Characterization of a resident population of adventitial macrophage progenitor cells in postnatal vasculature.

Rationale: Macrophages regulate blood vessel structure and function in health and disease. The origins of tissue macrophages are diverse, with evidence for local production and circulatory renewal.

Objective: We identified a vascular adventitial population containing macrophage progenitor cells and investigated their origins and fate.

Tissue factor pathway inhibitor blocks angiogenesis via its carboxyl terminus.

Objective: Tissue factor pathway inhibitor (TFPI) is the primary regulator of the tissue factor (TF) coagulation pathway. As such, TFPI may regulate the proangiogenic effects of TF. TFPI may also affect angiogenesis independently of TF, through sequences within its polybasic carboxyl terminus (TFPI C terminus [TFPIct]).

Identification of a monocyte-predisposed hierarchy of hematopoietic progenitor cells in the adventitia of postnatal murine aorta.

Background: Hematopoiesis originates from the dorsal aorta during embryogenesis. Although adult blood vessels harbor progenitor populations for endothelial and smooth muscle cells, it is not known if they contain hematopoietic progenitor or stem cells. Here, we hypothesized that the arterial wall is a source of hematopoietic progenitor and stem cells in postnatal life.

Vascular-directed tissue factor pathway inhibitor overexpression regulates plasma cholesterol and reduces atherosclerotic plaque development.

Rationale: Tissue factor pathway inhibitor (TFPI) is a potent regulator of the tissue factor pathway and is found in plasma in association with lipoproteins.

Objective: To determine the role of TFPI in the development of atherosclerosis, we bred mice which overexpress TFPI into the apolipoprotein E-deficient (apoE(-/-)) background.

Methods And Results: On a high-fat diet, smooth muscle 22alpha (SM22alpha)-TFPI/apoE(-/-) mice were shown to have less aortic plaque burden compared to apoE(-/-) mice.

Tissue factor pathway inhibitor overexpression inhibits hypoxia-induced pulmonary hypertension.

Pulmonary hypertension (PH) is a commonly recognized complication of chronic respiratory disease. Enhanced vasoconstriction, pulmonary vascular remodeling, and in situ thrombosis contribute to the increased pulmonary vascular resistance observed in PH associated with hypoxic lung disease. The tissue factor pathway regulates fibrin deposition in response to acute and chronic vascular injury.

Distribution of circulation-derived endothelial progenitors following systemic delivery.

Cells with an endothelial phenotype can be cultured from peripheral blood. These cells include cells of a monocytic origin with endothelial features (culture-modified mononuclear cells, CMMCs) and, at later time points, blood outgrowth endothelial cells (BOECs). Both are promising candidates for systemic cell-based cardiovascular therapies and each may have unique capabilities.

Magnetic forces enable rapid endothelialization of synthetic vascular grafts.

Background: Synthetic vascular grafts cannot be used in small vessels because of graft failure caused by thrombosis and neointima formation. Rapid endothelialization may overcome this limitation. We hypothesized that a magnetic graft would be able to capture and retain endothelial cells labeled with paramagnetic particles.

The effect of vascular smooth muscle cell-targeted expression of tissue factor pathway inhibitor in a murine model of arterial thrombosis.

Tissue factor pathway inhibitor (TFPI) is a Kunitz-type protease inhibitor that regulates the extrinsic pathway of coagulation by inhibiting the factor VIIa/tissue factor (TF) catalytic complex. TFPI is expressed by both endothelial and smooth muscle cells in the vasculature and circulates at low levels. The role of local vascular TFPI in thrombosis and the development of vascular disease is unknown.

Gene transfer of a novel vasoactive natriuretic peptide stimulates cGMP and lowers blood pressure in mice.

Dendroaspis natriuretic peptide (DNP) is a recently described peptide produced by Dendroaspis angusticeps with structural and functional similarities to mammalian natriuretic peptides. These similarities suggest a potential role for DNP in cardiovascular therapeutics. To determine the physiological effects of chronic delivery of DNP, a gene transfer approach using first generation adenoviral vectors was utilized.

Autologous culture-modified mononuclear cells confer vascular protection after arterial injury.

Background: Bone marrow-derived cells have been shown to contribute to endothelial replacement after vascular injury. In vitro culture of peripheral blood mononuclear cells produces cells with phenotypic characteristics of endothelium. To test the hypothesis that delivery of autologous culture-modified mononuclear cells (CMMCs) to injured arteries could attenuate the vascular response to injury, a rabbit model was studied.

Caveolin-1 can regulate vascular smooth muscle cell fate by switching platelet-derived growth factor signaling from a proliferative to an apoptotic pathway.

Background: Caveolin-1 is a regulator of signaling events originating from plasma membrane microdomains termed caveolae. This study was performed to determine the regulatory role of caveolin-1 on the proliferative events induced by platelet-derived growth factor (PDGF) in vascular smooth muscle cells (VSMCs).

Methods And Results: Treatment of VSMCs with PDGF for 24 hours resulted in a loss of caveolin-1 protein expression and plasma membrane-associated caveolae, despite a 3-fold increase in caveolin-1 mRNA.

Tissue factor pathway inhibitor deficiency enhances neointimal proliferation and formation in a murine model of vascular remodelling.

Tissue factor (TF) is a small-molecular-weight glycoprotein that initiates the extrinsic coagulation pathway but may have important noncoagulation vascular functions as well. Tissue factor pathway inhibitor (TFPI) is a major physiological inhibitor of TF-initiated coagulation. Enhancement of vascular TFPI either by overexpression using gene transfer or delivery of protein to the vessel has been shown to reduce neointimal formation.

Lipoprotein (a) binds and inactivates tissue factor pathway inhibitor: a novel link between lipoproteins and thrombosis.

Lipoprotein (a) [Lp(a)] has been associated with both anti-fibrinolytic and atherogenic effects. However, no direct link currently exists between this atherogenic lipoprotein and intravascular coagulation. The current study examined the binding and functional effects of Lp(a), its lipoprotein constituents, apoliprotein (a) [apo(a)] and low-density lipoprotein (LDL), and lysine-plasminogen (L-PLG), which shares significant homology with apo(a), on tissue factor pathway inhibitor (TFPI), a major regulator of tissue factor-mediated coagulation.

Role for tissue factor pathway in murine model of vascular remodeling.

Tissue factor (TF) is a low-molecular-weight glycoprotein that initiates the extrinsic clotting cascade and is considered a major regulator of arterial thrombogenicity. TF pathway inhibitor (TFPI) is a major physiological inhibitor of TF-initiated coagulation. The aim of this study was to define the complex interplay between TF and TFPI and the regulation of vascular thrombogenicity in a model of vascular remodeling.

The regulation of caveolin expression and localization by serum and heparin in vascular smooth muscle cells.

Caveolae have been implicated in growth factor receptor and G-protein coupled receptor signaling in vascular cells. It has been postulated that caveolin, the structural protein of caveolae, may act as a general tyrosine kinase inhibitor by binding and inhibiting signaling molecules involved in the activation of the MAP kinase proliferation cascade. Using an in vitro model of VSMC proliferation, we found that serum stimulation caused a dose dependent decrease in both caveolin-1 and caveolin-2 protein levels in human coronary artery smooth muscle cells.

Expression of tissue factor pathway inhibitor in vascular smooth muscle cells and its regulation by growth factors.

Tissue factor pathway inhibitor (TFPI) in vivo is thought to be synthesized mainly by endothelial cells. To date, no significant regulator of TFPI synthesis has been described. Vascular smooth muscle cells (VSMC) express tissue factor in vitro and in vivo, which may contribute to vascular thrombosis.

Presence of tissue factor pathway inhibitor in human atherosclerotic plaques is associated with reduced tissue factor activity.

Background: Plaque disruption and exposure of subendothelial procoagulants such as tissue factor (TF) to circulating factor VII/VIIa (FVII/VIIa) lead to intravascular thrombosis. Tissue factor pathway inhibitor (TFPI) is an endogenous inhibitor of TF-induced coagulation that binds to factor Xa and the TF-FVIIa catalytic complex in a two-step process. The aim of this study was to determine the expression of TFPI within human atherosclerotic plaque and its role in modulation of TF activity.

A novel assay in vitro of human islet amyloid polypeptide amyloidogenesis and effects of insulin secretory vesicle peptides on amyloid formation.

Human islet amyloid polypeptide (IAPP) is a 37-residue peptide that is co-secreted with insulin by the beta-cell and might be involved in the pathogenesis of non-insulin-dependent diabetes mellitus. We developed an improved assay in vitro based on the fluorescence of bound thioflavin T to study factors affecting amyloidogenesis. Monomeric IAPP formed amyloid fibrils, as detected by increased fluorescence and by electron microscopy.

Small heat shock proteins inhibit in vitro A beta(1-42) amyloidogenesis.

We demonstrate that small heat shock proteins (sHsp) inhibit in vitro amyloid formation by the Alzheimer's A beta(1-42) polypeptide as detected by a thioflavine T fluorescence assay and electron microscopy. Human sHsp27 (0.50-3.

Evaluation of vented blood culture media with sorbitol.

Two consecutive studies comparing the recovery of microorganisms from transiently vented blood cultures in tryptic soy or brain heart infusion broth with added sorbitol and that from tryptic soy broth without sorbitol failed to demonstrate any significant advantage of hypertonic media. A significantly greater number of organisms was isolated in both studies from the medium without sorbitol.

Evaluation of a biphasic medium for blood cultures.

A study comparing the recovery of microorganisms from a transiently vented biphasic brain heart infusion medium bottle and a vacuum bottle containing tryptic soy broth demonstrated that growth was initially detected on the slant of the biphasic bottle or on a routine subculture of either broth in nearly 50% of instances. All organisms were isolated equally well in both bottles, with the exception of Staphylococcus aureus, which was isolated significantly more frequently from the biphasic bottle, and anaerobic bacteria, which were isolated significantly more frequently from the tryptic soy broth bottle.