided the latest update on the usage of MSC in clinical trials and discussed the outcome of such studies in realizing the full potential of MSC use in clinical management of cardiac injury as a cellular therapy module.

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.

ILK promotes survival and self-renewal of hypoxic MSCs via the activation of lncTCF7-Wnt pathway induced by IL-6/STAT3 signaling

Mesenchymal stem cells (MSCs) have been applied in treating various diseases including myocardial infarction (MI) and achieved a bit of success; however, the decreased survival rate of MSCs after transplantation greatly limited the efficacy for cell therapy. How to improve the MSC survival rate in stem cell transplantation has undoubtedly become urgent and genetic engineering may be an ideal and feasible way. In this study, we explored the effects on MSCs survival and self-renewal by overexpression of integrin-linked kinase (ILK) in MSCs under hypoxic stimulation and aimed to reveal the molecular mechanisms from the point of paracrine function of MSCs. We first found that overexpression of ILK induced the expression and secretion of IL-6 increased significantly in MSCs under hypoxic stimulation, and the survival and self-renewal of MSCs exposed to hypoxia were enhanced after ILK overexpression. Then the activation of JAK2/STAT3 signaling was detected because of the increased IL-6, and an lncRNA, named lncTCF7, was upregulated remarkably, promoting the activation of Wnt pathway that was required for keeping cell viability and stemness of MSCs. Moreover, we further verified that inhibition of STAT3 signaling by WP1066 and silencing lncTCF7 expression eliminated the protective effects of ILK overexpression on cell survival and self-renewal of MSCs under hypoxic sitmulation. In conclusion, our results uncovered a novel function of ILK to promote MSC survival and self-renewal, suggesting more application potentials of MSC cell therapy on MI.

Fibroblast growth factor-2, but not the adipose tissue-derived stromal cells secretome, inhibits TGF-β1-induced differentiation of human cardiac fibroblasts into myofibroblasts

Transforming growth factor-β1 (TGF-β1) is a potent inducer of fibroblast to myofibroblast differentiation and contributes to the pro-fibrotic microenvironment during cardiac remodeling. Fibroblast growth factor-2 (FGF-2) is a growth factor secreted by adipose tissue-derived stromal cells (ASC) which can antagonize TGF-β1 signaling. We hypothesized that TGF-β1-induced cardiac fibroblast to myofibroblast differentiation is abrogated by FGF-2 and ASC conditioned medium (ASC-CMed). Our experiments demonstrated that TGF-β1 treatment-induced cardiac fibroblast differentiation into myofibroblasts, as evidenced by the formation of contractile stress fibers rich in αSMA. FGF-2 blocked the differentiation, as evidenced by the reduction in gene (TAGLN, p < 0.0001; ACTA2, p = 0.0056) and protein (αSMA, p = 0.0338) expression of mesenchymal markers and extracellular matrix components gene expression (COL1A1, p < 0.0001; COL3A1, p = 0.0029). ASC-CMed did not block myofibroblast differentiation. The treatment with FGF-2 increased matrix metalloproteinases gene expression (MMP1, p < 0.0001; MMP14, p = 0.0027) and decreased the expression of tissue inhibitor of metalloproteinase gene TIMP2 (p = 0.0023). ASC-CMed did not influence these genes. The proliferation of TGF-β1-induced human cardiac fibroblasts was restored by both FGF-2 (p = 0.0002) and ASC-CMed (p = 0.0121). The present study supports the anti-fibrotic effects of FGF-2 through the blockage of cardiac fibroblast differentiation into myofibroblasts. ASC-CMed, however, did not replicate the anti-fibrotic effects of FGF-2 in vitro.

ILK promotes angiogenic activity of mesenchymal stem cells in multiple myeloma

Angiogenic activity in solid tumors has been demonstrated to promote metastasis through the activation of certain proteins involved in the epithelial-mesenchymal transition-associated process. The molecular mechanism underlying multiple myeloma-induced angiogenesis involves angiogenic cytokines by plasma cells as well as their induction within the microenvironment. Integrin-linked kinase (ILK) is a highly evolutionarily conserved intracellular protein that was originally identified as an integrin-interacting protein, and extensive genetic and biochemical studies have identified ILK expression to be vital during tumor-driven angiogenesis. In the present study, it was identified that angiogenic factors were upregulated in mesenchymal stem cells (MSCs) that were co-cultured with multiple myeloma cell lines. It was also revealed that upregulated ILK expression significantly promoted the capillary-formation ability of MSCs. The concentrations of angiogenic factors were significantly decreased compared with non-targeting siRNA-transfected and control MSCs. MSCs may participate in inducing the angiogenic response in multiple myeloma depending on ILK expression.

Ascorbic acid promotes a TGFβ1-induced myofibroblast phenotype switch

l‐Ascorbic acid (AA), generally known as vitamin C, is a crucial cofactor for a variety of enzymes, including prolyl‐3‐hydroxylase (P3H), prolyl‐4‐hydroxylase (P4H), and lysyl hydroxylase (LH)‐mediated collagen maturation. Here, we investigated whether AA has additional functions in the regulation of the myofibroblast phenotype, besides its function in collagen biosynthesis. We found that AA positively influences TGFβ1‐induced expression of COL1A1,ACTA2, and COL4A1. Moreover, we demonstrated that AA promotes αSMA stress fiber formation as well as the synthesis and deposition of collagens type I and IV. Additionally, AA amplified the contractile phenotype of the myofibroblasts, as seen by increased contraction of a 3D collagen lattice. Moreover, AA increased the expression of several TGFβ1‐induced genes, including DDR1 and CCN2. Finally, we demonstrated that the mechanism of AA action seems independent of Smad2/3 signaling.

Mesenchymal Stromal Cells Cultured in Serum from Heart Failure Patients Are More Resistant to Simulated Chronic and Acute Stress

Despite regulatory issues surrounding the use of animal-derived cell culture supplements, most clinical cardiac cell therapy trials using mesenchymal stromal cells (MSCs) still rely on fetal bovine serum (FBS) for cell expansion before transplantation. We sought to investigate the effect of human serum from heart failure patients (HFS) on cord blood MSCs (CB-MSCs) during short-term culture under regular conditions and during simulated acute and chronic stress. Cell survival, proliferation, metabolic activity, and apoptosis were quantified, and gene expression profiles of selected apoptosis and cell cycle regulators were determined. Compared to FBS, HFS and serum from healthy donors (CS) showed similar effects by substantially increasing cell survival during chronic and acute stress and by increasing cell yields 5 days after acute stress. Shortly after the termination of acute stress, both HFS and CS resulted in a marked decrease in apoptotic cells. Transcriptome analysis suggested a decrease in TNF-mediated induction of caspases and decreased activation of mitochondrial apoptosis. Our data confirm that human serum from both healthy donors and heart failure patients results in increased cell yields and increased resistance to cellular stress signals. Therefore, we consider autologous serum a valid alternative to FBS in cell-based therapies addressing severe heart disease.

Cardiac shock wave therapy promotes arteriogenesis of coronary micrangium, and ILK is involved in the biomechanical effects by proteomic analysis

Cardiac Shock Wave Therapy (CSWT) improves myocardial perfusion and ameliorates cardiac remodeling after acute myocardial infarction (AMI), but the precise mechanisms remain obscure. Herein, we have applied CSWT to a rat model of AMI to demonstrate the arteriogenesis of coronary micrangium and protein expression changes in ischemic myocardium after CSWT. Four weeks after CSWT, the fraction shortening of rats was improved greatly and the cardiomyocyte apoptosis index was significantly lower than the AMI group (P < 0.05). Besides, the fibrotic area was markedly decreased in the CSWT group. In the infarction border zone, the thickness of smooth muscle layer was expanded apparently after CSWT. Label-free quantitative proteomic analysis and bioinformatics analysis revealed that the differentially expressed proteins were largely enriched in the focal adhesion signaling pathway. And integrin linked kinase (ILK) may be a key factor contributed to arteriogenesis of coronary micrangium during CSWT. In conclusion, non-invasive cardiac shock wave could promote arteriogenesis of coronary micrangium and alleviate myocardial apoptosis and fibrosis after AMI. Furthermore, focal adhesion signaling pathway may have a central role in the related signal network and ILK was closely related to the arteriogenesis of coronary micrangium during CSWT.

ANO1 inhibits cardiac fibrosis after myocardial infraction via TGF-β/smad3 pathway

As a newly identified factor in calcium-activated chloride channel, ANO1 participates in various physiological processes like proliferation and differentiation, and expresses in human cardiac fibroblasts. In this experiment, we investigated the function of ANO1 in cardiac fibrosis after myocardial infraction (MI) with methods of Western blotting, Quantitative real-time PCR (qRT-PCR), metabolic reduction of 3-(4,5-dimethylthiozol-2-yl)-2, 5-diphenyltetrazo-lium bromide (MTT), immunofluorescence and confocal imaging, and Masson’s trichrome staining. The results showed that the expression of ANO1 significantly increased in neonatal rats’ cardiac fibroblasts after hypoxia and in cardiac tissues after MI. After ANO1 over-expression, cardiac fibrosis was reduced in vitro and in vivo. Moreover, the expression of TGF-β and p-smad3 declined after ANO1over-expression in cardiac fiborblasts. In conclusion, ANO1 inhibits cardiac fibrosis after MI via TGF-β/smad3 pathway in rats.

Contributory Anti-Inflammatory Effects of Mesenchymal Stem Cells, Not Conditioned Media, On Ovalbumin-Induced Asthmatic Changes in Male Rats

Our aim in selecting an appropriate cell fraction and conditioned media (CM) was to achieve the suitable candidate for ameliorating long-term chronic asthmatic changes of respiratory tract. Thirty-six rats were classified into healthy and sensitized groups, which were further divided into three subgroups; rats received systemically 50 μl volume of PBS, CM, or 2 × 10⁶ rat bone marrow-derived mesenchymal stem cells (rBMMSCs). Tracheal responsiveness (TR), immunologic responses, and recruitment of rBMMSCs into the lungs were evaluated. A high degree of TR and total WBC and percentages of eosinophils and neutrophils was significantly recorded in all sensitized groups rather than of controls (p < 0.001 to p < 0.05). Concurrently, a significant improvement of TR and eosinophil and neutrophil return toward normal levels was evident in sensitized rats receiving cells as compared to parallel asthmatic animals. Flow cytometric monitoring of lymphocyte subpopulation revealed a decrease in the number of CD3⁺CD4⁺ and concurrent increase in CD3⁺CD8⁺ in all sensitized rats as compared to control (p < 0.001 to p < 0.05). Noticeably, no significant modulatory effects of either cell or CM administration were achieved on the CD3⁺CD4⁺ and CD3⁺CD8⁺ populations in non-asthmatic rats. Corroborating our results, the number of CD3⁺CD4⁺ tended to increase (p < 0.05) which coincided with a decreased manner of CD3⁺CD8⁺ populations as compared to other asthmatic groups (p < 0.01 to p < 0.05). Moreover, stem cells could efficiently transmigrate to the lung parenchyma, albeit the dynamic of asthmatic changes stimulated the rate of recruited cells. Our study shed light on superior effects of mesenchymal stem cells, but not CM, in attenuating chronic asthmatic changes in the model of rat.

Expression of integrin-linked kinase improves cardiac function in a swine model of myocardial infarction

Previous studies have described the beneficial effects of overexpressing integrin-linked kinase (ILK) after myocardial infarction (MI) in small animal models. However, the effects of ILK in pre-clinical large animals are not known. To move closer to clinical translation, we examined the effects of ILK gene transfer in a swine model of ischemic heart disease. Swine received percutaneous intracoronary injections of adenoviral vector expressing ILK (n=10) or empty ad-null (n=10) in the left anterior descending coronary artery (LAD) following LAD occlusion. Four weeks after transfection, we confirmed that transgene expression was restricted to the infarcted area in the cardiac tissue. Imaging studies demonstrated preserved cardiac function in the ILK group. ILK treatment was associated with reduced infarcted scar size and preserved left ventricular (LV) geometry (LV diameter and LV wall thickness). Enhanced angiogenesis was preserved in the ILK animals, along with reduction of apoptosis. ILK gene therapy improves cardiac remodeling and function in swine following MI associated with increased angiogenesis, reduced apoptosis, and increased cardiomyocyte proliferation with no signs of toxicity. These results may deliver a new approach to treat post-infarct remodeling and subsequent heart failure.

Bone marrow mesenchymal stem cells and their conditioned media could potentially ameliorate ovalbumin-induced asthmatic changes

BACKGROUND

The major feature of asthma is governed by chronic airway inflammation. This investigation was proposed to achieve the suitable candidate for ameliorating long-term chronic asthmatic changes of respiratory tract.

METHODS

36 rats were classified into healthy (C) and ovalbumin (OVA)-sensitized animals (S). To sensitize, the rats were exposed to OVA over a course of 32±1days. One day after sensitization, equal six different groups were subjected to experimental procedure (n=6); Rats only received intratracheally 50ml PBS (CPT and SPT groups), 50μl conditioned medium (CM) (CST and SST groups) and 50μl PBS containing 2×10⁶ rat bone marrow-derived mesenchymal stem cells (rBMMSCs) (CCT and SCT groups). Two weeks after treatment, tracheal responsiveness, immunologic responses and recruitment of rBMMSCs into the lung as well as pathological changes were evaluated.

RESULTS

A high degree of tracheal responsiveness, total white blood cell and percentages of eosinophil and neutrophil was significantly recorded in all sensitized groups rather than of controls (p<0.001 to p<0.05). Of interest, all above-mentioned parameters decreased significantly in SST and notably SCT groups as compared to S group (p<0.001 to p<0.05). The results revealed decrease number of blood CD3⁺CD4⁺ and concurrent increase in CD3⁺CD8⁺ in all sensitized rats as compared to control (p<0.001 to p<0.05). Noticeably, no significant modulatory effects of either cell or CM administration were achieved on the CD3⁺CD4⁺ and CD3⁺CD8⁺ populations in non-asthmatic rats. Moreover, the number of CD3⁺CD4⁺ in SST and SCT groups tended to increase, which coincided with a decreased manner of CD3⁺CD8⁺ populations as compared with S group (p<0.001 to p<0.05). However, the CD3⁺CD4⁺ cells in SCT rats were significantly higher than the group SST (p<0.01) whereas CD3⁺CD8⁺ cells diminished simultaneously (p<0.001). Real-time PCR analysis further showed that both CM and particularly MSCs changed the expression of interleukin (IL)-4 and IL-10 in the asthmatic groups to the near level of control rats (p<0.001 to p<0.05). Histopathological analysis revealed a profound reduction of lungs injuries in asthmatic rats when received CM and peculiarly mesenchymal stem cells (p<0.01 to p<0.05).

CONCLUSION

Our study shed light on the superior effects of rBMMSCs, rather than CM, in attenuating of chronic asthmatic changes in the rat model.

Paracrine Effects of Adipose-Derived Stem Cells on Matrix Stiffness-Induced Cardiac Myofibroblast Differentiation via Angiotensin II Type 1 Receptor and Smad7

Human mesenchymal stem cells (hMSCs) hold great promise in cardiac fibrosis therapy, due to their potential ability of inhibiting cardiac myofibroblast differentiation (a hallmark of cardiac fibrosis). However, the mechanism involved in their effects remains elusive. To explore this, it is necessary to develop an in vitro cardiac fibrosis model that incorporates pore size and native tissue-mimicking matrix stiffness, which may regulate cardiac myofibroblast differentiation. In the present study, collagen coated polyacrylamide hydrogel substrates were fabricated, in which the pore size was adjusted without altering the matrix stiffness. Stiffness is shown to regulate cardiac myofibroblast differentiation independently of pore size. Substrate at a stiffness of 30 kPa, which mimics the stiffness of native fibrotic cardiac tissue, was found to induce cardiac myofibroblast differentiation to create in vitro cardiac fibrosis model. Conditioned medium of hMSCs was applied to the model to determine its role and inhibitory mechanism on cardiac myofibroblast differentiation. It was found that hMSCs secrete hepatocyte growth factor (HGF) to inhibit cardiac myofibroblast differentiation via downregulation of angiotensin II type 1 receptor (AT₁R) and upregulation of Smad7. These findings would aid in establishment of the therapeutic use of hMSCs in cardiac fibrosis therapy in future.

Modeling Electrophysiological Coupling and Fusion between Human Mesenchymal Stem Cells and Cardiomyocytes

Human mesenchymal stem cell (hMSC) delivery has demonstrated promise in preclinical and clinical trials for myocardial infarction therapy; however, broad acceptance is hindered by limited understanding of hMSC-human cardiomyocyte (hCM) interactions. To better understand the electrophysiological consequences of direct heterocellular connections between hMSCs and hCMs, three original mathematical models were developed, representing an experimentally verified triad of hMSC families with distinct functional ion channel currents. The arrhythmogenic risk of such direct electrical interactions in the setting of healthy adult myocardium was predicted by coupling and fusing these hMSC models to the published ten Tusscher midcardial hCM model. Substantial variations in action potential waveform—such as decreased action potential duration (APD) and plateau height—were found when hCMs were coupled to the two hMSC models expressing functional delayed rectifier-like human ether à-go-go K⁺ channel 1 (hEAG1); the effects were exacerbated for fused hMSC-hCM hybrid cells. The third family of hMSCs (Type C), absent of hEAG1 activity, led to smaller single-cell action potential alterations during coupling and fusion, translating to longer tissue-level mean action potential wavelength. In a simulated 2-D monolayer of cardiac tissue, re-entry vulnerability with low (5%) hMSC insertion was approximately eight-fold lower with Type C hMSCs compared to hEAG1-functional hMSCs. A 20% decrease in APD dispersion by Type C hMSCs compared to hEAG1-active hMSCs supports the claim of reduced arrhythmogenic potential of this cell type with low hMSC insertion. However, at moderate (15%) and high (25%) hMSC insertion, the vulnerable window increased independent of hMSC type. In summary, this study provides novel electrophysiological models of hMSCs, predicts possible arrhythmogenic effects of hMSCs when directly coupled to healthy hCMs, and proposes that isolating a subset of hMSCs absent of hEAG1 activity may offer increased safety as a cell delivery cardiotherapy at low levels of hMSC-hCM coupling.

Myocardial infarction—better known as a heart attack—strikes on average every 43 seconds in America. An emerging approach to treat myocardial infarction patients involves the delivery of human mesenchymal stem cells (hMSCs) to the damaged heart. While clinical trials of this therapeutic approach have yet to report adverse effects on heart electrical rhythm, such consequences have been implicated in simpler experimental systems and thus remain a concern. In this study, we utilized mathematical modeling to simulate electrical interactions arising from direct coupling between hMSCs and human heart cells to develop insight into the possible adverse effects of this therapeutic approach on human heart electrical activity, and to assess a novel strategy for reducing some potential risks of this therapy. We developed the first mathematical models of electrical activity of three families of hMSCs based on published experimental data, and integrated these with previously established mathematical models of human heart cell electrical activity. Our computer simulations demonstrated that one particular family of hMSCs minimized the disturbances in cardiac electrical activity both at the single-cell and tissue levels, suggesting that isolating this specific sub-population of hMSCs for myocardial delivery could potentially increase the safety of future hMSC-based heart therapies.

Mesenchymal stem cells in cardiac regeneration: a detailed progress report of the last 6 years (2010-2015)

Mesenchymal stem cells have been used for cardiovascular regenerative therapy for decades. These cells have been established as one of the potential therapeutic agents, following several tests in animal models and clinical trials. In the process, various sources of mesenchymal stem cells have been identified which help in cardiac regeneration by either revitalizing the cardiac stem cells or revascularizing the arteries and veins of the heart. Although mesenchymal cell therapy has achieved considerable admiration, some challenges still remain that need to be overcome in order to establish it as a successful technique. This in-depth review is an attempt to summarize the major sources of mesenchymal stem cells involved in myocardial regeneration, the significant mechanisms involved in the process with a focus on studies (human and animal) conducted in the last 6 years and the challenges that remain to be addressed.

Genetic Engineering of Mesenchymal Stem Cells to Induce Their Migration and Survival

Mesenchymal stem cells (MSCs) are very attractive for regenerative medicine due to their relatively easy derivation and broad range of differentiation capabilities, either naturally or induced through cell engineering. However, efficient methods of delivery to diseased tissues and the long-term survival of grafted cells still need improvement. Here, we review genetic engineering approaches designed to enhance the migratory capacities of MSCs, as well as extend their survival after transplantation by the modulation of prosurvival approaches, including prevention of senescence and apoptosis. We highlight some of the latest examples that explore these pivotal points, which have great relevance in cell-based therapies.

Wnt signaling pathway in cardiac fibrosis: New insights and directions

OBJECTIVE

Wnt signaling pathway significantly participates in cardiac fibrosis and CFs activation. Therefore, we reviewed current evidence on the new perspectives and biological association between Wnt signaling pathway and cardiac fibrosis.

DESIGN AND METHODS

A PubMed database search was performed for studies of Wnt signaling pathway in cardiac fibrosis and CFs activation.

RESULTS

Numerous studies have shown that the Wnt signaling pathway significantly participates in cardiac fibrosis pathogenesis. The aim of this review is to describe the present knowledge about the Wnt signaling pathway significantly participating in cardiac fibrosis and CFs activation, and look ahead on new perspectives of Wnt signaling pathway research. Moreover, we will discuss the different insights that interact with the Wnt signaling pathway-regulated cardiac fibrosis. The Wnt proteins are glycoproteins that bind to the Fz receptors on the cell surface, which lead to several important biological functions, such as cell differentiation and proliferation. There are several signals among the characterized pathways of cardiac fibrosis, including Wnt/β-catenin signaling. In this review, new insight into the Wnt signaling pathway in cardiac fibrosis pathogenesis is discussed, with special emphasis on Wnt/β-catenin.

CONCLUSION

It seems reasonable to suggest the potential targets of Wnt signaling pathway and it can be developed as a therapeutic target for cardiac fibrosis.

Intracoronary Transplantation of Mesenchymal Stem Cells with Overexpressed Integrin-Linked Kinase Improves Cardiac Function in Porcine Myocardial Infarction

The effect of mesenchymal stem cell (MSCs)-based therapy on treating acute myocardial infarction (MI) is limited due to poor engraftment and limited regenerative potential. Here we engineered MSCs with integrin-linked kinase (ILK), a pleiotropic protein critically regulating cell survival, proliferation, differentiation, and angiogenesis. We firstly combined ferumoxytol with poly-L-lysine (PLL), and found this combination promisingly enabled MRI visualization of MSCs in vitro and in vivo with good safety. We provided visually direct evidence that intracoronary ILK-MSCs had substantially enhanced homing capacity to infarct myocardium in porcine following cardiac catheterization induced MI. Intracoronary transplantation of allogeneic ILK-MSCs, but not vector-MSCs, significantly enhanced global left ventricular ejection fraction (LVEF) by 7.8% compared with baseline, by 10.3% compared with vehicles, and inhibited myocardial remodeling compared with vehicles at 15-day follow-up. Compared with vector-MSCs, ILK-MSCs significantly improved regional LV contractile function, reduced scar size, fibrosis, cell apoptosis, and increased regional myocardial perfusion and cell proliferation. This preclinical study indicates that ILK-engineered MSCs might promote the clinical translation of MSC-based therapy in post-MI patients, and provides evidence that ferumoxytol labeling of cells combined with PLL is feasible in in vivo cell tracking.

Cardiosphere Conditioned Media Influence the Plasticity of Human Mediastinal Adipose Tissue-Derived Mesenchymal Stem Cells

Nowadays, cardiac regenerative medicine is facing many limitations because of the complexity to find the most suitable stem cell source and to understand the regenerative mechanisms involved. Mesenchymal stem cells (MSCs) have shown great regenerative potential due to their intrinsic properties and ability to restore cardiac functionality, directly by transdifferentiation and indirectly by paracrine effects. Yet, how MSCs could respond to definite cardiac-committing microenvironments, such as that created by resident cardiac progenitor cells in the form of cardiospheres (CSs), has never been addressed. Recently, a putative MSC pool has been described in the mediastinal fat (hmADMSCs), but both its biology and function remain hitherto unexplored. Accordingly, we investigated the potential of hmADMSCs to be committed toward a cardiovascular lineage after preconditioning with CS-conditioned media (CCM). Results indicated that CCM affects cell proliferation. Gene expression levels of multiple cardiovascular and stemness markers (MHC, KDR, Nkx2.5, Thy-1, c-kit, SMA) are significantly modulated, and the percentage of hmADMSCs preconditioned with CCM and positive for Nkx2.5, MHC, and KDR is significantly higher relative to FBS and explant-derived cell conditioned media (EDCM, the unselected stage before CS formation). Growth factor-specific and survival signaling pathways (i.e., Erk1/2, Akt, p38, mTOR, p53) present in CCM are all equally regulated. Nonetheless, earlier BAD phosphorylation (Ser112) occurs associated with the CS microenvironment (and to a lesser extent to EDCM), whereas faster phosphorylation of PRAS40 in FBS, and of Akt (Ser473) in EDCM and 5-azacytidine occurs compared to CCM. For the first time, we demonstrated that the MSC pool held in the mediastinal fat is adequately plastic to partially differentiate in vitro toward a cardiac-like lineage. Besides, we have provided novel evidence of the potent inductive niche-like microenvironment that the CS structure can reproduce in vitro. hmADMSCs can represent an interesting tool in order to exploit their possible role in cardiovascular diseases and treatment.

Direct intercellular communications dominate the interaction between adipose-derived MSCs and myofibroblasts against cardiac fibrosis

The onset of cardiac fibrosis post myocardial infarction greatly impairs the function of heart. Recent advances of cell transplantation showed great benefits to restore myocardial function, among which the mesenchymal stem cells (MSCs) has gained much attention. However, the underlying cellular mechanisms of MSC therapy are still not fully understood. Although paracrine effects of MSCs on residual cardiomyocytes have been discussed, the amelioration of fibrosis was rarely studied as the hostile environment cannot support the survival of most cell populations and impairs the diffusion of soluble factors. Here in order to decipher the potential mechanism of MSC therapy for cardiac fibrosis, we investigated the interplay between MSCs and cardiac myofibroblasts (mFBs) using interactive co-culture method, with comparison to paracrine approaches, namely treatment by MSC conditioned medium and gap co-culture method. Various fibrotic features of mFBs were analyzed and the most prominent anti-fibrosis effects were always obtained using direct co-culture that allowed cell-to-cell contacts. Hepatocyte growth factor (HGF), a well-known anti-fibrosis factor, was demonstrated to be a major contributor for MSCs' anti-fibrosis function. Moreover, physical contacts and tube-like structures between MSCs and mFBs were observed by live cell imaging and TEM which demonstrate the direct cellular interactions.

Adult vascular wall resident multipotent vascular stem cells, matrix metalloproteinases, and arterial aneurysms

Evidences have shown the presence of multipotent stem cells (SCs) at sites of arterial aneurysms: they can differentiate into smooth muscle cells (SMCs) and are activated after residing in a quiescent state in the vascular wall. Recent studies have implicated the role of matrix metalloproteinases in the pathogenesis of arterial aneurysms: in fact the increased synthesis of MMPs by arterial SMCs is thought to be a pivotal mechanism in aneurysm formation. The factors and signaling pathways involved in regulating wall resident SC recruitment, survival, proliferation, growth factor production, and differentiation may be also related to selective expression of different MMPs. This review explores the relationship between adult vascular wall resident multipotent vascular SCs, MMPs, and arterial aneurysms.

Atrial fibrosis in a chronic murine model of obstructive sleep apnea: mechanisms and prevention by mesenchymal stem cells

Background

OSA increases atrial fibrillation (AF) risk and is associated with poor AF treatment outcomes. However, a causal association is not firmly established and the mechanisms involved are poorly understood. The aims of this work were to determine whether chronic obstructive sleep apnea (OSA) induces an atrial pro-arrhythmogenic substrate and to explore whether mesenchymal stem cells (MSC) are able to prevent it in a rat model of OSA.

Methods

A custom-made setup was used to mimic recurrent OSA-like airway obstructions in rats. OSA-rats (n = 16) were subjected to 15-second obstructions, 60 apneas/hour, 6 hours/day during 21 consecutive days. Sham rats (n = 14) were placed in the setup but no obstructions were applied. In a second series of rats, MSC were administered to OSA-rats and saline to Sham-rats. Myocardial collagen deposit was evaluated in Picrosirius-red stained samples. mRNA expression of genes involved in collagen turnover, inflammation and oxidative stress were quantified by real time PCR. MMP-2 protein levels were quantified by Western Blot.

Results

A 43% greater interstitial collagen fraction was observed in the atria, but not in the ventricles, of OSA-rats compared to Sham-rats (Sham 8.32 ± 0.46% vs OSA 11.90 ± 0.59%, P < 0.01). Angiotensin-I Converting Enzyme (ACE) and Interleukin 6 (IL-6) expression were significantly increased in both atria, while Matrix Metalloproteinase-2 (MMP-2) expression was decreased. MSC administration blunted OSA-induced atrial fibrosis (Sham + Saline 8.39 ± 0.56% vs OSA + MSC 9.57 ± 0.31%, P = 0.11), as well as changes in MMP-2 and IL-6 expression. Interleukin 1-β (IL-1β) plasma concentration correlated to atrial but not ventricular fibrosis. Notably, a 2.5-fold increase in IL-1β plasma levels was observed in the OSA group, which was prevented in rats receiving MSC.

Conclusions

OSA induces selective atrial fibrosis in a chronic murine model, which can be mediated in part by the systemic and local inflammation and by decreased collagen-degradation. MSCs transplantation prevents atrial fibrosis, suggesting that these stem cells could counterbalance inflammation in OSA.

Reprogramming for cardiac regeneration

Treatment of cardiovascular diseases remains challenging considering the limited regeneration capacity of the heart muscle. Developments of reprogramming strategies to create in vitro and in vivo cardiomyocytes have been the focus point of a considerable amount of research in the past decades. The choice of cells to employ, the state-of-the-art methods for different reprogramming strategies, and their promises and future challenges before clinical entry, are all discussed here.