Bone marrow-derived mesenchymal stem cells (BMSCs) are multipotent stem cells that differentiate into a variety of cell types and widely used in tissue regeneration engineering. The purpose of this study is to investigate whether the cyclic biaxial stretching strain could promote the rat BMSCs (rBMSCs) to differentiate into cardiomyocyte-like cells in vitro. The second or third generation of rBMSCs were randomly divided into the cyclic stretching stain group, the control group and the blank group. Those rBMSCs in the cyclic stretching strain group were seeded on a silicone membrane with complete medium were exposed to biaxial stretching strain of 10% of membrane at a frequency of 1 Hz lasting for 6 h, 12 h and 24 h. Those in the control group were seeded on silicone membrane with complete medium. Those in the blank group were seeded in the 6-wells plates with complete medium. The mRNA expression of GATA4 and myocyte-specific enhancer factor 2C (MEF-2C) were detected by the real-time fluorescent quantification PCR and the protein expression of connexin 43 (Cx43) was detected by using the Western blot method. The results showed that the mRNA expression level of the GATA4 and MEF-2C, and the protein expression level of Cx43 were significantly higher in the cyclic stretching strain groups, compared with those in the relative control groups (P<0.05). It suggests that cyclic biaxial stretching strain could play a part in the induction of rBMSCs to differentiate into cardiomyocyte-like cells in vitro, but the differentiation mechanism is still unclear.
The aim of the current study is to investigate the effect of visfatin on cardiomyocyte hypertrophy. Cultured H9c2 cardiomyocytes were exposed to visfatin at different concentrations for different periods of time, and the markers of cardiomyocyte hypertrophy were detected. Moreover, pravastatin, the inhibitor of endoplasmic reticulum stress (ERS) or thapsigargin, an ERS agonist was used respectively to pre-treat the cells before visfatin stimulation. F-actin staining was performed to measure the cell surface change. The mRNA expressions of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP)and ERS markers including glucose-regulated protein 78(GRP78), C/EPB homologous protein (CHOP) and activating transcription factor 6 (ATF6) were assessed by real time RT-PCR. The change of protein level of GRP78 and CHOP was detected by Western blot. The experimental data demonstrated that exposure to 100 or 150 ng/mL concentrations of visfatin for 24 h, or 100 ng/mL of visfatin for 24 or 48 h, significantly increased the expression of markers for cardiomyocyte hypertrophy. Visfatin stimulation provoked ERS in H9c2 cells. Furthermore, pre-treatment with pravastatin partially inhibited the visfatin-induced mRNA expression of ANP and BNP in H9c2 cells, whereas thapsigargin promoted the visfatin-induced expression of cardiomyocyte hypertrophy markers. The results suggest that visfatin might induce cardiomyocyte hypertrophy via ERS -dependent pathways.
With the discovery of cardiac stem cell, the conception of the heart considered to be a terminally differentiated organ was changed. Cardiac stem cells possess the common characteristics of self-renew, clone formation and differentiating into cardiomyocyte, smooth muscle cell, and endothelial cell. Because of the properties of tissue specificity and lineage commitment, cardiac stem cells are considered to have great advantages over other stem cells in the treatment of cardiovascular disease. However, the low rate of engraftment still remains a problem to be solved. In recent years, people attempted to combine stem cell therapy with other ways, such as tissue engineering, gene therapy, exosome therapy, to cure cardiovascular diseases, aiming at finding better ways to treat the cardiovascular disease. This article is mainly for the reviewing of the mechanisms underlying the stem cell therapy and the combinatory use of new technology emerged these years.
Objective To establish a model of transplanting neonatal cardiomycytes into the wall of rat inferior vena cava. Methods Neonatal cardiomyocytes (n=6, 5×106cells each, A group) or medium (n=6, B group) only were transplanted into the wall of inferior vena cava in female Fisher rats. At 21 days after transplantation, the contraction of transplanted cardiomyocytes was assessed and the inferior vena cava was processed for histology. Results Distinct rhythmic beating of the vena cava at the site of cell transplantation before and after the aorties were clamped (at a rate 141± 47 rpm and 88± 44 rpm which was dramaticly lower than aortic beating, with a statistical difference at P value of 0.03). Cardiomyocyte was seen in 6 rats who had neonatal cardiomyocyte transplantation, but not in 6 rats receiving media. Hematoxylin and eosin staining showed viable cardiomyocytes in the wall of the vena cava in 6 rats treated with neonatal cardiomyocytes, but not in 6 rats receiving media. Conclusion This study shows that neonatal cardiomyocytes can survive, mature and spontaneously and rhythmically contract after they are transplanted in the wall of inferior vena cava.
Objective To investigate whether recombinant human serum albumin (rHSA) can replace traditional B27 as a basic medium for differentiation of human pluripotent stem cells (hPSCs) into cardiomyocytes. Methods hPSCs were seeded at a cell density of 1.2×104/cm2; until up to 75% confluency hPSCs were induced by differentiation medium containing various concentration of rHSA (0, 50, 100, 200 g/L). Light microscope and fluorescence microscope recorded the whole process of stem cells differentiating into myocardium. Flow cytometry was used to detect the cardiac differentiation efficiency at different concentrations of rHSA. Immunofluorescence staining was used to detect the cardiac specific protein α-actinin and troponin T (cTnT) and electron microscope to observe the ultrastructure of human pluripotent stem cell-derived cardiomyocytes (hPSC-CM) and beating rates of hPSC-CMs response to drugs. Results A large number of spontaneous beating cardiomyocytes were observed 9 days after induction and differentition. The percentage of colonies showing beating cardiomyocytes was 60.4% at the concentration of 200 g/L of rice derived-rHSA. Beating cardiomyocytes were α-actinin and cTnT positive. Ultrastructural analysis showed scattered sarcomeres and mitochondrial. hPSC-CMs were dose-dependent on isopropyl adrenaline and verapamil. Conclusion Using such simple media to differentiate hPSCs into functional cardiomyocytes is cost-effective and highly efficient, and can be used in the clinical research.
This study aimed to explore the role of miR-130a-3p in cardiomyocyte hypertrophy and its underlying mechanisms. Pressure-overload induced myocardial hypertrophy mice model was constructed by thoracic aortic constriction (TAC). In vitro, norepinephrine (NE) was used to stimulate neonatal rat cardiomyocytes (NRCMs) and H9c2 rat cardiomyocytes to induce hypertrophic phenotypes. The expression of miR-130a-3p was detected in mice hypertrophic myocardium, hypertrophic NRCMs and H9c2 cells. The mimics and inhibitors of miR-130a-3p were transfected into H9c2 cells to observe the role of miR-130a-3p on the hypertrophic phenotype change of cardiomyocytes separately. Furthermore, whether miR-130a-3p regulated hypertrophic related signaling pathways was explored. The results showed that the expression of miR-130a-3p was significantly decreased in hypertrophic myocardium, hypertrophic NRCMs and H9c2 cells. After transfection of miR-130a-3p mimics, the expression of hypertrophic marker genes, atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and β-myosin heavy chain (β-MHC), and the cell surface area were notably down-regulated compared with the control group (mimics N.C. + NE group). But after transfection of miR-130a-3p inhibitor, the expression of ANP, BNP and β-MHC in H9c2 cells increased significantly, and the cell area increased further. By Western blot, it was found that the protein phosphorylation level of Akt and mTOR were down-regulated after over-expression of miR-130a-3p. These results suggest that miR-130a-3p mimics may alleviate the degree of cardiomyocyte hypertrophy, meanwhile its inhibitor can further aggravate cardiomyocyte hypertrophy. Over-expression of miR-130a-3p may attenuate cardiomyocytes hypertrophy by affecting the Akt pathway.
Hypoxia inducible factor-1 (HIF-1) is the main transcription factor and the core regulator for cells to adapt to hypoxia, and oxygen homeostasis is achieved by controlling and utilizing oxygen delivery. Autophagy and apoptosis play an important role in determining cell fate and maintaining cell homeostasis. In recent years, it has been found that the dynamic change of HIF-1 expression plays a key role in the hypoxic adaptive response of cardiomyocytes. The regulation of HIF-1 on autophagy and apoptosis of hypoxic cardiomyocytes determines the survival of cardiomyocytes, which is of great significance for the prognosis of ischemic heart disease.
ObjectiveTo explore the role of joint regulation of Wnt and bone morphogenetic protein (BMP) signaling pathways in the differentiation of human induced pluripotent stem cells (hiPSCs) into cardiomyocytes.MethodsHiPSCs were cultured and observed under inverted phase contrast microscope. Immunofluorescence staining was used to observe the expressions of hiPSCs pluripotent markers (OCT3/4, NANOG, and TRA-1-60). HiPSCs were passaged which were taken for subsequent experiments within the 35th passage. When the fusion degree of hiPSCs was close to 100%, the CHIR99021 (Wnt pathway activator) was added on the 0th day of differentiation. Different concentrations of IWP4 (inhibitor of Wnt production) were added on the 3rd day of differentiation, and the best concentration of IWP4 was added at different time points. The optimal concentration and the best effective period of IWP4 were obtained by detecting the expression of troponin T (TNNT2) mRNA by real-time fluorescence quantitative PCR. Then, on the basis of adding CHIR99021 and IWP4, different concentrations of BMP-4 were added on the 5th day of differentiation, and the best concentration of BMP-4 was added at different time points. The optimal concentration and best effective period of BMP-4 were obtained by detecting the expression of TNNT2 mRNA. Finally, hiPSCs were divided into three groups: Wnt group, BMP group, and Wnt+BMP group. On the basis of adding CHIR99021 on the 0th day of differentiation, IWP4, BMP-4, and IWP4+BMP-4 were added into Wnt group, BMP group, and Wnt+BMP group respectively according to the screening results. Cells were collected on the 7th and the 15th days of differentiation. The expressions of myocardial precursor cell markers [ISL LIM homeobox 1 (ISL1), NK2 homeobox 5 (NKX2-5)] and cardiomyocyte specific markers [myocyte enhancer factor 2C (MEF2C), myosin light chain 2 (MYL2), MYL7, and TNNT2] were detected by real-time fluorescent quantitative PCR. Cells were collected on the 28th day of differentiation, and the expression of cardiac troponin T (cTnT) was detected by flow cytometry and immunofluorescence staining.ResultsThe results of cell mophology and immunoflurescence staining showed that the OCT3/4, NANOG, and TRA-1-60 were highly expressed in hiPSCs, which suggested that hiPSCs had characteristics of pluripotency. The optimal concentration of IWP4 was 10.0 μmol/L (P<0.05) and the best effective period was the 3rd day (P<0.05) in inducing hiPSCs to differentiate into cardiomyocytes. The optimal concentration of BMP-4 was 20.0 ng/mL (P<0.05) and the best effective period was the 3rd day (P<0.05). The relative expressions of ISL1, NKX2-5, MEF2C, MYL2, MYL7, and TNNT2 mRNAs, the positive expression ratio of cTnT detected by flow cytometry, and sarcomere structure detected by immunofluorescence staining of Wnt+BMP group were superior to those of Wnt group (P<0.05).ConclusionJoint regulation of Wnt and BMP signaling pathways can improve the differentiation efficiency of hiPSCs into cardiomyocytes.
Objective To investigate the effect of ginkgolide B (GB) on cysteinyl aspartate specific proteinase-3 (Caspase-3)/chromosome 10 deletion phosphatase-tension protein homologue (PTEN)/protein kinase B (Akt) pathway and cell proliferation and apoptosis in hypoxia/reoxygenation cardiomyocytes. Methods H9C2 cells were cultured in vitro. A control group was cultured in serum-free DMEM high glucose medium at 37°C and 5% CO2 for 28 hours. The remaining groups were prepared with hypoxia/reoxygenation models. A GB low-dose group and a GB high-dose group were treated with GB pretreatment with final concentration of 50 μmol/L and 200 μmol/L respectively at 1 h before hypoxia/reoxygenation. A carvedilol group was treated with carvedilol of a final concentration of 10 μmol/L at 1 h before hypoxia/reoxygenation. The proliferation and apoptosis of H9C2 cells were detected, and the levels of lactate dehydrogenase (LDH), malondialdehyde (MDA), reactive oxygen species (ROS), PTEN, Akt, phosphorylated Akt (p-Akt) and Caspase-3 in H9C2 cells were also detected. Results Compared with the control group, the proliferation rate of H9C2 cell, and the levels of PTEN, Akt and p-Akt in other groups decreased, and the apoptosis rate, and the levels of LDH, MDA, ROS and Caspase-3 increased (P<0.05). Compared with the hypoxia/reoxygenation group, the proliferation rate of H9C2 cell, and the levels of PTEN, Akt and p-Akt in all GB dose groups and the carvedilol group increased; the apoptosis rate, and the levels of LDH, MDA, ROS and Caspase-3 decreased, and the effect of GB was in a dose dependent manner; however, the effect of GB was not as strong as carvedilol (P<0.05). Conclusion GB can inhibit H9C2 cell apoptosis and promote H9C2 cell proliferation by activating Caspase-3/PTEN/Akt pathway.
Objective To investigate the expression of miR-31a-5p in myocardial infarction (MI) mice and its potential mechanism. Methods A dataset was downloaded from the gene expression database, and miR-31a-5p and its predicted target gene hypoxia-inducible factor-1α (HIF-1α) were screened using bioinformatics methods. The MI model was established by ligating the left anterior descending branch of the coronary artery in C57BL/6J male mice which were randomly divided into sham and MI groups (n=6 in each group). The in vitro hypoxic cell model was induced by treatment of H9c2 cells with cobalt chloride (CoCl2) and divided into a control group, a model group, a NC group, a miR-31a-5p mimic group and a miR-31a-5p inhibitor group. The degree of myocardial tissue fibrosis was stained by Masson and analyzed. The expression levels of miR-31a-5p and HIF-1α mRNA in mouse myocardial tissues and H9c2 cells were detected by qRT-PCR. Western blotting was used to detect the expression levels of B-cell lymphoma 2 (Bcl-2), cleaved-caspase 3 apoptotic protein in mouse myocardial tissues and HIF-1α and apoptotic protein in H9c2 cells, respectively. The dual luciferase reporter gene assay was used to verify the targeting relationship between miR-31a-5p and HIF-1α. Results Masson staining showed significantly increased fibrosis in MI mice (P<0.000 1); miR-31a-5p, cleaved-caspase 3 were significantly elevated and Bcl-2 was decreased in MI mice and CoCl2 treated H9c2 (P<0.05). The results of dual luciferase reporter assay showed that the relative luciferase activity of miR-31a-5p mimic cotransfected with HIF-1α-3'-UTR WT plasmid was reduced (P<0.000 1); miR-31a-5p mimic decreased HIF-1α expression and increased apoptotic protein levels in CoCl2 induced H9c2 cells (both P<0.05), while miR-31a-5p exerted the opposite effect. Conclusion miR-31a-5p can aggravate apoptosis in myocardial ischemia by targeting HIF-1α.