Regulated cell death pathways in cardiomyopathy.

Heart disease is a worldwide health menace. Both intractable primary and secondary cardiomyopathies contribute to malignant cardiac dysfunction and mortality. One of the key cellular processes associated with cardiomyopathy is cardiomyocyte death. Cardiomyocytes are terminally differentiated cells with very limited regenerative capacity. Various insults can lead to irreversible damage of cardiomyocytes, contributing to progression of cardiac dysfunction. Accumulating evidence indicates that majority of cardiomyocyte death is executed by regulating molecular pathways, including apoptosis, ferroptosis, autophagy, pyroptosis, and necroptosis. Importantly, these forms of regulated cell death (RCD) are cardinal features in the pathogenesis of various cardiomyopathies, including dilated cardiomyopathy, diabetic cardiomyopathy, sepsis-induced cardiomyopathy, and drug-induced cardiomyopathy. The relevance between abnormity of RCD with adverse outcome of cardiomyopathy has been unequivocally evident. Therefore, there is an urgent need to uncover the molecular and cellular mechanisms for RCD in order to better understand the pathogenesis of cardiomyopathies. In this review, we summarize the latest progress from studies on RCD pathways in cardiomyocytes in context of the pathogenesis of cardiomyopathies, with particular emphasis on apoptosis, necroptosis, ferroptosis, autophagy, and pyroptosis. We also elaborate the crosstalk among various forms of RCD in pathologically stressed myocardium and the prospects of therapeutic applications targeted to various cell death pathways.

MRTF-A alleviates myocardial ischemia reperfusion injury by inhibiting the inflammatory response and inducing autophagy.

Myocardin-related transcription factor A (MRTF-A) has an inhibitory effect on myocardial infarction; however, the mechanism is not clear. This study reveals the mechanism by which MRTF-A regulates autophagy to alleviate myocardial infarct-mediated inflammation, and the effect of silent information regulator 1 (SIRT1) on the myocardial protective effect of MRTF-A was also verified. MRTF-A significantly decreased cardiac damage induced by myocardial ischemia. In addition, MRTF-A decreased NLRP3 inflammasome activity, and significantly increased the expression of autophagy protein in myocardial ischemia tissue. Lipopolysaccharide (LPS) and 3-methyladenine (3-MA) eliminated the protective effects of MRTF-A. Furthermore, simultaneous overexpression of MRTF-A and SIRT1 effectively reduced the injury caused by myocardial ischemia; this was associated with downregulation of inflammatory factor proteins and when upregulation of autophagy-related proteins. Inhibition of SIRT1 activity partially suppressed these MRTF-A-induced cardioprotective effects. SIRT1 has a synergistic effect with MRTF-A to inhibit myocardial ischemia injury through reducing the inflammation response and inducing autophagy.

Regulation of Vascular Calcification by Growth Hormone-Releasing Hormone and Its Agonists.

RATIONALE: Vascular calcification (VC) is a marker of the severity of atherosclerotic disease. Hormones play important roles in regulating calcification; estrogen and parathyroid hormones exert opposing effects, the former alleviating VC and the latter exacerbating it. To date no treatment strategies have been developed to regulate clinical VC. OBJECTIVE: The objective of this study was to investigate the effect of growth hormone-releasing hormone (GHRH) and its agonist (GHRH-A) on the blocking of VC in a mouse model. METHODS AND RESULTS: Young adult osteoprotegerin-deficient mice were given daily subcutaneous injections of GHRH-A (MR409) for 4 weeks. Significant reductions in calcification of the aortas of MR409-treated mice were paralleled by markedly lower alkaline phosphatase activity and a dramatic reduction in the expression of transcription factors, including the osteogenic marker gene Runx2 and its downstream factors, osteonectin and osteocalcin. The mechanism of action of GHRH-A was dissected in smooth muscle cells isolated from human and mouse aortas. Calcification of smooth muscle cells induced by osteogenic medium was inhibited in the presence of GHRH or MR409, as evidenced by reduced alkaline phosphatase activity and Runx2 expression. Inhibition of calcification by MR409 was partially reversed by MIA602, a GHRH antagonist, or a GHRH receptor-selective small interfering RNA. Treatment with MR409 induced elevated cytosolic cAMP and its target, protein kinase A which in turn blocked nicotinamide adenine dinucleotide phosphate oxidase activity and reduced production of reactive oxygen species, thus blocking the phosphorylation of nuclear factor κB (p65), a key intermediate in the ligand of receptor activator for nuclear factor-κ B-Runx2/alkaline phosphatase osteogenesis program. A protein kinase A-selective small interfering RNA or the chemical inhibitor H89 abolished these beneficial effects of MR409. CONCLUSIONS: GHRH-A controls osteogenesis in smooth muscle cells by targeting cross talk between protein kinase A and nuclear factor κB (p65) and through the suppression of reactive oxygen species production that induces the Runx2 gene and alkaline phosphatase. Inflammation-mediated osteogenesis is thereby blocked. GHRH-A may represent a new pharmacological strategy to regulate VC.

[Analysis of Factors Influencing Peripheral Blood Stem Cell Collection of 151 Lymphoma Cases].

OBJECTIVE: To analyze the influential factors related to mobilization and collection of stem cells so as to improve the collection efficiency of autologous peripheral stem cell transplantation in lymphoma patients. METHODS: The peripheral blood stem cell collection data of 151 cases of lymphoma in our hospital was analyzed retrospectively. The relationship between the harvested CD34(+) stem cells and some factors, such as age, sex, height, weight, histological type, staging, mobilization programs, collecting days, blood transfusion, time and duration of chemotherapy, was analyzed. RESULTS: The single factor analysis showed that sex, height, weight, histological type, staging, mobilization program, collecting days, blood transfusion were not significantly associated with CD34(+) stem cells collection, respectively. Age (r = -0.248, P = 0.002), duration of sick and cycles of chemotherapy were significantly associated with CD34(+) cell collection. At the age older than 50 years, the collected CD34(+) cell number decreased significantly; and at the age older than 60 years, the CD34(+) cell number was greatly reduced; CD34(+) cells non-significantly correlated with peripheral blood WBC (r = 0.053, P = 0.527), but significantly with the percentage of mononuclear cells (r = 0.260, P = 0.002) and the absolute value of mononuclear cells (r = 0.338, P = 0.00003) . CONCLUSION: The patients less than 60 years old, fewer chemotherapy cycles, shorter duration time or PB mononuclear cells between (2-6) × 10(9)/L may contribute to the better mobilization and collection of peripheral blood stem cells.

Fractional Flow Reserve Guided Percutaneous Coronary Intervention Improves Clinical Outcome with Reduced Cost in Contemporary Clinical Practice.

BACKGROUND: Fractional flow reserve (FFR) is currently considered as the gold standard for evaluating the functional significance of coronary stenosis. However, its potential benefits in real-world practice remain unknown in China. This study aimed to test the hypothesis that the use of FFR is associated with improved outcome and reduced cost in Chinese real-world clinical practice. METHODS: A retrospective cohort study was carried out using the database of Second Affiliated Hospital of Zhejiang University, a tertiary and high-volume center in China. Clinical events were compared using the Cox proportional hazards model during a median follow-up of 13 months. RESULTS: The study cohort consisted of 366 consecutive patients referred for coronary revascularization with adjunct FFR and 366 matched controls, from 2010 to 2014. Major adverse cardiac events (MACEs) (death, myocardial infarction, repeated revascularization, or hospitalization for angina) at 4 years were found in 12.0% of angiography-guided patients and 4.9% in the FFR-guided group (P < 0.001). The mean number of implanted stents was significantly lower in FFR treated subjects (0.52 ± 0.82 stents) compared with the angiography-guided group (0.93 ± 0.96 stents) (P < 0.001). No difference in overall costs at initial hospitalization was observed between angiography-guided percutaneous coronary intervention (PCI) compared with FFR-guided PCI (RMB 33,000 Yuan, range: RMB 7393-44,700 Yuan) versus RMB 21,200 Yuan (RMB 19,100-47,100 Yuan) (P = 0.54). However, costs for MACEs during follow-up were significantly reduced in the FFR-guided arm (P < 0.001). CONCLUSIONS: In the contemporary clinical practice, FFR-guided PCI is associated with decreased use of stents, improved clinical outcome, and reduced costs, compared with angiography-guided PCI.

Meta-analysis of C242T polymorphism in CYBA genes: risk of acute coronary syndrome is lower in Asians but not in Caucasians.

BACKGROUND: A lot of studies have demonstrated that C242T polymorphism in CYBA genes may play an important role in the pathological process of acute coronary syndrome (ACS). However, the results are not consistent. To further evaluate this debate, we performed a meta-analysis to determine the relationship between C242T polymorphism and ACS. METHODS AND RESULTS: We screened PubMed/MEDLINE, EBSCIO, and EMBASE research reports until Mar. 2014 and extracted data from 10 studies involving 6102 ACS patients and 8669 controls. Subgroup analysis by ethnicity documented a significant decreased risk of ACS for C242T polymorphism in the Asian population under allelic comparison (odd ratio (OR) 0.73; 95% confidence intervals (CI) 0.64-0.83), dominant model (OR 0.71; 95% CI 0.62-0.82), and homozygote comparison (OR 0.57; 95% CI 0.35-0.92). However, in the overall population and especially with Caucasians, no significant association was uncovered. Further meta-regression analysis revealed that the heterogeneity among studies was largely attributed to ethnicity. No publication bias was detected through a funnel plot and an Egger's linear regression test. CONCLUSIONS: Taken together, our results suggest that the C242T polymorphism might be a protective factor against developing ACS in the Asian population. Further researches will be needed to identify the confounding factors which modified the protective effect of T allele among Caucasians.

Gorham-Stout syndrome in mainland China: a case series of 67 patients and review of the literature.

OBJECTIVE: Gorham-Stout syndrome (GSS) is a rare disorder of uncertain etiology and unpredictable prognosis. This study aims to present a comprehensive understanding of this rare entity. METHODS: A literature search in PubMed and three Chinese databases was performed to screen histologically proven GSS cases among Chinese residents in the mainland. We analyzed the patients' clinical characteristics, the value of different treatment modalities and their influence on the clinical outcome. RESULTS: Sixty-seven cases were finally enrolled. There were 43 men (64.2%) and 24 women (35.8%). The mean age at diagnosis was 28 years (1.5-71 years). The most common clinical symptoms included pain (n=40, 59.7%), functional impairment (n=13, 19.4%), and swelling (n=12, 17.9%). The radiographic presentation of 37 cases (55.2%) was disappearance of a portion of the bone. The others presented as radiolucent foci in the intramedullary or subcortical regions. A total of 42 cases provided data on therapy, these included surgery (n=27, 40.3%), radiation therapy (n=6, 9.0%), surgery combined with radiation therapy (n=2, 3.0%), and medicine therapy (n=7, 10.4%). For 30 of these 42 cases, follow-up data were available: 21 cases had the disorder locally controlled and 9 had a symptom progression. Fortunately, the disease is not fatal in the majority of cases. CONCLUSIONS: GSS has no specific symptoms and it should be taken into consideration when an unclear massive osteolysis occurs. The efficacies of different treatment modalities are still unpredictable and further research is required to assess the values of different treatments.

Angiopoietin-1 preconditioning enhances survival and functional recovery of mesenchymal stem cell transplantation.

OBJECTIVE: Mesenchymal stem cell (MSC) transplantation is a promising therapy for ischemic heart diseases. However, poor cell survival after transplantation greatly limits the therapeutic efficacy of MSCs. The purpose of this study was to investigate the protective effect of angiopoietin-1 (Ang1) preconditioning on MSC survival and subsequent heart function improvement after transplantation. METHODS: MSCs were cultured with or without 50 ng/ml Ang1 in complete medium for 24 h prior to experiments on cell survival and transplantation. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Hoechst staining were applied to evaluate MSC survival after serum deprivation in vitro, while cell survival in vivo was detected by terminal deoxynucleotidyl transferase biotin-dUPT nick end labeling (TUNEL) assay 24 and 72 h after transplantation. Heart function and infarct size were measured four weeks later by small animal echocardiography and Masson's trichrome staining, respectively. RESULTS: Ang1 preconditioning induced Akt phosphorylation and increased expression of Bcl-2 and the ratio of Bcl-2/Bax. In comparison with non-preconditioned MSCs, Ang1-preconditioned cell survival was significantly increased while the apoptotic rate decreased in vitro. However, the PI3K/Akt pathway inhibitor, LY294002, abrogated the protective effect of Ang1 preconditioning. After transplantation, the Ang1-preconditioned-MSC group showed a lower death rate, smaller infarct size, and better heart functional recovery compared to the non-preconditioned-MSC group. CONCLUSIONS: Ang1 preconditioning enhances MSC survival, contributing to further improvement of heart function.

Complex coronary lesions and rotational atherectomy: one hospital's experience.

OBJECTIVE: To evaluate the safety and effectiveness of rotational atherectomy followed by drug eluting stent (DES) implantation in patients with complex coronary lesions. METHODS: From August 2006 to August 2012, 253 consecutive patients with 289 lesions and who underwent rotational atherectomy in our center were enrolled in this study. RESULTS: The overall procedure success rate was 98% with the cost of two (0.8%) coronary perforations, three (1.2%) dissections, five (2.0%) slow flows or no flows, three (1.2%) peri-procedure myocardial infarctions, and two (0.8%) in hospital deaths. During follow-up (mean three years), one (0.4%) patient died, two (0.8%) patients had acute myocardial infarction, 14 (5.5%) had restenosis, and target lesion revascularization occurred in eight patients (3.2%). CONCLUSIONS: Rotational atherectomy followed by DES implantation is a safe and effective technique for patients with complex coronary lesions, especially calcified and non-dilatable lesions.

[One-stop hybrid cardiac surgery for adults with complex heart disease].

OBJECTIVE: To evaluate the efficacy and security of one-stop hybrid cardiac surgery for the treatment of adult patients with complex heart disease. METHODS: From November 2011 to March 2012, a total of 5 patients [4 male, mean age: (58.8 ± 14.7) years] underwent one-stop hybrid approach in the hybrid operating room. Two patients suffered from multi-coronary lesions, 2 patients were diagnosed with both valvular heart disease and coronary disease, and another 1 patient had valve disease and congenital heart disease (patent ductus arteriosus). Minimally invasive cardiac surgery (coronary artery bypass grafting for the left anterior descending or valvular surgery) and percutaneous intervention were performed in an enhanced operative unit. The efficacy and security of one-stop hybrid cardiac surgery were evaluated after the procedure. RESULTS: The one-stop hybrid procedure was successful in all patients. Left internal mammary artery grafts were unobstructed. A total of 6 non-left anterior descending coronary lesions were treated by percutaneous coronary intervention and 6 drug-eluting stents were implanted. There was no death, perioperative myocardial infarction, heart failure, prosthetic valve dysfunction, respiratory failure, stroke or repeat surgery during the procedure period. All patients remained free from angina, prosthetic valve dysfunction and patent ductus arteriosus recanalisation during the 3.2 months (rang 1 to 5 months) follow-up period. CONCLUSION: One-stop hybrid cardiac surgery provides a reasonable, feasible and safe alternative for treating adult patients with complex heart disease.

Nerve growth factor induces cord formation of mesenchymal stem cell by promoting proliferation and activating the PI3K/Akt signaling pathway.

AIM: To investigate whether nerve growth factor (NGF) induced angiogenesis of bone marrow mesenchymal stem cells (MSCs) and the underlying mechanisms. METHODS: Bone marrow MSCs were isolated from femors or tibias of Sprague-Dawley rat, and cultured. The cells were purified after 3 to 5 passages, seeded on Matrigel-coated 24-well plates and treated with NGF. Tube formation was observed 24 h later. Tropomyosin-related kinase A (TrkA) and p75NTR gene expression was examined using PCR analysis and flow cytometry. Growth curves were determined via cell counting. Expression of VEGF and pAkt/Akt were analyzed with Western blot. RESULTS: NGF (25, 50, 100 and 200 µg/L) promoted tube formation of MSCs. The tubular length reached the maximum of a 2.24-fold increase, when the cells were treated with NGF (50 µg/L). NGF (50 µg/L) significantly enhanced Akt phosphorylation. Pretreatment with the specific PI3K inhibitor LY294002 (10 µmol/L) blocked NGF-stimulated Akt phosphorylation, tube formation and angiogenesis. NGF (25-200 µg/L) did not affect the expression of TrkA and vascular endothelial growth factor (VEGF), but significantly suppressed the expression of p75NTR. NGF (50 µg/L) markedly increased the proliferation of MSCs. CONCLUSION: NGF promoted proliferation of MSCs and activated the PI3K/Akt signaling pathway, which may be responsible for NGF induction of MSC angiogenesis.

Tongxinluo promotes mesenchymal stem cell tube formation in vitro.

OBJECTIVE: To study whether Tongxinluo (TXL) can induce angiogenesis in bone marrow mesenchymal stem cells (MSCs), and to investigate the underlying mechanism. METHODS: Bone marrow MSCs were obtained from male Sprague-Dawley rats. We established an angiogenesis model in vitro via matrigel experiment. MSCs were seeded on matrigel coated 24-well plates, and treated by TXL 50 and 100 mg/L. After 24 h, we observed the tube formations of MSCs in the matrigel. Cell migration ability was examined by wound scratch test and transwell assay. Expressions of vascular endothelial growth factor (VEGF), fetal liver kinase-1 (Flk-1), matrix metalloproteinase-2 (MMP-2), MMP-9, and tissue inhibitor of metalloproteinase-2 (TIMP-2) were analyzed at the protein level by Western blot. Gelatin zymography assay was applied to investigating the MSC paracrine abilities of pro-MMP-2 and activated MMP-2. RESULTS: TXL promoted MSC tube formation in matrigel. The ratio of TXL 100 mg/L treated-MSC tubular length was increased 3.04-fold compared to the control group (P<0.05). Scratch test and transwell assay showed that TXL could improve the cell migration ability of MSCs. Western blot experiments showed that TXL promoted MSC synthesis of MMP-2, but it had no influence on the expressions of MMP-9 and TIMP-2. This effect was confirmed by gelatin zymography assay, which showed that TXL increased MSC secretion of pro-MMP-2 and activated MMP-2. VEGF expression of TXL treated-MSCs was increased compared to the control group. The expression of Flk-1 was not different among the groups. CONCLUSIONS: This study demonstrates that TXL can promote the tube formation of MSCs, and the underlying mechanisms are associated with increased migration ability of MSCs and the up-regulation of MMP-2 and VEGF expressions.

Heat shock protein 90 protects rat mesenchymal stem cells against hypoxia and serum deprivation-induced apoptosis via the PI3K/Akt and ERK1/2 pathways.

Mesenchymal stem cell (MSC) transplantation has shown a therapeutic potential to repair the ischemic and infracted myocardium, but the effects are limited by the apoptosis and loss of donor cells in host cardiac microenvironment. The aim of this study is to explore the cytoprotection of heat shock protein 90 (Hsp90) against hypoxia and serum deprivation-induced apoptosis and the possible mechanisms in rat MSCs. Cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis was assessed by Hoechst 33258 nuclear staining and flow cytometric analysis with annexin V/PI staining. The gene expression of Toll-like receptor-4 (TLR-4) and V-erb-b2 erythroblastic leukemia viral oncogene homolog 2 (ErbB2) was detected by real-time polymerase chain reaction (PCR). The protein levels of cleaved caspase-3, Bcl-2, Bcl-xL, Bax, total-ERK, phospho-ERK, total-Akt, phospho-Akt, and Hsp90 were detected by Western blot. The production of nitric oxide was measured by spectrophotometric assay. Hsp90 improves MSC viability and protects MSCs against apoptosis induced by serum deprivation and hypoxia. The protective role of Hsp90 not only elevates Bcl-2/Bax and Bcl-xL/Bax expression and attenuates cleaved caspase-3 expression via down-regulating membrane TLR-4 and ErbB2 receptors and then activating their downstream PI3K/Akt and ERK1/2 pathways, but also enhances the paracrine effect of MSCs. These findings demonstrated a novel and effective treatment strategy against MSC apoptosis in cell transplantation.

Optimal time for mesenchymal stem cell transplantation in rats with myocardial infarction.

BACKGROUND: Bone marrow mesenchymal stem cell (MSC) transplantation is a promising strategy in the treatment of myocardial infarction (MI). However, the time for transplanting cells remains controversial. The aim of this study was to find an optimal time point for cell transplantation. METHODS: MSCs were isolated and cultured from Sprague-Dawley (SD) rats. MI model was set up in SD rats by permanent ligation of left anterior descending coronary artery. MSCs were directly injected into the infarct border zone at 1 h, 1 week and 2 weeks after MI, respectively. Sham-operated and MI control groups received equal volume of phosphate buffered saline (PBS). At 4 weeks after MI, cardiac function was assessed by echocardiography; vessel density was analyzed on hematoxylin-eosin stained slides by light microscopy; the apoptosis of cardiomyocytes was evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay; the expressions of proteins were analyzed by Western blot. RESULTS: MSC transplantation improved cardiac function, reduced the apoptosis of cardiomyocytes and increased vessel density. These benefits were more obvious in 1-week group than in 1-h and 2-week groups. There are more obvious increases in the ratio of bcl-2/bax and the expression of vascular endothelial growth factor (VEGF) and more obvious decreases in the expression of cleaved-caspase-3 in 1-week group than those in other two groups. CONCLUSION: MSC transplantation was beneficial for the recovery of cardiac function. MSC transplantation at 1 week post-MI exerted the best effects on increases of cardiac function, anti-apoptosis and angiogenesis.

Formation of Kv2.1-FAK complex as a mechanism of FAK activation, cell polarization and enhanced motility.

Focal adhesion kinase (FAK) plays key roles in cell adhesion and migration. We now report that the delayed rectifier Kv2.1 potassium channel, through its LD-like motif in N-terminus, may interact with FAK and enhance phosphorylation of FAK(397) and FAK(576/577). Overlapping distribution of Kv2.1 and FAK was observed on soma and proximal dendrites of cortical neurons. FAK expression promotes a polarized membrane distribution of the Kv2.1 channel. In Kv2.1-transfected CHO cells, formation of the Kv2.1-FAK complex was stimulated by fibronectin/integrin and inhibited by the K(+) channel blocker tetraethylammonium (TEA). FAK phosphorylation was minimized by shRNA knockdown of the Kv2.1 channel, point mutations of the N-terminus, and TEA, respectively. Cell migration morphology was altered by Kv2.1 knockdown or TEA, hindering cell migration activity. In wound healing tests in vitro and a traumatic injury animal model, Kv2.1 expression and co-localization of Kv2.1 and FAK significantly enhanced directional cell migration and wound closure. It is suggested that the Kv2.1 channel may function as a promoting signal for FAK activation and cell motility.

Increased levels of lipoprotein(a) in non-smoking aortic dissection patients.

OBJECTIVES: To investigate lipoprotein(a) (Lp(a)) serum levels in patients with aortic dissection and the influence of smoking on the level of Lp(a) in aortic dissection patients. METHODS: An age-and sex-matched case-control study was conducted. Lp(a) levels in patients with aortic dissection (n = 52) and healthy subjects (n = 104) were studied. The strength of associations between Lp(a) serum levels and aortic dissection was assessed by means of multivariate logistic regression analysis. RESULTS: Patients with aortic dissection had significantly higher Lp(a) serum levels (median, 17.6 mg/dl; range, 6.4-88.7 mg/dl) compared to healthy individuals (median, 12.4 mg/dl; range, 4.9-26.4 mg/dl) (p = 0.005). The Lp(a) concentration in non-smoking patients with aortic dissection (median, 19.1 mg/dl, range, 10.5-88.7 mg/dl) significantly surpassed that of the smoking patients with aortic dissection of comparable age (median, 10.7 mg/dl; range, 6.4-22.1 mg/dl) (p < 0.0001). Multivariate analysis confirmed an independent association between Lp(a) and aortic dissection in the non-smoking population (p = 0.001). CONCLUSIONS: Serum Lp(a) level is significantly elevated in non-smoking patients with aortic dissection independently of other cardiovascular risk factors. Therefore, determination of Lp(a) levels may be important in identifying subjects at risk of aortic dissection among nonsmokers.

Angiopoietin-1 protects mesenchymal stem cells against serum deprivation and hypoxia-induced apoptosis through the PI3K/Akt pathway.

AIM: The angiopoietin-1 (Ang1)/Tie-2 signaling system not only plays a pivotal role in vessel growth, remodeling, and maturation, but also reduces apoptosis of endothelial cells, neurons, and cardiomyocytes. However, relatively little is known as to whether Ang1 has a protective effect on mesenchymal stem cells (MSC). The aim of the present study was to investigate the protective effect of Ang1/Tie-2 signaling on MSC against serum deprivation and hypoxia-induced apoptosis, and to determine the possible mechanisms. METHODS: Hoechst 33342 and terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP nick-end labeling staining were used to assess the apoptosis of MSC. The expression of Tie-2, Akt, Bcl-2, Bax, and cleaved caspase-9 and -3 was detected by Western blot analysis. RESULTS: This study showed that MSC expressed Tie-2 receptor, and Ang1 induced Tie-2 receptor phosphorylation. The protective effect of Ang1 on MSC was dose-dependent and peaked at 50 microg/L; however, the soluble Tie-2/Fc fusion protein, which acts as an inhibitor by sequestering Ang1, abrogated the anti-apoptotic effect. Ang1 induced Akt phosphorylation, increased the Bcl-2/Bax ratio, and decreased the activation of caspase-9 and -3. All these effects were attenuated by Tie-2/Fc and a phosphatidylinositol 3 kinase (PI3K) inhibitor, wortmannin. CONCLUSION: These results demonstrate that Ang1 can protect MSC against serum deprivation and hypoxia-induced apoptosis; Ang1/Tie-2 signaling and its downstream PI3K/Akt messenger pathway are crucial in the processes leading to MSC survival.

Heregulin protects mesenchymal stem cells from serum deprivation and hypoxia-induced apoptosis.

Heregulin can regulate the survival of cardiomyocytes, epithelial cells, neuron, glial cells, and other cell types through binding with the ErbB receptors. The aim of this study is to investigate the effects of heregulin (HRG) on the apoptosis of Bone marrow Mesenchymal stem cells (MSCs). We used the MSCs from adult Sprague-Dawley rats and the model of serum deprivation (SD) and hypoxia-induced apoptosis. The apoptosis was detected by TUNEL method. The apoptosis of MSCs significantly increased 12 h or 18 h after SD and hypoxia, but treatment with HRG significantly decreased the apoptosis induced by SD and hypoxia. Tyrphostin AG1478 (ErbB3/4 inhibitor) or Tyrphostin AG825 (ErbB2 inhibitor) could block this effects of HRG. Akt and ERK were activated by HRG under SD and hypoxia conditions, but HRG had no effects on the activation of JNK and p38. HRG also increased the ratio of Bcl-2/Bax and decreased the activation of caspase3 induced by SD and hypoxia. These results suggested HRG could decrease the apoptosis of MSCs induced by SD and hypoxia through the activation of Akt and ERK, the increase of Bcl-2/Bax ratio and the inhibition of caspase3 activation.

Bone marrow mesenchymal stem cell transplantation combined with perindopril treatment attenuates infarction remodelling in a rat model of acute myocardial infarction.

OBJECTIVE: This study was performed to evaluate whether implantation of mesenchymal stem cell (MSC) would reduce left ventricular remodelling from the molecular mechanisms compared with angiotensin-converting enzyme inhibitors (ACEIs) perindopril into ischemic myocardium after acute myocardial infarction. METHODS: Forty rats were divided into four groups: control, MSC, ACEI, MSC+ACEI groups. Bone marrow stem cell derived rat was injected immediately into a zone made ischemic by coronary artery ligation in MSC group and MSC+ACEI group. Phosphate-buffered saline (PBS) was injected into control group. Perindopril was administered p.o. to ACEI group and MSC+ACEI group. Six weeks after implantation, the rats were killed and heart sample was collected. Fibrillar collagen was observed by meliorative Masson's trichome stain. Western Blotting was employed to evaluate the protein expression of matrix metalloproteinase (MMP)-2, matrix metalloproteinase (MMP)-9 in infarction zone. The transcriptional level of MMP2, MMP9 and tissue inhibitor of matrix metalloproteinase (TIMP)-1 in infarction area was detected by reverse transcriptase PCR (RT-PCR) analysis. RESULTS: The fibrillar collagen area, the protein expression of MMP2, MMP9 and the transcriptional level of MMP2, MMP9 mRNA in infarction zone reduced in MSC group, ACEI group, and MSC+ACEI group. No significant difference was detected in the expression of TIMP1 mRNA among the 4 groups. CONCLUSION: Both MSC and ACEI could reduce infarction remodelling by altering collagen metabolism.