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Biomedical subjects

Hiroaki Matsubara

Publications and source records attributed to Hiroaki Matsubara.

At least 19 recordsLinked to original sources

Human cardiac stem cells exhibit mesenchymal features and are maintained through Akt/GSK-3beta signaling.

Recent evidence suggested that human cardiac stem cells (hCSCs) may have the clinical application for cardiac repair; however, their characteristics and the regulatory mechanisms of their growth have not been fully investigated. Here, we show the novel property of hCSCs with respect to their origin and tissue distribution in human heart, and demonstrate the signaling pathway that regulates their growth and survival. Telomerase-active hCSCs were predominantly present in the right atrium and outflow tract of the heart (infant > adult) and had a mesenchymal cell-like phenotype. These hCSCs expressed the embryonic stem cell markers and differentiated into cardiomyocytes to support cardiac function when transplanted them into ischemic myocardium. Inhibition of Akt pathway impaired the hCSC proliferation and induced apoptosis, whereas inhibition of glycogen synthase kinase-3 (GSK-3) enhanced their growth and survival. We conclude that hCSCs exhibit mesenchymal features and that Akt/GSK-3beta may be crucial modulators for hCSC maintenance in human heart.

Adult↗

Skeletal myosphere-derived progenitor cell transplantation promotes neovascularization in delta-sarcoglycan knockdown cardiomyopathy.

Bone marrow cells have been shown to contribute to neovascularization in ischemic hearts, whereas their impaired maturation to restore the delta-sarcoglycan (delta-SG) expression responsible for focal myocardial degeneration limits their utility to treat the pathogenesis of cardiomyopathy. Here, we report the isolation of multipotent progenitor cells from adult skeletal muscle, based on their ability to generate floating-myospheres. Myosphere-derived progenitor cells (MDPCs) are distinguishable from myogenic C2C12 cells and differentiate into vascular smooth muscle cells and mesenchymal progeny. The mutation in the delta-SG has been shown to develop vascular spasm to affect sarcolemma structure causing cardiomyopathy. We originally generated delta-SD knockdown (KD) mice and transplanted MDPCs into the hearts. MDPCs enhanced neoangiogenesis and restored delta-SG expression in impaired vasculatures through trans-differentiation, leading to improvement of cardiac function associated with paracrine effectors secretion. We propose that MDPCs may be the promising progenitor cells in skeletal muscle to treat delta-sarcoglycan complex mutant cardiomyopathy.

Animals↗

MicroRNA-1 facilitates skeletal myogenic differentiation without affecting osteoblastic and adipogenic differentiation.

MicroRNAs (miRNAs) are small non-coding RNAs emerging as important post-transcriptional gene regulators. In this study, we examined the role of miR-1, an miRNA specifically expressed in cardiac and skeletal muscle tissue, on the myogenic, osteoblastic, and adipogenic differentiation of C2C12 cells. Upon induction of myogenic differentiation, miR-1 was robustly expressed. Retrovirus-mediated overexpression of miR-1 markedly enhanced expression of muscle creatine kinase, sarcomeric myosin, and alpha-actinin, while the effects on myogenin and MyoD expression were modest. Formation of myotubes was significantly augmented in miR-1-overexpressing cells, indicating miR-1 expression enhanced not only myogenic differentiation but also maturation into myotubes. In contrast, osteoblastic and adipogenic differentiation was not affected by forced expression of miR-1. Thus, the muscle-specific miRNA, miR-1, plays important roles in controlling myogenic differentiation and maturation in lineage-committed cells, rather than functioning in fate determination.

3T3-L1 Cells↗

Novel transcripts of Nox1 are regulated by alternative promoters and expressed under phenotypic modulation of vascular smooth muscle cells.

NADPH oxidase is implicated in the pathogenesis of various cardiovascular disorders. In vascular smooth muscle cells (VSMC), expression of NOX1 (NADPH oxidase 1), a catalytic subunit of NADPH oxidase, is low and is induced upon stimulation by vasoactive factors, while it is abundantly expressed in colon epithelial cells. To clarify the regulatory mechanisms underlying such cell-specific expression, the upstream regions directing transcription of the NOX1 gene were explored. In P53LMACO1 cells, a cell line originated from mouse VSMCs, two novel Nox1 mRNA species, the c- and f-type, were isolated. These transcripts contained 5'-untranslated regions that differed from the colon type mRNA (a-type) and encoded an additional N-terminal peptide of 28 amino acids. When these transcripts were fused to the c-myc tag and expressed in human embryonic kidney 293 cells, a fraction of translated proteins demonstrated the size containing the additional peptide. Proteins encoded by the c- and f-type mRNAs exhibited superoxide-producing activities equivalent to the activity of the a-type form. The a-type mRNA was expressed in the colon and in the intact aorta, whereas the c-type mRNA was detected in the primary cultured VSMCs migrated from aortic explants, in vascular tissue of a wire-injury model and in the thoracic aorta of mice infused with angiotensin II. The promoter region of the c-type mRNA exhibited transcriptional activity in P53LMACO1 cells, but not in MCE301 cells, a mouse colon epithelial cell line. These results suggest that expression of the Nox1 gene is regulated by alternative promoters and that the novel c-type transcript is induced under phenotypic modulation of VSMCs.

Angiotensin II↗

Glia maturation factor-gamma is preferentially expressed in microvascular endothelial and inflammatory cells and modulates actin cytoskeleton reorganization.

Actin cytoskeleton reorganization is a fundamental process for actin-based cellular functions such as cytokinesis, phagocytosis, and chemotaxis. Regulating actin cytoskeleton reorganization is therefore an attractive approach to control endothelial and inflammatory cells function and to treat cardiovascular diseases. Here, we identified glia maturation factor-gamma (GMFG) as a novel factor in actin cytoskeleton reorganization and is expressed preferentially in microvascular endothelial and inflammatory cells. During mouse embryogenesis, GMFG was expressed predominantly in blood islands of the yolk sac, where endothelial and hematopoietic cells develop simultaneously. In endothelial cells, GMFG was colocalized with F-actin in membrane ruffles and was associated with F-actin assessed by actin co-sedimentation assay. Interestingly, GMFG was phosphorylated at N-terminal serine, and its phosphorylation was enhanced by coexpression of dominant active Rac1 and Cdc42. Furthermore, a pseudophosphorylated form of GMFG (GMFG-S2E) demonstrated higher association with F-actin. Stable expression of GMFG-S2E remarkably enhanced stimulus-responsive lamellipodia and subsequent membrane ruffle formation in HeLa cells presumably through its interaction with Arp2/3 complex. Expression of GMFG enhanced actin-based cellular functions such as migration and tube-formation in endothelial cells. Moreover, we found that GMFG expression was significantly increased in a cardiac ischemia/reperfusion model where inflammation and angiogenesis take place actively. Taken together, our findings define a novel pathway in the regulation of actin-based cellular functions. Regulating GMFG function may provide a novel approach to modulate the pathophysiology of cardiovascular diseases.

Actin Depolymerizing Factors↗

Myocardium-targeted delivery of endothelial progenitor cells by ultrasound-mediated microbubble destruction improves cardiac function via an angiogenic response.

Application of ultrasound-mediated destruction of microbubbles (US + Bubble) to skeletal muscle creates capillary ruptures leading to leakage of the cell components. We studied whether US + Bubble combined with bone-marrow-derived mononuclear cells (BM-MNCs) infusion enables the targeted delivery of endothelial-lineage cells into the myocardium and improves cardiac function of the cardiomyopathy model due to the paucity of neocapillary formation. Pulsed US was applied to the anterior chest of BIOTO2 cardiomyopathy hamsters for 90 s after the intravenous injection of microbubble (Optison) followed by infusion of BM-MNCs. Cardiac samples from US + microbubble + BM-MNCs (US + Bubble + BM), US + Bubble, US + BM without Bubble, and saline infusion control groups were analyzed 12 weeks after treatment. Labeled BM-MNCs transplanted by US + Bubble were found to be mainly localized in the microvessels, but not by US stimulation without microbubble (121.2 +/- 24.5 vs. 2.80 +/- 1.30 cells/mm2, P < 0.001). Capillary densities in US + Bubble + BM group were increased 1.7-fold (P < 0.05) over the control, and neither US + Bubble nor US + BM enhanced neocapillary formation. 99mTc-Tetrofosmin scintigraphy revealed that blood perfusion area in the US + Bubble + BM group was 48% greater than the control (P < 0.01). US + Bubble stimulation induces the expression of adhesion molecules (VCAM-1 and ICAM-1) in capillaries, and the US + Bubble-mediated supply of BM-MNCs increased the myocardial content of VEGF and bFGF. The left ventricular wt/body wt, area of cardiac fibrosis, and apoptotic cell numbers in the US + Bubble + BM group significantly (P < 0.05) decreased by 82%, 73%, and 64% relative to the control, respectively. The cardiac function in myopathic hamsters (assessed by fractional shortening) was markedly improved 36% (P < 0.05) by US + Bubble + BM treatment. Targeted delivery of BM-MNCs by US + Bubble to the myocardium of the cardiomyopathic hamster increased the capillary densities and regional blood flow and inhibited cardiac remodeling, resulting in the prevention of heart failure. This non-invasive cell delivery system may be useful as a novel efficient approach for angiogenic cell therapy to the myocardium.

Angiogenesis Inducing Agents↗

Erythropoietin-mobilized endothelial progenitors enhance reendothelialization via Akt-endothelial nitric oxide synthase activation and prevent neointimal hyperplasia.

We investigated whether the mobilization of endothelial progenitor cells (EPCs) by exogenous erythropoietin (Epo) promotes the repair of injured endothelium. Recombinant human Epo was injected (1000 IU/kg for the initial 3 days) after wire injury of the femoral artery of mice. Neointimal formation was inhibited by Epo to 48% of the control (P<0.05) in an NO-dependent manner. Epo induced a 1.4-fold increase in reendothelialized area of day 14 denuded vessels, 55% of which was derived from bone marrow (BM) cells. Epo increased the circulating Sca-1(+)/Flk-1(+) EPCs (2.0-fold, P<0.05) with endothelial properties NO dependently. BM replacement by GFP- or beta-galactosidase-overexpressing cells showed that Epo stimulated both differentiation of BM-derived EPCs and proliferation of resident ECs. BM-derived ECs increased 2.2- to 2.7-fold (P<0.05) in the Epo-induced neoendothelium, where the expression of Epo receptor was upregulated. Epo induced Akt/eNOS phosphorylation and NO synthesis on EPCs and exerted an antiapoptotic action on wire-injured arteries. In conclusion, Epo treatment inhibits the neointimal hyperplasia after arterial injury in an NO-dependent manner by acting on the injured vessels and mobilizing EPCs to the neo-endothelium.

Animals↗

Usefulness of paroxetine in depressed men with paroxysmal atrial fibrillation.

The occurrence and the duration of paroxysmal atrial fibrillation (AF) are influenced by vagal tone. Paroxetine, an antidepressant, can modulate vagal tone at the level of the mid-brain and inhibit the vasovagal reflex. In this study, oral paroxetine 10 mg/day was administered to patients with multidrug-resistant paroxysmal AF. Nine consecutive men responded favorably to the drug. In 3 patients, AF resolved completely. One patient could not tolerate the drug because of nausea and nervousness. These preliminary results suggest that paroxetine could be a choice in the pharmacologic treatment of paroxysmal AF.

Adult↗

Cardiac hypertrophy diminished the effects of isoproterenol on delayed rectifier potassium current in rat heart.

We investigated the association between sympathetic nerve activity and delayed rectifier potassium current (I(K)) in hypertrophic rat hearts. Left ventricular hypertrophy was induced by a 50% constriction of suprarenal abdominal aorta for 6 weeks. The effects of isoproterenol on action potential duration (APD), I(K), and L-type calcium current (I(Ca)) were investigated using the whole-cell patch clamp technique. In hypertrophic rats, I(K) was decreased by 28.2%, resulting in significant APD(90) (90% repolarization) prolongation (sham: 55 +/- 3.9, hypertrophy: 98 +/- 11 ms, P = 0.01). Isoproterenol (100 nM)-stimulated I(K) was increased by 54.9% +/- 0.10% in sham-operated rats, but not in hypertrophic rats. On the other hand, isoproterenol increased I(Ca) in both sham-operated (77.7% +/- 7.6%) and hypertrophic rats (69.6% +/- 9.7%). Consequently, isoproterenol prolonged further APD in hypertrophic rats (98 +/- 11 vs. 145 +/- 8.6 ms, P < 0.01), but not in sham-operated rats (55 +/- 3.9 vs. 61 +/- 5.6 ms, n.s.). Forskolin (1 microM, an adenylyl cyclase stimulator) did not enhance I(K) in hypertrophic rats, but IBMX (100 microM, a nonselective phosphodiesterase inhibitor) enhanced the current (30.2 +/- 0.05%), as much as in sham-operated rats. We concluded that in hypertrophic hearts, I(K) was not increased by isoproterenol because of the enhanced activity of phosphodiesterase, which leads to excessive APD prolongation.

1-Methyl-3-isobutylxanthine↗

Nicorandil regulates Bcl-2 family proteins and protects cardiac myocytes against hypoxia-induced apoptosis.

Nicorandil has been shown to inhibit myocyte apoptosis by opening of mitochondrial ATP-sensitive potassium (mitoK(ATP)) channels and nitrate-like effect against oxidative stress. However, the detailed mechanism of nicorandil-mediated cardioprotection under hypoxic conditions remains to be largely unknown. The present study examined whether nicorandil can inhibit apoptosis via regulation of Bcl-2 family proteins in hypoxic myocytes. Neonatal rat cardiac myocytes were exposed to hypoxia for 7 hours. Hypoxia-induced myocyte apoptosis (13.9+/-0.9%) under glucose-rich conditions. Myocyte apoptosis was accompanied by loss of mitochondrial membrane potential (Deltapsi(m)), cytochrome c release from mitochondria into cytosol, and activation of caspase-3. Hypoxia also significantly increased Bax and decreased Bcl-2 mRNA and protein expression, thereby increasing Bax/Bcl-2 ratio. Nicorandil 100 micromol/l significantly decreased the percentage of apoptotic myocytes (7.2+/-0.5%) by inhibiting loss of Deltapsi(m) and translocation of cytochrome c. These effects of nicorandil were partially but significantly inhibited by cotreatment of either 500 micromol/l 5-hydroxydecanoate, a selective mitoK(ATP) channel antagonist, or 10 micromol/l 1H-[1,2,4]oxidazolo[4,3-a]quinoxalin-1-one (ODQ), an inhibitor of soluble guanylate cyclase. Moreover, nicorandil significantly inhibited the hypoxia-induced changes in Bax and Bcl-2 expression, and concomitant increased Bax and decreased Bcl-2 immunoreactivity in mitochondria. These effects of nicorandil in Bax and Bcl-2 expression were significantly blunted by cotreatment of ODQ and 5-HD, respectively. Cotreatment of KT5823, an inhibitor of protein kinase G, significantly blocked the effect of nicorandil on Bax expression and 8-bromo-cyclic guanosine 3',5' monophosphate (8-bromo-cGMP), a cGMP analog, mimicked the effect of nicorandil on Bax expression. The present study demonstrates that nicorandil regulates Bcl-2 family proteins via opening of mitoK(ATP) channels and nitric oxide-cGMP signaling and inhibits hypoxia-induced mitochondrial death pathway.

Animals↗

Rigid molecular tripod with an adamantane framework and thiol legs. Synthesis and observation of an ordered monolayer on Au111.

Tripod-shaped trithiols 1-3, containing CH2SH groups at the three bridgehead positions of the adamantane framework and a halogen-containing group [Br (1), p-BrC6H4 (2), or p-IC6H4 (3)] at the fourth bridgehead, were synthesized, and self-assembled monolayers (SAMs) were prepared on atomically flat Au111 surfaces. The three-point chemisorption of these tripods was confirmed by polarization modulation infrared reflection absorption spectroscopy, which showed the absence of a S-H stretching band. Scanning tunneling microscopy of the SAM of 1 exhibited a hexagonal arrangement of the adsorbed molecule with a lattice constant of 8.7 angstroms. A unidirectionally oriented, head-to-tail array of 1, which allows the close approach of neighboring molecules, is proposed as a reasonable model of the two-dimensional crystal, where the adsorbed sulfur atoms form a quasi-(radical3 x radical3)R30 degrees lattice. The charge of the electrochemical reductive desorption of the SAM of 1 was in good agreement with the expected surface coverage, while the SAMs of 2 and 3 showed somewhat less (ca. 70%) charge. The large negative reduction peak potentials, observed for the SAM of 1, are taken to indicate a tight anchoring of this tripod by three sulfur atoms.

Journal Article↗

Resting ST-segment depression predicts exercise-induced subendocardial ischemia in patients with hypertrophic cardiomyopathy.

BACKGROUND: Patients with hypertrophic cardiomyopathy (HCM) sometimes display characteristic electrocardiographic (ECG) findings at rest and develop subendocardial ischemia during exercise in the absence of coronary lesions. However, their relationship has not yet been fully clarified. METHODS: Exercise Tc-99m-tetrofosmin myocardial scintigraphy was performed in 48 patients with non-obstructive HCM. We quantified transient left ventricular cavity dilation (LVCD) on exercise scintigrams, a parameter of subendocardial ischemia, and correlated the results with the ECG findings at rest and during exercise. RESULTS: Transient LVCD occurred during exercise in 17 (35%) patients with HCM. Hemodynamic parameters during exercise did not differ between HCM patients with and without transient LVCD. Multiple logistic regression analysis showed that transient LVCD was significantly associated with ST-segment depression at rest (chi2=5.00, odds ratio=5.70, 95% confidence intervals 1.24-26.18, P=0.025) and a greater total number of leads with resting ST-segment depression (chi2=6.38, odds ratio=1.60, 95% confidence intervals 1.12-2.42, P=0.012). The degree of LVCD was correlated with the total number of leads with ST-segment depression at rest (P=0.002); the optimal cutoff for the diagnosis of transient LVCD was 3 with a sensitivity of 65%, a specificity of 90%, and an accuracy of 81%. CONCLUSIONS: In patients with HCM, ST-segment depression at rest was accompanied by exercise-induced subendocardial perfusion abnormality as detected by myocardial scintigraphy. ST-segment depression at rest suggests that the subendocardium is predisposed to exertional ischemia.

Aged↗

Granulocyte colony-stimulating factor-mobilized circulating c-Kit+/Flk-1+ progenitor cells regenerate endothelium and inhibit neointimal hyperplasia after vascular injury.

BACKGROUND: Granulocyte colony-stimulating factor (G-CSF) treatment was shown to inhibit neointimal formation of balloon-injured vessels, whereas neither the identification of progenitor cells involved in G-CSF-mediated endothelial regeneration with a bone marrow (BM) transplant experiment nor the functional properties of regenerated endothelium have been studied. METHODS AND RESULTS: Recombinant human G-CSF (100 microg/kg per day) was injected daily for 14 days starting 3 days before balloon injury in the rat carotid artery. Neointimal formation of denuded vessels on day 14 was markedly attenuated by G-CSF (39% versus the control; P<0.05). Endothelial cell-specific immunostaining revealed an enhancement of re-endothelialization (1.8-fold increase versus the control; P<0.05) and inhibition of extravasation of Evans Blue dye (47%; P=0.02). The regenerated endothelium exhibited acetylcholine-mediated vasodilatation in NO-dependent manner. G-CSF increased the circulating c-Kit+/Flk-1+ cells (9.1-fold; P<0.02), which showed endothelial properties in vitro (acetylated low-density lipoprotein uptake and lectin binding) and incorporated into the regenerated endothelium in vivo. A BM replacement experiment with green fluorescent protein (GFP)-overexpressing cells showed that BM-derived GFP+/CD31+ endothelial cells occupied 39% of the total luminal length in the G-CSF-mediated neo-endothelium (2% in the control). CONCLUSIONS: The G-CSF-induced mobilization of BM-derived c-Kit+/Flk-1+ cells contributes to endothelial regeneration, and this cytokine therapy may be a feasible strategy for the promotion of re-endothelialization after angioplasty.

Animals↗

Systolic outward motion of the left ventricular apical wall as detected by magnetic resonance tagging in patients with apical hypertrophic cardiomyopathy.

Patients with apical hypertrophic cardiomyopathy (APH) associated with paradoxic jet flow (ie, diastolic flow away from the apex) may gradually develop an apical aneurysm, which often leads to arrhythmia and mural thrombus formation. We observed systolic outward motion of the left ventricular apical myocardium in patients with APH using a magnetic resonance tagging procedure and examined the relationship of the outward motion to echocardiographic and scintigraphic findings and to cardiac events. Systolic displacement of the myocardial tags of the apical region perpendicular to the long axis in the 4-chamber view was recorded in 31 patients with APH. Of these patients, 14 showed no outward movement of tags (group A), and 17 showed outward movement (group B). In group B, apical hypertrophy was more severe (35 +/- 7 mm vs. 29 +/- 6 mm, p < 0.05), paradoxic jet flow was more frequent (64% vs. 14%, p < 0.05) and the defect score in I-123-beta-methyliodophenylpentadecanoic acid scintigraphy was higher (2.1 +/- 0.7 vs. 1.3 +/- 0.7, p < 0.01). During a mean follow-up period of 55 months, only 1 patient experienced paroxysmal atrial fibrillation in group A. In group B, 1 patient died suddenly, 1 was admitted to hospital because of congestive heart failure, 2 developed angina pectoris, 2 exhibited non-sustained ventricular tachycardia, and 1 showed multifocal premature ventricular contraction; in these 7 patients the outward movement was greater than in the 10 patients in Group B who had no cardiac events (1.00 +/- 0.59 vs. 0.52 +/- 0.40, p < 0.05). Hence, our results show that outward tag displacement is frequently associated with severe apical hypertrophy, paradoxic jet flow, apical ischemia, and cardiac events. The tagging method may be useful in assessing the severity of APH and predicting the occurrence of cardiac events at an early stage.

Adult↗

Relation of obesity to acute myocardial infarction in Japanese patients.

BACKGROUND: It remains uncertain whether obesity is an independent risk factor for coronary heart disease in young adults, as well as adults, in Japan. METHODS AND RESULTS: In the present study, 1,260 cases of acute myocardial infarction (AMI) and 3,775 community controls were recruited from the AMI-Kyoto Multi-Center Risk Study and Kyoto Citizen's Health and Nutrition Study, respectively. Obesity and other risk factors were retrospectively examined between cases and controls in each subgroup of young males (20-40 years), middle-aged males or females (40-60 years), older males or females (60-80 years), and very old males or females (80-100 years). In young, middle-aged, and older males, as well as in older females, cases had a higher body mass index (BMI) than controls. In young males, as well as in middle-aged and older females, cases had a higher prevalence of smoking than controls. Except for very old males, the prevalences of hypercholesterolemia, hypertension, and diabetes mellitus were higher in each subgroup of cases than in controls. Multivariate logistic regression analysis revealed that obesity (BMI >or=25) was an independent risk for AMI in young and middle-aged males, but not in females, whereas smoking was an independent risk for AMI in middle-aged and older females as well as in older males. CONCLUSIONS: Obesity is significantly associated with AMI, independent of the classic coronary risk factors, in young and middle-aged males. These findings support the current emphasis on controlling obesity to prevent coronary events in young Japanese male adults.

Adult↗

Medium-term prognosis of young Japanese adults having acute myocardial infarction.

BACKGROUND: Data on the medium- and long-term prognosis of young Japanese patients with acute myocardial infarction (AMI) are still lacking. METHODS AND RESULTS: In the present study, 1,458 AMI patients were enrolled in the AMI-Kyoto Multi-Center Risk Study between January 2000 and December 2003. Of these, clinical characteristics and medium-term prognosis were retrospectively compared in 21 young patients < 40 years (young group), and 190 non-young patients 60-70 years old (non-young group) who could be followed after hospital discharge. The young group was all male and had higher prevalence of current smoking and greater body mass index, but previous myocardial infarction (MI) and hypertension were more prevalent in the non-young group. The young group had a higher prevalence of single-vessel disease and a lesser incidence of left circumflex coronary artery as the culprit lesion. The acquisition rates of Thrombolysis In Myocardial Infarction 3 flow after primary percutaneous coronary intervention did not differ between the 2 groups, but the data of maximal creatine kinase was significantly higher in the young group. During the follow-up period (average 2.42 years for young, 2.37 years for non-young), survival and event-free survival rates and incidence of major adverse cardiac events (MACE) did not differ between the 2 groups. The predictor of MACE during follow-up period was the presence of multivessel disease in the young group, whereas the presence of multivessel disease, history of previous MI and longer hospitalization were the predictors of MACE in the non-young group. CONCLUSIONS: These results suggest that the medium-term prognosis in young AMI patients is comparable to that of non-young AMI patients in Japan.

Adult↗