Stem cells and repair of the heart

Identification of potential therapeutic targets from bioinformatics analysis of necroptosis and immune infiltration in acute myocardial infarction

INTRODUCTION

Acute myocardial infarction (AMI) is a serious, deadly disease with a high incidence. However, it remains unclear how necroptosis affects the pathophysiology of AMI. Using bioinformatic analyses, this study investigated necroptosis in AMI.

METHODS

We obtained the GSE66360 dataset related to AMI by the GEO database. Venn diagrams were used to identify necroptosis-related differential genes (NRDEGs). The genes with differential expression in AMI were analyzed using gene set enrichment analysis, and a PPI network was established. A transcription factor prediction and enrichment analysis were conducted for the NRDEGs, and the relationships between AMI, NRDEGs, and immune cells were determined. Finally, in the additional dataset, NRDEG expression levels, immune infiltration, and ROC curve analysis were confirmed, and gene expression levels were further verified experimentally.

RESULTS

GSEA revealed that necroptosis pathways were significantly enriched in AMI. We identified 10 NRDEGs, including TNF, TLR4, FTH1 and so on. Enrichment analysis indicated that the NOD-like receptor and NF-kappa B signaling pathways were significantly enriched. Four NRDEGs, FTH1, IFNGR1, STAT3, and TLR4, were identified; however, additional datasets and further experimental validation are required to confirm their roles. In addition, we determined that a high abundance of macrophages and neutrophils prompted AMI development.

CONCLUSIONS

In this study, four potential genes that affect the development of AMI through necroptosis (FTH1, IFNGR1, STAT3, and TLR4) were identified. In addition, we found that a high abundance of macrophages and neutrophils affected AMI. This helps determine the pathological mechanism of necroptosis and immune cells that influence AMI and provides a novel strategy for targeted therapy.

Humanin inhibits lymphatic endothelial cells dysfunction to alleviate myocardial infarction-reperfusion injury via BNIP3-mediated mitophagy

OBJECTIVE

Acute myocardial infarction (AMI) ranks among the top contributors to sudden death and disability worldwide. It should be noted that current therapies always cause increased reperfusion damage. Evidence suggests that humanin (HN) reduces mitochondrial dysfunction to have cardio-protective effects against MI-reperfusion injury. In this context, we hypothesized that HN may attenuate MI-reperfusion injury by alleviating lymphatic endothelial cells dysfunction through the regulation of mitophagy.

MATERIALS AND METHODS

In this study, primary lymphatic endothelial cells were selected as the experimental model. Cells were maintained under 1% O2 to induce a hypoxic phenotype. For in vivo experiments, the left coronary arteries of C57/BL6 mice were clamped for 45 min followed by 24 h reperfusion to develop MI-reperfusion injury. The volume of infarcted myocardium in MI-reperfusion injury mouse models were TTC staining. PCR and western blot were used to quantify the expression of autophagy-, mitophagy- and mitochondria-related markers. The fibrosis and apoptosis in the ischemic area were evaluated for Masson staining and TUNEL respectively. We also used western blot to analyze the expression of VE-Cadherin in lymphatic endothelial cells.

RESULTS

We firstly exhibited a specific mechanism by which HN mitigates MI-reperfusion injury. We demonstrated that HN effectively reduces such injury in vivo and also inhibits dysfunction in lymphatic endothelial cells in vitro. Importantly, this inhibitory effect is mediated through BNIP3-associated mitophagy.

CONCLUSIONS

In conclusion, HN alleviates myocardial infarction-reperfusion injury by inhibiting lymphatic endothelial cells dysfunction, primarily through BNIP3-mediated mitophagy.

Extracellular vesicles in cardiac repair and regeneration: Beyond stem-cell-based approaches

The adult human heart poorly regenerate after injury due to the low self-renewal capability retained by adult cardiomyocytes. In the last two decades, several clinical studies have reported the ability of stem cells to induce cardiac regeneration. However, low cell integration and survival into the tissue has limited stem-cell-based clinical approaches. More recently, the release of paracrine mediators including extracellular vesicles (EV) has been recognized as the most relevant mechanism driving benefits upon cell-based therapy. In particular, EV have emerged as key mediators of cardiac repair after damage, in terms of reduction of apoptosis, resolution of inflammation and new blood vessel formation. Herein, mechanisms involved in cardiac damage and regeneration, and current applications of EV and their small non-coding RNAs (miRNAs) in regenerative medicine are discussed.

Sequential transplantation of exosomes and mesenchymal stem cells pretreated with a combination of hypoxia and Tongxinluo efficiently facilitates cardiac repair

Background

Bone marrow-derived mesenchymal stem cells (MSCs), which possess immunomodulatory characteristic, are promising candidates for the treatment of acute myocardial infarction (AMI). However, the low retention and survival rate of MSCs in the ischemic heart limit their therapeutic efficacy. Strategies either modifying MSCs or alleviating the inflammatory environment, which facilitates the recruitment and survival of the engrafted MSCs, may solve the problem. Thus, we aimed to explore the therapeutic efficacy of sequential transplantation of exosomes and combinatorial pretreated MSCs in the treatment of AMI.

Methods

Exosomes derived from MSCs were delivered to infarcted hearts through intramyocardial injection followed by the intravenous infusion of differentially pretreated MSCs on Day 3 post-AMI. Enzyme linked immunosorbent assay (ELISA) was performed to evaluate the inflammation level as well as the SDF-1 levels in the infarcted border zone of the heart. Echocardiography and histological analysis were performed to assess cardiac function, infarct size, collagen area and angiogenesis.

Results

Sequential transplantation of exosomes and the combinatorial pretreated MSCs significantly facilitated cardiac repair compared to AMI rats treated with exosomes alone. Notably, compared to the other three methods of cotransplantation, combinatorial pretreatment with hypoxia and Tongxinluo (TXL) markedly enhanced the CXCR4 level of MSCs and promoted recruitment, which resulted in better cardiac function, smaller infarct size and enhanced angiogenesis. We further demonstrated that exosomes effectively reduced apoptosis in MSCs in vitro.

Conclusion

Sequential delivery of exosomes and pretreated MSCs facilitated cardiac repair post-AMI, and combined pretreatment with hypoxia and TXL better enhanced the cardioprotective effects. This method provides new insight into the clinical translation of stem cell-based therapy for AMI.

Role of Stem Cell-Derived Microvesicles in Cardiovascular Disease

The role of stem cells in augmenting reparative processes in the heart after ischemic injury has been successfully demonstrated in small and large animal models. However, the outcomes of cell therapy in clinical trials have been somewhat variable, with overall effects of autologous stem cell therapies demonstrating a modest improvement in cardiac structure and function. How stem cells repair the heart after cardiac injury is still not well understood. Most recent studies suggest that adult derived stem cells act primarily through paracrine signaling to exert beneficial effects, including modulation of immune response, stimulation of new blood vessel formation, or by inducing mature myocytes to transiently reenter the cell cycle, rather than robust direct differentiation of the transplanted cells into myocytes. In addition, data from multiple laboratory results confirmed clearance of stem cells themselves within a few days still leading to functional benefits further confirming the role of paracrine signaling in augmenting cardiac reparative processes rather than direct differentiation of cells. These findings rapidly evolved the field of extracellular vesicles specifically microvesicles (MVs) as they are active hubs of autocrine, paracrine, and endocrine signaling targeting different biological processes. The beneficial effects seen after stem cell transplantation could be linked to the cardioprotective factors packaged in the MVs secreted from stem cells. Therefore, stem cell MVs provide a new avenue for the treatment of cardiovascular disease through a multitude of mechanisms including cellular communication within the stem cell niches, delivery of genetic information, regulation of the immune system in the heart, and stimulation of angiogenesis which will be discussed in this review.

Screening and Identification of Potential Hub Genes in Myocardial Infarction Through Bioinformatics Analysis

Background

Myocardial infarction (MI) is a common cause of death worldwide. It is characterized by coronary artery occlusion that causes ischemia and hypoxia of myocardial cells, leading to irreversible myocardial damage.

Materials and Methods

To explore potential targets for treatment of MI, we reorganized and analyzed two microarray datasets (GSE4648 and GSE775). The GEO2R tool was used to screen for differentially expressed genes (DEGs) between infarcted and normal myocardium. We used the Database for Annotation, Visualization and Integrated Discovery (DAVID) to perform Gene Ontology functional annotation analysis (GO analysis) and the Kyoto Encyclopedia of Genes and Genomes for pathway enrichment analysis (KEGG analysis). We examined protein-protein interactions to characterize the relationship between differentially expressed genes, and we screened potential hub genes according to the degree of connection. PCR and Western blotting were used to identify the core genes.

Results

At different times of infarction, a total of 35 genes showed upregulation at all times; however, none of the genes showed downregulation at all 3 times. Similarly, 10 hub genes with high degrees of connectivity were identified. In vivo and in vitro experiments suggested that expression levels of MMP-9 increased at various times after myocardial infarction and that expression increased in a variety of cells simultaneously.

Conclusion

Expression levels of MMP-9 increase throughout the course of acute myocardial infarction, and this expression has both positive and negative sides. Further studies are needed to explore the role of MMP-9 in MI treatment. The potential values of Il6, Spp1, Ptgs2, Serpine1, Plaur, Cxcl5, Lgals3, Serpinb2, and Cd14 are also worth exploring.

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.

The homing of bone marrow stem cells is differentially activated in ischemic and valvular heart diseases and influenced by beta-blockers

Background

Cell homing is the mechanism by which an injury releases signaling molecules that cause recruitment, proliferation, migration and differentiation of progenitor cells. Stromal derived factor-1 (SDF-1) and its receptor CXCR4 are key molecules involved in homing and little is known about their activation in cardiopathies. Here, we assessed the homing activation status of bone marrow cells (BMC) concerning the SDF-1 and CXCR4 expression in ischemic (IHD) and valvular (VHD) heart diseases.

Methods

The SDF-1 and inflammatory profile were analyzed by ELISA from plasma obtained bone marrow of ischemic heart patients (IHD, n = 41), valvular heart patients (VHD, n = 30) and healthy controls (C, n = 9). Flow cytometry was used to evaluate CXCR4 (CD184) expression on the surface of bone marrow cells, and the CXCR4 expression was estimated by real-time quantitative PCR.

Results

The SDF-1 levels in the groups IHD, VHD and control were, respectively, 230, 530 and 620 pg/mL (P = 0.483), and was decreased in VHD patients using beta-blockers (263 pg/mL) when compared with other (844 pg/mL) (P = 0.023). Compared with IHD, the VHD group showed higher CXCR4 (P = 0.071) and CXCR7 (P = 0.082) mRNA expression although no difference in the level of CXCR4⁺ bone marrow cells was found between groups (P = 0.360).

Conclusion

In conclusion, pathophysiological differences between IHD and VHD can affect the molecules involved in the activation of homing. In addition, the use of beta-blockers appears to interfere in this mechanism, a fact that should be considered in protocols that use BMC.

Stem Cell Therapy: A New Therapeutic Option for Cardiovascular Diseases

Cardiovascular diseases are known as one of major causes of morbidity and mortality worldwide. Despite the many advancement in therapies are associated with cardiovascular diseases, it seems that finding of new therapeutic option is necessary. Cell therapy is one of attractive therapeutic platforms for treatment of a variety of diseases such as cardiovascular diseases. Among of various types of cell therapy, stem cell therapy has been emerged as an effective therapeutic approach in this area. Stem cells divided into multipotent stem cells and pluripotent stem cells. A large number studies indicated that utilization of each of them are associated with a variety of advantages and disadvantages. Multiple lines evidence indicated that stem cell therapy could be used as suitable therapeutic approach for treatment of cardiovascular diseases. Many clinical trials have been performed for assessing efficiency of stem cell therapies in human. However, stem cell therapy are associated with some challenges, but, it seems resolving of them could contribute to using of them as effective therapeutic approach for patients who suffering from cardiovascular diseases. In the current review, we summarized current therapeutic strategies based on stem cells for cardiovascular diseases. J. Cell. Biochem. 119: 95-104, 2018. © 2017 Wiley Periodicals, Inc.

Direct Cardiac Reprogramming as a Novel Therapeutic Strategy for Treatment of Myocardial Infarction

Direct reprogramming of fibroblasts into induced cardiomyocytes (iCMs) holds great promise as a novel therapy for the treatment of heart failure, a common and morbid disease that is usually caused by irreversible loss of functional cardiomyocytes (CMs). Recently, we and others showed that in a murine model of acute myocardial infarction, delivery of three transcription factors, Gata4, Mef2c, and Tbx5 converted endogenous cardiac fibroblasts into functional iCMs. These iCMs integrated electrically and mechanically with surrounding myocardium, resulting in a reduction in scar size and an improvement in heart function. Our findings suggest that iCM reprogramming may be a means of regenerating functional CMs in vivo for patients with heart disease. However, because relatively little is known about the factors that regulate iCM reprogramming, the applicability of iCM reprogramming is currently limited to the experimental settings in which it has been attempted. Specific hurdles include the relatively low conversion rate of iCMs and the need for reprogramming to occur in the context of acute injury. Therefore, before this treatment can become a viable therapy for human heart disease, the optimal condition for efficient iCM generation must be determined. Here, we provide a detailed protocol for both in vitro and in vivo iCM generation that has been optimized so far in our lab. We hope that this protocol will lay a foundation for future further improvement of iCM generation and provide a platform for mechanistic studies.

Stem cell therapy for chronic ischaemic heart disease and congestive heart failure

BACKGROUND

A promising approach to the treatment of chronic ischaemic heart disease and congestive heart failure is the use of stem cells. The last decade has seen a plethora of randomised controlled trials developed worldwide, which have generated conflicting results.

OBJECTIVES

The critical evaluation of clinical evidence on the safety and efficacy of autologous adult bone marrow-derived stem/progenitor cells as a treatment for chronic ischaemic heart disease and congestive heart failure.

SEARCH METHODS

We searched CENTRAL in the Cochrane Library, MEDLINE, Embase, CINAHL, LILACS, and four ongoing trial databases for relevant trials up to 14 December 2015.

SELECTION CRITERIA

Eligible studies were randomised controlled trials comparing autologous adult stem/progenitor cells with no cells in people with chronic ischaemic heart disease and congestive heart failure. We included co-interventions, such as primary angioplasty, surgery, or administration of stem cell mobilising agents, when administered to treatment and control arms equally.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all references for eligibility, assessed trial quality, and extracted data. We undertook a quantitative evaluation of data using random-effects meta-analyses. We evaluated heterogeneity using the I2 statistic and explored substantial heterogeneity (I2 greater than 50%) through subgroup analyses. We assessed the quality of the evidence using the GRADE approach. We created a 'Summary of findings' table using GRADEprofiler (GRADEpro), excluding studies with a high or unclear risk of selection bias. We focused our summary of findings on long-term follow-up of mortality, morbidity outcomes, and left ventricular ejection fraction measured by magnetic resonance imaging.

MAIN RESULTS

We included 38 randomised controlled trials involving 1907 participants (1114 cell therapy, 793 controls) in this review update. Twenty-three trials were at high or unclear risk of selection bias. Other sources of potential bias included lack of blinding of participants (12 trials) and full or partial commercial sponsorship (13 trials).Cell therapy reduced the incidence of long-term mortality (≥ 12 months) (risk ratio (RR) 0.42, 95% confidence interval (CI) 0.21 to 0.87; participants = 491; studies = 9; I2 = 0%; low-quality evidence). Periprocedural adverse events associated with the mapping or cell/placebo injection procedure were infrequent. Cell therapy was also associated with a long-term reduction in the incidence of non-fatal myocardial infarction (RR 0.38, 95% CI 0.15 to 0.97; participants = 345; studies = 5; I2 = 0%; low-quality evidence) and incidence of arrhythmias (RR 0.42, 95% CI 0.18 to 0.99; participants = 82; studies = 1; low-quality evidence). However, we found no evidence that cell therapy affects the risk of rehospitalisation for heart failure (RR 0.63, 95% CI 0.36 to 1.09; participants = 375; studies = 6; I2 = 0%; low-quality evidence) or composite incidence of mortality, non-fatal myocardial infarction, and/or rehospitalisation for heart failure (RR 0.64, 95% CI 0.38 to 1.08; participants = 141; studies = 3; I2 = 0%; low-quality evidence), or long-term left ventricular ejection fraction when measured by magnetic resonance imaging (mean difference -1.60, 95% CI -8.70 to 5.50; participants = 25; studies = 1; low-quality evidence).

AUTHORS' CONCLUSIONS

This systematic review and meta-analysis found low-quality evidence that treatment with bone marrow-derived stem/progenitor cells reduces mortality and improves left ventricular ejection fraction over short- and long-term follow-up and may reduce the incidence of non-fatal myocardial infarction and improve New York Heart Association (NYHA) Functional Classification in people with chronic ischaemic heart disease and congestive heart failure. These findings should be interpreted with caution, as event rates were generally low, leading to a lack of precision.

Therapeutic Angiogenesis With Bone Marrow—Derived Stem Cells

Despite that advances in medical treatment and interventional procedures have reduced the mortality rate in patients with coronary artery disease, the number of patients with refractory myocardial ischemia and congestive heart failure is rapidly increasing. Experimental studies have demonstrated that bone marrow (BM) contains adult stem cells that can induce neovascularization and improve heart function in ischemic myocardium. Recent insights into the understanding of the mechanisms involved in proliferation, recruitment, mobilization, and incorporation of BM-derived stem cells into the myocardium and blood vessels have prompted development of cellular transplantation therapy for heart diseases refractory to conventional therapy. Initial preliminary clinical studies indicated potential clinical benefit of BM therapy in patients with acute myocardial infarction and chronic myocardial ischemia. Nevertheless, many obstacles remain, such as long-term safety and optimal timing and treatment strategies for BM cell therapy, and these issues need to be addressed in rationally designed, randomized clinical trials.

MECHANICAL CHARACTERIZATION OF ABDOMINAL AORTIC ANEURYSM WALL IN RAT MODEL TREATED BY MESENCHYMAL STEM CELLS

In this work, we study the mechanical properties of abdominal aortic aneurysms (AAAs) treated by cell therapy. Based on the xenograft model in rats, we analyze the effects of the injection of bone marrow mesenchymal stem cells (MSCs) on the stiffness of the arterial wall. Uniaxial tests performed on control, treated and untreated samples, have led to the identification of a nonlinear behavior law, using a mechanical model based on a stress-stretch exponential relation. The comparison of the mechanical behavior shows the benefits of the proposed cell therapy which improves the mechanical strength of the aneurysmal vessel wall. A histological study has shown the favorable change expression of elastin and collagen which are involved in the mechanical behavior of repaired arterial tissue. Thus, this work is part of MSCs biological understanding and it contributes to evaluate the approaches used in cell therapy and regenerative medicine to treat AAAs.

Stem Cells and Regenerative Medicine: Myth or Reality of the 21th Century

Since the 1960s and the therapeutic use of hematopoietic stem cells of bone marrow origin, there has been an increasing interest in the study of undifferentiated progenitors that have the ability to proliferate and differentiate into various tissues. Stem cells (SC) with different potency can be isolated and characterised. Despite the promise of embryonic stem cells, in many cases, adult or even fetal stem cells provide a more interesting approach for clinical applications. It is undeniable that mesenchymal stem cells (MSC) from bone marrow, adipose tissue, or Wharton's Jelly are of potential interest for clinical applications in regenerative medicine because they are easily available without ethical problems for their uses. During the last 10 years, these multipotent cells have generated considerable interest and have particularly been shown to escape to allogeneic immune response and be capable of immunomodulatory activity. These properties may be of a great interest for regenerative medicine. Different clinical applications are under study (cardiac insufficiency, atherosclerosis, stroke, bone and cartilage deterioration, diabetes, urology, liver, ophthalmology, and organ's reconstruction). This review focuses mainly on tissue and organ regeneration using SC and in particular MSC.

c-kit(+) cells: the tell-tale heart of cardiac regeneration?

Cardiovascular disease is the leading cause of morbidity and mortality in the developed world. Although ongoing therapeutic strategies ameliorate symptoms and prolong life for patients with cardiovascular diseases, they do not solve the critical issue related to the loss of cardiac tissue. Accordingly, stem/progenitor cell therapy has emerged as a paramount approach for cardiac repair and regeneration. In this regard, c-kit(+) cells have animated much interest and controversy. These cells are self-renewing, clonogenic, and multipotent and display a noteworthy potential to differentiate into all cardiovascular lineages. However, their functional contribution to cardiomyocyte turnover is one of the centrally debated issues concerning their regenerative potential. Regardless, plentiful preclinical and clinical studies have been conducted which provide evidence for the capacity of c-kit(+) cells to improve cardiac function. The purpose of this review is to give a comprehensive, impartial, critical description and evaluation of the literature on c-kit(+) cells from bench to bedside in order to address their true potential, benefits and controversies.

Altered protein secretions during interactions between adipose tissue- or bone marrow-derived stromal cells and inflammatory cells

Introduction

Paracrine effects can be exploited in cell-based therapies that secrete factors, such as chemokines and cytokines, and can recruit inflammatory cells to transplants. In this study, mouse adipose tissue-derived stromal cells (ASCs) and bone marrow-derived stromal cells (ST2 cells) were used to examine changes in paracrine interactions with inflammation cells.

Methods

Green fluorescent protein positive (GFP⁺) bone marrow cells (BMCs) were injected into an irradiated mouse via the femoral vein, and ASCs and ST2 cells were transplanted intradermally. Subsequently, an in vivo imaging system was used to observe behaviors of GFP⁺ BMCs. To detect bone marrow-derived inflammatory cells which migrated to the ASC and ST2 cell transplantation area, the sections were immunostained using antibodies against Gr1, CD11c, and F4/80, and secretory proteins were detected in culture medium using enzyme-linked immunosorbent assay.

Results

Many bone marrow-derived inflammatory cells migrated to ASC and ST2 cell transplantation sites. Among these, neutrophils were detected during the early period and macrophages were predominantly detected at a later point in time. Many chemokines, cytokines, growth factors, matrix metalloproteinases (MMPs), and tissue inhibitors of metalloproteinases (TIMPs) were secreted in abundance from ASCs, and the secretion increased by co-culturing with inflammatory cells, except for secretions of insulin-like growth factor-1, MMP-9 and MMP-13. Although secretions from ST2 cells were less than those from ASCs, co-culture with inflammatory cells increased these secretions to levels similar to those of ASCs. However, unlike ASCs, the ST2 cells did not secrete angiostatin, MMP-2, or MMP-3. Finally, ASCs secreted not only proinflammatory cytokines, angiogenic factors and MMPs but also anti-inflammatory cytokines, anti-angiogenesis factors, and TIMPs.

Conclusions

The effects of cell-based therapies using ASCs and ST2 cells are depended on paracrine effects that are mediated by chemokines, cytokines, growth factors, MMPs, and TIMPs, which comprise responses to interactions between transplanted cells and inflammatory cells. Moreover, paracrine effects of transplanted cells are influenced by inflammatory cells, and are moderated by a balance of secreted inhibitors.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0052-y) contains supplementary material, which is available to authorized users.

Hegemony in the marketplace of biomedical innovation: consumer demand and stem cell science

The global political economy of stem cell therapies is characterised by an established biomedical hegemony of expertise, governance and values in collision with an increasingly informed health consumer demand able to define and pursue its own interest. How does the hegemony then deal with the challenge from the consumer market and what does this tell us about its modus operandi? In developing a theoretical framework to answer these questions, the paper begins with an analysis of the nature of the hegemony of biomedical innovation in general, its close relationship with the research funding market, the current political modes of consumer incorporation, and the ideological role performed by bioethics as legitimating agency. Secondly, taking the case of stem cell innovation, it explores the hegemonic challenge posed by consumer demand working through the global practice based market of medical innovation, the response of the national and international institutions of science and their reassertion of the values of the orthodox model, and the supporting contribution of bioethics. Finally, the paper addresses the tensions within the hegemonic model of stem cell innovation between the key roles and values of scientist and clinician, the exacerbation of these tensions by the increasingly visible demands of health consumers, and the emergence of political compromise.

Stem cell therapy for chronic ischaemic heart disease and congestive heart failure

BACKGROUND

A promising approach to the treatment of chronic ischaemic heart disease (IHD) and heart failure is the use of stem cells. The last decade has seen a plethora of randomised controlled trials (RCTs) developed worldwide which have generated conflicting results.

OBJECTIVES

The critical evaluation of clinical evidence on the safety and efficacy of autologous adult bone marrow-derived stem cells (BMSC) as a treatment for chronic ischaemic heart disease (IHD) and heart failure.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2013, Issue 3), MEDLINE (from 1950), EMBASE (from 1974), CINAHL (from 1982) and the Transfusion Evidence Library (from 1980), together with ongoing trial databases, for relevant trials up to 31st March 2013.

SELECTION CRITERIA

Eligible studies included RCTs comparing autologous adult stem/progenitor cells with no autologous stem/progenitor cells in participants with chronic IHD and heart failure. Co-interventions such as primary angioplasty, surgery or administration of stem cell mobilising agents, were included where administered to treatment and control arms equally.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all references for eligibility, assessed trial quality and extracted data. We undertook a quantitative evaluation of data using fixed-effect meta-analyses. We evaluated heterogeneity using the I² statistic; we explored considerable heterogeneity (I² > 75%) using a random-effects model and subgroup analyses.

MAIN RESULTS

We include 23 RCTs involving 1255 participants in this review. Risk of bias was generally low, with the majority of studies reporting appropriate methods of randomisation and blinding, Autologous bone marrow stem cell treatment reduced the incidence of mortality (risk ratio (RR) 0.28, 95% confidence interval (CI) 0.14 to 0.53, P = 0.0001, 8 studies, 494 participants, low quality evidence) and rehospitalisation due to heart failure (RR 0.26, 95% CI 0.07 to 0.94, P = 0.04, 2 studies, 198 participants, low quality evidence) in the long term (≥12 months). The treatment had no clear effect on mortality (RR 0.68, 95% CI 0.32 to 1.41, P = 0.30, 21 studies, 1138 participants, low quality evidence) or rehospitalisation due to heart failure (RR 0.36, 95% CI 0.12 to 1.06, P = 0.06, 4 studies, 236 participants, low quality evidence) in the short term (< 12 months), which is compatible with benefit, no difference or harm. The treatment was also associated with a reduction in left ventricular end systolic volume (LVESV) (mean difference (MD) -14.64 ml, 95% CI -20.88 ml to -8.39 ml, P < 0.00001, 3 studies, 153 participants, moderate quality evidence) and stroke volume index (MD 6.52, 95% CI 1.51 to 11.54, P = 0.01, 2 studies, 62 participants, moderate quality evidence), and an improvement in left ventricular ejection fraction (LVEF) (MD 2.62%, 95% CI 0.50% to 4.73%, P = 0.02, 6 studies, 254 participants, moderate quality evidence), all at long-term follow-up. Overall, we observed a reduction in functional class (New York Heart Association (NYHA) class) in favour of BMSC treatment during short-term follow-up (MD -0.63, 95% CI -1.08 to -0.19, P = 0.005, 11 studies, 486 participants, moderate quality evidence) and long-term follow-up (MD -0.91, 95% CI -1.38 to -0.44, P = 0.0002, 4 studies, 196 participants, moderate quality evidence), as well as a difference in Canadian Cardiovascular Society score in favour of BMSC (MD -0.81, 95% CI -1.55 to -0.07, P = 0.03, 8 studies, 379 participants, moderate quality evidence). Of 19 trials in which adverse events were reported, adverse events relating to the BMSC treatment or procedure occurred in only four individuals. No long-term adverse events were reported. Subgroup analyses conducted for outcomes such as LVEF and NYHA class revealed that (i) route of administration, (ii) baseline LVEF, (iii) cell type, and (iv) clinical condition are important factors that may influence treatment effect.

AUTHORS' CONCLUSIONS

This systematic review and meta-analysis found moderate quality evidence that BMSC treatment improves LVEF. Unlike in trials where BMSC were administered following acute myocardial infarction (AMI), we found some evidence for a potential beneficial clinical effect in terms of mortality and performance status in the long term (after at least one year) in people who suffer from chronic IHD and heart failure, although the quality of evidence was low.

Transplantation of mesenchymal stem cells carrying the human receptor activity-modifying protein 1 gene improves cardiac function and inhibits neointimal proliferation in the carotid angioplasty and myocardial infarction rabbit model

Although transplanting mesenchymal stem cells (MSCs) can improve cardiac function and contribute to endothelial recovery in a damaged artery, natural MSCs may induce neointimal hyperplasia by directly or indirectly acting on vascular smooth muscle cells (VSMCs). Receptor activity-modifying protein 1 (RAMP1) is the component and the determinant of ligand specificity of calcitonin gene-related peptide (CGRP). It is recently reported that CGRP and its receptor involve the proliferation and the apoptosis in vivo and in vitro, and the exogenous RAMP1 enhances the antiproliferation effect of CGRP in VSMCs. Here, we investigated the effects of MSCs overexpressing the human receptor activity-modifying protein 1 (hRAMP1) on heart function and artery repair in rabbit models of myocardial infarction (MI) reperfusion and carotid artery injury. MSCs transfected with a recombinant adenovirus containing the hRAMP1 gene (EGFP-hRAMP1-MSCs) were injected into the rabbit models via the ear vein at 24 h after carotid artery injury and MI 7 days post-EGFP-hRAMP1-MSC transplantation. The cells that expressed both enhance green fluorescent protein (EGFP) and CD31 were detected in the neointima of the damaged artery via immunofluorescence. EGFP-hRAMP1 expression was observed in the injured artery and infarcted myocardium by western blot analysis, confirming that the engineered MSCs targeted the injured artery and infarcted myocardium and expressed hRAMP1 protein. Compared with the EGFP-MSCs group, the EGFP-hRAMP1-MSCs group had a significantly smaller infarcted area and improved cardiac function by 28 days after cell transplantation, as detected by triphenyltetrazolium chloride staining and echocardiography. Additionally, arterial hematoxylin-eosin staining revealed that the area of the neointima and the area ratio of intima/media were significantly decreased in the EGFP-hRAMP1-MSCs group. An immunohistological study showed that the expression of α-smooth muscle antigen and proliferating cell nuclear antigen in the neointima cells of the carotid artery of the EGFP-hRAMP1-MSCs group was approximately 50% lower than that of the EGFP-MSCs group, suggesting that hRAMP1 expression may inhibit VSMCs proliferation within the neointima. Therefore, compared with natural MSCs, EGFP-hRAMP1-engineered MSCs improved infarcted heart function and endothelial recovery from artery injury more efficiently, which will provide valuable information for the development of MSC-based therapy.

miR-24 regulates intrinsic apoptosis pathway in mouse cardiomyocytes

Numerous cardiac diseases, including myocardial infarction (MI) and chronic heart failure, have been associated with cardiomyocyte apoptosis. Promoting cell survival by inhibiting apoptosis is one of the effective strategies to attenuate cardiac dysfunction caused by cardiomyocyte loss. miR-24 has been shown as an anti-apoptotic microRNA in various animal models. In vivo delivery of miR-24 into a mouse MI model suppressed cardiac cell death, attenuated infarct size, and rescued cardiac dysfunction. However, the molecular pathway by which miR-24 inhibits cardiomyocyte apoptosis is not known. Here we found that miR-24 negatively regulates mouse primary cadiomyocyte cell death through functioning in the intrinsic apoptotic pathways. In ER-mediated intrinsic pathway, miR-24 genetically interacts with the CEBP homologous gene CHOP as knocking down of CHOP partially attenuated the induced apoptosis by miR-24 inhibition. In mitochondria-involved intrinsic pathway, miR-24 inhibits the initiation of apoptosis through suppression of Cytochrome C release and Bax translocation from cytosol to mitochondria. These results provide mechanistic insights into the miR-24 mediated anti-apoptotic effects in murine cardiomyocytes.

Effect of hypoxic paracrine media on calcium-regulatory proteins in infarcted rat myocardium

Background and Objectives

An increase in intracellular calcium concentration due to loss of Ca²⁺ homeostasis triggers arrhythmia or cardiac cell death in the heart. Paracrine factors released from stem cells have beneficial cardioprotective effects. However, the mechanism of modulation of Ca²⁺ homeostasis by paracrine factors in ischemic myocardium remains unclear.

Materials and Methods

We isolated rat bone marrow-derived mesenchymal stem cells (MSCs), and prepared paracrine media (PM) from MSCs under hypoxic or normoxic conditions (hypoxic PM and normoxic PM). We induced rat myocardial infarction by left anterior descending ligation for 1 hour, and treated PM into the border region of infarcted myocardium (n=6/group) to identify the alteration in calcium-regulated proteins. We isolated and stained the heart tissue with specific calcium-related antibodies after 11 days.

Results

The hypoxic PM treatment increased Ca²⁺-related proteins such as L-type Ca²⁺ channel, sarcoplasmic reticulum Ca²⁺ ATPase, Na⁺/K⁺ ATPase, and calmodulin, whereas the normoxic PM treatment increased those proteins only slightly. The sodium-calcium exchanger was significantly reduced by hypoxic PM treatment, compared to moderate suppression by the normoxic PM treatment.

Conclusion

Our results suggest that hypoxic PM was significantly associated with the positive regulation of Ca²⁺ homeostasis in infarcted myocardium.

Direct cardiac reprogramming: from developmental biology to cardiac regeneration

Heart disease affects millions worldwide and is a progressive condition involving loss of cardiomyocytes. The human heart has limited endogenous regenerative capacity and is thus an important target for novel regenerative medicine approaches. Although cell-based regenerative therapies hold promise, cellular reprogramming of endogenous cardiac fibroblasts, which represent more than half of the cells in the mammalian heart, may be an attractive alternative strategy for regenerating cardiac muscle. Recent advances leveraging years of developmental biology point to the feasibility of generating de novo cardiomyocyte-like cells from terminally differentiated nonmyocytes in the heart in situ after ischemic damage. Here, we review the progress in cardiac reprogramming methods and consider the opportunities and challenges that lie ahead in refining this technology for regenerative medicine.

Assessment of three techniques for delivering stem cells to the heart using PET and MR imaging

BACKGROUND

Stem cell therapy has a promising potential for the curing of various degenerative diseases, including congestive heart failure (CHF). In this study, we determined the efficacy of different delivery methods for stem cell administration to the heart for the treatment of CHF. Both positron emission tomography (PET) and magnetic resonance imaging (MRI) were utilized to assess the distribution of delivered stem cells.

METHODS

Adipose-derived stem cells of male rats were labeled with super-paramagnetic iron oxide (SPIO) and 18 F-fluorodeoxyglucose (FDG). The left anterior descending coronary artery (LAD) of the female rats was occluded to induce acute ischemic myocardial injury. Immediately after the LAD occlusion, the double-labeled stem cells were injected into the ischemic myocardium (n = 5), left ventricle (n = 5), or tail vein (n = 4). In another group of animals (n = 3), the stem cells were injected directly into the infarct rim 1 week after the LAD occlusion. Whole-body PET images and MR images were acquired to determine biodistribution of the stem cells. After the imaging, the animals were euthanized and retention of the stem cells in the vital organs was determined by measuring the cDNA specific to the Y chromosome.

RESULTS

PET images showed that retention of the stem cells in the ischemic myocardium was dependent on the cell delivery method. The tail vein injection resulted in the least cell retention in the heart (1.2% ± 0.6% of total injected cells). Left ventricle injection led to 3.5% ± 0.9% cell retention and direct myocardial injection resulted in the highest rate of cell retention (14% ± 4%) in the heart. In the animals treated 1 week after the LAD occlusion, rate of cell retention in the heart was only 4.5% ±1.1%, suggesting that tissue injury has a negative impact on cell homing. In addition, there was a good agreement between the results obtained through PET-MR imaging and histochemical measurements.

CONCLUSION

PET-MR imaging is a reliable technique for noninvasive tracking of implanted stem cells in vivo. Direct injection of stem cells into the myocardium is the most effective way for cell transplantation to the heart in heart failure models.

Dissecting the molecular relationship among various cardiogenic progenitor cells

RATIONALE

Multiple progenitors derived from the heart and bone marrow (BM) have been used for cardiac repair. Despite this, not much is known about the molecular identity and relationship among these progenitors. To develop a robust stem cell therapy for the heart, it is critical to understand the molecular identity of the multiple cardiogenic progenitor cells.

OBJECTIVE

This study is the first report of high-throughput transcriptional profiling of cardiogenic progenitor cells carried out on an identical platform.

METHOD AND RESULTS

Microarray-based transcriptional profiling was carried out for 3 cardiac (ckit(+), Sca1(+), and side population) and 2 BM (ckit(+) and mesenchymal stem cell) progenitors, obtained from age- and sex-matched wild-type C57BL/6 mice. Analysis indicated that cardiac-derived ckit(+) population was very distinct from Sca1(+) and side population cells in the downregulation of genes encoding for cell-cell and cell-matrix adhesion proteins, and in the upregulation of developmental genes. Significant enrichment of transcripts involved in DNA replication and repair was observed in BM-derived progenitors. The BM ckit(+) cells seemed to have the least correlation with the other progenitors, with enrichment of immature neutrophil-specific molecules.

CONCLUSIONS

Our study indicates that cardiac ckit(+) cells represent the most primitive population in the rodent heart. Primitive cells of cardiac versus BM origin differ significantly with respect to stemness and cardiac lineage-specific genes, and molecules involved in DNA replication and repair. The detailed molecular profile of progenitors reported here will serve as a useful reference to determine the molecular identity of progenitors used in future preclinical and clinical studies.

Selective isolation of nanog-positive human amniotic mesenchymal cells and differentiation into cardiomyocytes

Adult cardiomyocytes have little ability to regenerate, thus cardiac regeneration therapy represents a potential method for treating severe heart failure. Human amniotic mesenchymal cells (hAMCs) have the potential to be a useful cell source for cardiac regeneration therapy. We attempted to isolate stem cells from hAMCs and differentiate them into cardiomyocytes. Nanog promoter-Cre plasmid and cytomegalovirus (CMV) promoter-loxP-STOP-loxP-Red-puro(r) plasmid were co-transfected into immortalized hAMCs (iHAMs). Nanog-positive iHAMs were treated with 5-azacytidine (5-aza), trichostatin A (TA), activin A (AA), and bone morphogenetic protein-4 (BMP-4), or co-cultured with murine fetal cardiomyocytes for cardiomyocytes differentiation. Isolated Nanog-positive iHAMs were analyzed by quantitative RT-PCR and immunofluorescent staining before and after differentiation. Expression of Nanog, Oct3/4, Sox2, and Klf4 was significantly higher in Nanog-positive than in Nanog-negative iHAMs. Nanog-positive iHAMs were stained for Nanog and Oct3/4 in the nucleus. Nanog-positive iHAMs treated with 5-aza expressed Nkx2.5, GATA-4, human atrial natriuretic peptide (hANP), cardiac troponin T (cTnT), myocin light chain (Mlc)-2a, Mlc-2v, β-myosin heavy chain (β-MHC), hyperpolarization-activated cyclic nucleotide gated channels (HCN)-4, and inwardly rectifying potassium channels (Kir)-2.1. Although Nanog-positive iHAMs treated with TA, AA, or BMP-4 expressed several cardiac markers, no contraction was observed. Co-cultured Nanog-positive iHAMs with murine fetal cardiomyocytes spontaneously contracted in a synchronized manner and expressed the cardiac markers. In conclusion, Nanog-positive hAMCs with characteristics of stem cells were isolated and differentiated into cardiomyocyte-like cells, suggesting that these isolated hAMCs could be a useful cell source for cardiac regeneration therapy.

Angiogenesis following cell injection is induced by an excess inflammatory response coordinated by bone marrow cells

The aim of this study was to identify novel angiogenic mechanisms underlying the regenerative process. To that end, interactions between adipose tissue-derived stromal cells (ASCs) and bone marrow cells (BMCs) were initially investigated using real-time fluorescence optical imaging. To monitor cell behavior in mice, we injected green fluorescent protein-positive (GFP(+)) BMCs into the tail vein and injected PKH26-labeled ASCs behind the ears. Angiogenesis and inflammation were observed at these sites via an optical imaging probe. Injected GFP(+) BMCs migrated from the blood vessels into the tissues surrounding the ASC injection sites. Many of the migrating GFP(+) BMCs discovered at the ASC injection sites were inflammatory cells, including Gr-1(+), CD11b(+), and F4/80(+) cells. ASCs cocultured with inflammatory cells secreted increased levels of chemokines such as macrophage inflammatory protein (MIP)-1α, MIP-1β, keratinocyte-derived chemokines, and monocyte chemotactic protein 1. Similarly, these ASCs secreted increased levels of angiogenic growth factors such as hepatocyte growth factor and vascular endothelial growth factor. However, when anti-CXC chemokine receptor type 4 antibody was injected at regular intervals, the migration of GFP(+) BMCs (especially Gr-1(+) and CD11b(+) cells) to ASC injection sites was inhibited, as was angiogenesis. The collective influence of the injected ASCs and BMC-derived inflammatory cells promoted acute inflammation and angiogenesis. Together, the results suggest that the outcome of cell-based angiogenic therapy is influenced not only by the injected cells but also by the effect of intrinsic inflammatory cells.

[Cell therapy for ischemic heart disease]

Ischemic heart disease is the leading cause of death and heart failure worldwide. That is why it is important to develop new therapeutic modalities to decrease mortality and long-term complications in these patients. One of the main lines of research worldwide is myocardial regeneration, using progenitor cells in order to improve systolic and diastolic function in patients with ischemic heart disease, as well as to increase their survival. There have been carried out, with great enthusiasm worldwide, human and animal studies to define the usefulness of stem cells in the management of patients with ischemic heart disease. Today, regenerative therapy in ischemic heart disease is considered a novel therapeutic tool, with substantial theoretical benefits and few side effects. Here we present the scientific principles that support the use of this therapy, discuss the current clinical evidence available; and point out the controversial issues still not clarified on its use and usefulness in the short and long term.

Computerized left ventricular regional ejection fraction analysis for detection of ischemic coronary artery disease with multidetector CT angiography

Regional ejection fraction (REF) provides important functional information of the left ventricular regional myocardium. We aimed to test the diagnostic accuracy of computerized REF analysis for detecting the ischemia and significant stenosis with multidetector CT angiography (MDCT). This is a retrospective study including 155 patients who underwent MDCT scans for evaluation of coronary artery disease. Among them, 83 patients also underwent SPECT imaging and invasive coronary angiography (ICA). Two groups of patients were defined: Control group with 0 coronary artery calcium and normal global and regional ventricular function, and comparison group. REF measurement was performed on all patients using computerized software. Control group REF measurements will be used as reference standard (mean-2SD REF/mean global ejection fraction) to define abnormal REF. The sensitivity, specificity, positive and negative predictive value of REF in detecting perfusion defects (fixed and reversible) was 73, 80, 75 and 79 % respectively, in a patient based analysis of comparison group. The diagnostic accuracy of REF in predicting significant stenosis (>50 %) on ICA compared with SPECT was 72 versus 61 % and 85 versus 79 % in patient and vessel based analysis of comparison group, respectively. ROC curve analysis showed REF to be a better predictor of perfusion defects on SPECT compared with significant stenosis (>50 %) alone or stenosis combined with REF (P < 0.05). The computerized assessment of REF analysis is comparable to SPECT in predicting ischemia and a better predictor of significant stenosis than SPECT. This study also provides reference standard to define abnormal values.

The effects of age, disease state, and granulocyte colony-stimulating factor on progenitor cell count and function in patients undergoing cell therapy for cardiac disease

The potential of autologous bone marrow (BM)-derived progenitor/stem cell (BMSC) therapy for cardiac repair maybe limited by patient-related factors, such as age and the disease process itself. In this exploratory analysis, we assessed the impact of age, different disease states, and granulocyte colony-stimulating factor (G-CSF) therapy on progenitor cell concentration and function in patients recruited to our clinical trials of BMSC therapy for ischaemic heart failure (IHD), dilated cardiomyopathy (DCM), and acute myocardial infarction (AMI). The concentrations of CD34+ cells and endothelial progenitor cells (EPCs) were measured in the peripheral blood (PB) and BM of 201 patients. Additionally, cell mobilization following G-CSF and the functional capability of CD34+ cells (using a colony-forming unit assay) were assessed. We found that older age was associated with a lower PB CD34+ cell concentration in the whole study group as well as blunting the effect of G-CSF on BMSC mobilization in IHD patients. Nonischaemic heart failure (DCM) was associated with a significantly higher baseline PB CD34+ and EPC concentration compared to IHD. Following G-CSF treatment, the CD34+ cell concentration was greater in the BM compared to PB, however, the PB CD34+ cells appeared to have a greater and improved (compared to baseline) functional potential. Our results suggest treatment with G-CSF improves the functional potential of mobilized circulating progenitor cells compared to those in the BM. Further work is required to determine which source of cells is best for the purposes of cardiac repair following G-CSF therapy.

TGF-β family signaling in stem cells

BACKGROUND

The diversity of cell types and tissue types that originate throughout development derives from the differentiation potential of embryonic stem cells and somatic stem cells. While the former are pluripotent, and thus can give rise to a full differentiation spectrum, the latter have limited differentiation potential but drive tissue remodeling. Additionally cancer tissues also have a small population of self-renewing cells with stem cell properties. These cancer stem cells may arise through dedifferentiation from non-stem cells in cancer tissues, illustrating their plasticity, and may greatly contribute to the resistance of cancers to chemotherapies.

SCOPE OF REVIEW

The capacity of the different types of stem cells for self-renewal, the establishment and maintenance of their differentiation potential, and the selection of differentiation programs are greatly defined by the interplay of signaling molecules provided by both the stem cells themselves, and their microenvironment, the niche. Here we discuss common and divergent roles of TGF-β family signaling in the regulation of embryonic, reprogrammed pluripotent, somatic, and cancer stem cells.

MAJOR CONCLUSIONS

Increasing evidence highlights the similarities between responses of normal and cancer stem cells to signaling molecules, provided or activated by their microenvironment. While TGF-β family signaling regulates stemness of normal and cancer stem cells, its effects are diverse and depend on the cell types and physiological state of the cells.

GENERAL SIGNIFICANCE

Further mechanistic studies will provide a better understanding of the roles of TGF-β family signaling in the regulation of stem cells. These basic studies may lead to the development of a new therapeutic or prognostic strategies for the treatment of cancers. This article is part of a Special Issue entitled Biochemistry of Stem Cells.

Immunohistochemical detection of differentially localized up-regulation of lysyl oxidase and down-regulation of matrix metalloproteinase-1 in rhesus monkey model of chronic myocardial infarction

Myocardial remodeling after ischemic infarction is characterized by collagen accumulation leading to replacement and interstitial fibrosis. Type I and III collagens are predominant components in cardiac fibrosis. Lysyl oxidase (LOX) facilitates the cross-linking of type I and III fibrils, resulting in the formation of stiff fibers and their subsequent tissue deposition. However, the matrix metalloproteinases (MMPs), a family of zinc-dependent enzymes, function in the degradation of the collagen components of extracellular matrix. Tissue inhibitors for MMPs (TIMPs) manipulate the action of MMPs. To understand the contribution of these molecules to cardiac fibrosis, we developed a rhesus monkey model to determine the changes in LOX, MMP1 and TIMP1 in relation to collagen deposition after myocardial ischemic infarction. Male rhesus monkeys were subjected to left anterior descending artery ligation along with sham-operated controls. Histological examination and immunochemistry were performed eight weeks after the ischemic injury. The results showed that both type I and III collagens were increased in the scar area and in the interstitium, and the ratio of type I/III collagens also increased in the scar area but not in the interstitium. The expression of LOX was up-regulated, but the expression of MMP1 was down-regulated in residual myocytes of the scar area and the border zone. The expression of TIMP1 was not changed. The data thus demonstrated that the collagen deposition in infarcted myocardium is correlated with an enhanced cross-linking capacity and a decreased degradation process.

A REPAIR ALGORITHM FOR RADIAL BASIS FUNCTION NEURAL NETWORK AND ITS APPLICATION TO CHEMICAL OXYGEN DEMAND MODELING

This paper presents a repair algorithm for the design of a Radial Basis Function (RBF) neural network. The proposed repair RBF (RRBF) algorithm starts from a single prototype randomly initialized in the feature space. The algorithm has two main phases: an architecture learning phase and a parameter adjustment phase. The architecture learning phase uses a repair strategy based on a sensitivity analysis (SA) of the network's output to judge when and where hidden nodes should be added to the network. New nodes are added to repair the architecture when the prototype does not meet the requirements. The parameter adjustment phase uses an adjustment strategy where the capabilities of the network are improved by modifying all the weights. The algorithm is applied to two application areas: approximating a non-linear function, and modeling the key parameter, chemical oxygen demand (COD) used in the waste water treatment process. The results of simulation show that the algorithm provides an efficient solution to both problems.

Cloning and characterization of a trypsin-like serine protease gene, a novel regeneration-related gene from Apostichopus japonicus

Trypsin-like serine protease (TLS) plays an important role in many physiological processes including wound healing, phlogosis reaction, blood clotting, regeneration etc. In this paper, a 1216 bp full-length cDNA sequence of TLS including 39 bp 5' UTR and 355 bp 3'UTR coding for a theoretical 273 amino acids protein was cloned from Apostichopus japonicus by means of the RACE technique for the first time. Bioinformatic analysis revealed that the gene with a 20 residues N-terminal signal peptide and a conserved C-terminal domain belongs to the trypsin-like serine protease superfamily. His78, Asp130 and Ser223 are the principal residues of the catalytic center. In-situ hybridization (ISH) analysis revealed that the TLS gene was widely distributed in different tissues. The expression patterns during different regeneration stages of the TLS gene in the body wall, intestine and respiratory trees were investigated using real-time quantitative PCR. The results show that there was a remarkable and temporary up-regulation of TLS gene expression in the body wall within 1h and subsequent down-regulation of TLS similar to intestine and respiratory trees. With the recovery of tissues, the expression level of the TLS gene was gradually up-regulated and finally reached normal levels. TLS was regulated during different regeneration stages suggesting that TLS is important in the regeneration process of A. japonicus.

Potential for stem cell use in congenital heart disease

This article reports on the evolving field of stem cell therapy and its impact on the management of cardiac pathology, in particular congenital heart disease. To date, stem cell therapy has focused on cardiomyoplasty for heart muscle disease, stem cell therapies are already in clinical use for these disorders. Research is now also supporting the potential role of stem cell therapy for congenital heart disease. In the future it may be possible to use stem cells to create cellular grafts and structures that may be surgically implanted into the disordered heart using bioengineering technology. Different types of stem cells have been evaluated and the identification of specific cardiac stem cells offers great potential. Preliminary animal studies investigating fetal cardiac therapies are also underway. These new directions for stem cell research provide exciting potential for the future management of congenital heart disease.

Stem cells in liver failure

Orthotopic liver transplantation (OLT) represents the only reliable therapeutic approach for acute liver failure (ALF), liver failure associated to end-stage chronic liver diseases (CLD) and non-metastatic liver cancer. The clinical impact of liver failure is relevant because of the still high ALF mortality and the increasing worldwide prevalence of cirrhosis that, in turn, is the main predisposing cause for hepatocellular carcinoma (HCC). Moreover, in the next decade because an increased number of patients reaching end-stage disease and requiring OLT may face a shortage of donor livers. This clinical scenario led several laboratories to explore the feasibility and efficiency of alternative approaches, involving cellular therapy, to counteract liver failure. The present chapter overviews results and concepts emerged from recent experimental and clinical studies in which adult or embryonic hepatocytes, hepatic stem/progenitor cells, induced pluripotent stem (iPS) cells as well as extrahepatic stem cells have been used as putative transplantable cell sources.

Investigating the secretome: lessons about the cells that comprise the heart

The cell/environment interface is composed of the proteins of plasma membrane which face the extracellular space and by the proteins secreted directly by the cell of origin or by neighboring cells. The secreted proteins can act as extracellular matrix proteins and/or autocrine/paracrine proteins. This report discusses the technical aspects involved in the identification and characterization of the secreted proteins of specific cell types that comprise the heart. These aspects include the culturing of the cells, cell co-culturing and quantitative labeling, conditioned media collection and dealing with high abundant serum proteins, post-translational modification enrichment, the use of protein separation methods and mass spectrometry, protein identification and validation and the incorporation of pathway analysis to better understand the novel discovery on the background of already known experimental biological systems. The proteomic methods have the solid emplacement in cardiovascular research and the identification of proteins secreted by cardiac cells has been used in various applications such as determination the specificity between secretomes of different cell types, e.g. cardiac stem cells and cardiac myocytes, for the global secretome screening of e.g. human arterial smooth muscle cells, for the mapping of the beneficial effect of conditioned medium of one cell type on the other cell type, e.g. conditioned medium of human mesenchymal stem cells on cardiac myocytes, and for the searching the candidate paracrine factors and potential biomarkers.

Bone marrow mononuclear cells and acute myocardial infarction

Stem cell transplantation is emerging as a potential therapy to treat heart diseases. Promising results from early animal studies led to an explosion of small, non-controlled clinical trials that created even further excitement by showing that stem cell transplantation improved left ventricular systolic function and enhanced remodelling. However, the specific mechanisms by which these cells improve heart function remain largely unknown. A large variety of cell types have been considered to possess the regenerative ability needed to repair the damaged heart. One of the most studied cell types is the bone marrow-derived mononuclear cells and these form the focus of this review. This review article aims to provide an overview of their use in the setting of acute myocardial infarction, the challenges it faces and the future of stem cell therapy in heart disease.

Evolution of oxygen utilization in multicellular organisms and implications for cell signalling in tissue engineering

Oxygen is one of the critically defining elements resulting in the existence of eukaryotic life on this planet. The rise and fall of this element can be tracked through time and corresponds with the evolution of diverse life forms, development of efficient energy production (oxidative phosphorylation) in single cell organisms, the evolution of multicellular organisms and the regulation of complex cell phenotypes. By understanding these events, we can plot the effect of oxygen on evolution and its direct influence on different forms of life today, from the whole organism to specific cells within multicellular organisms. In the emerging field of tissue engineering, understanding the role of different levels of oxygen for normal cell function as well as control of complex signalling cascades is paramount to effectively build 3D tissues in vitro and their subsequent survival when implanted.

Characterisation of electrophysiological conduction in cardiomyocyte co-cultures using co-occurrence analysis

Cardiac arrhythmias are disturbances of the electrical conduction pattern in the heart with severe clinical implications. The damage of existing cells or the transplantation of foreign cells may disturb functional conduction pathways and may increase the risk of arrhythmias. Although these conduction disturbances are easily accessible with the human eye, there is no algorithmic method to extract quantitative features that quickly portray the conduction pattern. Here, we show that co-occurrence analysis, a well-established method for feature recognition in texture analysis, provides insightful quantitative information about the uniformity and the homogeneity of an excitation wave. As a first proof-of-principle, we illustrate the potential of co-occurrence analysis by means of conduction patterns of cardiomyocyte-fibroblast co-cultures, generated both in vitro and in silico. To characterise signal propagation in vitro, we perform a conduction analysis of co-cultured murine HL-1 cardiomyocytes and murine 3T3 fibroblasts using microelectrode arrays. To characterise signal propagation in silico, we establish a conduction analysis of co-cultured electrically active, conductive cardiomyocytes and non-conductive fibroblasts using the finite element method. Our results demonstrate that co-occurrence analysis is a powerful tool to create purity-conduction relationships and to quickly quantify conduction patterns in terms of co-occurrence energy and contrast. We anticipate this first preliminary study to be a starting point for more sophisticated analyses of different co-culture systems. In particular, in view of stem cell therapies, we expect co-occurrence analysis to provide valuable quantitative insight into the integration of foreign cells into a functional host system.