Factors released from embryonic stem cells inhibit apoptosis of H9c2 cells

PTEN-AKT pathway attenuates apoptosis and adverse remodeling in ponatinib-induced skeletal muscle toxicity following BMP-7 treatment

Tyrosine kinase inhibitors (TKIs) including ponatinib are commonly used to treat cancer patients. Unfortunately, TKIs induce cardiac as well as skeletal muscle dysfunction as a side effect. Therefore, detailed mechanistic studies are required to understand its pathogenesis and to develop a therapeutic treatment. The current study was undertaken to examine whether ponatinib induces apoptosis and apoptotic mechanisms both in vitro and in vivo models and furthermore to test the potential of bone morphogenetic protein 7 (BMP-7) as a possible treatment option for its attenuation. Sol8 cells, a mouse myogenic cell line was exposed to ponatinib to generate an apoptotic cell culture model and were subsequently treated with BMP-7 to understand its protective effects. For the in vivo model, C57BL/6J mice were administered with ponatinib to understand apoptosis, cell signaling apoptotic mechanisms, and adverse muscle remodeling and its attenuation with BMP-7. TUNEL staining, immunohistochemistry (IHC), and real-time polymerase chain reaction (RT-PCR) methods were used. Our data show significantly (p < 0.05) increased TUNEL staining, caspase-3, BAX/Bcl2 ratio in the in vitro model. Furthermore, our in vivo muscle data show ponatinib-induced muscle myopathy, and loss in muscle function. The observed muscle myopathy was associated with increased apoptosis, caspase-3 staining, and BAX/Bcl-2 ratio as confirmed with IHC and RT-PCR. Furthermore, our data show a significant (p < 0.05) increase in the involvement of cell signaling apoptotic regulator protein PTEN and a decrease in cell survival protein AKT. These results suggest that increased apoptosis following ponatinib treatment showed an increase in skeletal muscle remodeling, sarcopenia, and fibrosis. Furthermore, BMP-7 treatment significantly (p < 0.05) attenuated ponatinib-induced apoptosis, BAX/Bcl2 ratio, decreased PTEN, and increased cell survival protein AKT, decreased adverse muscle remodeling, and improved muscle function. Overall, we provide evidence that ponatinib-induces apoptosis leading to sarcopenia and muscle myopathy with decreased function which was attenuated by BMP-7.

Normothermic Ex Vivo Heart Perfusion with Mesenchymal Stem Cell-Derived Conditioned Medium Improves Myocardial Tissue Protection in Rat Donation after Circulatory Death Hearts

Objective. Adopting hearts from donation after circulatory death (DCD) is a promising approach to enlarge the donor pool. Nevertheless, DCD hearts experience severe warm ischemia/reperfusion (I/R) injury. Recent studies have demonstrated that conditioned medium (CM) derived from bone marrow mesenchymal stem cells (BMSCs) has the potential of reducing organ I/R injury. Therefore, we investigated whether DCD heart preservation with normothermic ex vivo heart perfusion (EVHP) and BMSCs-CM treatment could alleviate myocardial warm I/R injury in the DCD hearts. Methods. We randomly divided donor rats into two groups: (1) DCD-Control group and (2) DCD-CM group. Before DCD heart preservation with the normothermic EVHP system for 105 minutes, rats suffered from a 25-minute warm ischemia injury in the DCD procedure. Vehicle or CM (300 μl) was added to the perfusate at the beginning of the perfusion process. The cardiac function of DCD hearts in the DCD-Control and DCD-CM groups was measured every 30 minutes. Besides, non-DCD hearts were harvested from the beating-heart rats. Results. The antibody array demonstrated that the CM contained 14 bioactive factors involved in apoptosis, inflammation, and oxidative stress. Warm ischemia injury resulted in a significant increase in the level of oxidative stress, inflammation, and apoptosis in the DCD hearts of DCD-Control group. Furthermore, compared with the DCD-Control group, CM treatment increased the developed pressure, $\text{dP}/\text{d}{\text{t}}_{\max }$ and $\text{dP}/\text{d}{\text{t}}_{\min }$ of the left ventricular in the DCD hearts during a 90-minute EVHP. Moreover, the administration of CM attenuated the level of oxidative stress, inflammation, and apoptosis in the DCD hearts of the DCD-CM group. Conclusions. Normothermic EVHP combined with CM treatment can alleviate warm I/R injury in the DCD hearts by decreasing the level of oxidative stress, inflammatory response, and apoptosis, which might alleviate the shortage of donor hearts by adopting DCD hearts.

Comprehensive analysis of expression, prognosis and immune infiltration for TIMPs in glioblastoma

Background

Tissue inhibitors of metalloproteinase (TIMP) family proteins are peptidases involved in extracellular matrix (ECM) degradation. Various diseases are related to TIMPs, and the primary reason is that TIMPs can indirectly regulate remodelling of the ECM and cell signalling by regulating matrix metalloproteinase (MMP) activity. However, the link between TIMPs and glioblastoma (GBM) is unclear.

Objective

This study aimed to explore the role of TIMP expression and immune infiltration in GBM.

Methods

Oncomine, GEPIA, OSgbm, LinkedOmics, STRING, GeneMANIA, Enrichr, and TIMER were used to conduct differential expression, prognosis, and immune infiltration analyses of TIMPs in GBM.

Results

All members of the TIMP family had significantly higher expression levels in GBM. High TIMP3 expression correlated with better overall survival (OS) and disease-specific survival (DSS) in GBM patients. TIMP4 was associated with a long OS in GBM patients. We found a positive relationship between TIMP3 and TIMP4, identifying gene sets with similar or opposite expression directions to those in GBM patients. TIMPs and associated genes are mainly associated with extracellular matrix organization and involve proteoglycan pathways in cancer. The expression levels of TIMPs in GBM correlate with the infiltration of various immune cells, including CD4+ T cells, macrophages, neutrophils, B cells, CD8⁺ T cells, and dendritic cells.

Conclusions

Our study inspires new ideas for the role of TIMPs in GBM and provides new directions for multiple treatment modalities, including immunotherapy, in GBM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-021-02477-1.

Exosomes derived from cardiac parasympathetic ganglionic neurons inhibit apoptosis in hyperglycemic cardiomyoblasts

Diabetic cardiomyopathy is known to involve two forms of cardiac cell death: apoptosis and necrosis. However, it remains unknown whether hyperglycemia-induced apoptosis in the H9c2 cell culture system is inhibited by parasympathetic ganglionic neurons (PGN) derived exosomes (exos). We isolated PGN and sympathetic ganglionic neurons (SGN) from the right stellate ganglion in rats, and derived exos from these sources. H9c2 cells were divided into 4 groups: (1) Control, (2) H9c2 + Glucose (100 mmol/L), (3) H9c2 + Glucose + PGN-exos, and (4) H9c2 + Glucose + SGN-exos. We determined cell proliferation and viability with an MTT assay kit, and assessed apoptotic cell death with TUNEL staining and ELISA. Data were further confirmed by analyzing the presence of pro-apoptotic proteins Caspase-3 and Bax, and anti-apoptotic protein Bcl-2. Glucose exposed H9c2 cells significantly reduced cell viability, which was improved by PGN-exos, but not by SGN-exos. Furthermore, increased apoptosis in hyperglycemia in H9c2 cells was confirmed with TUNEL staining and cell death ELISA which demonstrated significantly (p < 0.05) reduction with PGN-exos treatment, but not with SGN-exos. Moreover, high expression of pro-apoptotic proteins Caspase-3 and Bax was reduced following treatment with PGN-exos; however, SGN-exos were unable to reduce the expression. Significantly reduced anti-apoptotic protein Bcl-2 following glucose treatment was improved with PGN-exos. Therefore, our data suggest that hyperglycemia induces apoptosis in H9c2 cells and decreases cell viability, and that PGN-exos are able to inhibit apoptosis, improve cell viability, and restore levels of anti-apoptotic protein Bcl-2.

Exosomes derived from embryonic stem cells inhibit doxorubicin and inflammation-induced pyroptosis in muscle cells

Doxorubicin (Dox) is an effective anticancer drug. Unfortunately, it causes cardiac and muscle toxicity due to increased oxidative stress and inflammation; however, it remains unknown whether Dox induces "pyroptosis" - an inflammation-mediated cell death. We investigated whether Dox induces pyroptosis in mouse soleus muscle (Sol 8) cells in vitro and to show the protective effect of embryonic stem cell exosomes (ES-exos) on pyroptosis. Dox and inflammation-induced in vitro model was generated. Pyroptosis was confirmed using immunohistochemistry (with putative markers caspase-1, IL-1β, and pro-inflammatory cytokine IL-18) and Western blotting of caspase-1 and IL-1β. The results show significant increase in the expression of caspase-1, IL-1β, and IL-18 following treatment with Dox, which was inhibited by ES-exos but not mouse embryonic fibroblast exosomes. Moreover, GW4869 compound inhibited functional activity of ES-exos, suggesting these vesicles are key players in the inhibition of pyroptosis. These results suggest that Dox induces inflammatory pyroptosis in Sol 8 cells, which is attenuated by ES-exos in vitro.

Attenuation of teratoma formation by p27 overexpression in induced pluripotent stem cells

BACKGROUND

Pluripotent stem cells, such as embryonic stem cells or induced pluripotent stem cells, have a great potential for regenerative medicine. Induced pluripotent stem cells, in particular, are suitable for replacement of tissue by autologous transplantation. However, tumorigenicity is a major risk in clinical application of both embryonic stem cells and induced pluripotent stem cells. This study explores the possibility of manipulating the cell cycle for inhibition of tumorigenicity.

METHODS

We genetically modified mouse induced pluripotent stem cells (miPSCs) to overexpress p27 tumor suppressor and examined their proliferation rate, gene expression, cardiac differentiation, tumorigenicity, and therapeutic potential in a mouse model of coronary artery ligation.

RESULTS

Overexpression of p27 inhibited cell division of miPSCs, and that inhibition was dependent on the expression level of p27. p27 overexpressing miPSCs had pluripotency characteristics but lost stemness earlier than normal miPSCs during embryoid body and teratoma formation. These cellular characteristics led to none or smaller teratoma when the cells were injected into nude mice. Transplantation of both miPSCs and p27 overexpressing miPSCs into the infarcted mouse heart reduced the infarction size and improved left ventricular function.

CONCLUSIONS

The overexpression of p27 attenuated tumorigenicity by reducing proliferation and earlier loss of stemness of miPSCs. The overexpression of p27 did not affect pluripotency and differentiation characteristics of miPSC. Therefore, regulation of the proliferation rate of miPSCs offers great therapeutic potential for repair of the injured myocardium.

Cystatin C is a disease-associated protein subject to multiple regulation

A protease inhibitor, cystatin C (Cst C), is a secreted cysteine protease inhibitor abundantly expressed in body fluids. Clinically, it is mostly used to measure glomerular filtration rate as a marker for kidney function due to its relatively small molecular weight and easy detection. However, recent findings suggest that Cst C is regulated at both transcriptional and post‐translational levels, and Cst C production from haematopoietic cell lineages contributes significantly to the systematic pools of Cst C. Furthermore, Cst C is directly linked to many pathologic processes through various mechanisms. Thus fluctuation of Cst C levels might have serious clinical implications rather than a mere reflection of kidney functions. Here, we summarize the pathophysiological roles of Cst C dependent and independent on its inhibition of proteases, outline its change of expression by various stimuli, and elucidate the regulatory mechanisms to control this disease‐related protease inhibitor. Finally, we discuss the clinical implications of these findings for translational gains.

Embryonic Stem Cells and Released Factors Stimulate c-kit(+)/FLK-1(+) Progenitor Cells and Promote Neovascularization in Doxorubicin-Induced Cardiomyopathy

Vascular apoptosis plays a pivotal role in the development and progression of a myriad of cardiac dysfunctions, but has yet to be investigated in doxorubicin-induced cardiomyopathy (DIC). Additionally, the neovascularization potential and resulting functional consequences of embryonic stem (ES) cells and factors released from these cells in the chronic DIC myocardium remain largely unknown. To this end, we transplanted conditioned media (CM) and ES cells in the DIC-injured heart and evaluated their potential to inhibit vascular cell death, activate endogenous c-kit(+) and FLK-1(+) cells, enhance neovascularization, and augment left ventricular dysfunction. Data presented suggest transplanted CM and ES cells significantly blunt vascular cell apoptosis consequent to DIC. Quantitative immunohistochemistry data demonstrate significantly increased c-kit(+) and FLK-1(+) cells, as well as enhanced differentiated CD31(+) cells in the CM and ES cell groups relative to DIC controls. Heart function, including fractional shortening and ejection fraction, assessed by transthoracic echocardiography, was significantly improved following CM and ES cell transplantation. In conclusion, our data suggest that transplantation of CM and ES cells inhibit vascular apoptosis, activate endogenous c-kit(+) and FLK-1(+) cells and differentiate them into endothelial cells, enhance neovascularization, and improve cardiac function in the DIC-injured myocardium.

Akt-mTOR Pathway Inhibits Apoptosis and Fibrosis in Doxorubicin-Induced Cardiotoxicity Following Embryonic Stem Cell Transplantation

Doxorubicin (DOX) is an effective chemotherapeutic drug used for the treatment of a variety of malignancies. Unfortunately, time and dose-dependent DOX therapy induces cardiotoxicity and heart failure. We previously reported that transplanted embryonic stem (ES) cells and the conditioned medium (CM) can repair and regenerate injured myocardium in acute DOX-induced cardiomyopathy (DIC). However, the effectiveness of ES cell and CM therapeutics has not been challenged in the chronic DIC model. To this end, the long-term impact of ES cells and CM on apoptosis, fibrosis, cytoplasmic vacuolization, oxidative stress, and their associated mediators were examined. Four weeks post-DIC, ES cells and CM-transplanted hearts showed a significant decrease in cardiac apoptotic nuclei, which was consequent to modulation of signaling molecules in the Akt pathway including PTEN, Akt, and mTOR. Cytoplasmic vacuolization was reduced following treatment with ES cells and CM, as was cardiac fibrosis, which was attributable to downregulation of MMP-9 activity. Oxidative stress, as evidenced by DHE staining and lipid peroxide concentration, was significantly diminished, and preservation of the antioxidant defense system was observed following CM and ES cell transplantation. In conclusion, our data suggest that transplanted ES cells and CM have long-term potentiation to significantly mitigate various adverse pathological mechanisms present in the injured chronic DIC heart.

Cytokine functions of TIMP-1

The tissue inhibitors of metalloproteinases (TIMPs) are well recognized for their role in extracellular matrix remodeling by controlling the activity of matrix metalloproteinases (MMPs). Independent of MMP inhibition, TIMPs act as signaling molecules with cytokine-like activities thereby influencing various biological processes including cell growth, apoptosis, differentiation, angiogenesis, and oncogenesis. Recent studies on TIMP-1's cytokine functions have identified complex regulatory networks involving a specific surface receptor and subsequent signaling pathways including miRNA-mediated posttranscriptional regulation of gene expression that ultimately control the fate and behavior of the cells. The present review summarizes the current knowledge on TIMP-1 as a cytokine modulator of cell functions, outlines recent progress in defining molecular pathways that transmit TIMP-1 signals from the cell periphery into the nucleus, and discusses TIMP-1's role as a cytokine in the pathophysiology of cancer and other human diseases.

Cardiac fibroblasts protect cardiomyocytes against lethal ischemia-reperfusion injury

Roles of cardiac fibroblasts (CFs) in the regulation of myocardial structure and function have been emphasized in the last decade. Their implications in pathophysiological aspects of chronic heart diseases such as myocardial remodeling and fibrosis are now well established; however their contribution to the acute phase of ischemia-reperfusion injury still remains elusive. We hypothesized that CF may contribute to cardiomyocyte (CM) protection against ischemia-reperfusion injuries. Experiments performed on isolated neonatal rat CF and CM demonstrated that the presence of CF in co-cultures increases CM viability (58 ± 2% versus 30 ± 2% in control) against hypoxia-reoxygenation injury, in a paracrine manner. It was confirmed by a similar effect of hypoxic CF secretome alone on CM viability (51 ± 9% versus 31 ± 4% in untreated cells). These findings were corroborated by in vivo experiments in a mice model of myocardial infarction in which a 25% infarct size reduction was observed in CF secretome treated mice compared to control. Tissue inhibitor of metalloproteinases-1 (TIMPs-1) alone, abundantly detected in CF secretome, was able to decrease CM cell death (35%) and experiments with pharmacological inhibitors of PI3K/Akt and ERK1/2 pathways provided more evidence that this paracrine protection is partly mediated by these signaling pathways. In vivo experiments strengthened that TIMP-1 alone was able to decrease infarct size (37%) and were validated by depletion experiments demonstrating that CF secretome cardioprotection was abolished by TIMP-1 depletion. Our data demonstrated for the first time that CFs participate in cardioprotection during the acute phase of ischemia-reperfusion via a paracrine pathway involving TIMP-1.

SMAD-PI3K-Akt-mTOR pathway mediates BMP-7 polarization of monocytes into M2 macrophages

Previously we demonstrated that bone morphogenetic protein-7 (BMP-7) treatment polarizes monocytes into M2 macrophages and increases the expression of anti-inflammatory cytokines. Despite these findings, the mechanisms for the observed BMP-7 induced monocyte polarization into M2 macrophages are completely unknown. In this study, we demonstrate the mechanisms involved in the polarization of monocytes into M2 macrophages. Apoptotic conditioned media (ACM) was generated to mimic the stressed conditions, inducing monocyte polarization. Monocytes were treated with ACM along with BMP-7 and/or its inhibitor, follistatin, for 48 hours. Furthermore, an inhibitor of the PI3K pathway, LY-294002, was also studied. Our data show that BMP-7 induces polarization of monocytes into M2 macrophages while significantly increasing the expression of anti-inflammatory markers, arginase-1 and IL-10, and significantly (p<0.05) decreasing the expression of pro-inflammatory markers iNOS, IL-6, TNF-α and MCP-1; (p<0.05). Moreover, addition of the PI3K inhibitor, LY-294002, significantly (p<0.05) decreases upregulation of IL-10 and arginase-1, suggesting involvement of the PI3K pathway in M2 macrophage polarization. Next, following BMP-7 treatment, a significant (p<0.05) increase in p-SMAD1/5/8 and p-PI3K expression resulting in downstream activation of p-Akt and p-mTOR was observed. Furthermore, expression of p-PTEN, an inhibitor of the PI3K pathway, was significantly (p<0.05) increased in the ACM group. However, BMP-7 treatment inhibited its expression, suggesting involvement of the PI3K-Akt-mTOR pathway. In conclusion, we demonstrate that BMP-7 polarizes monocytes into M2 macrophages and enhances anti-inflammatory cytokine expression which is mediated by the activated SMAD-PI3K-Akt-mTOR pathway.

Natural haemozoin induces expression and release of human monocyte tissue inhibitor of metalloproteinase-1

Recently matrix metalloproteinase-9 (MMP-9) and its endogenous inhibitor (tissue inhibitor of metalloproteinase-1, TIMP-1) have been implicated in complicated malaria. In vivo, mice with cerebral malaria (CM) display high levels of both MMP-9 and TIMP-1, and in human patients TIMP-1 serum levels directly correlate with disease severity. In vitro, natural haemozoin (nHZ, malarial pigment) enhances monocyte MMP-9 expression and release. The present study analyses the effects of nHZ on TIMP-1 regulation in human adherent monocytes. nHZ induced TIMP-1 mRNA expression and protein release, and promoted TNF-α, IL-1β, and MIP-1α/CCL3 production. Blocking antibodies or recombinant cytokines abrogated or mimicked nHZ effects on TIMP-1, respectively. p38 MAPK and NF-κB inhibitors blocked all nHZ effects on TIMP-1 and pro-inflammatory molecules. Still, total gelatinolytic activity was enhanced by nHZ despite TIMP-1 induction. Collectively, these data indicate that nHZ induces inflammation-mediated expression and release of human monocyte TIMP-1 through p38 MAPK- and NF-κB-dependent mechanisms. However, TIMP-1 induction is not sufficient to counterbalance nHZ-dependent MMP-9 enhancement. Future investigation on proteinase-independent functions of TIMP-1 (i.e. cell survival promotion and growth/differentiation inhibition) is needed to clarify the role of TIMP-1 in malaria pathogenesis.

Comparison of the direct effects of human adipose- and bone-marrow-derived stem cells on postischemic cardiomyoblasts in an in vitro simulated ischemia-reperfusion model

Regenerative therapies hold a promising and exciting future for the cure of yet untreatable diseases, and mesenchymal stem cells are in the forefront of this approach. However, the relative efficacy and the mechanism of action of different types of mesenchymal stem cells are still incompletely understood. We aimed to evaluate the effects of human adipose- (hASC) and bone-marrow-derived stem cells (hBMSCs) and adipose-derived stem cell conditioned media (ACM) on the viability of cardiomyoblasts in an in vitro ischemia-reperfusion (I-R) model. Flow cytometric viability analysis revealed that both cell treatments led to similarly increased percentages of living cells, while treatment with ACM did not (I-R model: 12.13 ± 0.75%; hASC: 24.66 ± 2.49%; hBMSC: 25.41 ± 1.99%; ACM: 13.94 ± 1.44%). Metabolic activity measurement (I-R model: 0.065 ± 0.033; hASC: 0.652 ± 0.089; hBMSC: 0.607 ± 0.059; ACM: 0.225 ± 0.013; arbitrary units) and lactate dehydrogenase assay (I-R model: 0.225 ± 0.006; hASC: 0.148 ± 0.005; hBMSC: 0.146 ± 0.004; ACM: 0.208 ± 0.009; arbitrary units) confirmed the flow cytometric results while also indicated a slight beneficial effect of ACM. Our results highlight that mesenchymal stem cells have the same efficacy when used directly on postischemic cells, and differences found between them in preclinical and clinical investigations are rather related to other possible causes such as their immunomodulatory or angiogenic properties.

ES micro-environment enhances stemness and inhibits apoptosis in human limbal stem cells via the maintenance of telomerase activity

Our previous work had found that telomerase rejuvenated in the cytoplasm of corneal epithelial cells cultured in embryonic stem cell-conditioned medium, the functional properties of stem-like corneal epithelial cells can be enhanced by co-culturing with embryonic stem cells (ESCs) via activation of the integrinβ1-FAK-PI3K/Akt signaling pathway. The goal of this study was to explore the potential molecular mechanisms of the ES micro-environment that enhance the stem cell-like phenotype and inhibit apoptosis in human limbal stem cells (LSC). The LSC were cultured in different media, either CnT-20 medium or CnT-20 +20% ES culture supernatant (ESC-CM). We observed that LSC cultured in ESC-CM had an increased proliferative capacity, greater serial passage capacity, higher colony-forming efficiency (CFE) and higher levels of stem cell-associated marker than those cultured in CnT-20. Compared with CnT-20, ESC-CM enhanced the undifferentiated status and inhibited apoptosis in the LSC by promoting the maintenance of telomerase activity, which could reduce the generation of reactive oxygen species (ROS), maintain the membrane potential (Δψm) at higher levels and reduce the expression of the p21 protein. Our findings indicated that ESC-CM system induced LSC to maintain a stem cell phenotype and inhibit the process of apoptosis. These effects might partially be achieved via the telomerase-p21-mitochondrial axis and the activation of the FAK/Wnt signaling pathways. This study may have high impact and clinic implication on the expansion of LSC in regenerative medicine, especially for ocular surface reconstruction.

Pretreatment of therapeutic cells with poly(ADP-ribose) polymerase inhibitor enhances their efficacy in an in vitro model of cell-based therapy in myocardial infarct

The potential of cell-based therapies in diseases involving ischemia-reperfusion is greatly hampered by the excessive loss of administered cells in the harsh and oxidative environment where these cells are supposed to act. Therefore, we investigated if inhibition of poly(ADP-ribose) polymerase (PARP) in the therapeutically added cells would lead to their increased viability and, subsequently, to an enhanced effect in an in vitro simulated ischemia-reperfusion (I-R) setting. Ischemic conditions were simulated by oxygen and glucose deprivation for 160 min using H9c2 rat cardiomyoblast cells. After 30 min of reperfusion, these cells received 4 types of treatments: no added cells (I-R model), fluorescently labeled (Vybrant DiD) therapeutic H9c2 cells with vehicle (H9c2) or PARP inhibitor (10 μM or 100 μM PJ34) pretreatment. We assessed viability (live, apoptotic and necrotic) of both ‘postischemic’ and therapeutic cells with flow cytometric analysis using calcein-AM/ethidium homodimer-2 fluorescent staining after 24 h of co-culture. Further measurements on necrosis and metabolic activity were performed using lactate dehydrogenase (LDH) release and resazurin based assays. The percentage of surviving therapeutic cells increased significantly with PARP inhibition (untreated, 52.02±5.01%; 10 μM PJ34, 63.38±4.50%; 100 μM PJ34, 64.99±3.47%). The percentage of necrotic cells decreased in a similar manner (untreated, 37.23±4.40%; 10 μM PJ34, 26.83±3.49%; 100 μM PJ34, 24.96±2.43%). Notably, the survival of the cells that suffered I-R injury was also significantly higher when treated with PARP-inhibited therapeutic cells (I-R model, 36.44±5.05%; H9c2, 42.81±5.11%; 10 μM PJ34, 52.07±5.80%; 100 μM PJ34, 54.95±5.55%), while necrosis was inhibited (I-R model, 43.64±4.00%; H9c2, 37.29±4.55%; 10 μM PJ34, 30.18±4.60%; 100 μM PJ34, 25.52±3.47%). In subsequent experiments, PARP inhibition decreased LDH-release of the observed combined cell population and enhanced the metabolic activity. Thus, our results suggest that pretreating the therapeutically added cells with a PARP inhibitor could be beneficial in the setting of cell-based therapies.

Gene expression signatures of extracellular matrix and growth factors during embryonic stem cell differentiation

Pluripotent stem cells are uniquely capable of differentiating into somatic cell derivatives of all three germ lineages, therefore holding tremendous promise for developmental biology studies and regenerative medicine therapies. Although temporal patterns of phenotypic gene expression have been relatively well characterized during the course of differentiation, coincident patterns of endogenous extracellular matrix (ECM) and growth factor expression that accompany pluripotent stem cell differentiation remain much less well-defined. Thus, the objective of this study was to examine the global dynamic profiles of ECM and growth factor genes associated with early stages of pluripotent mouse embryonic stem cell (ESC) differentiation. Gene expression analysis of ECM and growth factors by ESCs differentiating as embryoid bodies for up to 14 days was assessed using PCR arrays (172 unique genes total), and the results were examined using a variety of data mining methods. As expected, decreases in the expression of genes regulating pluripotent stem cell fate preceded subsequent increases in morphogen expression associated with differentiation. Pathway analysis generated solely from ECM and growth factor gene expression highlighted morphogenic cell processes within the embryoid bodies, such as cell growth, migration, and intercellular signaling, that are required for primitive tissue and organ developmental events. In addition, systems analysis of ECM and growth factor gene expression alone identified intracellular molecules and signaling pathways involved in the progression of pluripotent stem cell differentiation that were not contained within the array data set. Overall, these studies represent a novel framework to dissect the complex, dynamic nature of the extracellular biochemical milieu of stem cell microenvironments that regulate pluripotent cell fate decisions and morphogenesis.

Controlled release of dexamethasone from peptide nanofiber gels to modulate inflammatory response

New biomaterials that have the ability to locally suppress an immune response could have broad therapeutic use in the treatment of diseases characterized by acute or chronic inflammation or as a strategy to facilitate improved efficacy in cell or tissue transplantation. We report here on the preparation of a modular peptide amphiphile (PA) capable of releasing an anti-inflammatory drug, dexamethasone (Dex), by conjugation via a labile hydrazone linkage. This molecule self-assembled in water into long supramolecular nanofibers when mixed with a similar PA lacking the drug conjugate, and the addition of calcium salt to screen electrostatic repulsion between nanofibers promoted gel formation. These nanofiber gels demonstrated sustained release of soluble Dex for over one month in physiologic media. The Dex released from these gels maintained its anti-inflammatory activity when evaluated in vitro using a human inflammatory reporter cell line and furthermore preserved cardiomyocyte viability upon induced oxidative stress. The ability of this gel to mitigate the inflammatory response in cell transplantation strategies was evaluated using cell-surrogate polystyrene microparticles suspended in the nanofiber gel that were then subcutaneously injected into mice. Live animal luminescence imaging using the chemiluminescent reporter molecule luminol showed a significant reduction in inflammation at the site where particles were injected with Dex-PA compared to the site of injection for particles within a control PA in the same animal. Histological evidence suggested a marked reduction in the number of infiltrating inflammatory cells when particles were delivered within Dex-PA nanofiber gels, and very little inflammation was observed at either 3 days or 21 days post-implantation. The use of Dex-PA could facilitate localized anti-inflammatory activity as a component of biomaterials designed for various applications in regenerative medicine and could specifically be a useful module for PA-based therapies. More broadly, these studies define a versatile strategy for facile synthesis of self-assembling peptide-based materials with the ability to control drug release.

Bone morphogenetic protein 7 polarizes THP-1 cells into M2 macrophages

It was hypothesized that monocyte treatment with bone morphogenetic protein 7 (BMP7) would significantly enhance monocyte polarization into M2 macrophages as well as increasing the levels of anti-inflammatory cytokines. In a cell culture system using monocytes (human acute monocytic leukemia cell line THP-1), we studied the effects of BMP7 on monocytes polarizing into M2 macrophages. The data demonstrate that THP-1 cells contain a BMP type II receptor (BMPR2), and that its activation is significantly (p < 0.05) increased following treatment with BMP7. Furthermore, there was an increase of M2 macrophages, BMPR2, and anti-inflammatory cytokines interleukin (IL)-10 and IL-1ra compared with the respective controls. Moreover, treatment with BMP7 caused a significant (p < 0.05) decrease in the levels of pro-inflammatory cytokines IL-6, tumour necrosis factor (TNF-α), and monocyte chemotactic protein-1 (MCP-1), compared with the controls. In conclusion, we suggest for the first time that BMP7 has a unique potential to polarize monocytes into M2 macrophages, required for tissue repair, which will have significant applications for the treatment of atherosclerosis.

Cell Therapy Limits Myofibroblast Differentiation and Structural Cardiac Remodeling

Background—

Experimental cell therapy attenuates maladaptive cardiac remodeling and improves heart function. Paracrine mechanisms have been proposed. The effect of cell therapy on post infarction cardiac fibroblast and extracellular matrix (ECM) regulation was examined.

Methods and Results—

Vascular smooth muscle cells (VSMC) were injected into the border zone of subacute infarcted syngeneic Fischer rat hearts and compared with medium-injected controls. Twelve weeks post injection, cell-treated hearts showed preserved ECM content and attenuated structural chamber remodeling. Myofibroblast activation (α-smooth muscle actin expression) was decreased significantly, while basic fibroblast growth factor (bFGF) expression, a known inhibitor of transforming growth factor β-1–induced fibroblast differentiation, was increased. Matrix metalloproteinase-2 expression and activation by gelatin zymography was unchanged between groups, while its endogenous inhibitor, tissue inhibitors of matrix metalloproteinase (TIMP)-2, showed both increased expression and enhanced inhibitory capacity in cell-treated hearts. To define paracrine mechanisms, in vitro effects of VSMC conditioned media on myofibroblast activation were assessed by 3-D collagen gel contraction assay. VSMC conditioned media significantly inhibited collagen contraction, while a specific bFGF inhibitor abolished this paracrine response. TIMP-2 induced collagen contraction, but the effect was suppressed in the presence of bFGF.

Conclusions—

Extracellular matrix dysregulation post myocardial infarction is improved by cell therapy. These data suggest that cell transplantation attenuates myofibroblast activation and subsequent maladaptive structural chamber remodeling through paracrine mechanisms involving bFGF and TIMP-2.

Mesenchymal stem cells secrete multiple cytokines that promote angiogenesis and have contrasting effects on chemotaxis and apoptosis

We have previously shown that mesenchymal stem cells (MSC) improve function upon integration in ischemic myocardium. We examined whether specific cytokines and growth factors produced by MSCs are able to affect angiogenesis, cellular migration and apoptosis. Conditioned media (CM) was prepared by culturing MSC for 48 hours. CM displayed significantly elevated levels of VEGF, Monocyte Chemoattractant Protein-1 (MCP-1), macrophage inflammatory protein-1α (MIP-1α), MIP-1β and monokine induced by IFN-γ (MIG) compared to control media. MSC contained RNA for these factors as detected by RT-PCR. CM was able to induce angiogenesis in canine vascular endothelial cells. MCP-1 and MIP-1α increased cell migration of MSC while VEGF reduced it. H9c2 cells treated with CM under hypoxic conditions for 24 hours displayed a 16% reduction in caspase-3 activity compared to controls. PI 3-kinase γ inhibitor had no effect on controls but reversed the effect of CM on caspase-3 activity. MCP-1 alone mimicked the protective effect of CM while the PI 3-Kγ inhibitor did not reverse the effect of MCP-1. CM reduced phospho-BAD (Ser112) and phospho-Akt (Ser473) while increasing phospho-Akt (Thr308). MCP-1 reduced the level of phospho-Akt (Ser473) while having no effect on the other two; the PI 3-Kγ inhibitor did not alter the MCP-1 effect. ERK 1/2 phosphorylation was reduced in CM treated H9c2 cells, and inhibition of ERK 1/2 reduced the phosphorylation of Akt (Ser473), Akt (Thr308) and Bad (Ser112). In conclusion, MSC synthesize and secrete multiple paracrine factors that are able to affect MSC migration, promote angiogenesis and reduce apoptosis. While both MCP-1 and PI3-kinase are involved in the protective effect, they are independent of each other. It is likely that multiple pro-survival factors in addition to MCP-1 are secreted by MSC which act on divergent intracellular signaling pathways.

[Embryonic stem cells in the treatment of severe cardiac insufficiency]

The experience accumulated in cardiac cell therapy suggests that regeneration of extensively necrotic myocardial areas is unlikely to be achieved by the sole paracrine effects of the grafted cells but rather requires the conversion of these cells into cardiomyocytes featuring the capacity to substitute for those which have been irreversibly lost. In this setting, the use of human pluripotent embryonic stem cells has a strong rationale. The experimental results obtained in animal models of myocardial infarction are encouraging. However, the switch to clinical applications still requires to address some critical issues, among which optimizing cardiac specification of the embryonic stem cells, purifying the resulting progenitor cells so as to graft a purified population devoid from any contamination by residual pluripotent cells which carry the risk of tumorigenesis and controlling the expected allogeneic rejection by clinically acceptable methods. If the solution to these problems is a pre-requisite, the therapeutic success of this approach will also depend on the capacity to efficiently transfer the cells to the target tissue, to keep them alive once engrafted and to allow them to spatially organize in such a way that they can contribute to the contractile function of the heart.

Overexpression of TIMP-1 in embryonic stem cells attenuates adverse cardiac remodeling following myocardial infarction

Transplanted embryonic stem (ES) cells, following myocardial infarction (MI), contribute to limited cardiac repair and regeneration with improved function. Therefore, novel strategies are still needed to understand the effects of genetically modified transplanted stem cells on cardiac remodeling. The present study evaluates whether transplanted mouse ES cells overexpressing TIMP-1, an antiapoptotic and antifibrotic protein, can enhance cardiac myocyte differentiation, inhibit native cardiac myocyte apoptosis, reduce fibrosis, and improve cardiac function in the infarcted myocardium. MI was produced in C57BL/6 mice by coronary artery ligation. TIMP-1-ES cells, ES cells, or culture medium (control) were transplanted into the peri-infarct region of the heart. Immunofluorescence, TUNEL staining, caspase-3 activity, ELISAs, histology, and echocardiography were used to identify newly differentiated cardiac myocytes and assess apoptosis, fibrosis, and heart function. Two weeks post-MI, significantly (p < 0.05) enhanced engraftment and cardiac myocyte differentiation was observed in TIMP-1-ES cell-transplanted hearts compared with hearts transplanted with ES cells and control. Hearts transplanted with TIMP-1-ES cells demonstrated a reduction in apoptosis as well as an increase (p< 0.05) in p-Akt activity compared with ES cells or culture media controls. Infarct size and interstitial and vascular fibrosis were significantly (p< 0.05) decreased in the TIMP-1-ES cell group compared to controls. Furthermore, MMP-9, a key profibrotic protein, was significantly (p < 0.01) reduced following TIMP-1-ES cell transplantation. Echocardiography data showed fractional shortening and ejection fraction were significantly (p< 0.05) improved in the TIMP-1-ES cell group compared with respective controls. Our data suggest that transplanted ES cells overexpressing TIMP-1 attenuate adverse myocardial remodeling and improve cardiac function compared with ES cells that may have therapeutic potential in regenerative medicine.

Embryonic stem cells improve cardiac function in Doxorubicin-induced cardiomyopathy mediated through multiple mechanisms

Doxorubicin (DOX) is an effective antineoplastic agent used for the treatment of a variety of cancers. Unfortunately, its use is limited as this drug induces cardiotoxicity and heart failure as a side effect. There is no report that describes whether transplanted embryonic stem (ES) cells or their conditioned medium (CM) in DOX-induced cardiomyopathy (DIC) can repair and regenerate myocardium. Therefore, we transplanted ES cells or CM in DIC to examine apoptosis, fibrosis, cytoplasmic vacuolization, and myofibrillar loss and their associated Akt and ERK pathway. Moreover, we also determined activation of endogenous c-kit(+ve) cardiac stem cells (CSCs), levels of HGF and IGF-1, growth factors required for c-kit cell activation, and their differentiation into cardiac myocytes, which also contributes in cardiac regeneration and improved heart function. We generated DIC in C57Bl/6 mice (cumulative dose of DOX 12 mg/kg body weight, IP), and animals were treated with ES cells, CM, or cell culture medium in controls. Two weeks post-DIC, ES cells or CM transplanted hearts showed a significant (p < 0.05) decrease in cardiac apoptotic nuclei and their regulation with Akt and ERK pathway. Cardiac fibrosis observed in the ES cell or CM groups was significantly less compared with DOX and cell culture medium groups (p < 0.05). Next, cytoplasmic vacuolization and myofibrillar loss was reduced (p < 0.05) following treatment with ES cells or CM. Moreover, our data also demonstrated increased levels of c-kit(+ve) CSCs in ES cells or CM hearts and differentiated cardiac myocytes from these CSCs, suggesting endogenous cardiac regeneration. Importantly, the levels of HFG and IGF-1 were significantly increased in ES cells or CM transplanted hearts. In conclusion, we reported that transplanted ES cells or CM in DIC hearts significantly decreases various adverse pathological mechanisms as well as enhances cardiac regeneration that effectively contributes to improved heart function.

Embryonic stem cells for severe heart failure: why and how?

The experience accumulated in cardiac cell therapy suggests that regeneration of extensively necrotic myocardial areas is unlikely to be achieved by the sole paracrine effects of the grafted cells but rather requires the conversion of these cells into cardiomyocytes featuring the capacity to substitute for those which have been irreversibly lost. In this setting, the use of human pluripotent embryonic stem cells has a strong rationale. The experimental results obtained in animal models of myocardial infarction are encouraging. However, the switch to clinical applications still requires to address some critical issues, among which the optimization of the cardiac specification of the embryonic stem cells, the purification of the resulting progenitor cells so as to graft a purified population devoid from any contamination by residual pluripotent cells which carry the risk of tumorigenesis, and the control of the expected allogeneic rejection by clinically acceptable methods. If the solution to these problems is a prerequisite, the therapeutic success of this approach will also depend on the capacity to efficiently transfer the cells to the target tissue, to keep them alive once engrafted, and to allow them to spatially organize in such a way that they can contribute to the contractile function of the heart.

Cell therapy in the heart

Cell therapy is emerging as a new strategy to circumvent the adverse effects of heart disease. Many experimental and clinical studies investigating the transplantation of cells into the injured myocardium have yielded promising results. Moreover, data from these reports show that transplanted stem cells can engraft within the myocardium, differentiate into major cardiac cell types, and improve cardiac function. However, results from clinical trials show conflicting results. These trials demonstrate significant improvements in cardiac function for up to 6 months. However, these improved functions were diminished when examined at 18 months. In this review, we will discuss the current literature available on cell transplantation, covering studies ranging from animal models to clinical trials.

Preconditioning approach in stem cell therapy for the treatment of infarcted heart

Nearly two decades of research in regenerative medicine have been focused on the development of stem cells as a therapeutic option for treatment of the ischemic heart. Given the ability of stem cells to regenerate the damaged tissue, stem-cell-based therapy is an ideal approach for cardiovascular disorders. Preclinical studies in experimental animal models and clinical trials to determine the safety and efficacy of stem cell therapy have produced encouraging results that promise angiomyogenic repair of the ischemically damaged heart. Despite these promising results, stem cell therapy is still confronted with issues ranging from uncertainty about the as-yet-undetermined "ideal" donor cell type to the nonoptimized cell delivery strategies to harness optimal clinical benefits. Moreover, these lacunae have significantly hampered the progress of the heart cell therapy approach from bench to bedside for routine clinical applications. Massive death of donor cells in the infarcted myocardium during acute phase postengraftment is one of the areas of prime concern, which immensely lowers the efficacy of the procedure. An overview of the published data relevant to stem cell therapy is provided here and the various strategies that have been adopted to develop and optimize the protocols to enhance donor stem cell survival posttransplantation are discussed, with special focus on the preconditioning approach.

A Peptide-Based Material for Therapeutic Carbon Monoxide Delivery

We report on the preparation of the first material for therapeutic delivery of CO. A peptide amphiphile was synthesized with a covalently attached ruthenium tricarbonyl. Self-assembled nanofiber gels containing this peptide spontaneously released CO with prolonged release kinetics compared to soluble CO donors. Oxidatively stressed cardiomyocytes had improved viability when treated with this peptide, demonstrating its potential as a biodegradable gel for localized therapeutic CO delivery.

Induced pluripotent stem (iPS) cells repair and regenerate infarcted myocardium

Cardiac myocyte differentiation reported thus far is from iPS cells generated from mouse and human fibroblasts. However, there is no article on the generation of iPS cells from cardiac ventricular specific cell types such as H9c2 cells. Therefore, whether transduced H9c2 cells, originally isolated from embryonic cardiac ventricular tissue, will be able to generate iPS cells and have the potential to repair and regenerate infarcted myocardium remains completely elusive. We transduced H9c2 cells with four stemness factors, Oct3/4, Sox2, Klf4, and c-Myc, and successfully reprogrammed them into iPS cells. These iPS cells were able to differentiate into beating cardiac myocytes and positively stained for cardiac specific sarcomeric α-actin and myosin heavy chain proteins. Following transplantation in the infarcted myocardium, there were newly differentiated cardiac myocytes and formation of gap junction proteins at 2 weeks post-myocardial infarction (MI), suggesting newly formed cardiac myocytes were integrated into the native myocardium. Furthermore, transplanted iPS cells significantly (p < 0.05) inhibited apoptosis and fibrosis and improved cardiac function compared with MI and MI+H9c2 cell groups. Moreover, our iPS cell derived cardiac myocyte differentiation in vitro and in vivo was comparable to embryonic stem cells in the present study. In conclusion we report for the first time that we have H9c2 cell-derived iPS cells which contain the potential to differentiate into cardiac myocytes in the cell culture system and repair and regenerate infarcted myocardium with improved cardiac function in vivo.

MicroRNA-1 transfected embryonic stem cells enhance cardiac myocyte differentiation and inhibit apoptosis by modulating the PTEN/Akt pathway in the infarcted heart

microRNAs (miRs) have emerged as critical modulators of various physiological processes including stem cell differentiation. Indeed, miR-1 has been reported to play an integral role in the regulation of cardiac muscle progenitor cell differentiation. However, whether overexpression of miR-1 in embryonic stem (ES) cells (miR-1-ES cells) will enhance cardiac myocyte differentiation following transplantation into the infarcted myocardium is unknown. In the present study, myocardial infarction (MI) was produced in C57BL/6 mice by left anterior descending artery ligation. miR-1-ES cells, ES cells, or culture medium (control) was transplanted into the border zone of the infarcted heart, and 2 wk post-MI, cardiac myocyte differentiation, adverse ventricular remodeling, and cardiac function were assessed. We provide evidence demonstrating enhanced cardiac myocyte commitment of transplanted miR-1-ES cells in the mouse infarcted heart as compared with ES cells. Assessment of apoptosis revealed that overexpression of miR-1 in transplanted ES cells protected host myocardium from MI-induced apoptosis through activation of p-AKT and inhibition of caspase-3, phosphatase and tensin homolog, and superoxide production. A significant reduction in interstitial and vascular fibrosis was quantified in miR-1-ES cell and ES cell transplanted groups compared with control MI. However, no statistical significance between miR-1-ES cell and ES cell groups was observed. Finally, mice receiving miR-1-ES cell transplantation post-MI had significantly improved heart function compared with respective controls (P < 0.05). Our data suggest miR-1 drives cardiac myocyte differentiation from transplanted ES cells and inhibits apoptosis post-MI, ultimately giving rise to enhanced cardiac repair, regeneration, and function.

Ex vivo-expanded bone marrow CD34(+) for acute myocardial infarction treatment: in vitro and in vivo studies

BACKGROUND AIMS

Bone marrow (BM)-derived cells appear to be a promising therapeutic source for the treatment of acute myocardial infarction (AMI). However, the quantity and quality of the cells to be used, along with the appropriate time of administration, still need to be defined. We thus investigated the use of BM CD34(+)-derived cells as cells suitable for a cell therapy protocol (CTP) in the treatment of experimental AMI.

METHODS

The need for a large number of cells was satisfied by the use of a previously established protocol allowing the expansion of human CD34(+) cells isolated from neonatal and adult hematopoietic tissues. We evaluated gene expression, endothelial differentiation potential and cytokine release by BM-derived cells during in vitro culture. Basal and expanded CD34(+) cells were used as a delivery product in a murine AMI model consisting of a coronary artery ligation (CAL). Cardiac function recovery was evaluated after injecting basal or expanded cells.

RESULTS

Gene expression analysis of in vitro-expanded cells revealed that endothelial markers were up-regulated during culture. Moreover, expanded cells generated a CD14(+) subpopulation able to differentiate efficiently into VE-cadherin-expressing cells. In vivo, we observed a cardiac function recovery in mice sequentially treated with basal and expanded cells injected 4 h and 7 days after CAL, respectively.

CONCLUSIONS

Our data suggest that combining basal and expanded BM-derived CD34(+) cells in a specific temporal pattern of administration might represent a promising strategy for a successful cell-based therapy.

The Presence of Apoptotic Bone Marrow Cells Impairs the Efficacy of Cardiac Cell Therapy

Injection of autologous bone marrow cells into infarcted myocardium has been proposed to limit the deterioration of cardiac function following myocardial infarction (MI); unfortunately, the beneficial effects observed have been modest. One of the limiting factors is believed to be poor local survival of the injected cells, but the potential impact of apoptosis among the injected cells has yet to be assessed. Therefore, this study aimed to quantify the apoptosis rate in bone marrow mononuclear cells (BMMCs) prepared for cardiac therapy, and to analyze their effects in vitro on cardiomyoblast apoptosis and in vivo on cardiac function recovery following MI. Using rabbit BMMCs prepared by Ficoll gradient, apoptotic cells were detected via Annexin V (AnV) staining. The effects of depleting the apoptotic cell population by means of AnV magnetic beads was tested in vitro after coculture with cardiomyoblasts (H9c2 cells) and in vivo after cell injection into the infarcted area. Left ventricular ejection fraction and scar extent were assessed by echography and histology 2 months later. After Ficoll gradient isolation, 37.3% (33.4–37.9%) of BMMCs were found to be apoptotic (ApoBase BMMCs). AnV depletion decreased the proportion of apoptotic cells to 20% (17.6–32%) (ApoLow BMMCs). Rabbits treated in vivo with ApoLow BMMCs after MI presented with significantly improved left ventricular ejection fraction [41.4% (41.0–43.6%) vs. 34.6% (34.6–35.9%), p = 0.03), reduced scar extent [20.4% (17.9–24.3%) vs. 25.6% (17.9–27.9%), p = 0.057], and reduced rate of cardiomyocyte apoptosis compared to those treated with ApoBase BMMCs. H9c2 apoptosis was found to be higher after coculture with ApoBase than with ApoLow BMMCs [25.6% (22.6–29.6%) vs. 10.1% (6.6–12.6%), p = 0.03], a result partially reproduced by cocultures with microparticle-rich supernatants from BMMCs. The presence of apoptotic cells among BMMCs impairs the efficacy of cardiac cell therapy after MI, an effect possibly mediated by apoptotic microparticles.

Mesenchymal stem cells overexpressing CXCR4 attenuate remodeling of postmyocardial infarction by releasing matrix metalloproteinase-9

Myocardial infarction (MI) results in loss of myofibers in the ischemic zone of the heart, followed by scar formation. These factors increase barriers to mobilization of mesenchymal stem cells (MSC), thereby impeding their effectiveness in cardiac repair. This study examined MSC overexpressing CXCR4 (MSC(CX4)) to determine penetration into infarcted myocardium by releasing collagen degrading enzyme, matrix metalloproteinase-9 (MMP-9). In vitro, mouse MSC were utilized, including MSC using adenoviral transduction, to express CXCR4/green fluorescent protein (GFP) (MSC(CX4)), Null/GFP (MSC(Null)), MSC treated with siRNA targeting CXCR4 (MSC(siR)), MSC treated with control siRNA(MSC(Con-siR)), MSC(CX4) treated with siRNA targeting MMP-9 (MSC(CX4-siRMP9)) and MMP-14 (MSC(CX4-siRMP14)), MSC derived from MMP-9 knockout mouse with adenoviral transduction for GFP (MSC(MP9-)), or MSC(MP9-) plus overexpressing CXCR4 (MSC(MP9-CX4)). The ability to cross the basement membrane was evaluated in all MSC using a trans-collagen gel invasion assay. The CXCR4 and MMP expression were analyzed by Western blot. In vivo, MSC with various treatments were infused into mice via tail vein injections 7 days after MI. Echocardiography was performed before harvesting hearts for analysis at 4 weeks after MSC injection. Both in vitro and in vivo studies demonstrated upregulation of MMP-9 induced by MSC(CX4), promoting increased GFP(+) cell migration into the infarcted area in comparison to control group. This enhanced response was associated with reduced left ventricular (LV) fibrosis, increased LV free wall thickness, angiogenesis, and improved LV function. Under hypoxic conditions, MMP-9 is upregulated in MSC(CX4), thus facilitating cross of the basement membrane, resulting in an improved remodeling of post-MI tissue.

ES cells overexpressing microRNA-1 attenuate apoptosis in the injured myocardium

MicroRNAs (miRs) are small, single-stranded, noncoding RNA's involved in post-transcriptional negative gene regulation. Recent investigations have underscored the integral role of miRs in various biological processes including innate immunity, cell-cycle regulation, metabolism, differentiation, and cell death. In the present study, we overexpressed miR-1, a muscle-specific miR, in embryonic stem cells (miR-1-ES cells), transplanted them into the infarcted myocardium, and evaluated their impact on cardiac apoptosis and function. We provide evidence demonstrating reduced apoptosis following transplantation of miR-1-ES cells 4 weeks post-myocardial infarction as compared to respective controls assessed by TUNEL staining and a capsase-3 activity assay. Moreover, we show significant elevation in p-Akt levels and diminished PTEN levels in hearts transplanted with miR-1-ES cells as determined by enzyme-linked immunoassays. Finally, using echocardiography, we reveal mice receiving miR-1-ES cell transplantation post-myocardial infarction had significantly improved fractional shortening and ejection fraction compared with respective controls. Our data suggest transplanted miR-1-ES cells inhibit apoptosis, mediated through the PTEN/Akt pathway, leading to improved cardiac function in the infarcted myocardium.

Clusterin protects H9c2 cardiomyocytes from oxidative stress-induced apoptosis via Akt/GSK-3β signaling pathway

Clusterin is a secretory glycoprotein, which is highly up-regulated in a variety of normal and injury tissues undergoing apoptosis including infarct region of the myocardium. Here, we report that clusterin protects H9c2 cardiomyocytes from H2O2-induced apoptosis by triggering the activation of Akt and GSK-3β. Treatment with H2O2 induces apoptosis of H9c2 cells by promoting caspase cleavage and cytochrome c release from mitochondria. However, co-treatment with clusterin reverses the induction of apoptotic signaling by H2O2, thereby recovers cell viability. The protective effect of clusterin on H2O2-induced apoptosis is impaired by PI3K inhibitor LY294002, which effectively suppresses clusterin-induced activation of Akt and GSK-3β. In addition, the protective effect of clusterin is independent on its receptor megalin, because inhibition of megalin has no effect on clusterin-mediated Akt/GSK-3β phosphoylation and H9c2 cell viability. Collectively, these results suggest that clusterin has a role protecting cardiomyocytes from oxidative stress and the Akt/GSK-3β signaling mediates anti-apoptotic effect of clusterin.

TGF-β2 treatment enhances cytoprotective factors released from embryonic stem cells and inhibits apoptosis in infarcted myocardium

We investigated whether factors released from mouse embryonic stem (ES) cells primed with and without transforming growth factor (TGF)-β2 inhibit iodoacetic acid (IAA)- and H(2)O(2)-induced apoptosis in the cell culture system as well as after transplantation in the infarcted heart. We generated conditioned media (CMs) from ES cells primed with and without TGF-β2 and determined their effects on IAA- and H(2)O(2)-induced apoptosis in H9c2 cells. We also transplanted both ES-CMs in the infarcted heart to determine the effects on apoptosis and cardiac function after myocardial infarction (MI) at day (D)1 and D14. Terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) staining, apoptotic ELISA, and cell viability data demonstrated significantly (P < 0.05) reduced apoptosis with ES-CM compared with controls in both cell culture models. Moreover, TGF-β2-primed ES-CM (T-ES-CM) demonstrated enhanced beneficial effects, with further reduced (P < 0.05) apoptosis compared with ES-CM, suggesting the a presence of additional cytoprotective released factors after TGF-β2 treatment. Next, our in vivo apoptosis data suggested significant decrease in apoptosis with both ES-CMs compared with MI alone at D1 and D14. Notably, T-ES-CM demonstrated significant (P < 0.05) inhibition of apoptosis and fibrosis with improved cardiac function compared with ES-CM at D14, whereas no such effects were observed at D1. Next, we confirmed that apoptosis is mediated through a prosurvival Akt pathway. Moreover, we determined that after TGF-β2 treatment there was a two- to fivefold increase in cytoprotective released factors (interleukin-10, stem cell factor, tissue inhibitor of matrix metalloproteinase-1, and VEGF) with T-ES-CM compared with ES-CM. In conclusion, we suggest that factors released from ES cells with and without TGF-β2 treatment contain antiapoptotic factors that inhibit apoptosis in vitro and in vivo. We also suggest that T-ES-CM demonstrates additional beneficial effects that provide useful information for future therapeutic applications in regenerative medicine.

Factors Released from Embryonic Stem Cells Stimulate c-kit-FLK-1(+ve) Progenitor Cells and Enhance Neovascularization

We examined whether factors released from embryonic stem (ES) cells inhibit cardiac and vascular cell apoptosis and stimulate endogenous progenitor cells that enhance neovascularization with improved cardiac function. We generated and transplanted ES-conditioned medium (CM) in the infarcted heart to examine effects on cardiac and vascular apoptosis, activation of endogenous c-kit and FLK-1(+ve) cells, and their role in cardiac neovascularization. TUNEL, caspase-3 activity, immunohistochemistry, H&E, and Masson's trichrome stains were used to determine the effect of transplanted ES-CM on cardiac apoptosis and neovascularization. TUNEL staining and caspase-3 activity confirm significantly (p < 0.05) reduced apoptosis in MI+ES-CM compared with MI+ cell culture medium. Immunohistochemistry demonstrated increased (p < 0.05, 53%) c-kit(+ve) and FLK-1(+ve) positive cells, as well as increased (p < 0.05, 67%) differentiated CD31-positive cells in ES-CM groups compared with respective controls. Furthermore, significantly (p < 0.05) increased coronary artery vessels were observed in ES-CM transplanted hearts compared with control. Heart function was significantly improved following ES-CM transplantation. Next, we observed significantly increased (p < 0.05) levels of c-kit activation proteins (HGF and IGF-1), anti-apoptosis factors (IGF-1 and total antioxidants), and neovascularization protein (VEGF). In conclusion, we suggest that ES-CM following transplantation in the infarcted heart inhibits apoptosis, activates cardiac endogenous c-kit and FLK-1(+ve) cells, and differentiates them into endothelial cells (ECs) that enhances neovascularization with improved cardiac function.

Stem cell therapy for ischemic heart disease

Stem cell transplantation has emerged as a novel treatment option for ischemic heart disease. Different cell types have been utilized and the recent development of induced pluripotent stem cells has generated tremendous excitement in the regenerative field. Bone marrow-derived multipotent progenitor cell transplantation in preclinical large animal models of postinfarction left ventricular remodeling has demonstrated long-term functional and bioenergetic improvement. These beneficial effects are observed despite no significant engraftment of bone marrow cells in the myocardium and even lower differentiation of these cells into cardiomyocytes. It is thought to be related to the paracrine effect of these stem cells, which secrete factors that lead to long-term gene expression changes in the host myocardium, thereby promoting neovascularization, inhibiting apoptosis, and stimulating resident cardiac progenitor cells. Future studies are warranted to examine the changes in the recipient myocardium after stem cell transplantation and to investigate the signaling pathways involved in these effects.

Enhancement of long-term proliferative capacity of rabbit corneal epithelial cells by embryonic stem cell conditioned medium

Induction of autologous stem cells for directed differentiation has become a predominant method to obtain autologous cells for tissue reconstruction. However, the low inducing efficiency and contamination with other type of cells hinder its clinical utilization. Here we report a novel phenomenon that the corneal epithelial cells maintain long-term proliferative capacity and tissue-specific cell phenotype by factors secreted from murine embryonic stem cells (ESCs). The rabbit corneal epithelial cells grew very well in culture medium with addition of 40% ESC conditioned medium (ESC-CM). These corneal epithelial cells have been serially subcultured for more than 20 passages and maintained high cell purity, cobble-stone-like morphology, enhanced colony forming efficiency, normal diploid, and capacity to regenerate a functional stratified corneal epithelial equivalent. More importantly, these cells did not form tumor, and the cells lost their proliferative capacity after withdrawal of ESC-CM. The long-term proliferative capacity of corneal epithelial cells is partly resulted from enhancement of cell survival and colony formation, and mediated by ectopic expression of telomerase. Our findings indicate that this new ESC-CM culture system can generate low-immunogenic autologous cells sufficiently for use in regenerative medicine.

Nonmitogenic survival-enhancing autocrine factors including cyclophilin A contribute to density-dependent mouse embryonic stem cell growth

An improved understanding of the role of extracellular factors in controlling the embryonic stem cell (ESC) phenotype will aid the development of cell-based therapies. While the role of extracellular factors in controlling the pluripotency and differentiation of embryonic stem cells (ESCs) has been the subject of much investigation, the identity and role of extrinsic factors in modulating ESC growth under conditions supporting self-renewal remain largely unknown. We demonstrate that mouse ESC (mESC) growth is density dependent and that one of the mechanisms underlying this phenomenon is the action of survival-enhancing autocrine factors. Proteomic analysis of proteins secreted by mouse ESCs demonstrates significant levels of cyclophilin A which increases the growth rate of mouse ESCs in a dose-dependent manner. Additionally, inhibition of the cyclophilin A receptor CD147 decreases the growth rate of mESCs. These findings identify cyclophilin A as a novel survival-enhancing autocrine factor in mouse ESC cultures.

Profiling pancreatic cancer-secreted proteome using 15N amino acids and serum-free media

OBJECTIVES

A new method of determining protein turnover by labeling protein with N amino acids was used in conjunction with serum-free cell culture to profile secreted proteins that are released by MIA PaCa-2 pancreatic cancer cells in culture.

METHODS

MIA PaCa-2 cells were first cultured in Dulbecco modified Eagle medium (Gibco by Invitrogen, Carlsbad, Calif) with 10% fetal bovine serum, then in serum-free modified Eagle medium with or without 50% N algal amino acid mixture. The effect of oxythiamine chloride on secreteome was studied. Secreteome from cell culture media was analyzed by 2-dimensional (2D) gel electrophoresis. Differentially expressed proteins were detected and identified. Protein turnover rates were calculated according to the newly established method. Western blot and enzyme-linked immunosorbent assay were used to validate identified proteins.

RESULTS

Among the 14 differentially expressed proteins after oxythiamine treatment, tissue inhibitor of metalloproteases-1 and cytokeratin-10 were identified as 2 newly synthesized secreted proteins caused by substantial N incorporation. The inhibition of tissue inhibitor of metalloproteases-1 expression in MIA PaCa-2 cells by oxythiamine treatment was first demonstrated by 2D gel electrophoresis and further validated by Western blotting and enzyme-linked immunosorbent assay analyses.

CONCLUSIONS

Our method of labeling protein with N amino acids in conjunction with serum-free cell culture allows the identification of actively secreted proteins from pancreatic cancer cells and is a useful method for serum biomarker discovery.

Embryonic stem cells in cardiac repair and regeneration

Cell transplantation is a subject of fast-growing research with a potential of a therapeutic approach for the treatment of heart diseases. Clinical applications require preparation of large number of donor cells. Stem cell studies published to date demonstrate that scientists have not reached the general consensus to use an optimal cell type for better cardiac repair and regeneration. We used embryonic stem (ES) cells and their released factors for cardiac repair and regeneration. The major concern of cardiac regeneration with stem cells includes engraftment, differentiation, and teratoma formation after ES cell transplantation. Our current knowledge of ES cell transplantation in the heart is very limited. This review discusses the use of various growth factors to enhance ES cells engraftment and differentiation, as well as the issue of teratoma formation.