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ABSTRACT: The metabolic syndrome (MS), a condition characterized by several risk factors for coronary artery disease, including obesity, is associated with endothelial dysfunction and oxidative stress. Because proper endothelial function is essential for signaling of certain growth factors (vascular endothelial growth factor, VEGF) we hypothesized that coronary collateral growth (CCG) is impaired in a model of the MS. To test this hypothesis, we stimulated coronary collateral growth in pre-diabetic Zucker obese fatty rats (OZR) and lean littermates (LZR) by using episodic, repetitive ischemia (RI: 40 s left anterior descending arterial occlusion, 24/d for 14 d). Myocardial blood flow (MBF, radioactive microspheres) was measured in the normal (NZ) and collateral-dependent (ischemic) zones (CZ); CCG was assessed as a ratio of CZ/NZ flow (unity represents complete restoration of CZ flow). In LZR, CZ/NZ ratio increased from 0.18 +/- 0.03 to 0.81 +/- 0.07 after RI (P < 0.05). In contrast, in OZR rats CZ/NZ did not increase after RI (0.15 +/- 0.04 vs 0.18 +/- 0.04). To rectify abrogated collateral growth in OZR, we employed VEGF gene therapy (VEGF-transduced, strained-matched, cultured vascular smooth muscle cells [cVSMCs], delivered intracoronary). VEGF therapy modestly but not significantly increased the CZ/NZ ratio after RI (0.16 +/- 0.05 vs 0.33 +/- 0.06). To facilitate VEGF signaling,we reduced oxidative stress by transducing cVSMCs with both ecSOD and VEGF. This increased the CZ/NZ flow ratio after RI to 0.52 +/- 0.04 (p < 0.05 vs. OZR [(0.19 +/- 0.04]) indicating partial restoration of collateral growth. Our results demonstrate that coronary collateral growth is impaired in a model of the metabolic syndrome and that growth factor gene therapy with VEGF is made far more effective when it is coupled to an intervention that reduces oxidative stress.
Archiv für Kreislaufforschung 05/2007; 102(3):217-23. · 7.35 Impact Factor
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ABSTRACT: Bone marrow mesenchymal stem cells (CMG cells) are multipotent and can be induced by 5-azacytidine to differentiate into cardiomyocytes. We characterized the electrophysiological properties of these cardiomyocytes and investigated their potential for use as transplantable bio-pacemakers. After differentiation, action potentials in spontaneously beating cardiomyocytes were initially sinus node-like, but subsequently became ventricular cardiomyocyte-like. RT-PCR established that ion channels mediating I(K1) and I(Kr) were expressed before differentiation. After differentiation, ion channels underlying ICa,L and If were expressed first, followed by ion channels mediating I(to) and I(K,ATP). Differentiated CMG cells expressed beta-adrenergic receptors and increased their beat rate in response to isoproterenol. CMG cardiomyocytes were purified using GFP fluorescence and transplanted into the free walls of the left ventricles of mice. The transplanted cardiomyocytes survived and connected to surrounding recipient cardiomyocytes via intercalated discs. Although further innovation is required, the present findings provide evidence of the potential for bone marrow-derived cardiomyocytes to be used as bio-pacemakers.
Medical & Biological Engineering & Computing 03/2007; 45(2):209-20. · 1.88 Impact Factor
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ABSTRACT: We have previously isolated cardiomyogenic cells from murine bone marrow (CMG cells). Regenerated cardiomyocytes are important candidates for cell transplantation, but as they are stem cell derived, they can be contaminated with various cell types, thereby requiring characterization and purification. Our objectives were to increase the efficiency of cell transplantation and to protect the recipients from possible adverse effects using an efficient and effective purification process as well as to characterize regenerated cardiomyocytes.
Noncardiomyocytes were eliminated from a mixture of stem-cell-derived cells using a fluorescence-activated cell sorter to specifically isolate CMG cells transfected with a recombinant plasmid containing enhanced green fluorescent protein (EGFP) cDNA under the control of the myosin light chain-2v (MLC-2v) promoter. Gene expression and the action potential were investigated, and purified cells were transplanted into the heart of adult mice.
Six percent to 24% of transfected CMG cells expressed EGFP after differentiation was induced, and a strong EGFP-positive fraction was selected. All the sorted cells began spontaneous beating after 3 weeks. These cells expressed cardiomyocyte-specific genes such as alpha-skeletal actin, beta-myosin heavy chain, MLC-2v, and CaV1.2 and incorporated bromodeoxyuridine for 5 days. The isolated EGFP-positive cells were expanded for 5 days and then transplanted into the left ventricle of adult mouse hearts. The transplanted cells survived for at least 3 months and were oriented in parallel to the cardiomyocytes of the recipient heart.
The purification and transplantation of differentiated cardiomyocytes from adult stem cells provides a viable model of tissue engineering for the treatment of heart failure.
Cardiovascular Research 03/2005; 65(2):334-44. · 6.06 Impact Factor
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ABSTRACT: For therapeutic angiogenesis to achieve clinical relevance, it must be effective, with minimal side effects to other end organ systems. We developed a cardiac-specific gene delivery mechanism by transfecting autologous vascular smooth muscle cells (VSMC) with VEGF and administering these cells via intracoronary injection. We evaluated the efficacy of this protocol by its ability to stimulate angiogenesis in the presence of a subthreshold stimulus for collateralization. A modified canine repetitive coronary occlusion model was utilized in these experiments with left anterior descending coronary artery occlusions for 2 min every 2 h four times per day for 21 days. An intramyocardial catheter in the perfusion territory of the left anterior descending coronary artery measured proteins in the myocardial interstitial fluid. VSMC from jugular vein explants were isolated, amplified in culture for 3 wk, and transfected with a plasmid expressing VEGF-165 and/or enhanced green fluorescent protein. Cells were injected before commencement of occlusions. VEGF levels in myocardial interstitial fluid were significantly higher in VEGF-transfected animals than in sham (repetitive occlusions without cell transplantation) and control (repetitive occlusions with enhanced green fluorescent protein-transfected cells) animals at the onset of occlusions (P < 0.05). In the VEGF group, collateral flow was increased at day 7 and remained higher than in sham and control groups thereafter. We found that intracoronary administration of VEGF-transfected autologous VSMC effectively promotes collateral development. This approach may provide a way to confine delivery of a gene to a specified organ, thus minimizing complications related to gene transfection in nontargeted organ systems.
AJP Heart and Circulatory Physiology 08/2004; 287(2):H488-93. · 3.71 Impact Factor
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ABSTRACT: Ischemic injury to the kidney results in blood vessel loss and predisposition to chronic renal disease. Angiostatin is a proteolytic cleavage product of plasminogen that inhibits angiogenesis, promotes apoptosis of endothelial cells, and disrupts capillary integrity. A combination of lysine-Sepharose enrichment followed by Western blotting was used to study the expression of angiostatin in response to the induction of ischemic renal injury. No angiostatin products were readily detectable in kidneys of sham-operated control rats. In contrast, both 38- and 50-kDa forms of angiostatin were dramatically enhanced in the first 3 days following 45-min ischemia-reperfusion injury. Renal angiostatin levels declined but remained detectable at late time points postrecovery (8-35 days postischemia). Angiostatin-like immunoreactivity was also elevated in the plasma and in urine for up to 35 days following injury. Lysine-Sepharose extracts of either kidney or urine inhibited vascular endothelial cell growth factor-induced proliferation of human aortic endothelial cells in vitro; an effect that was blocked by coincubation with an angiostatin antibody. RT-PCR verified that mRNA of the parent protein plasminogen was produced in the liver, but it was not present in either sham-operated or postischemic kidney. Matrix metalloproteinase (MMP)-2 and MMP-9, which may mediate angiostatin generation, were enhanced in postischemic kidney tissue and were localized to the renal tubules, interstitial cells, and the tubulo-interstitial space. These data indicate the possible local synthesis of angiostatin following acute renal failure (ARF) and suggest a possible role for MMPs in this activity. Renal angiostatin generation following ARF may modulate renal capillary density postischemia and thereby influence chronic renal function.
American journal of physiology. Renal physiology 06/2004; 286(5):F893-902. · 3.68 Impact Factor
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Eriko Kuwabara,
Fujiya Furuyama,
Kunihisa Ito,
Etsuro Tanaka, Naoichiro Hattan,
Hisanori Fujikura,
Koji Kimura,
Takako Goto,
Takashi Hayashi,
Hiroyuki Taira,
Yoshiro Shinozaki,
Keiji Umetani,
Kazuyuki Hyodo,
Kenkichi Tanioka,
Ryo Mochizuki,
Toshiaki Kawai,
Shirosaku Koide,
Hidezo Mori
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ABSTRACT: Tail blood flow is crucial for dissipating body heat in rats. Angiographies are convenient tools to evaluate tail circulation. However, conventional angiographies do not have sufficient sensitivity or spatial resolution for small vessels. Recently, we developed a novel microangiographic system using monochromatic synchrotron radiation and a high-definition video camera system. Here, we report an evaluation of rat tail circulation under heat stress using the synchrotron radiation microangiographic system. We performed an experiment using the microangiography of the caudal artery before and after heating up WKAH/HkmSlc rats to rectal temperature of 39 degrees C. The images were digitized and temporal subtraction was performed, and the diameters of caudal arteries were evaluated. After heating, the medial caudal artery was markedly dilated (320 +/- 53 to 853 +/- 243 micro m in diameter, p<0.001), while no significant change was observed in the lateral caudal arteries (139 +/- 42 to 167 +/- 73 micro m) and segmental anastomosing vessels. The heat stress allowed for visualization of the superficial caudal arteries with a diameter of approximately 60 micro m, not visible prior to heating. Thus, synchrotron radiation microangiography demonstrated that the rat tail possessed dual sets of arteries; one set was highly sensitive to heat-induced vasodilation (medial caudal artery and superficial caudal arteries) and the other set was less sensitive (lateral caudal arteries and segmental anastomosing vessels).
The Japanese Journal of Physiology 10/2002; 52(5):403-8. · 1.04 Impact Factor
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ABSTRACT: The control of coronary blood flow has been studied for decades, but despite our extensive efforts, the critical regulators
of flow are largely unknown. One purpose of this review is to summarize some recent concepts about the control of coronary
flow and also point out areas where additional knowledge must be acquired. A second purpose of this review is to highlight
the need for additional noninvasive measurements of flow that undoubtedly will require further evolution of contemporary technologies,
and also application of specific methods toward noninvasive measurements of coronary blood flow. Only after the development
of such measurements will the scientific community begin to understand the intricacies of the regulation of coronary flow
in human beings.
Journal of Nuclear Cardiology 08/2001; 8(5):599-605. · 2.67 Impact Factor
