Intra-myocardial delivery of mesenchymal stem cells ameliorates left ventricular and cardiomyocyte contractile dysfunction following myocardial infarction. Toxicol Lett. 2010;195:119-126. [PMID: 20303399 DOI: 10.1016/j.toxlet.2010.03.009]

A review of therapeutic approaches for post-infarction left ventricular remodeling

Left ventricular remodeling is an adaptive process initially developed in response to acute myocardial infarction (AMI), but it ends up with negative adverse outcomes such as infarcted wall thinning, ventricular dilation, and cardiac dysfunction. A prolonged excessive inflammatory reaction to cardiomyocytes death and necrosis plays the crucial role in the pathophysiological mechanisms. The pharmacological treatment includes nitroglycerine, β-blockers, ACEi/ARBs, SGLT2i, mineralocorticoid receptor antagonists, and some miscellaneous aspects. Stem cells therapy, CD34+ cells transplantation and gene therapy constitute the promissing therapeutic approaches for post AMI cardiac remodeling, thereby enhancing angiogenesis, cardiomyocytes differenciation and left ventricular function on top of inhibiting apoptosis, inflammation, and collagen deposition. All these lead to reduce infarct size, scar formation and myocardial fibrosis.

The beneficial effects of mesenchymal stem cells and their exosomes on myocardial infarction and critical considerations for enhancing their efficacy

Mesenchymal stem cells (MSCs) are multipotent stromal cells with regenerative, anti-inflammatory, and immunomodulatory properties. MSCs and their exosomes significantly improved structural and functional alterations after myocardial infarction (MI) in preclinical studies and clinical trials. By reprograming intracellular signaling pathways, MSCs attenuate inflammatory response, oxidative stress, apoptosis, pyroptosis, and endoplasmic reticulum (ER) stress and improve angiogenesis, mitochondrial biogenesis, and myocardial remodeling after MI. MSC-derived exosomes contain a mixture of non-coding RNAs, growth factors, anti-inflammatory mediators, and anti-fibrotic factors. Although primary results from clinical trials were promising, greater efficacies can be achieved by controlling several modifiable factors. The optimum timing of transplantation, route of administration, origin of MSCs, number of doses, and number of cells per dose need to be further investigated by future studies. Newly, highly effective MSC delivery systems have been developed to improve the efficacy of MSCs and their exosomes. Moreover, MSCs can be more efficacious after being pretreated with non-coding RNAs, growth factors, anti-inflammatory or inflammatory mediators, and hypoxia. Similarly, viral vector-mediated overexpression of particular genes can augment the protective effects of MSCs on MI. Therefore, future clinical trials must consider these advances in preclinical studies to properly reflect the efficacy of MSCs or their exosomes for MI.

Human umbilical cord mesenchymal stem cells combined with pirfenidone upregulates the expression of RGS2 in the pulmonary fibrosis in mice

Objective

The therapeutic effect of umbilical cord-derived mesenchymal stem cells (hUC-MSCs) in combination with pirfenidone (PFD) on pulmonary fibrosis in mice and its possible mechanism were investigated.

Methods

C57BL/6 mice were randomly divided into six groups: control group, model group, P₁₀ group, P₃₀ group, P₁₀₀ group, and P₃₀₀ group. Modeled by tracheal intubation with 3 mg/kg bleomycin drip, each dose of PFD was administered daily by gavage from day 7 onwards. The mice were observed continuously for 21 days and survival was recorded. Lung tissues were collected on day 21, and hematoxylin–eosin (HE) and Masson staining were performed to assess morphological changes and collagen deposition in the lungs. Collagen content was measured by the Sircol method, and fibrosis marker levels were detected by PCR and Western blot. Another batch of C57BL/6 mice was then randomly divided into five groups: hUC-MSC control group, model group, P₁₀₀ group, hUC-MSC treatment group, and hUC-MSCs + P₃₀ group. On day 7, 5 × 10⁵ hUC-MSCs were injected into the tail vein, the mice were administered PFD gavage daily from day 7 onwards, and their survival was recorded. Lung tissues were collected on day 21 to detect pathological changes, the collagen content, and the expression of regulator of G protein signaling 2 (RGS2). Pulmonary myofibroblasts (MFBs) were divided into an MFB group and an MFB + hUC-MSCs group; different doses of PFD were administered to each group, and the levels of RGS2, intracellular Ca²⁺, and fibrosis markers were recorded for each group.

Results

Compared with other PFD group doses, the P₁₀₀ group had significantly improved mouse survival and lung pathology and significantly reduced collagen and fibrosis marker levels (p < 0.05). The hUC-MSCs + P₃₀ group had significantly improved mouse survival and lung pathology, significantly reduced collagen content and fibrosis marker levels (p < 0.05), and the efficacy was better than that of the P₁₀₀ and hUC-MSCs groups (p < 0.05). RGS2 expression was significantly higher in the MSCs + P₃₀ group compared with the P₁₀₀ and hUC-MSCs groups (p < 0.05). PFD increased RGS2 expression in MFBs (p < 0.05) in a dose-dependent manner. Compared with PFD and hUC-MSCs treatment alone, combination of hUC-MSCs and PFD increased RGS2 protein levels, significantly decreased intracellular Ca²⁺ concentration, and significantly reduced fibrosis markers.

Conclusion

The findings suggest that hUC-MSCs combined with low-dose PFD have a therapeutic effect better than that of the two treatments used separately. Its effect on attenuating bleomycin-induced pulmonary fibrosis in mice is related to the increase of RGS2.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02192-6.

Beclin1 haploinsufficiency compromises mesenchymal stem cell-offered cardioprotection against myocardial infarction

Mesenchymal stem cells (MSCs)-based therapy has displayed some promises in ischemia heart diseases although its efficacy may be affected by changes in surrounding environments. This study evaluated the role of autophagy insufficiency using Beclin1 haploinsufficiency (BECN+/-) on intra-myocardial MSC transplantation-evoked effect against myocardial infarction. Donor MSCs from C57BL/6 mice were labelled with cell-tracker CM Dil and were delivered into LV free wall adjacent to infarct region in wild-type (WT) and BECN+/- recipient mice following ligation of left main coronary artery (MI-MSCs). Ten days following MI, myocardial function was assessed using echocardiography. Cardiomyocyte contractility and intracellular Ca2+ were monitored using cardiomyocytes from the area-at-risk adjacent to infarct. CM-Dil labeled cells were tracked in MSCs recipient mice using fluorescence microscopy. Lectin, Masson trichrome staining and Western blot analysis were employed to determine cardiomyocyte area, scar fibrosis, apoptosis and inflammation. MI insult triggered scar fibrosis, LV chamber dilation, decreased fractional shortening, ejection fraction, cardiomyocyte shortening, maximal velocity of shortening and relengthening as well as prolonged relengthening, which were abrogated or attenuated by MSCs therapy in WT but not BECN+/- mice. MI decreased intracellular Ca2+ rise and decay in response to electrical stimuli without affecting resting intracellular Ca2+, which were reconciled by MSCs in WT but not BECN+/- mice. MSCs further attenuated MI-induced mitochondrial ultrastructural injury, apoptosis, inflammation and autophagy defects in peri-infarct area in WT but not BECN+/- mice. Collectively, our results suggested that autophagy insufficiency dampened in MSCs-elicited cardioprotection associated with dampened apoptosis and inflammation.

Dual Stem Cell Therapy Improves the Myocardial Recovery Post-Infarction through Reciprocal Modulation of Cell Functions

Mesenchymal stromal cells (MSC) are promising candidates for regenerative therapy of the infarcted heart. However, poor cell retention within the transplantation site limits their potential. We hypothesized that MSC benefits could be enhanced through a dual-cell approach using jointly endothelial colony forming cells (ECFC) and MSC. To assess this, we comparatively evaluated the effects of the therapy with MSC and ECFC versus MSC-only in a mouse model of myocardial infarction. Heart function was assessed by echocardiography, and the molecular crosstalk between MSC and ECFC was evaluated in vitro through direct or indirect co-culture systems. We found that dual-cell therapy improved cardiac function in terms of ejection fraction and stroke volume. In vitro experiments showed that ECFC augmented MSC effector properties by increasing Connexin 43 and Integrin alpha-5 and the secretion of healing-associated molecules. Moreover, MSC prompted the organization of ECFC into vascular networks. This indicated a reciprocal modulation in the functionality of MSC and ECFC. In conclusion, the crosstalk between MSC and ECFC augments the therapeutic properties of MSC and enhances the angiogenic properties of ECFC. Our data consolidate the dual-cell therapy as a step forward for the development of effective treatments for patients affected by myocardial infarction.

Consistent Long-Term Therapeutic Efficacy of Human Umbilical Cord Matrix-Derived Mesenchymal Stromal Cells After Myocardial Infarction Despite Individual Differences and Transient Engraftment

Human mesenchymal stem cells gather special interest as a universal and feasible add-on therapy for myocardial infarction (MI). In particular, human umbilical cord matrix-derived mesenchymal stromal cells (UCM-MSC) are advantageous since can be easily obtained and display high expansion potential. Using isolation protocols compliant with cell therapy, we previously showed UCM-MSC preserved cardiac function and attenuated remodeling 2 weeks after MI. In this study, UCM-MSC from two umbilical cords, UC-A and UC-B, were transplanted in a murine MI model to investigate consistency and durability of the therapeutic benefits. Both cellular products improved cardiac function and limited adverse cardiac remodeling 12 weeks post-ischemic injury, supporting sustained and long-term beneficial therapeutic effect. Donor associated variability was found in the modulation of cardiac remodeling and activation of the Akt-mTOR-GSK3β survival pathway. In vitro, the two cell products displayed similar ability to induce the formation of vessel-like structures and comparable transcriptome in normoxia and hypoxia, apart from UCM-MSCs proliferation and expression differences in a small subset of genes associated with MHC Class I. These findings support that UCM-MSC are strong candidates to assist the treatment of MI whilst calling for the discussion on methodologies to characterize and select best performing UCM-MSC before clinical application.

Cardioprotective Role of Melatonin in Acute Myocardial Infarction

Melatonin is a pleiotropic, indole secreted, and synthesized by the human pineal gland. Melatonin has biological effects including anti-apoptosis, protecting mitochondria, anti-oxidation, anti-inflammation, and stimulating target cells to secrete cytokines. Its protective effect on cardiomyocytes in acute myocardial infarction (AMI) has caused widespread interest in the actions of this molecule. The effects of melatonin against oxidative stress, promoting autophagic repair of cells, regulating immune and inflammatory responses, enhancing mitochondrial function, and relieving endoplasmic reticulum stress, play crucial roles in protecting cardiomyocytes from infarction. Mitochondrial apoptosis and dysfunction are common occurrence in cardiomyocyte injury after myocardial infarction. This review focuses on the targets of melatonin in protecting cardiomyocytes in AMI, the main molecular signaling pathways that melatonin influences in its endogenous protective role in myocardial infarction, and the developmental prospect of melatonin in myocardial infarction treatment.

Anti-fibrotic mechanisms of exogenously-expanded mesenchymal stromal cells for fibrotic diseases

Most chronic diseases involving inflammation have a fibrotic component that involves remodeling and excess accumulation of extracellular matrix components. Left unchecked, fibrosis leads to organ failure and death. Mesenchymal stromal cells (MSCs) are emerging as a potent cell-based therapy for a wide spectrum of fibrotic conditions due to their immunomodulatory, anti-inflammatory and anti-fibrotic properties. This review provides an overview of known mechanisms by which MSCs mediate their anti-fibrotic actions and in relation to animal models of pulmonary, liver, renal and cardiac fibrosis. Recent MSC clinical trials results in liver, lung, skin, kidney and hearts are discussed and next steps for future MSC-based therapies including pre-activated or genetically-modified cells, or extracellular vesicles are also considered.

Notch signal pathway - therapeutic target for regulation of reparative processes in the heart

Notch signaling pathway is a universal regulator of cell fate in embryogenesis and in maintaining the cell homeostasis of adult tissue. Through local cell-cell interactions, he controls neighboring cells behavior and determines their capacity for self-renewal, growth, survival, differentiation, and apoptosis. Recent studies have shown that the control of regenerative processes in the heart is also carried out with the participation of Notch system. At the heart of Notch regulates migration bone marrow progenitors and stimulates the proliferation of cardiomyocytes, cardiac progenitor cell activity, limits cardiomyocyte hypertrophy and fibrosis progression and stimulates angiogenesis. Notch signaling pathway may be regarded as a very promising target for the development of drugs for the stimulation of regeneration in the myocardium.

Placenta-Derived Adherent Stromal Cells Improve Diabetes Mellitus-Associated Left Ventricular Diastolic Performance

Left ventricular (LV) diastolic dysfunction is among others attributed to cardiomyocyte stiffness. Mesenchymal stromal cells (MSC) have cardiac-protective properties. We explored whether intravenous (i.v.) application of PLacenta-eXpanded (PLX) MSC-like cells (PLX) improves LV diastolic relaxation in streptozotocin (STZ)-induced diabetic mice and investigated underlying mechanisms. Diabetes mellitus was induced by STZ application (50 mg/kg body weight) during five subsequent days. One week after the first STZ injection, PLX or saline were i.v. applied. Two weeks later, mice were hemodynamically characterized and sacrificed. At this early stage of diabetic cardiomyopathy with low-grade inflammation and no cardiac fibrosis, PLX reduced LV vascular cell adhesion molecule-1, transforming growth factor-β1, and interferon-γ mRNA expression, induced the percentage of circulating regulatory T cells, and decreased the splenic pro-fibrotic potential in STZ mice. STZ + PLX mice exhibited higher LV vascular endothelial growth factor mRNA expression and arteriole density versus STZ mice. In vitro, hyperglycemic PLX conditioned medium restored the hyperglycemia-impaired tube formation and adhesion capacity of human umbelical vein endothelial cells (HUVEC) via increasing nitric oxide (NO) bioavailability. PLX further induced the diabetes-downregulated activity of the NO downstream protein kinase G, as well as of protein kinase A, in STZ mice, which was associated with a raise in phosphorylation of the titin isoforms N2BA and N2B. Concomitantly, the passive force was lower in single isolated cardiomyocytes from STZ + PLX versus from STZ mice, which led to an improvement of LV diastolic relaxation. We conclude that i.v. PLX injection improves diabetes mellitus-associated diastolic performance via decreasing cardiomyocyte stiffness. Stem Cells Translational Medicine 2017;6:2135-2145.

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.

Multipotent bone marrow stromal cell therapy promotes endogenous cell proliferation following ischemic stroke

Despite extensive research over the years, there still exists some debate as to what constitutes the optimal therapeutic strategy to promote recovery following stroke. Due to the complexity of injured brain pathophysiology, treatment approaches should ideally address numerous factors, ultimately aiming to promote tissue protection, axonal regrowth and functional recovery. This study extends the understanding of the effects of bone marrow stromal cell (BMSC) treatment following experimentally induced ischemic stroke in rats. Focal ischemic brain injury was experimentally induced in rats by placing a preformed clot into the middle cerebral artery. Animals were injected intravenously with BMSCs at 24 h after stroke and were killed 7 days post injury. When administered BMSCs following stroke, the neurological outcome was significantly improved relative to controls. There was an increase in the number of BMSCs labelled with BrdU present in the injured hemisphere of the brain compared to the non-injured side. Furthermore, administration of BMSCs also led to increases in astrocytosis, vascularization and endogenous proliferation. These findings provide insight into the mechanisms of action of BMSC treatment and further argue for the therapeutic potential of BMSCs as an effective treatment following cerebral stroke.

Inhibition of Oct 3/4 mitigates the cardiac progenitor-derived myocardial repair in infarcted myocardium

Background

Recent evidence has demonstrated that cardiac progenitor cells play an essential role in the induction of angiomyogenesis in infarcted myocardium. We and others have shown that engraftment of c-kit⁺ cardiac stem cells (CSCs) into infarcted hearts led to myocardium regeneration and neovascularization, which was associated with an improvement of ventricular function. The purpose of this study is aimed at investigating the functional role of transcription factor (TF) Oct3/4 in facilitating CSCs to promote myocardium regeneration and preserve cardiac performance in the post-MI heart.

Methods

c-kit⁺ CSCs were isolated from adult hearts and re-introduced into the infarcted myocardium in which the mouse MI model was created by permanent ligation of the left anterior descending artery (LAD). The Oct3/4 of CSCs was inhibited by transfection of Oct3/4 siRNA, and transfection of CSCs with control siRNA serves as control groups. Myocardial functions were evaluated by echocardiographic measurement. Histological analysis was employed to assess newly formed cardiogenesis, neovascularization, and cell proliferations. Terminal deoxynucleotidyltransferase (TdT) nick-end labeling (TUNEL) was carried out to assess apoptotic cardiomyocytes. Real time polymerase chain reaction and Western blot were carried out to evaluate the level of Oct 3/4 in CSCs.

Results

Two weeks after engraftment, CSCs increased ventricular functional recovery as shown by a serial echocardiographic measurement, which is concomitant with the suppression of cardiac hypertrophy and attenuation of myocardial interstitial fibrosis. Suppression of Oct 3/4 of CSCs abrogated functional improvements and mitigated the hypertrophic response and cardiac remodeling. Transplantation of c-kit⁺ CSCs into MI hearts promoted cardiac regeneration and neovascularization, which were abolished with the knockdown of Oct3/4. Additionally, suppression of Oct3/4 abrogated myocyte proliferation in the CSC-engrafted myocardium.

Conclusion

Our results indicate that CSCs-derived cardiac regeneration improves the restoration of cardiac function and is mediated through Oct 3/4.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0252-5) contains supplementary material, which is available to authorized users.

Therapeutic angiogenesis promotes efficacy of human umbilical cord matrix stem cell transplantation in cardiac repair

OBJECTIVES

Although previous studies have confirmed the beneficial effects of human umbilical cord matrix stem cell (hUCM) transplantation post myocardial infarction (MI), but this stem cell resource has no potential to induce angiogenesis. In order to achieve the process of angiogenesis and cardiomyocyte regeneration, two required factors for cardiac repair agents were examined namely; hUCM and VEGF on an infarcted heart. The main objective of this research is to investigate the combinatory effect of dhUCM and VEGF transplantation on an infarcted heart.

MATERIALS AND METHODS

45 min of ligating the left anterior descending coronary artery, the MI-induced animals received 50 μl PBS, 5 μg VEGF, 5×10(6) hUCM cells alone, combined with 5 μg VEGF and 5×10(6) differentiated hUCM cells alone or combined with 5 μg VEGF through intramyocardial injection. MI group, without hUCM and VEGF served as the control group. Left ventricular function and angiogenesis were also evaluated.

RESULTS

After eight weeks post MI, there were significant rise in left ventricular ejection farction in dhUCM+VEGF group compared to the other treated and non-treated groups (P<0.05). Fibrosis tissue was markedly lower in the dhUCM+VEGF and hUCM+VEGF groups compared to the other treated and non-treated groups (P<0.05). Despite these benefits, vascular density in dhUCM+VEGF group was not markedly different compared to VEGF and hUCM+VEGF groups. The transplanted hUCM and dhUCM cells survived and migrated to the infarcted area.

CONCLUSION

Our findings demonstrated that the dhUCM cells transplantation combined with VEGF were more efficient on an infarcted heart.

Stem cell therapy for cardiovascular disease: the demise of alchemy and rise of pharmacology

Regenerative medicine holds great promise as a way of addressing the limitations of current treatments of ischaemic disease. In preclinical models, transplantation of different types of stem cells or progenitor cells results in improved recovery from ischaemia. Furthermore, experimental studies indicate that cell therapy influences a spectrum of processes, including neovascularization and cardiomyogenesis as well as inflammation, apoptosis and interstitial fibrosis. Thus, distinct strategies might be required for specific regenerative needs. Nonetheless, clinical studies have so far investigated a relatively small number of options, focusing mainly on the use of bone marrow-derived cells. Rapid clinical translation resulted in a number of small clinical trials that do not have sufficient power to address the therapeutic potential of the new approach. Moreover, full exploitation has been hindered so far by the absence of a solid theoretical framework and inadequate development plans. This article reviews the current knowledge on cell therapy and proposes a model theory for interpretation of experimental and clinical outcomes from a pharmacological perspective. Eventually, with an increased association between cell therapy and traditional pharmacotherapy, we will soon need to adopt a unified theory for understanding how the two practices additively interact for a patient's benefit.

Stem cell mechanisms during left ventricular remodeling post-myocardial infarction: Repair and regeneration

Post-myocardial infarction (MI), the left ventricle (LV) undergoes a series of events collectively referred to as remodeling. As a result, damaged myocardium is replaced with fibrotic tissue consequently leading to contractile dysfunction and ultimately heart failure. LV remodeling post-MI includes inflammatory, fibrotic, and neovascularization responses that involve regulated cell recruitment and function. Stem cells (SCs) have been transplanted post-MI for treatment of LV remodeling and shown to improve LV function by reduction in scar tissue formation in humans and animal models of MI. The promising results obtained from the application of SCs post-MI have sparked a massive effort to identify the optimal SC for regeneration of cardiomyocytes and the paradigm for clinical applications. Although SC transplantations are generally associated with new tissue formation, SCs also secrete cytokines, chemokines and growth factors that robustly regulate cell behavior in a paracrine fashion during the remodeling process. In this review, the different types of SCs used for cardiomyogenesis, markers of differentiation, paracrine factor secretion, and strategies for cell recruitment and delivery are addressed.

Comparison of cardiac stem cells and mesenchymal stem cells transplantation on the cardiac electrophysiology in rats with myocardial infarction

INTRODUCTION

Whether transplanted cardiac stem cells (CSCs) and mesenchymal stem cells (MSCs) improved ventricular fibrillation threshold (VFT) similarly is still unclear. We sought to compare the effects of the CSC and MSC transplantation on the electrophysiological characteristics and VFT in rats with myocardial infarction (MI).

METHODS

MI was induced in 30 male Sprague-Dawley rats. Two weeks later, animals were randomized to receive 5 × 10(6) CSCs labeled with PKH26 in PBS or 5 × 10(6) MSCs labeled with PKH26 in phosphate buffer solution(PBS) or PBS alone injection into the infarcted anterior ventricular free wall. Six weeks after the injection, electrophysiological characteristics and VFT were measured. Labeled CSCs and MSCs were observed in 5 μm cryostat sections from each heart.

RESULTS

Malignant ventricular arrhythmias were significantly (P = 0.0055) less inducible in the CSC group than the MSC group. The VFTs were improved in the CSC group compared with the MSC group. Labeled CSCs and MSCs were identified in the infarct zone and infarct marginal zone. Labeled CSCs expressed Connexin-43, von Willebrand factor, α-smooth muscle actin and α-sarcomeric actin,while the Labeled MSCs expressed von Willebrand factor, α-smooth muscle actin and α-sarcomeric actin in vivo.

CONCLUSIONS

After 6 weeks of cell transplantation, CSCs are superior to MSCs in modulating the electrophysiological abnormality and improving the VFT in rats with MI. CSCs and MSCs express markers that suggest muscle, endothelium and vascular smooth muscle phenotypes in vivo, but MSCs rarely express Connexin-43.

Outcome improvement of cellular cardiomyoplasty using triple therapy: mesenchymal stem cell+erythropoietin+vascular endothelial growth factor

To improve cellular cardiomyoplasty efficacy after myocardial infarction (MI), we postulated that combining mesenchymal stem cells (MSCs) transplantation with anti-apoptotic and angiogenic effects of erythropoietin (EPO) and vascular endothelial growth factor (VEGF) may provide better prognosis in an infarcted heart 48 rats, underwent left anterior descending artery ligation, were divided into eight groups and treated as follows: Group 1: MSC+EPO+VEGF, Group 2: MSC+EPO, Group 3: MSC+VEGF, Group 4: MSC, Group 5: EPO+VEGF, Group 6: EPO, Group 7: VEGF and Group 8: Control. After MI induction, EPO and VEGF were injected subcutaneously at the dose of 3000 U/kg and 3 µg/kg respectively. MSCs were transplanted one week after MI. In the fourteenth and sixteenth days after infarction, EPO was injected again. Echocardiography demonstrated that all treatments improved left ventricular function significantly (before vs. after treatment) but in control group ejection fraction deteriorated over the 2-months period. Percent of ejection fraction recovery in all treatment groups were significantly greater than control (P<0.05). Compared with the control group, all treatments attenuated cell death in peri-infarct areas significantly, except groups 6 and 7. Vascular density of all treatment groups were more than control group but this superiority was statistically significant only in group 1 (P<0.01). All of our treatments had beneficial effects to some extent but MSC transplantation combined with EPO and VEGF administration resulted in superior therapeutic outcome in enhancing cell survival and neovascularization.

The effect of bone marrow- and adipose tissue-derived mesenchymal stem cell transplantation on myocardial remodelling in the rat model of ischaemic heart failure

This study aimed to investigate the effect of bone marrow- and adipose tissue-derived mesenchymal stem cell (BM-MSC and AD-MSC respectively) transplantation on left ventricular function and infarct area (IA) in the rat model of ischaemic heart failure. In anaesthetized Wistar rats, the left coronary artery (LCA) was occluded for 40 min with subsequent reperfusion for 7 days. Seven days following surgery, the animals with LCA occlusion/reperfusion were randomized into three groups: (i) Controls received intramyocardial injection of vehicle at three different locations within the peri-infarct zone, (ii) BM-MSC: cells were injected in the same way as in previous group (10(6) ), (iii) AD-MSC: using the same protocol as used in the BM-MSC group. In addition there was also a sham-treated group that had no injection. Two weeks following MSC transplantation, the hearts were isolated and perfused according to the Langendorff method followed by 30-min global ischaemia and 90-min reperfusion. After this IA was determined histologically. During Langendorff perfusion initial and postischaemic LV functions were the same in all groups although LV pressure at the 10th minute of reperfusion was higher in the AD-MSC group compared to controls. However, LV pressure during 30-min global ischaemia was significantly higher in BM-MSC as compared to controls and AD-MSC. The sham treated animals showed the same results as those seen with BM-MSC. Thus, BM-MSC transplantation, in contrast to transplantation of AD-MSC, resulted in better preservation of the LV ability to contract during ischaemia. Furthermore, IA was significantly smaller in BM-MSC group as compared to the controls and the AD-MSC groups. Thus this study has demonstrated that treatment with BM-MSC both ameliorates LV function and reduces histological scar size.

Oxidative activation of Ca(2+)/calmodulin-activated kinase II mediates ER stress-induced cardiac dysfunction and apoptosis

Endoplasmic reticulum (ER) stress elicits oxidative stress and intracellular Ca(2+) derangement via activation of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). This study was designed to examine the role of CaMKII in ER stress-induced cardiac dysfunction and apoptosis as well as the effect of antioxidant catalase. Wild-type FVB and transgenic mice with cardiac-specific overexpression of catalase were challenged with the ER stress inducer tunicamycin (3 mg/kg ip for 48 h). Presence of ER stress was verified using the ER stress protein markers immunoglobulin binding protein (BiP) and C/EBP homologous protein (CHOP), the effect of which was unaffected by catalase overexpression. Echocardiographic assessment revealed that tunicamycin elicited cardiac remodeling (enlarged end-systolic diameter without affecting diastolic and ventricular wall thickness), depressed fractional shortening, ejection fraction, and cardiomyocyte contractile capacity, intracellular Ca(2+) mishandling, accumulation of reactive oxygen species (superoxide production and NADPH oxidase p47phox level), CaMKII oxidation, and apoptosis (evidenced by Bax, Bcl-2/Bax ratio, and TUNEL staining), the effects of which were obliterated by catalase. Interestingly, tunicamycin-induced cardiomyocyte mechanical anomalies and cell death were ablated by the CaMKII inhibitor KN93, in a manner reminiscent of catalase. These data favored a permissive role of oxidative stress and CaMKII activation in ER stress-induced cardiac dysfunction and cell death. Our data further revealed the therapeutic potential of antioxidant or CaMKII inhibition in cardiac pathological conditions associated with ER stress. This research shows for the first time that contractile dysfunction caused by ER stress is a result of the oxidative activation of the CaMKII pathway.

Carvedilol enhances mesenchymal stem cell therapy for myocardial infarction via inhibition of caspase-3 expression

Adult stem cells have shown great promise toward repairing infarcted heart and restoring cardiac function. Mesenchymal stem cells (MSCs), because of their inherent multipotent nature and their ability to secrete a multitude of growth factors and cytokines, have been used for cardiac repair with encouraging results. Preclinical studies showed that MSCs injected into infarcted hearts improve cardiac function and attenuate fibrosis. Although stem cell transplantation is a promising therapeutic option to repair the infarcted heart, it is faced with a number of challenges, including the survival of the transplanted cells in the ischemic region, due to excessive oxidative stress present in the ischemic region. The objective of this study was to determine the effect of Carvedilol (Carv), a nonselective β-blocker with antioxidant properties, on the survival and engraftment of MSCs in the infarcted heart. MSCs were subjected to a simulated host-tissue environment, similar to the one present in the infarcted myocardium, by culturing them in the presence of hydrogen peroxide (H(2)O(2)) to induce oxidative stress. MSCs were treated with 2.5 μM Carv for 1 h in serum-free medium, followed by treatment with H(2)O(2) for 2 h. The treated cells exhibited significant protection against H(2)O(2)-induced cell death versus untreated controls as determined by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assays. Likewise, transplantation of MSCs after permanent left coronary artery ligation and treatment of animals after myocardial infarction (MI) with Carv (5 mg/kg b.wt.) led to significant improvement in cardiac function, decreased fibrosis, and caspase-3 expression compared with the MI or MSC-alone groups.

Mesenchymal stem cells: characteristics, sources, and mechanisms of action

This article provides an overview of mesenchymal stem cell (MSC) biology. In the first section, the characteristics that are routinely used to define MSCs-adherence, proliferation, multi-lineage potential, and "cluster of differentiation" marker profiles-are discussed. In the second section, the major tissues and body fluids that are used as sources for equine MSCs are presented, along with the comparative biologic activities of MSCs from specific locations. Finally, the current understanding of the mechanisms by which MSCs influence repair and regeneration are discussed, with an emphasis on the clinical importance of MSC trophic activities.

Repair mechanisms of bone marrow mesenchymal stem cells in myocardial infarction

The prognosis of patients with myocardial infarction (MI) and resultant chronic heart failure remains extremely poor despite advances in optimal medical therapy and interventional procedures. Animal experiments and clinical trials using adult stem cell therapy following MI have shown a global improvement of myocardial function. Bone marrow-derived mesenchymal stem cells (MSCs) hold promise for cardiac repair following MI, due to their multilineage, self-renewal and proliferation potential. In addition, MSCs can be easily isolated, expanded in culture, and have immunoprivileged properties to the host tissue. Experimental studies and clinical trials have revealed that MSCs not only differentiate into cardiomyocytes and vascular cells, but also secrete amounts of growth factors and cytokines which may mediate endogenous regeneration via activation of resident cardiac stem cells and other stem cells, as well as induce neovascularization, anti-inflammation, anti-apoptosis, anti-remodelling and cardiac contractility in a paracrine manner. It has also been postulated that the anti-arrhythmic and cardiac nerve sprouting potential of MSCs may contribute to their beneficial effects in cardiac repair. Most molecular and cellular mechanisms involved in the MSC-based therapy after MI are still unclear at present. This article reviews the potential repair mechanisms of MSCs in the setting of MI.

Mesenchymal stem cells for cardiovascular regeneration

Despite recent studies suggesting that the heart has instrinsic mechanisms of self-regeneration following myocardial infarction, it cannot regenerate itself to an optimal level. Mesenchymal stem cells (MSCs) are currently being investigated for regeneration of mesenchyme-derived tissues, such as bone, cartilage and tendon. In vitro evidence suggests that MSCs can also differentiate into cardiomyogenic and vasculogenic lineages, offering another cell source for cardiovascular regeneration. In vivo, MSCs may contribute to the re-growth and protection of vasculature and cardiomyocytes, mediated by paracrine actions, and/or persist within the myocardium in a differentiated state; although proof of cardiomyocytic phenotype and functional integration remains elusive. Herein, we review the evidence of MSCs as a cell source for cardiovascular regeneration, as well as their limitations that may prevent them from being effectively used in the clinic.

Dual-modal tracking of transplanted mesenchymal stem cells after myocardial infarction

PURPOSE

Results for implantation efficiency and effective improvement of cardiac function in the field of mesenchymal stem cells (MSCs) are controversial. To attempt to clarify this debate, we utilized magnetic resonance imaging (MRI) and near-infrared optical imaging (OI) to explore the effects of different delivery modes of mesenchymal stem cells on cell retention time and cardiac function after myocardial infarction (MI).

METHODS

Rat MSCs were labeled with superparamagnetic iron oxide nanoparticles and 1, 1'-dioctadecyl-3,3,3',3'-tetramethylindodicarbocyanine, 4-chlorobenzenesulfonate salt (DiD) for noninvasive cell tracking in a rat MI model. Rats underwent coronary artery ligation and were randomized into three experimental groups: intravenous (IV), intramyocardial (IM), and a control group. The first two groups referred to the route of delivery of the transplanted dual-labeled MSCs; whereas the control group was given an IV injection of serum-free medium one day post-MI. Cellular engraftment was determined 1 day and 7 days post cell delivery by measuring the iron and optical signals in explanted organs. Prussian blue staining and fluorescent microscopy were performed on histological sections for iron and DiD, respectively. Cardiac function was measured by echocardiography on day 7.

RESULTS

The cardiac function of the IM group increased significantly compared to the IV and control groups at day 7. In the IM group, labeled cells were visualized in the infracted heart by serial MRI, and the intensity by OI was significantly higher on day 1. In the IV group, the heart signals were significantly attenuated by dual-modal tracking at two time points, but the lung signals in OI were significantly stronger than the IM group at both time points.

CONCLUSION

IM injection of MSCs increased cell engraftment within infarcted hearts and improved cardiac function after MI. However, IV infusion has a low efficacy due to the cell trapping in the lung. Therefore, direct injection may provide an advantage over IV, with regard to retention of stem cells and protection of cardiac function.

Growth factor regulation of proliferation and survival of multipotential stromal cells

Multipotential stromal cells (MSCs) have been touted to provide an alternative to conservative procedures of therapy, be it heart transplants, bone reconstruction, kidney grafts, or skin, neuronal and cartilage repair. A wide gap exists, however, between the number of MSCs that can be obtained from the donor site and the number of MSCs needed for implantation to regenerate tissue. Standard methods of MSC expansion being followed in laboratories are not fully suitable due to time and age-related constraints for autologous therapies, and transplant issues leave questions for allogenic therapies. Beyond these issues of sufficient numbers, there also exists a problem of MSC survival at the graft. Experiments in small animals have shown that MSCs do not persist well in the graft environment. Either there is no incorporation into the host tissue, or, if there is incorporation, most of the cells are lost within a month. The use of growth and other trophic factors may be helpful in counteracting these twin issues of MSC expansion and death. Growth factors are known to influence cell proliferation, motility, survival and morphogenesis. In the case of MSCs, it would be beneficial that the growth factor does not induce differentiation at an early stage since the number of early-differentiating progenitors would be very low. The present review looks at the effect of and downstream signaling of various growth factors on proliferation and survival in MSCs.

Mesenchymal stem cells as therapeutics and vehicles for gene and drug delivery

Mesenchymal stem cells (MSCs) possess a set of several fairly unique properties which make them ideally suited both for cellular therapies/regenerative medicine, and as vehicles for gene and drug delivery. These include: 1) relative ease of isolation; 2) the ability to differentiate into a wide variety of seemingly functional cell types of both mesenchymal and non-mesenchymal origin; 3) the ability to be extensively expanded in culture without a loss of differentiative capacity; 4) they are not only hypoimmunogenic, but they produce immunosuppression upon transplantation; 5) their pronounced anti-inflammatory properties; and 6) their ability to home to damaged tissues, tumors, and metastases following in vivo administration. In this review, we summarize the latest research in the use of mesenchymal stem cells in regenerative medicine, as immunomodulatory/anti-inflammatory agents, and as vehicles for transferring both therapeutic genes in genetic disease and genes designed to destroy malignant cells.