ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Abstract—Human umbilical cord blood (UCB) contains high numbers of endothelial progenitors cells (EPCs) characterized by coexpression of CD34 and CD133 markers. Prior studies have shown that CD34+/CD133+EPCs from the cord or peripheral blood (PB) can give rise to endothelial cells and induce angiogenesis in ischemic tissues. In the present study, it is shown that freshly isolated human cord blood CD34+cells injected into ischemic adductor muscles gave rise to endothelial and, unexpectedly, to skeletal muscle cells in mice. In fact, the treated limbs exhibited enhanced arteriole length density and regenerating muscle fiber density. Under similar experimental conditions, CD34−cells did not enhance the formation of new arterioles and regenerating muscle fibers. In nonischemic limbs CD34+cells increased arteriole length density but did not promote formation of new muscle fibers. Endothelial and myogenic differentiation ability was maintained in CD34+cells after ex vivo expansion. Myogenic conversion of human cord blood CD34+cells was also observed in vitro by coculture onto mouse myoblasts. These results show that human cord blood CD34+cells differentiate into endothelial and skeletal muscle cells, thus providing an indication of human EPCs plasticity. The full text of this article is available online at http://www.circresaha.org.

ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Abstract—Nitric oxide (NO) is produced from virtually all cell types composing the myocardium and regulates cardiac function through both vascular-dependent and -independent effects. The former include regulation of coronary vessel tone, thrombogenicity, and proliferative and inflammatory properties as well as cellular cross-talk supporting angiogenesis. The latter comprise the direct effects of NO on several aspects of cardiomyocyte contractility, from the fine regulation of excitation-contraction coupling to modulation of (presynaptic and postsynaptic) autonomic signaling and mitochondrial respiration. This multifaceted involvement of NO in cardiac physiology is supported by a tight molecular regulation of the three NO synthases, from cellular spatial confinement to posttranslational allosteric modulation by specific interacting proteins, acting in concert to restrict the influence of NO to a particular intracellular target in a stimulus-specific manner. Loss of this specificity, such as produced on excessive NO delivery from inflammatory cells (or cytokine-stimulated cardiomyocytes themselves), may result in profound cellular disturbances leading to heart failure. Future therapeutic manipulations of cardiac NO synthesis will necessarily draw on additional characterization of the cellular and molecular determinants for the net effect of this versatile radical on the cardiomyocyte biology.

ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Abstract—Randomized clinical trials have not provided conclusive data that hormone replacement therapy confers cardioprotection against coronary artery disease in postmenopausal women. However, other studies have shown that estrogens can induce beneficial effects on the vasculature. Nevertheless, the specific contribution of estrogen receptors (ERs) &agr; and &bgr; on vascular cells is not well characterized. Therefore, we used an antisense gene therapy approach to investigate the contribution of ER&agr; and ER&bgr; on p38 and p42/44 mitogen-activated protein kinase (MAPK) activation and on vascular cell responsiveness. Treatment of porcine smooth muscle cells (PSMCs) with platelet-derived growth factor-BB induced p38 and p42/44 MAPK activation and their migration and proliferation. These effects were prevented by pretreatment with 17&bgr;-estradiol (17&bgr;E). The inhibitory effects of 17&bgr;E on PSMCs were abrogated by the downregulation of ER&bgr; protein expression with selective ER&bgr; mRNA antisense oligomers, whereas the downregulation of ER&agr; had no effect. However, treatment of porcine aortic endothelial cells with 17&bgr;E promoted p38 and p42/44 MAPK phosphorylation and their migration and proliferation. These effects were ER&agr; dependent, as defined by antisense gene therapy. These results suggest that in PSMCs, 17&bgr;E reduces p42/44 and p38 MAPK activity through ER&bgr; stimulation, whereas in contrast, in porcine aortic endothelial cells, 17&bgr;E induces p42/44 and p38 MAPK through ER&agr; activation. 17&bgr;E may contribute to the vascular healing process and to the prevention of restenosis by improving reendothelialization through ER&agr; activation and by decreasing smooth muscle cell migration and proliferation through ER&bgr; stimulation.

ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Abstract—Atherosclerosis involves cellular immune responses and altered vascular smooth muscle cell (VSMC) function. Nitric oxide (NO)/cGMP is uniquely capable of inhibiting key processes in atherosclerosis. In this study, we determined the effects of NO/cGMP and their molecular mechanisms in the regulation of NF-&kgr;B–dependent gene expression in VSMCs. We found that cGMP-elevating agents such as the NO donorS-nitroso-N-acetylpenicillamine (SNAP) and C-type natriuretic peptide (CNP), reduced TNF-&agr;–induced NF-&kgr;B–dependent reporter gene expression in rat aortic VSMCs in a cGMP-dependent manner. The effects of SNAP and CNP on NF-&kgr;B are mediated by cAMP-dependent protein kinase (PKA) but not cGMP-dependent protein kinase (PKG) based on the findings that the selective PKA inhibitor, PKI, abolished the effects of SNAP and CNP on NF-&kgr;B, whereas the PKG inhibitor Rp-8-Br-PET-cGMP had no effect. Inhibition of cGMP-inhibited cAMP-hydrolyzing phosphodiesterase 3 (PDE3) blocked SNAP- and CNP-elicited effects on NF-&kgr;B–dependent transcription. Furthermore, cGMP analogues such as 8-pCPT-cGMP, which selectively activates PKG but does not inhibit PDE3, had no effect on NF-&kgr;B–mediated transcription. Activation of PKA by SNAP or cAMP-elevating agents not only inhibited TNF-&agr;–induced NF-&kgr;B–dependent reporter gene expression but also reduced endogenous NF-&kgr;B–dependent adhesion molecule and chemokine expression. These results suggest that SNAP and CNP exert inhibitory effects on NF-&kgr;B–dependent transcription by activation of PKA via cGMP-dependent inhibition of PDE3 activity. Therefore, PDE3 is a novel mediator of inflammation in VSMCs.

ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Abstract—Fibroblast growth factor (FGF)/FGF receptor (FGFR) signaling plays a crucial role in mesoderm formation and patterning.Heartlessmutant studies inDrosophilasuggest that FGFR1, among the different FGFRs, may play a role in cardiogenesis. However,fgfr1−/−mice die during gastrulation before heart formation. To establish the contribution of FGFR1 in cardiac development, we investigated the capacity of murinefgfr1+/−andfgfr1−/−embryonic stem (ES) cells to differentiate to cardiomyocytes in vitro. Clusters of pulsating cardiomyocytes were observed in >90% of 3-dimensional embryoid bodies (EBs) originated fromfgfr1+/−ES cells at day 9 to 10 of differentiation. In contrast, 10% or less offgfr1−/−EBs showed beating foci at day 16. Accordingly,fgfr1−/−EBs were characterized by impaired expression of early cardiac transcription factorsNkx2.5andd-Handand of late structural cardiac genesmyosin heavy chain(MHC)-&agr;,MHC-&bgr;, andventricular myosin light chain. Homozygousfgfr1mutation resulted also in alterations of the expression of mesoderm-related early genes, includingnodal,BMP2, BMP4,T(bra), andsonic hedgehog. Nevertheless,fgfr1+/−andfgfr1−/−EBs similarly express cardiogenic precursor, endothelial, hematopoietic, and skeletal muscle markers, indicating thatfgfr1-null mutation exerts a selective effect on cardiomyocyte development in differentiating ES cells. Accordingly, inhibitors of FGFR signaling, including the FGFR1 tyrosine kinase inhibitor SU 5402, the MEK1/2 inhibitor U0126, and the protein kinase C inhibitor GF109 all prevented cardiomyocyte differentiation infgfr1+/−EBs without affecting the expression of the hematopoietic/endothelial markerflk-1. In conclusion, the data point to a nonredundant role for FGFR1-mediated signaling in cardiomyocyte development.

ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Abstract—Roughly half of the cells of the heart consist of nonmyocardial cells, with fibroblasts representing the predominant cell type. It is well established that individual cardiomyocytes and fibroblasts in culture establish gap junctional communication at the single cell level (short-range interaction). However, it is not known whether such coupling permits activation of cardiac tissue over extended distances (long-range interaction). Long-range interactions may be responsible for electrical synchronization of donor and recipient tissue after heart transplantation and may play a role in arrhythmogenesis. This question was investigated using a novel heterocellular culture model with strands of cardiomyocytes interrupted by cardiac fibroblasts over defined distances. With use of optical recording techniques, it could be shown that impulse propagation along fibroblast inserts was successful over distances up to 300 &mgr;m and was characterized by length-dependent local propagation delays ranging from 11 to 68 ms (apparent local “conduction velocities” 4.6±1.8 mm/s, n=23). Involvement of mechanical stretch in this phenomenon was excluded by showing that inserts consisting of communication-deficient HeLa cells were incapable of supporting propagation. In contrast, HeLa cells expressing connexin43 permitted impulse conduction over distances as long as 600 &mgr;m. Immunocytochemistry showed that fibroblasts and cardiomyocytes expressed connexin43 and connexin45, whereas connexin40 was absent. These results illustrate that fibroblasts of cardiac origin are capable of synchronizing electrical activity of multicellular cardiac tissue over extended distances through electrotonic interactions. This synchronization is accompanied by extremely large local conduction delays, which might contribute to the generation of arrhythmias in fibrotic hearts.

ISSN:0009-7330    

出版商:OVID    

年代:2003

数据来源: OVID