Hepatocyte growth factor or vascular endothelial growth factor gene transfer maximizes mesenchymal stem cell-based myocardial salvage after acute myocardial infarction

Identification of gene variants associated with hypoxia pathway in acute coronary syndrome: a pilot study

Hypoxic condition is known to play an important role in the development of acute coronary syndrome (ACS) and understanding mechanism of hypoxic effects is essential to develop new treatment strategies for ACS. Based on the phenotypic features of cardiovascular diseases, it is claimed that genetic factors play an important role in the development genome-wide association studies have been studied to clarify the molecular mechanisms underlying heritable and prevalent phenotype. The claim was to investigate possible roles of gene polymorphisms involving in hypoxia pathway on ACS in this pilot study. DNA samples of 100 ACS cases and 100 controls from a Department of Cardiology, Istanbul University, were genotyped with Illumina CytoSNP-12 BeadChip 300 K Array. The additive model used for statistical analysis, and Correlation/Trend Test selected as a statistical process. It was determined different criteria for association analysis as case/control and number of plugged vessels. P value calculated with each SNP and score generated with -log10(P). Also, hypoxia pathway analysis was applied to find statistically significant genes. As a result of bioinformatic analysis, it was claimed that PIAS4 (rs735842) and VEGFA (rs699947) were the most statistically significant variants associated in hypoxia pathway analysis. Due to the information of literature, there have been no prior studies of possible interactions of hypoxia pathways the etiology of acute coroner syndromes in the same research. Detailed studies with larger sample groups are necessary to clarify the role of hypoxia in the development of disease.

Mesenchymal stem cells overexpressing integrin-linked kinase attenuate left ventricular remodeling and improve cardiac function after myocardial infarction

In the present study, we investigated whether mesenchymal stem cells (MSCs) overexpressing integrin-linked kinase (ILK) might regulate ventricular remodeling and cardiac function in a porcine myocardial infarction model. ILK-modified MSCs (ILK-MSCs) (n = 8), MSCs (n = 8) or placebo (n = 8) were injected into peri-infarct myocardium 7 days after ligation of the left anterior descending coronary artery. ILK expression was confirmed by immunofluorescence, real-time PCR, Western blot analysis, and flow cytometry. In vitro assays indicated increased proliferation and reduced apoptosis of MSCs due to overexpression of ILK. Echocardiographic, single-photon emission computed tomography and positron emission tomography analyses demonstrated preserved cardiac function and myocardial perfusion. Reduced fibrosis, increased cardiomyocyte proliferation, and enhanced angiogenesis were observed in the ILK-MSC group. Reduced apoptosis, as demonstrated by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling analysis, was also noted. In conclusion, ILK promotes MSC proliferation and suppresses apoptosis. ILK-MSC transplantation improves ventricular remodeling and cardiac function in pigs after MI. It is associated with increased angiogenesis, reduced apoptosis, and increased cardiomyocyte proliferation. This may represent a new approach to the treatment of post-infarct remodeling and subsequent heart failure.

Targeted delivery of vascular endothelial growth factor improves stem cell therapy in a rat myocardial infarction model

Rebuilding of infarcted myocardium by mesenchymal stem cells (MSCs) has not been successful because of poor cell survival due in part to insufficient blood supply after myocardial infarction (MI). We hypothesize that targeted delivery of vascular endothelial growth factor (VEGF) to MI can help regenerate vasculature in support of MSC therapy in a rat model of MI. VEGF-encapsulated immunoliposomes targeting overexpressed P-selectin in MI tissue were infused by tail vein immediately after MI. One week later, MSCs were injected intramyocardially. The cardiac function loss was moderated slightly by targeted delivery of VEGF or MSC treatment. Targeted VEGF+MSC combination treatment showed highest attenuation in cardiac function loss. The combination treatment also increased blood vessel density (80%) and decreased collagen content in post-MI tissue (33%). Engraftment of MSCs in the combination treatment group was significantly increased and the engrafted cells contributed to the restoration of blood vessels.

FROM THE CLINICAL EDITOR

VEGF immunoliposomes targeting myocardial infarction tissue resulted in significantly higher attenuation of cardiac function loss when used in combination with mesenchymal stem cells. MSCs were previously found to have poor ability to restore cardiac tissue, likely as a result of poor blood supply in the affected areas. This new method counterbalances that weakness by the known effects of VEGF, as demonstrated in a rat model.

Protein synthesis and secretion in human mesenchymal cells derived from bone marrow, adipose tissue and Wharton's jelly

Introduction

Different mesenchymal stromal cells (MSC) have been successfully isolated and expanded in vitro and nowadays they are tested in clinical trials for a wide variety of diseases. Whether all MSC express the same cell surface markers or have a similar secretion profile is still controversial, making it difficult to decide which stromal cell may be better for a particular application.

Methods

We isolated human mesenchymal stromal cells from bone marrow (BM), adipose tissue (AT) and Wharton’s jelly (WJ) and cultured them in fetal bovine serum supplemented media. We evaluated proliferation, in vitro differentiation (osteogenic, adipogenic and chondrogenic potential), expression of cell surface markers and protein secretion using Luminex and ELISA assays.

Results

Cell proliferation was higher for WJ-MSC, followed by AT-MSC. Differences in surface expression markers were observed only for CD54 and CD146. WJ-MSC secreted higher concentrations of chemokines, pro-inflammatory proteins and growth factors. AT-MSC showed a better pro-angiogenic profile and secreted higher amounts of extracellular matrix components and metalloproteinases.

Conclusions

Mesenchymal stromal cells purified from different tissues have different angiogenic, inflammatory and matrix remodeling potential properties. These abilities should be further characterized in order to choose the best protocols for their therapeutic use.

Relationship between vascular endothelial growth factor and left ventricular dimension in patients with acute myocardial infarction

BACKGROUND

Although vascular endothelial growth factor (VEGF) is elevated in patients with acute myocardial infarction (AMI), the clinical significance of its elevation remains unclear. The present study was designed to determine the relationship between VEGF and left ventricular dimension in patients with AMI.

METHODS AND RESULTS

Plasma VEGF levels were examined by enzyme-linked immunosorbent assay daily for one week and then weekly for four weeks in 38 patients with AMI (65.4 ± 1.7 years). Left ventriculography was performed at 14 days, 6 months, and 2 years after the onset of AMI. Plasma VEGF levels were significantly elevated and reached a peak on day 6. Peak plasma VEGF levels positively correlated with both end-diastolic and end-systolic volume indices at 14 days after the onset of AMI. When patients with AMI were divided into two groups according to plasma VEGF levels on admission, left ventricular volume indices were higher in the high VEGF group than in the low VEGF group at the subacute phase of AMI (14 days). These differences were no longer present in the chronic phase of AMI.

CONCLUSION

Plasma VEGF levels were increased in patients with AMI, and peak levels were associated with left ventricular volume indices in the subacute phase, suggesting an important role of endogenous VEGF in the left ventricular dimension in patients with AMI.

Multimodality molecular imaging to monitor transplanted stem cells for the treatment of ischemic heart disease

PURPOSE

Non-invasive techniques to monitor the survival and migration of transplanted stem cells in real-time is crucial for the success of stem cell therapy. The aim of this study was to explore multimodality molecular imaging to monitor transplanted stem cells with a triple-fused reporter gene [TGF; herpes simplex virus type 1 thymidine kinase (HSV1-tk), enhanced green fluorescence protein (eGFP), and firefly luciferase (FLuc)] in acute myocardial infarction rat models.

METHODS

Rat myocardial infarction was established by ligating the left anterior descending coronary artery. A recombinant adenovirus carrying TGF (Ad5-TGF) was constructed. After transfection with Ad5-TGF, 5 × 10(6) bone marrow mesenchymal stem cells (BMSCs) were transplanted into the anterior wall of the left ventricle (n = 14). Untransfected BMSCs were as controls (n = 8). MicroPET/CT, fluorescence and bioluminescence imaging were performed. Continuous images were obtained at day 2, 3 and 7 after transplantation with all three imaging modalities and additional images were performed with bioluminescence imaging until day 15 after transplantation.

RESULTS

High signals in the heart area were observed using microPET/CT, fluorescence and bioluminescence imaging of infarcted rats injected with Ad5-TGF-transfected BMSCs, whereas no signals were observed in controls. Semi-quantitative analysis showed the gradual decrease of signals in all three imaging modalities with time. Immunohistochemistry assays confirmed the location of the TGF protein expression was the same as the site of stem cell-specific marker expression, suggesting that TGF tracked the stem cells in situ.

CONCLUSIONS

We demonstrated that TGF could be used as a reporter gene to monitor stem cells in a myocardial infarction model by multimodality molecular imaging.

Mesenchymal stem/stromal cells as a pharmacological and therapeutic approach to accelerate angiogenesis

Mesenchymal stem cells or multipotent stromal cells (MSCs) have initially captured attention in the scientific world because of their differentiation potential into osteoblasts, chondroblasts and adipocytes and possible transdifferentiation into neurons, glial cells and endothelial cells. This broad plasticity was originally hypothesized as the key mechanism of their demonstrated efficacy in numerous animal models of disease as well as in clinical settings. However, there is accumulating evidence suggesting that the beneficial effects of MSCs are predominantly caused by the multitude of bioactive molecules secreted by these remarkable cells. Numerous angiogenic factors, growth factors and cytokines have been discovered in the MSC secretome, all have been demonstrated to alter endothelial cell behavior in vitro and induce angiogenesis in vivo. As a consequence, MSCs have been widely explored as a promising treatment strategy in disorders caused by insufficient angiogenesis such as chronic wounds, stroke and myocardial infarction. In this review, we will summarize into detail the angiogenic factors found in the MSC secretome and their therapeutic mode of action in pathologies caused by limited blood vessel formation. Also the application of MSC as a vehicle to deliver drugs and/or genes in (anti-)angiogenesis will be discussed. Furthermore, the literature describing MSC transdifferentiation into endothelial cells will be evaluated critically.

Extracellular matrix remodeling following myocardial infarction influences the therapeutic potential of mesenchymal stem cells

INTRODUCTION

Although stem cell therapy is a promising treatment for myocardial infarction, the minimal functional improvements observed clinically limit its widespread application. A need exists to maximize the therapeutic potential of these stem cells by first understanding what factors within the infarct microenvironment affect their ability to regenerate the necrotic tissue. In this study, we assessed both differentiation capacity and paracrine signaling as a function of extracellular matrix remodeling after myocardial infarction.

METHODS

Mechanical and compositional changes to the decellularized infarcted myocardium were characterized to understand how the extracellular environment, specifically, was altered as a function of time after coronary artery ligation in Sprague-Dawley rats. These alterations were first modeled in a polyacrylamide gel system to understand how the variables of composition and stiffness drive mesenchymal stem cell differentiation towards a cardiac lineage. Finally, the paracrine secretome was characterized as a function of matrix remodeling through gene and protein expression and conditioned media studies.

RESULTS

The decellularized infarct tissue revealed significant alterations in both the mechanical and compositional properties of the ECM with remodeling following infarction. This altered microenvironment dynamically regulates the potential for early cardiac differentiation. Whereas Nkx2.5 expression is limited in the presence of chronic remodeled matrix of increased stiffness, GATA4 expression is enhanced. In addition, the remodeled matrix promotes the expression of several proangiogenic, prosurvival, antifibrotic, and immunomodulatory growth factors. In particular, an increase in HGF and SDF1 expression and secretion by mesenchymal stem cells can rescue oxidatively stressed cardiomyocytes in vitro.

CONCLUSIONS

This study demonstrated that decellularization of diseased tissue allows for the exclusive analysis of the remodeled matrix and its ability to influence significantly the cellular phenotype. Characterization of cell fate as a function of myocardial remodeling following infarction is critical in developing the ideal strategy for cell implantation to maximize tissue regeneration and to ultimately reduce the prevalence and severity of heart failure.

Disparate effects of single endothelin-A and -B receptor blocker therapy on the progression of renal injury in advanced renovascular disease

We hypothesized that chronic specific endothelin (ET)-A receptor blockade therapy would reverse renal dysfunction and injury in advanced experimental renovascular disease. To test this, unilateral renovascular disease was induced in 19 pigs and after 6 weeks, single-kidney hemodynamics and function was quantified in vivo using computed-tomography. All pigs with renovascular disease were divided such that 7 were untreated, 7 were treated with ET-A blockers, and 5 were treated with ET-B blockers. Four weeks later, all pigs were re-studied in vivo, then euthanized and ex vivo studies performed on the stenotic kidney to quantify microvascular density, remodeling, renal oxidative stress, inflammation, and fibrosis. RBF, GFR, and redox status were significantly improved in the stenotic kidney after ET-A but not ET-B blockade. Furthermore, only ET-A blockade therapy reversed renal microvascular rarefaction and diminished remodeling, which was accompanied by a marked decreased in renal inflammatory and fibrogenic activity. Thus, ET-A but not ET-B blockade ameliorated renal injury in pigs with advanced renovascular disease by stimulating microvascular proliferation and decreasing the progression of microvascular remodeling, renal inflammation and fibrosis in the stenotic kidney. These effects were functionally consequential since ET-A blockade improved single kidney microvascular endothelial function, RBF, and GFR, and decreased albuminuria.

Renal vascular structure and rarefaction

An intact microcirculation is vital for diffusion of oxygen and nutrients and for removal of toxins of every organ and system in the human body. The functional and/or anatomical loss of microvessels is known as rarefaction, which can compromise the normal organ function and have been suggested as a possible starting point of several diseases. The purpose of this overview is to discuss the potential underlying mechanisms leading to renal microvascular rarefaction, and the potential consequences on renal function and on the progression of renal damage. Although the kidney is a special organ that receives much more blood than its metabolic needs, experimental and clinical evidence indicates that renal microvascular rarefaction is associated to prevalent cardiovascular diseases such as diabetes, hypertension, and atherosclerosis, either as cause or consequence. On the other hand, emerging experimental evidence using progenitor cells or angiogenic cytokines supports the feasibility of therapeutic interventions capable of modifying the progressive nature of microvascular rarefaction in the kidney. This overview will also attempt to discuss the potential renoprotective mechanisms of the therapeutic targeting of the renal microcirculation.

Quantification of Mesenchymal Stem Cell (MSC) delivery to a target site using in vivo confocal microscopy

The ability to deliver cells to appropriate target tissues is a prerequisite for successful cell-based therapy. To optimize cell therapy it is therefore necessary to develop a robust method of in vivo cell delivery quantification. Here we examine Mesenchymal Stem Cells (MSCs) labeled with a series of 4 membrane dyes from which we select the optimal dye combination for pair-wise comparisons of delivery to inflamed tissue in the mouse ear using confocal fluorescence imaging. The use of an optimized dye pair for simultaneous tracking of two cell populations in the same animal enables quantification of a test population that is referenced to an internal control population, thereby eliminating intra-subject variations and variations in injected cell numbers. Consistent results were obtained even when the administered cell number varied by more than an order of magnitude, demonstrating an ability to neutralize one of the largest sources of in vivo experimental error and to greatly reduce the number of cells required to evaluate cell delivery. With this method, we are able to show a small but significant increase in the delivery of cytokine pre-treated MSCs (TNF-α & IFN-γ) compared to control MSCs. Our results suggest future directions for screening cell strategies using our in vivo cell delivery assay, which may be useful to develop methods to maximize cell therapeutic potential.

Investigation of growth conditions for the expansion of porcine mesenchymal stem cells on microcarriers in stirred cultures

The extensive use of mesenchymal stem cells (MCS) in tissue engineering and cell therapy increases the necessity to improve their expansion. Among these, porcine MCS are valuable models for tissue engineering and are classically expanded in static T-flasks. In this work, different processes of stirred cultures were evaluated and compared. First, the effect of glucose, glutamine, antioxidant, and growth factors concentrations on porcine MSC expansion were analyzed in a suitable medium by performing kinetic studies. Results showed that a lower glucose concentration (5.5 mM) enabled to increase maximal cell concentration by 40 % compared with a higher one (25 mM), while addition of 2 to 6 mM of glutamine increased maximal cell concentration by more than 25 % compared with no glutamine supplementation. Moreover, supplementation with 1 μM thioctic acid increased maximal cell concentration by 40 % compared with no supplementation. Using this adapted medium, microcarriers cultures were performed and compared with T-flasks expansion. Porcine MSC were shown to be able to proliferate on the five types of microcarriers tested. Moreover, cultures on Cytodex 1, Cytopore 2, and Cultispher G exhibited a MSC growth rate more than 40 % higher compared with expansion in T-flasks, while MSC metabolism was similar.

Transplantation of bone marrow‑derived endothelial progenitor cells overexpressing Delta‑like‑4 enhances functional neovascularization in ischemic myocardium

Delta‑like‑4 (Dll‑4) prevents excess angiogenic sprouting and promotes the formation of a well‑differentiated vascular network. Therefore, transplantation of Dll‑4‑overexpressing endothelial progenitor cells (EPCs) was hypothesized to be superior to transplantation of EPCs in the treatment of ischemic heart disease. In the current study, EPCs harvested from C57BL/6 mouse bone marrow were infected in vitro with Dll‑4 (EPCDll‑4+) or Dll‑4 knockdown (EPCDll‑4‑) with recombinant lentiviral vectors and the control cells were non‑transfected or transduced with mock vectors (EPCnull). Eight‑week‑old C57BL/6 mice underwent ligation of the left anterior descending artery to establish a myocardial infarction (MI) model. The ligated animals were randomly divided into 5 groups, which, following one week, were intravenously injected with EPCs, EPCnull, EPCDll‑4+, EPCDll‑4‑ or medium. Two weeks later, echocardiographic assessment, western blotting, fluorescent microsphere and histological studies were performed. The results demonstrated that the number of mature vessels and blood flow in ischemic myocardium were increased in the EPCDll‑4+ group, but were markedly decreased in the EPCDll‑4‑ group compared with the control groups. The expression levels of Dll‑4, hairy/enhancer of split (Hes)‑related protein 1 (Hey‑1), phosphorylation of mammalian target of rapamycin (mTOR) and p70S6 kinase (p70S6K) were significantly increased in the EPCDll‑4+ group, while they were markedly decreased in the EPCDll‑4‑ group. Furthermore, for EPCDll‑4+‑treated animals, an enhanced cardiac function was observed as assessed by echocardiography. Thus, the transplantation of Dll‑4‑overexpressing EPCs stimulates neovascularization effectively, increases the blood flow to the ischemic zone and improves cardiac function. These effects may be due to the activation of Notch/Hey‑1/mTOR/p70S6K signaling pathways, which are initiated by Dll‑4.

Hypoxia preconditioned bone marrow mesenchymal stem cells promote liver regeneration in a rat massive hepatectomy model

Introduction

Bone marrow mesenchymal stem cells (BMMSCs) have been reported to facilitate liver regeneration after toxic injuries. However, the effect of BMMSCs on liver regeneration after massive hepatectomy is barely studied. Here we explored whether infusion of BMMSCs promotes liver regeneration in a rat massive hepatectomy model.

Methods

Hypoxia preconditioning was achieved by culturing BMMSCs under a hypoxia environment. Then 85% hepatectomy was performed and hypoxia or normoxia preconditioned BMMSCs were infused into the portal vein. A group of rats received vascular endothelial growth factor (VEGF) neutralizing antibody perioperatively, and underwent 85% hepatectomy and a subsequent infusion of hypoxia preconditioned BMMSCs to verify the role of VEGF in the effects of BMMSCs on liver regeneration. Liver samples were collected and liver regeneration was evaluated postoperatively.

Results

Hypoxia preconditioning enhanced the expression of VEGF in BMMSCs in vitro. Infusion of BMMSCs promoted proliferation of hepatocytes, reflected by elevated cyclin D₁ expression and proliferating cell nuclear antigen-positive hepatocytes. However, BMMSC infusion did not improve the serum albumin level, liver weight/body weight ratio, and survival after operation. Infusion of hypoxia preconditioned BMMSCs significantly elevated cyclin D₁, proliferating cell nuclear antigen-positive hepatocytes, liver weight/body weight ratio, and survival compared with normoxia preconditioned BMMSCs, accompanied by an increased serum albumin level. The level of VEGF in liver homogenate was much higher in hypoxia preconditioned BMMSC-treated animals than in other groups. In addition, the perioperative injection of VEGF neutralizing antibody significantly blocked the therapeutic effects of hypoxia preconditioned BMMSCs on liver injury and regeneration in this model.

Conclusion

Hypoxia preconditioned BMMSCs enhanced liver regeneration after massive hepatectomy in rats, possibly by upregulating the level of VEGF.

Bone-derived mesenchymal stromal cells from HIV transgenic mice exhibit altered proliferation, differentiation capacity and paracrine functions along with impaired therapeutic potential in kidney injury

Mesenchymal stem cells (MSCs) secrete paracrine factors that could be cytoprotective and serve roles in immunoregulation during tissue injury. Although MSCs express HIV receptors, and co-receptors, and are susceptible to HIV infection, whether HIV-1 may affect biological properties of MSCs needs more study. We evaluated cellular proliferation, differentiation and paracrine functions of MSCs isolated from compact bones of healthy control mice and Tg26 HIV-1 transgenic mice. The ability of MSCs to protect against cisplatin toxicity was studied in cultured renal tubular cells as well as in intact mice. We successfully isolated MSCs from healthy mice and Tg26 HIV-1 transgenic mice and found the latter expressed viral Nef, Vpu, NL4-3 and Vif genes. The proliferation and differentiation of Tg26 HIV-1 MSCs was inferior to MSCs from healthy mice. Moreover, transplantation of Tg26 HIV-1 MSCs less effectively improved outcomes compared with healthy MSCs in mice with acute kidney injury. Also, Tg26 HIV-1 MSCs secreted multiple cytokines, but at significantly lower levels than healthy MSCs, which resulted in failure of conditioned medium from these MSCs to protect cultured renal tubular cells from cisplatin toxicity. Therefore, HIV-1 had adverse biological effects on MSCs extending to their proliferation, differentiation, function, and therapeutic potential. These findings will help in advancing mechanistical insight in renal injury and repair in the setting of HIV-1 infection.

Overexpression of MicroRNA-1 improves the efficacy of mesenchymal stem cell transplantation after myocardial infarction

BACKGROUND

The aim of this research was to study whether transplantation of mesenchymal stem cells (MSCs) overexpressing microRNA-1 into mouse infarcted myocardium can enhance cardiac myocyte differentiation and improve cardiac function efficiently.

METHODS

Eight-week-old female C57BL/6 mice underwent ligation of the left coronary artery to produce models of myocardial infarction. The ligated animals were randomly divided into 4 groups (20 in each). One week later, they were intramyocardially injected at the heart infarcted zone with microRNA-1-transduced MSCs (MSC(miR-1) group), mock-vector-transduced MSCs (MSC(null) group), MSCs (MSC group) or medium (PBS group). At 4 weeks post-transplantation, transthoracic echocardiographic assessment, histological evaluation and Western blot were performed.

RESULTS

The transplanted MSCs were able to differentiate into cardiomyocytes in the infarcted zone. Cardiac function in the MSC, MSC(null) and MSC(miR-1) groups was significantly improved compared to the PBS group (p < 0.01 or p < 0.001). However, treatment of MSCs expressing microRNA-1 was more effective for cardiac repair and improved cardiac function more efficiently by enhancing cell survival and cardiac myocyte differentiation compared to the MSC group or the MSC(null) groups (p < 0.05 or p < 0.01, respectively).

CONCLUSIONS

Transplantation of microRNA-1-transfected MSCs was more conducive to repair of infarct injury and improved heart function by enhancing transplanted cells survival and cardiomyogenic differentiation.

Molecular imaging: the key to advancing cardiac stem cell therapy

Cardiac stem cell therapy continues to hold promise for the treatment of ischemic heart disease despite the fact that early promising pre-clinical findings have yet to be translated into consistent clinical success. The latest human studies have collectively identified a pressing need to better understand stem cell behavior in humans and called for more incorporation of noninvasive imaging techniques into the design and evaluation of human stem cell therapy trials. This review discusses the various molecular imaging techniques validated to date for studying stem cells in living subjects, with a particular emphasis on their utilities in assessing the acute retention and the long-term survival of transplanted stem cells. These imaging techniques will be essential for advancing cardiac stem cell therapy by providing the means to both guide ongoing optimization and predict treatment response in humans.

Targeting androgen receptor in bone marrow mesenchymal stem cells leads to better transplantation therapy efficacy in liver cirrhosis

Transplantation of bone marrow mesenchymal stem cells (BM-MSCs) has been considered as an alternative therapy, replacing liver transplantation in clinical trials, to treat liver cirrhosis, an irreversible disease that may eventually lead to liver cancer development. However, low survival rate of the BM-MSCs leading to unsatisfactory efficacy remains a major concern. Gender differences have been suggested in BM-MSCs therapeutic application, but the effect of the androgen receptor (AR), a key factor in male sexual phenotype, in this application is not clear. Using two liver cirrhosis mouse models induced by CCl4 or thioacetamide, we showed that targeting AR in the BM-MSCs improved their self-renewal and migration potentials and increased paracrine effects to exert anti-inflammatory and anti-fibrotic actions to enhance liver repair. Mechanism dissection studies suggested that knocking out AR in BM-MSCs led to improved self-renewal and migration by alteration of the signaling of epidermal growth factor receptor and matrix metalloproteinase 9 and resulted in suppression of infiltrating macrophages and hepatic stellate cell activation through modulation of interleukin (IL)1R/IL1Ra signaling. Therapeutic approaches using either AR/small interfering RNA or the AR degradation enhancer, ASC-J9, to target AR in BM-MSCs all led to increased efficacy for liver repair.

CONCLUSION

Targeting AR, a key factor in male sexual phenotype, in BM-MSCs improves transplantation therapeutic efficacy for treating liver fibrosis.

Transplantation of bone marrow-derived MSCs improves cisplatinum-induced renal injury through paracrine mechanisms

Mesenchymal stem cells (MSCs) have been reported to preserve renal function in various models of acute kidney injury (AKI). Different routes were used to transplant MSCs but the role of cell transplantation routes in directing outcomes has been unknown. In the present study, we evaluated organ bio-distributions of transplanted MSCs, and correlated survival of transplanted cells with outcomes in mice with cisplatinum-induced AKI. We found that after intravenous administration, MSCs were largely localized in pulmonary capillaries and only a minute fraction of MSCs entered kidneys and the cells survived only transiently. Therefore, we also transplanted MSCs via intraperitoneal and renal subcapsular routes. Transplanted MSCs survived longer in peritoneal cavity and renal subcapsular space. Interestingly, when MSC transplantation was followed by cisplatinum-induced AKI, renal morphology and renal functions were better preserved, irrespective of the cell transplantation route. As transplanted MSCs did not migrate to kidneys from either peritoneal cavity or renal subcapsular space, this finding suggested that migration of cells was not required for the beneficial response. The possibility of indirect mechanisms was confirmed when administration of the conditioned medium from MSCs also protected renal tubular cells from cisplatinum-induced cytotoxicity. We identified presence of over forty regulatory cytokines in the conditioned medium obtained from MSCs. Since paracrine factors released by transplanted cells accounted for improvements, it appears that the route of cell transplantation is not critical for realizing benefits of cell therapy with MSCs in AKI. Studies of specific cytokines secreted by MSCs will help to obtain new therapeutic mechanisms for renal protection.

The relative contribution of paracine effect versus direct differentiation on adipose-derived stem cell transplantation mediated cardiac repair

BACKGROUND

Recent studies have demonstrated that transplantation of adipose-derived stem cell (ADSC) can improve cardiac function in animal models of myocardial infarction (MI). However, the mechanisms underlying the beneficial effect are not fully understood. In this study, we characterized the paracrine effect of transplanted ADSC and investigated its relative importance versus direct differentiation in ADSC transplantation mediated cardiac repair.

METHODOLOGY/PRINCIPAL FINDINGS

MI was experimentally induced in mice by ligation of the left anterior descending coronary artery. Either human ADSC, conditioned medium (CM) collected from the same amount of ADSC or control medium was injected into the peri-infarct region immediately after MI. Compared with the control group, both ADSC and ADSC-CM significantly reduced myocardial infarct size and improved cardiac function. The therapeutic efficacy of ADSC was moderately superior to ADSC-CM. ADSC-CM significantly reduced cardiomyocyte apoptosis in the infarct border zone, to a similar degree with ADSC treatment. ADSC enhanced angiogenesis in the infarct border zone, but to a stronger degree than that seen in the ADSC-CM treatment. ADSC was able to differentiate to endothelial cell and smooth muscle cell in post-MI heart; these ADSC-derived vascular cells amount to about 9% of the enhanced angiogenesis. No cardiomyocyte differentiated from ADSC was found.

CONCLUSIONS

ADSC-CM is sufficient to improve cardiac function of infarcted hearts. The therapeutic function of ADSC transplantation is mainly induced by paracrine-mediated cardioprotection and angiogenesis, while ADSC differentiation contributes a minor benefit by being involved in angiogenesis. Highlights 1 ADSC-CM is sufficient to exert a therapeutic potential. 2. ADSC was able to differentiate to vascular cells but not cardiomyocyte. 3. ADSC derived vascular cells amount to about 9% of the enhanced angiogenesis. 4. Paracrine effect is the major mechanism of ADSC therapeutic function for MI.

Hypoxic conditioning enhances the angiogenic paracrine activity of human adipose-derived stem cells

Human adipose-derived stem cells (ASCs) secrete cytokines and growth factors that can be harnessed in a paracrine fashion for promotion of angiogenesis, cell survival, and activation of endogenous stem cells. We recently showed that hypoxia is a powerful stimulus for an angiogenic activity from ASCs in vitro and here we investigate the biological significance of this paracrine activity in an in vivo angiogenesis model. A single in vitro exposure of ASCs to severe hypoxia (<0.1% O2) significantly increased both the transcriptional and translational level of the vascular endothelial growth factor-A (VEGF-A) and angiogenin (ANG). The angiogenicity of the ASC-conditioned medium (ASC(CM)) was assessed by implanting ASC(CM)-treated polyvinyl alcohol sponges subcutaneously for 2 weeks in mice. The morphometric analysis of anti-CD31-immunolabeled sponge sections demonstrated an increased angiogenesis with hypoxic ASC(CM) treatment compared to normoxic control ASC(CM) treatment (percentage vascular volume; 6.0%±0.5% in the hypoxic ASC(CM) vs. 4.1%±0.7% in the normoxic ASC(CM), P<0.05). Reduction of VEGF-A and ANG levels in the ASC(CM) with respective neutralizing antibodies before sponge implantation showed a significantly diminished angiogenic response (3.5%±0.5% in anti-VEGF-A treated, 3.2%±0.7% in anti-ANG treated, and 3.5%±0.6% in anti-VEGF-A/ANG treated). Further, both the normoxic and hypoxic ASC(CM) were able to sustain in vivo lymphangiogenesis in sponges. Collectively, the model demonstrated that the increased paracrine production of the VEGF-A and ANG in hypoxic-conditioned ASCs in vitro translated to an in vivo effect with a favorable biological significance. These results further illustrate the potential for utilization of an in vitro optimized ASC(CM) for in vivo angiogenesis-related applications as an effective cell-free technology.

Timing of umbilical cord blood derived mesenchymal stem cells transplantation determines therapeutic efficacy in the neonatal hyperoxic lung injury

Intratracheal transplantation of human umbilical cord blood (UCB)-derived mesenchymal stem cells (MSCs) attenuates the hyperoxia-induced neonatal lung injury. The aim of this study was to optimize the timing of MSCs transplantation. Newborn Sprague-Dawley rats were randomly exposed to hyperoxia (90% for 2 weeks and 60% for 1 week) or normoxia after birth for 21 days. Human UCB-derived MSCs (5×10(5) cells) were delivered intratracheally early at postnatal day (P) 3 (HT3), late at P10 (HT10) or combined early+late at P3+10 (HT3+10). Hyperoxia-induced increase in mortality, TUNEL positive cells, ED1 positive alveolar macrophages, myeloperoxidase activity and collagen levels, retarded growth and reduced alveolarization as evidenced by increased mean linear intercept and mean alveolar volume were significantly better attenuated in both HT3 and HT3+10 than in HT10. Hyperoxia-induced up-regulation of both cytosolic and membrane p47(phox) indicative of oxidative stress, and increased inflammatory markers such as tumor necrosis factor-α, interleukin (IL) -1α, IL-1β, IL-6, and transforming growth factor-β measured by ELISA, and tissue inhibitor of metalloproteinase-1, CXCL7, RANTES, L-selectin and soluble intercellular adhesion molecule-1 measured by protein array were consistently more attenuated in both HT3 and HT3+10 than in HT10. Hyperoxia-induced decrease in hepatocyte growth factor and vascular endothelial growth factor was significantly up-regulated in both HT3 and HT3+10, but not in HT10. In summary, intratracheal transplantation of human UCB derived MSCs time-dependently attenuated hyperoxia-induced lung injury in neonatal rats, showing significant protection only in the early but not in the late phase of inflammation. There were no synergies with combined early+late MSCs transplantation.

Mesenchymal stem cell-derived exosomes increase ATP levels, decrease oxidative stress and activate PI3K/Akt pathway to enhance myocardial viability and prevent adverse remodeling after myocardial ischemia/reperfusion injury

We have previously identified exosomes as the paracrine factor secreted by mesenchymal stem cells. Recently, we found that the key features of reperfusion injury, namely loss of ATP/NADH, increased oxidative stress and cell death were underpinned by proteomic deficiencies in ischemic/reperfused myocardium, and could be ameliorated by proteins in exosomes. To test this hypothesis in vivo, mice (C57Bl6/J) underwent 30 min ischemia, followed by reperfusion (I/R injury). Purified exosomes or saline was administered 5 min before reperfusion. Exosomes reduced infarct size by 45% compared to saline treatment. Langendorff experiments revealed that intact but not lysed exosomes enhanced viability of the ischemic/reperfused myocardium. Exosome treated animals exhibited significant preservation of left ventricular geometry and contractile performance during 28 days follow-up. Within an hour after reperfusion, exosome treatment increased levels of ATP and NADH, decreased oxidative stress, increased phosphorylated-Akt and phosphorylated-GSK-3β, and reduced phosphorylated-c-JNK in ischemic/reperfused hearts. Subsequently, both local and systemic inflammation were significantly reduced 24h after reperfusion. In conclusion, our study shows that intact exosomes restore bioenergetics, reduce oxidative stress and activate pro-survival signaling, thereby enhancing cardiac function and geometry after myocardial I/R injury. Hence, mesenchymal stem cell-derived exosomes are a potential adjuvant to reperfusion therapy for myocardial infarction.

Pharmacologically active microcarriers influence VEGF-A effects on mesenchymal stem cell survival

Resistance of transplanted mesenchymal stem cells (MSCs) in post-ischemic heart is limited by their poor vitality. Vascular-endothelial-growth-factor-A (VEGF-A) as such or slowly released by fibronectin-coated pharmacologically-active-microcarriers (FN-PAM-VEGF) could differently affect survival kinases and anti-apoptotic mediator (e.g. Bcl-2). Therefore VEGF-A or FN-PAM-VEGF could differently enhance cell proliferation, and/or resistance to hypoxia/reoxygenation (H/R) of MSCs. To test these hypotheses MSCs were incubated for 6-days with VEGF-A alone or with FN-PAM-VEGF. In addition, MSCs pre-treated for 24-hrs with VEGF-A or FN-PAM-VEGF were subsequently exposed to H/R (72-hrs 3% O₂ and 3-hrs of reoxygenation). Cell-proliferation and post-hypoxic vitality were determined. Kinases were studied at 30-min., 1- and 3-days of treatment. Cell-proliferation increased about twofold (P < 0.01) 6-days after VEGF-A treatment, but by a lesser extent (55% increase) with FN-PAM-VEGF (P < 0.05). While MSC pre-treatment with VEGF-A confirmed cell-proliferation, pre-treatment with FN-PAM-VEGF protected MSCs against H/R. In the early phase of treatments, VEGF-A increased phospho-Akt, phospho-ERK-1/2 and phospho-PKCε compared to the untreated cells or FN-PAM-VEGF. Afterword, kinase phosphorylations were higher with VGEF, except for ERK-1/2, which was similarly increased by both treatments at 3 days. Only FN-PAM-VEGF significantly increased Bcl-2 levels. After H/R, lactate dehydrogenase release and cleaved Caspase-3 levels were mainly reduced by FN-PAM-VEGF. While VEGF-A enhances MSC proliferation in normoxia, FN-PAM-VEGF mainly hampers post-hypoxic MSC death. These different effects underscore the necessity of approaches suited to the various conditions. The use of FN-PAM-VEGF could be considered as a novel approach for enhancing MSC survival and regeneration in hostile environment of post-ischemic tissues.

Allogeneic Adipose-Derived Stem Cells with Low Immunogenicity Constructing Tissue-Engineered Bone for Repairing Bone Defects in Pigs

The ideal cells for tissue engineering should have the following characteristics: easy obtainment, safety, immune privilege, the capability of self-renewal, and multipotency. Adipose-derived stem cells (ADSCs) are a promising candidate. However, the immunogenicity of allogeneic mesenchymal stem cells limits their long-term benefits. In this study, we introduced human cytomegalovirus US2/US3 gene into the ADSCs to decrease the expression of MHC I protein of ADSCs and reduce the activation of T-cells of the recipient animals. Moreover, the biosafety and biological characteristics of ADSCs transfected with the US2/US3 genes (ADSCs-US2/US3) were similar to normal ADSCs. Then we took ADSCs-US2/US3 to construct a tissue-engineered bone for repairing bone defects in pigs and found that there were no great differences in repair effects or healing time between the allogeneic ADSCs-US2/US3 group and the autologous ADSC group. These results suggest that allogeneic ADSCs-US2/US3 have the advantages of biological safety, low immunogenicity, and effective osteogenesis. Such barely immunogenic ADSCs will be crucial for the success of future tissue-regenerative approaches.

Hepatocyte growth factor mediates mesenchymal stem cell–induced recovery in multiple sclerosis models

Mesenchymal stem cells have emerged as a potential therapy for a range of neural insults. In animal models of multiple sclerosis, an autoimmune disease that targets oligodendrocytes and myelin, treatment with human MSCs results in functional improvement that reflects both modulation of the immune response and myelin repair. Here we demonstrate that conditioned medium (CM) from human MSCs reduces functional deficits in mouse MOG_35–55-induced EAE and promotes the development of oligodendrocytes and neurons. Functional assays identify a critical role for Hepatocyte Growth Factor (HGF) and its primary receptor cMet in MSCs stimulated recovery in EAE, neural cell development and remyelination. Active MSC-CM contains HGF and exogenously supplied HGF promotes recovery in EAE while cMet and anti-HGF antibodies block the functional recovery mediated by HGF and MSC-CM. Systemic treatment with HGF dramatically accelerated remyelination in lysolecithin-induced rat dorsal spinal cord lesions and in slice cultures. Together these data strongly implicate HGF in mediating MSC-stimulated functional recovery in animal models of multiple sclerosis.

MSCs transfected with hepatocyte growth factor or vascular endothelial growth factor improve cardiac function in the infarcted porcine heart by increasing angiogenesis and reducing fibrosis

BACKGROUND

Cell transplantation and gene therapy have been demonstrated to have beneficial effects after a myocardial infarction (MI). Here, we used a large animal model of MI to investigate the beneficial effects of mesenchymal stem cells (MSCs) transfected with hepatocyte growth factor (HGF) or vascular endothelial growth factor (VEGF) genes.

METHODS

A porcine MI model was created by balloon occlusion of the distal left anterior descending artery for 90 min followed by reperfusion. At 1 week after MI, the pigs were infused via the coronary vein with saline (n=8), MSCs + AdNull(n=8), MSC+VEGF(n=10), or MSC+HGF(n=10). Cardiac function and myocardial perfusion were evaluated by using echocardiography and gated cardiac perfusion imaging before and 4 weeks after transplantation. Morphometric and histological analyses were performed.

RESULTS

All cell-implanted groups had better cardiac function than the saline control group. There were further functional improvements in the MSC+HGF group, accompanied by smaller infarct sizes, increased cell survival, and less collagen deposition. Blood vessel densities in the damaged area and cardiac perfusion were significantly greater in the MSC+AdNull group than in the saline control group, and further increased in the MSC+VEGF/HGF groups. Tissue fibrosis was significantly less extensive in the MSC and MSC+VEGF groups than in the saline control group and was most reduced in the MSC+HGF group.

CONCLUSION

MSCs (alone or transfected with VEGF/HGF) delivered into the infarcted porcine heart via the coronary vein improved cardiac function and perfusion, probably by increasing angiogenesis and reducing fibrosis. MSC+HGF was superior to MSC+VEGF, possibly owing to its enhanced antifibrotic effect.

Effects of hepatocyte growth factor overexpressed bone marrow-derived mesenchymal stem cells on prevention from left ventricular remodelling and functional improvement in infarcted rat hearts

Bone marrow-derived mesenchymal stem cells (BM-MSCs ) transplantation has been reported to be a promising therapy for myocardial infarction (MI). However, low survival rate of BM-MSCs in infarcted heart is one of the major limitations for the perspective clinical application. In this study, we aimed to investigate the effect of hepatocyte growth factor (HGF) on left ventricular function improvement of HGF gene-modified BM-MSCs (HGF-MSCs) after its delivery into the infarcted rat hearts. BM-MSCs were isolated with fibroblast-like morphology and expressed CD44+CD29+CD90+/CD34-CD45-CD31-CD11a. After 5-azacytidine induction in vitro, 20%-30% of the cells were positively stained for desmin, cardiac-specific cardiac troponin I and connexin-43. Histological staining revealed that 2 weeks after MI is an optimal time point with decreased neutrophil infiltration and increased vascular number. Minimal infarct size and best haemodynamic analysis were also observed after cell injection at 2 weeks compared with that of 1 h, 1 week or 4 weeks. Echocardiogram confirmed that transplantation with HGF-MSCs significantly improved left ventricular function compared with other groups in rat MI models. MSCs and HGF-MSCslabelled with DAPI were detected 4 weeks after MI in the infarcted area. Decreased infarcted scar area and increased angiogenesis formation could be found in HGF-MSCs group than in other groups as demonstrated by hematoxylin and eosin (H&E) staining and factor VIII staining. These results indicate that HGF-MSCs transplantation could enhance the contractile function and attenuate left ventricular remodelling efficiently in rats with MI.

Combining adult stem cells and polymeric devices for tissue engineering in infarcted myocardium

An increasing number of studies in cardiac cell therapy have provided encouraging results for cardiac repair. Adult stem cells may overcome ethical and availability concerns, with the additional advantages, in some cases, to allow autologous grafts to be performed. However, the major problems of cell survival, cell fate determination and engraftment after transplantation, still remain. Tissue-engineering strategies combining scaffolds and cells have been developed and have to be adapted for each type of application to enhance stem cell function. Scaffold properties required for cardiac cell therapy are here discussed. New tissue engineering advances that may be implemented in combination with adult stem cells for myocardial infarction therapy are also presented. Biomaterials not only provide a 3D support for the cells but may also mimic the structural architecture of the heart. Using hydrogels or particulate systems, the biophysical and biochemical microenvironments of transplanted cells can also be controlled. Advances in biomaterial engineering have permitted the development of sophisticated drug-releasing materials with a biomimetic 3D support that allow a better control of the microenvironment of transplanted cells.

Transplantation of microencapsulated Schwann cells and mesenchymal stem cells augment angiogenesis and improve heart function

Because of their plasticity and availability, bone-marrow-derived mesenchymal stem cells (MSC) are a potential cell source for treating ischemic heart disease. Schwann cells (SC) play a critical role in neural remodeling and angiogenesis because of their secretion of cytokines such as vascular endothelial growth factor (VEGF). Cell microencapsulation, surrounding cells with a semipermeable polymeric membrane, is a promising tool to shelter cells from the recipient's immune system. We investigated whether transplantation of microencapsulated SC (MC-SC) and MSC together could improve heart function by augmenting angiogenesis in acute myocardial infarction (AMI). Sprague-Dawley rats with ligation of the left anterior descending artery to induce AMI were randomly divided for cell transplantation into four groups-MC-SC+MSC, MC+MSC, MSC, MC-SC, and controls. Echocardiography was performed at 3 days and 2 and 4 weeks after AMI. Rat hearts were harvested on day 28 after transplantation and examined by immunohistochemistry and western blot analysis. Echocardiography revealed differences among the groups in fractional shortening and end-systolic and end-diastolic dimensions (P < 0.05). The number of BrdU-positive cells was greater with MC-SC+MSC transplantation than the other groups (P < 0.01). The vessel density and VEGF level in the infarcted zone was significantly increased with MC-SC+MSC transplantation (P < 0.05). These results show that transplanting a combination of MC-SC and MSC could augment angiogenesis and improve heart function in AMI.

Impact of low levels of vascular endothelial growth factor after myocardial infarction on 6-month clinical outcome. Results from the Nagoya Acute Myocardial Infarction Study

BACKGROUND

Vascular endothelial growth factor (VEGF) is induced by myocardial ischemia and is thought to facilitate cardiovascular repair after acute myocardial infarction (AMI). However, the association between the plasma VEGF levels and clinical outcome in AMI patients is unclear.

METHODS AND RESULTS

We evaluated 879 AMI patients undergoing successful primary revascularization within 24h of symptom onset. The patients were classified into 3 groups according to tertiles of plasma VEGF levels at 7 days after the onset of AMI. Major adverse cardiovascular and cerebrovascular events (MACCE), defined as cardiac death, recurrent acute coronary syndrome, hospital readmission for heart failure, or stroke, were assessed during the 6-month follow-up period. The incidence of MACCE was the least frequent in the middle tertile. Compared to the middle tertile, patients in the low tertile were at a significantly higher risk for MACCE even after adjusting for baseline characteristics (hazard ratio [HR] 2.67, 95% confidence interval [CI] 1.18-6.06, P=0.019). An absence of statin treatment before onset and a younger age (HR 0.54, 0.87; 95%CI 0.33-0.90, 0.76-0.99; P=0.017, 0.037; respectively) were significantly associated with low VEGF.

CONCLUSIONS

Low plasma VEGF levels at 7 days after the onset of AMI were associated with a significantly increased risk for MACCE during 6 months of follow-up.

Excitation-contraction coupling in ventricular myocytes is enhanced by paracrine signaling from mesenchymal stem cells

In clinical trials mesenchymal stem cells (MSCs) are transplanted into cardiac ischemic regions to decrease infarct size and improve contractility. However, the mechanism and time course of MSC-mediated cardioprotection are incompletely understood. We tested the hypothesis that paracrine signaling by MSCs promotes changes in cardiac excitation-contraction (EC) coupling that protects myocytes from cell death and enhances contractility. Isolated mouse ventricular myocytes (VMs) were treated with control tyrode, MSC conditioned-tyrode (ConT) or co-cultured with MSCs. The Ca handling properties of VMs were monitored by laser scanning confocal microscopy and whole cell voltage clamp. ConT superfusion of VMs resulted in a time dependent increase of the Ca transient amplitude (ConT(15min): ΔF/F(0)=3.52±0.38, n=14; Ctrl(15min): ΔF/F(0)=2.41±0.35, n=14) and acceleration of the Ca transient decay (τ: ConT: 269±18ms n=14; vs. Ctrl: 315±57ms, n=14). Voltage clamp recordings confirmed a ConT induced increase in I(Ca,L) (ConT: -5.9±0.5 pA/pF n=11; vs. Ctrl: -4.04±0.3 pA/pF, n=12). The change of τ resulted from increased SERCA activity. Changes in the Ca transient amplitude and τ were prevented by the PI3K inhibitors Wortmannin (100nmol/L) and LY294002 (10μmol/L) and the Akt inhibitor V (20μmol/L) indicating regulation through PI3K signal transduction and Akt activation which was confirmed by western blotting. A change in τ was also prevented in eNOS(-/-) myocytes or by inhibition of eNOS suggesting an NO mediated regulation of SERCA activity. Since paracrine signaling further resulted in increased survival of VMs we propose that the Akt induced change in Ca signaling is also a mechanism by which MSCs mediate an anti-apoptotic effect.

Non-invasive bioluminescence imaging of myoblast-mediated hypoxia-inducible factor-1 alpha gene transfer

PURPOSE

We tested a novel imaging strategy, in which both the survival of transplanted myoblasts and their therapeutic transgene expression, a recombinant hypoxia-inducible factor-1α (HIF-1α-VP2), can be monitored using firefly luciferase (fluc) and Renilla luciferase (hrl) bioluminescence reporter genes, respectively.

PROCEDURES

The plasmid pUbi-hrl-pUbi-HIF-1α-VP2, which expresses both hrl and HIF-1α-VP2 using two ubiquitin promoters, was characterized in vitro. C2c12 myoblasts stably expressing fluc and transiently transfected with pUbi-hrl-pUbi-HIF-1α-VP2 were injected into the mouse hindlimb. Both hrl and fluc expression were monitored using bioluminescence imaging (BLI).

RESULTS

Strong correlations existed between the expression of hRL and each of HIF-1α-VP2, VEGF, and PlGF (r(2) > 0.83, r(2) > 0.82, and r(2) > 0.97, respectively). In vivo, both transplanted cells and HIF-1α-VP2 transgene expression were successfully imaged using BLI.

CONCLUSIONS

An objective evaluation of myoblast-mediated gene transfer in living mice can be performed by monitoring both the survival and the transgene expression of transplanted myoblasts using the techniques developed herein.

A long road for stem cells to cure sick hearts: update on recent clinical trials

The contribution of stem cells to cure damaged hearts has finally been unraveled. A large number of preclinical and clinical studies have showed beneficial outcomes after myocardial infarction. In this review, the current understanding of stem cell therapy in preclinical and clinical experiences is summarized. Stem cells from bone marrow have shown a potential to improve cardiac performance after myocardial infarction in animal and early clinical studies. Clinical trials from all over the world have provided safety assessments of stem cell therapy with marginal improvement of clinical outcomes. Thus, further investigations should be encouraged to resolve the discrepancies between studies, clinical issues, and unclear translational findings. This review provides information and commentary on key trials for stem cell-based treat-ment of cardiovascular disease.

Empowering adult stem cells for myocardial regeneration

Treatment strategies for heart failure remain a high priority for ongoing research due to the profound unmet need in clinical disease coupled with lack of significant translational progress. The underlying issue is the same whether the cause is acute damage, chronic stress from disease, or aging: progressive loss of functional cardiomyocytes and diminished hemodynamic output. To stave off cardiomyocyte losses, a number of strategic approaches have been embraced in recent years involving both molecular and cellular approaches to augment myocardial structure and performance. Resultant excitement surrounding regenerative medicine in the heart has been tempered by realizations that reparative processes in the heart are insufficient to restore damaged myocardium to normal functional capacity and that cellular cardiomyoplasty is hampered by poor survival, proliferation, engraftment, and differentiation of the donated population. To overcome these limitations, a combination of molecular and cellular approaches must be adopted involving use of genetic engineering to enhance resistance to cell death and increase regenerative capacity. This review highlights biological properties of approached to potentiate stem cell-mediated regeneration to promote enhanced myocardial regeneration, persistence of donated cells, and long-lasting tissue repair. Optimizing cell delivery and harnessing the power of survival signaling cascades for ex vivo genetic modification of stem cells before reintroduction into the patient will be critical to enhance the efficacy of cellular cardiomyoplasty. Once this goal is achieved, then cell-based therapy has great promise for treatment of heart failure to combat the loss of cardiac structure and function associated with acute damage, chronic disease, or aging.

Meta-analysis of randomized controlled trials for the incidence and risk of treatment-related mortality in patients with cancer treated with vascular endothelial growth factor tyrosine kinase inhibitors

PURPOSE

Vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitors (TKIs) have become the cornerstone in the treatment of several malignancies. These drugs have also been associated with an increase in the risk of potentially life-threatening adverse events, such as arterial thrombotic events, bleeding, congestive heart failure, and others. We performed an up-to-date meta-analysis to determine the risk of fatal adverse events (FAEs) in patients with cancer treated with VEGFR TKIs.

METHODS

MEDLINE and PubMed databases were searched for articles published from January 1966 to February 2011. Eligible studies were limited to trials of US Food and Drug Administration-approved VEGFR TKIs (pazopanib, sunitinib, and sorafenib) that reported on patients with cancer with any primary tumor type, randomized design, and adequate safety profile. Statistical analyses were conducted to calculate the summary incidence, relative risk (RR), and 95% CIs by using random-effects or fixed-effects models on the basis of the heterogeneity of included studies.

RESULTS

In all, 4,679 patients from 10 randomized controlled trials (RCTs) were included, with 2,856 from sorafenib, 1,388 from sunitinib, and 435 from pazopanib trials. The incidence of FAEs related to VEGFR TKIs was 1.5% (95% CI, 0.8% to 2.4%) with an RR of 2.23 (95% CI, 1.12 to 4.44; P = .023) compared with control patients. On subgroup analysis, no difference in the rate of FAEs was found between different VEGFR TKIs or tumor types. No evidence of publication bias was observed.

CONCLUSION

In a meta-analysis of RCTs, the use of VEGFR TKIs was associated with an increased risk of FAEs compared with control patients.

Comparative analysis of paracrine factor expression in human adult mesenchymal stem cells derived from bone marrow, adipose, and dermal tissue

Human adult mesenchymal stem cells (MSCs) support the engineering of functional tissue constructs by secreting angiogenic and cytoprotective factors, which act in a paracrine fashion to influence cell survival and vascularization. MSCs have been isolated from many different tissue sources, but little is known about how paracrine factor secretion varies between different MSC populations. We evaluated paracrine factor expression patterns in MSCs isolated from adipose tissue (ASCs), bone marrow (BMSCs), and dermal tissues [dermal sheath cells (DSCs) and dermal papilla cells (DPCs)]. Specifically, mRNA expression analysis identified insulin-like growth factor-1 (IGF-1), vascular endothelial growth factor-D (VEGF-D), and interleukin-8 (IL-8) to be expressed at higher levels in ASCs compared with other MSC populations whereas VEGF-A, angiogenin, basic fibroblast growth factor (bFGF), and nerve growth factor (NGF) were expressed at comparable levels among the MSC populations examined. Analysis of conditioned media (CM) protein confirmed the comparable level of angiogenin and VEGF-A secretion in all MSC populations and showed that DSCs and DPCs produced significantly higher concentrations of leptin. Functional assays examining in vitro angiogenic paracrine activity showed that incubation of endothelial cells in ASC(CM) resulted in increased tubulogenic efficiency compared with that observed in DPC(CM). Using neutralizing antibodies we concluded that VEGF-A and VEGF-D were 2 of the major growth factors secreted by ASCs that supported endothelial tubulogenesis. The variation in paracrine factors of different MSC populations contributes to different levels of angiogenic activity and ASCs maybe preferred over other MSC populations for augmenting therapeutic approaches dependent upon angiogenesis.

Mesenchymal stromal cells for cell therapy: besides supporting hematopoiesis

Mesenchymal stromal cells (MSC) have attracted the attention of scientists and clinicians due to their self-renewal, capacity for multipotent differentiation, and immunomodulatory properties. Some essential problems remain to be solved before the clinical application of MSC. Platelet lysate (PL) has recently been used as a substitute for FBS in MSC amplification in vitro to achieve clinically applicable numbers of MSC. In addition to promising trials in regenerative medicine, such as in the treatment of major bone defects and myocardial infarction, MSC have shown therapeutic effect other than direct hematopoiesis support in hematopoietic reconstruction. It has been confirmed that MSC promote hematopoietic cell engraftment and immune recovery after allogeneic hematopoietic stem cell transplantation, probably through the provision of cytokines, matrix proteins, and cell-to-cell contacts. Their suppressive effects on immune cells, including T cells, B cells, NK cells and DC cells, suggest MSCs as a novel therapy for GVHD and other autoimmune disorders. These cells thus present as promising candidates for cellular therapy in the fields of regenerative medicine, allogeneic hematopoietic stem cell transplantation, and autoimmune disorders.

Management of treatment-related toxicity with targeted therapies for renal cell carcinoma: evidence-based practice and best practices

The advent of targeted agents for the treatment of advanced renal cell carcinoma has led to dramatic improvements in therapy. However, the chronic use of these medications has also led to the identification of new toxicities that require long-term management. Effective management of toxicity is needed to maximize the benefits of treatment and improve patients' quality of life. In addition, toxicity from these agents may affect treatment compliance, particularly with daily oral agents. This review delineates the toxicities that require monitoring, the underlying pathophysiology (when known), and treatments that may have benefits in relieving symptoms and side effects.

Pretreating mesenchymal stem cells with interleukin-1β and transforming growth factor-β synergistically increases vascular endothelial growth factor production and improves mesenchymal stem cell-mediated myocardial protection after acute ischemia

BACKGROUND

Mesenchymal stem cells (MSCs) improve postischemic myocardial function in part through their secretion of growth factors such as vascular endothelial growth factor (VEGF). Pretreating MSCs with various cytokines or small molecules can improve VEGF secretion and MSC-mediated cardioprotection. However, whether 1 cytokine can potentiate the effect of another cytokine in MSC pretreatment to achieve a synergistic effect on VEGF production and cardioprotection is poorly studied.

METHODS

MSCs were treated with interleukin (IL)-1β and/or transforming growth factor (TGF)-β1 for 24 hours before experiments. VEGF production was determined by enzyme-linked immunosorbent assay. Isolated hearts from adult male Sprague-Dawley rats were subjected to 15 minutes of equilibration, 25 minutes of ischemia, and 40 minutes reperfusion. Hearts (n = 5-7 per group) were randomly infused with vehicle, untreated MSCs, or MSCs pretreated with IL-1β and/or TGF-β1. Specific inhibitors were used to delineate the roles of p38 mitogen-activated protein kinase (MAPK) and SMAD3 in IL-1β- and TGF-β1-mediated stimulation of MSCs.

RESULTS

MSCs cotreated with IL-1β and TGF-β1 exhibited synergistically increased VEGF secretion, and they greatly improved postischemic myocardial functional recovery. Ablation of p38 MAPK and SMAD3 activation with specific inhibitors negated both IL-1β- and TGF-β1-mediated VEGF production in MSCs and the ability of these pretreated MSCs to improve myocardial recovery after ischemia.

CONCLUSION

Pretreating MSCs with 2 cytokines may be useful to fully realize the potential of cell-based therapies for ischemic tissues.

N-cadherin determines individual variations in the therapeutic efficacy of human umbilical cord blood-derived mesenchymal stem cells in a rat model of myocardial infarction

In this study, we established and characterized human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) from four different donors. However, the hUCB-MSCs showed remarkable variations in their therapeutic efficacy for repairing rat infarcted myocardium (including the process of angiogenesis) 8 weeks after transplantation. In addition, we observed that the level of vascular endothelial growth factor (VEGF) is correlated with the therapeutic efficacy of the four hUCB-MSCs. Next, to investigate the practical application of hUCB-MSCs, we searched for surface signature molecules that could serve as indicators of therapeutic efficacy. The gene for N-cadherin was the only cell surface gene that was highly expressed in the most effective hUCB-MSCs, both at the transcriptional and translational levels. We observed downregulation and upregulation of VEGF in response to N-cadherin blocking and N-cadherin overexpression, respectively. Activation of extracellular signal-regulated kinase (ERK), but not protein kinase B, was increased when N-cadherin expression was increased, whereas disruption of N-cadherin-mediated cell-cell contact induced suppression of ERK activation and led to VEGF downregulation. Moreover, by investigating hUCB-MSCs overexpressing N-cadherin or N-cadherin knockdown hUCB-MSCs, we confirmed the in vivo function of N-cadherin. In addition, we observed that DiI-labeled hUCB-MSCs express N-cadherin in the peri-infarct area and interact with cardiomyocytes.

Endogenous serum erythropoietin and no-reflow in patients with ST-elevation myocardial infarction

BACKGROUND

In models of acute ischaemia, erythropoietin (EPO) administration has been found to attenuate vascular injury largely through reduced apoptosis, suppressed inflammation and increased nitric oxide availability. We studied the association between circulating endogenous EPO and no-reflow in patients with first ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI).

METHODS

Blood sampling was performed before PPCI. Consecutive patients with (n = 24) or without (n = 24) evidence of angiographic no-reflow after PPCI were enrolled. Angiographic no-reflow was defined as Thrombolysis in Myocardial Infarction (TIMI) flow ≤ 2 or as TIMI flow = 3 but with myocardial blush grade < 2. We also assessed electrocardiographic (ECG) no-reflow as ≤ 50% resolution of maximal ST elevation 60 min after PPCI.

RESULTS

Baseline characteristics did not correlate significantly with EPO concentrations. In contrast, both angiographic and ECG no-reflow correlated with lower EPO levels at univariate analysis [median (interquartile): 4·2 (0·6-9·5) vs. 12·2 (5·2-20·3) mIU mL(-1), P = 0·001, and 4·0 (0·6-7·1) vs. 9·3 (1·0-12·6) mIU mL(-1), P = 0·01, respectively]. At multivariable analysis, decreasing EPO tertiles and left anterior descending as the infarct-related artery were the only factors that predicted both angiographic and ECG no-reflow (P = 0·017 and P = 0·02 for EPO; P < 0·005 and P > 0·05 for left anterior descending artery, respectively).

CONCLUSIONS

We found an independent, graded, inverse relation between endogenous EPO levels and angiographic and ECG no-reflow following PPCI. In animal models of ischaemia, EPO has been found to be protective. In humans, endogenous EPO may contribute to offset the mechanisms responsible for no-reflow.