摘要:

Delivery of young bone marrow–derived stem cells offers a novel approach for restoring the impaired senescent cardiac angiogenic function that may underlie the increased morbidity and mortality associated with ischemic heart disease in older individuals. Recently, we reported that alterations in endothelial cells of the aging heart lead to a dysregulation in the cardiac myocyte platelet-derived growth factor (PDGF)-B–induced paracrine pathway, which contributes to impaired cardiac angiogenic function. Based on these results, we hypothesized that cellular restoration of the PDGF pathway by bone marrow–derived endothelial precursor cells (EPCs) could reverse the aging-associated decline in angiogenic activity. In vitro studies revealed that young murine (3-month-old) bone marrow–derived EPCs recapitulated the cardiac myocyte–induced expression of PDGF-B, whereas EPCs from the bone marrow of aging mice (18-month-old) did not express PDGF-B when cultured in the presence of cardiac myocytes. Transplantation of young, but not old, genetically marked syngeneic bone marrow cells into intact, unirradiated aging mice that populated the endogenous senescent murine bone marrow incorporated into the neovasculature of subsequently transplanted syngeneic neonatal myocardium. Moreover, the young bone marrow–derived EPCs restored the senescent host angiogenic PDGF-B induction pathway and cardiac angiogenesis, with graft survival and myocardial activity in the aging murine host (cardiac allograft viability: 3-month-old controls, 8/8; 18-month-old controls, 1/8; 18-month-old donors receiving bone marrow from 3-month-old mice, 15/16; or 18-month-old mice, 0/6;P<0.05). These results may offer a foundation for the development of novel therapies for the prevention and treatment of cardiovascular disease associated with aging. The full text of this article is available at http://www.circresaha.org.

ISSN:0009-7330    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Although rapid progress is being made in many areas of molecular cardiology, issues pertaining to the origins of heart-forming cells, the mechanisms responsible for cardiogenic induction, and the pathways that regulate cardiomyocyte proliferation during embryonic and adult life remain unanswered. In the present study, we review approaches and studies that have shed some light on cardiomyocyte cell cycle regulation. For reference, an initial description of cardiomyogenic induction and morphogenesis is provided, which is followed by a summary of published cell cycle analyses during these stages of cardiac ontology. A review of studies examining cardiomyocyte cell cycle analysis and de novo cardiomyogenic induction in the adult heart is then presented. Finally, studies in which cardiomyocyte cell cycle activity was experimentally manipulated in vitro and in vivo are reviewed. It is hoped that this compilation will serve to stimulate thought and experimentation in this intriguing area of cardiomyocyte cell biology.

ISSN:0009-7330    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Glycogen synthase kinase-3&bgr; (GSK-3&bgr;) is a ubiquitously expressed constitutively active serine/threonine kinase that phosphorylates cellular substrates and thereby regulates a wide variety of cellular functions, including development, metabolism, gene transcription, protein translation, cytoskeletal organization, cell cycle regulation, and apoptosis. The activity of GSK-3&bgr; is negatively regulated by protein kinase B/Akt and by the Wnt signaling pathway. Increasing lines of evidence show that GSK-3&bgr; is an essential negative regulator of cardiac hypertrophy and that the inhibition of GSK-3&bgr; by hypertrophic stimuli is an important mechanism contributing to the development of cardiac hypertrophy. GSK-3&bgr; also plays an important role in regulating cardiac development. In this review, the role of GSK-3&bgr; in cardiac hypertrophy and development and the potential underlying mechanisms are discussed.

ISSN:0009-7330    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Previous studies demonstrated that interleukin-10 (IL-10) overexpression decreases formation of early fatty-streak lesions in mice independent of lipoprotein levels. The present studies, using bone marrow transplantation, demonstrate that overexpression of IL-10 by T cells inhibits advanced atherosclerotic lesions in LDL receptor–null mice fed an atherogenic diet. In mice receiving bone marrow from the IL-10 transgenic mice compared with those receiving wild-type marrow, there was a 47% decrease in lesion size and a marked decrease in lesion complexity with an 80% reduction in the necrotic core. Accumulation of cholesterol and phospholipid oxidation products in the aorta was decreased by 50% to 80%, unrelated to plasma lipid or IL-10 levels. Our studies also provide insight into the mechanism of the IL-10–mediated decrease in lesion size. Although a strong influence toward a Th1 phenotype has previously been demonstrated in atherosclerotic models, T lymphocytes in the IL-10 transgenic (Tg) group revealed a marked shift to a Th2 phenotype, with decreased IFN-&ggr; production and an increase in IL-10. Evaluation of specific immunoglobulin subclasses demonstrated a preponderance of IgG1isotype, characteristic of a Th2 influence on B cell immunoglobulin class-switching in the IL-10 Tg group. A major finding of these studies was altered monocyte/macrophage function in the IL-10 Tg group. Monocytes showed a decrease in activation resulting in decreased expression of IFN-&ggr;. Furthermore, macrophage foam cells within lesions of the IL-10 Tg group exhibited markedly decreased apoptosis. These studies demonstrate that T lymphocyte IL-10 can influence the function of other immune cells to reduce the development of advanced atherosclerotic lesions in mice.

ISSN:0009-7330    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

This study examined the potential role of angiotensin type 2 (AT2) receptor on angiogenesis in a model of surgically induced hindlimb ischemia. Ischemia was produced by femoral artery ligature in both wild-type and AT2gene–deleted mice (Agtr2−/Y). After 28 days, angiogenesis was quantitated by microangiography, capillary density measurement, and laser Doppler perfusion imaging. Protein levels of vascular endothelial growth factor (VEGF), endothelial nitric oxide synthase (eNOS), Bax, and Bcl-2 were determined by Western blot analysis in hindlimbs. The AT2mRNA level (assessed by semiquantitative RT-PCR) was increased in the ischemic hindlimb of wild-type mice. Angiographic vessel density and laser Doppler perfusion data showed significant improvement in ischemic/nonischemic leg ratio, 1.9- and 1.7-fold, respectively, inAgtr2−/Y mice compared with controls. In ischemic leg ofAgtr2−/Y mice, revascularization was associated with an increase in the antiapoptotic protein content, Bcl-2 (211% of basal), and a decrease (60% of basal) in the number of cell death, determined by TUNEL method. Angiotensin II treatment (0.3 mg/kg per day) raised angiogenic score, blood perfusion, and both VEGF and eNOS protein content in ischemic leg of wild-type control but did not modulate the enhanced angiogenic response observed in untreatedAgtr2−/Y mice. Finally, immunohistochemistry analysis revealed that VEGF was mainly localized to myocyte, whereas eNOS-positive staining was mainly observed in the capillary of ischemic leg of both wild-type and AT2-deficient mice. This study demonstrates for the first time that the AT2receptor subtype may negatively modulate ischemia-induced angiogenesis through an activation of the apoptotic process.

ISSN:0009-7330    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

The cGMP-dependent protein kinase type I (cGKI) is a major mediator of NO/cGMP-induced vasorelaxation. Smooth muscle expresses two isoforms of cGKI, cGKI&agr; and cGKI&bgr;, but the specific role of each isoform in vascular smooth muscle cells (VSMCs) is poorly understood. We have used a genetic deletion/rescue strategy to analyze the functional significance of cGKI isoforms in the regulation of the cytosolic Ca2+concentration by NO/cGMP in VSMCs. Cultured mouse aortic VSMCs endogenously expressed both cGKI&agr; and cGKI&bgr;. The NO donor diethylamine NONOate (DEA-NO) and the membrane-permeable cGMP analogue 8-bromo-cGMP inhibited noradrenaline-induced Ca2+transients in wild-type VSMCs but not in VSMCs genetically deficient for both cGKI&agr; and cGKI&bgr;. The defective Ca2+regulation in cGKI-knockout cells could be rescued by transfection of a fusion construct consisting of cGKI&agr; and enhanced green fluorescent protein (EGFP) but not by a cGKI&bgr;-EGFP construct. Fluorescence imaging indicated that the cGKI&agr;-EGFP fusion protein was concentrated in the perinuclear/endoplasmic reticulum region of live VSMCs, whereas the cGKI&bgr;-EGFP protein was more homogeneously distributed in the cytoplasm. These results suggest that one component of NO/cGMP-induced smooth muscle relaxation is the activation of the cGKI&agr; isoform, which decreases the noradrenaline-stimulated cytosolic Ca2+level.

ISSN:0009-7330    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Blood vessel cells express the 2 known estrogen receptors, &agr; and &bgr; (ER&agr;, ER&bgr;), which are thought to mediate estrogen inhibition of vascular injury and atherosclerosis, but the relative role of ER&agr; and ER&bgr; in these events is controversial. Estrogen inhibits the vascular injury response to the same extent in ovariectomized female wild-type mice and in the original single gene knockout mice for ER&agr; (ER&agr;KOChapel Hill[ER&agr;KOCH]) and ER&bgr; (ER&bgr;KOChapel Hill[ER&bgr;KOCH]). In double gene knockout mice generated by crossing these animals (ER&agr;,&bgr;KOCH), estrogen no longer inhibits medial thickening after vascular injury, but still inhibits vascular smooth muscle cell proliferation and increases uterine weight. The partial retention of estrogen responsiveness in ER&agr;,&bgr;KOCHmice could be due either to the presence of a novel, unidentified estrogen receptor or to functional expression of an estrogen receptor-&agr; splice variant in the parental ER&agr;KOCHmice. To distinguish between these possibilities, we studied recently generated mice fully null for estrogen receptor &agr; (ER&agr;KOStrasbourg[ER&agr;KOSt]) and examined the effect of estrogen on the response to vascular injury. In the present study, we show that after vascular injury in ovariectomized ER&agr;KOStmice, estrogen has no detectable effect on any measure of vascular injury, including medial area, proteoglycan deposition, or smooth muscle cell proliferation. These data demonstrate that estrogen receptor-&agr; mediates the protective effects of estrogen on the response to vascular injury.

ISSN:0009-7330    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Matrix metalloproteinases (MMPs) are proteolytic enzymes that degrade extracellular matrix proteins. These enzymes are implicated in a variety of physiological and pathological events characterized by extracellular matrix remodeling. Recent studies suggest that MMPs may have a signaling capacity, but direct evidence supporting this concept is lacking. In the present study, we demonstrate that outside-in signals delivered by exogenous MMP-1 (interstitial collagenase) markedly increase the number of tyrosine-phosphorylated proteins in platelets. Active MMP-1 also targets &bgr;3integrins to areas of cell contact and primes platelets for aggregation. Examination of the endogenous enzyme demonstrated that activated platelets process latent MMP-1 into its active form. Neutralization of MMP-1 activity with MMP inhibitors or specific blocking antibodies markedly attenuates agonist-induced phosphorylation of intracellular proteins, movement of &bgr;3integrins to cell contact points, and intercellular aggregation. The finding that MMP-1 is rapidly activated in platelets and controls functional responses identifies a new role for this metalloproteinase as a signaling molecule that regulates thrombotic events.

ISSN:0009-7330    

出版商:OVID    

年代:2002

数据来源: OVID