Angiogenic microvascular endothelial cells release microparticles rich in tissue factor that promotes postischemic collateral vessel formation

OBJECTIVE

Therapeutic angiogenesis is a promising strategy for treating ischemia. Our previous work showed that endogenous endothelial tissue factor (TF) expression induces intracrine signaling and switches-on angiogenesis in microvascular endothelial cells (mECs). We have hypothesized that activated mECs could exert a further paracrine regulation through the release of TF-rich microvascular endothelial microparticles (mEMPs) and induce neovascularization of ischemic tissues.

APPROACH AND RESULTS

Here, we describe for the first time that activated mECs are able to induce reparative neovascularization in ischemic zones by releasing TF-rich microparticles. We show in vitro and in vivo that mEMPs released by both wild-type and TF-upregulated-mECs induce angiogenesis and collateral vessel formation, whereas TF-poor mEMPs derived from TF-silenced mECs are not able to trigger angiogenesis. Isolated TF-bearing mEMPs delivered to nonperfused adductor muscles in a murine hindlimb ischemia model enhance collateral flow and capillary formation evidenced by MRI. TF-bearing mEMPs increase angiogenesis operating via paracrine regulation of neighboring endothelial cells, signaling through the β1-integrin pathway Rac1-ERK1/2-ETS1 and triggering CCL2 (chemokine [C-C motif] ligand 2) production to form new and competent mature neovessels.

CONCLUSIONS

These findings demonstrate that TF-rich mEMPs released by microvascular endothelial cells can overcome the consequences of arterial occlusion and tissue ischemia by promoting postischemic neovascularization and tissue reperfusion.

Monocyte-secreted Wnt5a interacts with FZD5 in microvascular endothelial cells and induces angiogenesis through tissue factor signaling

Angiogenesis during reactive and pathologic processes is characteristically associated with inflammation. Inflammatory cells participate in angiogenesis by secreting different molecules that affect endothelial cell functions. We had previously shown that induced tissue factor (TF) expression in activated microvascular endothelial cells (mEC) is able to induce angiogenesis via autocrine regulation. However, the signals that induce TF expression in mEC are not fully known. Here, we demonstrate that monocyte paracrine cross-talk with mECs triggers mEC-TF expression. We have identified that monocyte-secreted Wnt5a induces TF expression in mEC and functionally induces cell monolayer repair and angiotube formation in vitro as well as microvessel formation in vivo. Monocyte-secreted Wnt5a activates FZD5 in mECs, which signals to induce the release of intracellular Ca(2+) and increase NFκB transcription activity and TF gene expression. In sum, Wnt5a secreted by monocytes signals through the noncanonical Wnt-FZD5 pathway in mECs to induce TF expression that induces angiogenesis by autocrine regulation.

Changes in thrombus composition and profilin-1 release in acute myocardial infarction

AIM

Thrombus formation is a dynamic process regulated by flow, blood cells, and plasma proteins. The present study was performed to investigate the characteristics of human coronary thrombus in ST-segment elevation myocardial infarction (STEMI).

METHODS AND RESULTS

Patients admitted with ST-elevation myocardial infarction, in which thrombectomy was performed, were included (n = 86). Intracoronary thrombi and blood from the culprit coronary site and the systemic circulation were obtained during percutaneous coronary intervention (PCI). Thrombi were categorized by onset-of-pain-to-PCI elapsed time in thrombus of <3 (T3) and more than 6 h of evolution (T6). Clinical, morphological, and proteomic variables were investigated. While T3 were mainly composed by platelets and fibrin(ogen), T6 were characterized by a reduced platelet content, increased leucocytes infiltration (including monocytes, neutrophils, T-cells, and B-cells), and appearance of undifferentiated progenitor cells. Significant differences between T3 and T6 were found in the cell cytoskeleton-associated proteome (beta-actin and tropomyosin 3 and 4). By discovery proteomics, we have identified profilin-1 (Pfn-1) in the coronary thrombi and detected higher levels in T3 than in T6. While plasma Pfn-1 levels were low in T3 patients, levels significantly increased in both coronary and peripheral circulation in T6 patients indicating release. In vitro platelet aggregation studies showed that platelets secrete Pfn-1 upon complete activation.

CONCLUSION

Coronary thrombi show rapid dynamic changes both in structure and cell composition as a function of elapsed onset-of-pain-to-PCI time. Aged ischaemic thrombi were more likely to have reduced Pfn-1 content releasing Pfn-1 to the circulation. Onset-of-pain-to-PCI elapsed time in STEMI patients and hence age of occlusive thrombus can be profiled by Pfn-1 levels found in the peripheral circulation.

Short- and long-term biomechanical and morphological study of new suture types in abdominal wall closure

To perform an abdominal-wall closure, a continuous suture is the preferred method. The suture materials that are most commonly employed in abdominal surgery are polypropylene and polydioxanone. However, in recent times, new products have been marketed, such as non-absorbable polyurethane with elastic properties (Assuplus(®), Assut Europe, Italy) and absorbable barbed polydioxanone (Filbloc(®), Assut Europe, Italy). The purpose of this study was to compare the ability of those against the standard polypropylene (Surgipro(TM), Covidien, USA) and polydioxanone (Assufil(®), Assut Europe, Italy) to mimic the biomechanical behavior of the abdominal wall closure. Comparison of the sutures was made first with the materials alone and later in a laparotomy closure of a rabbit abdomen, used as an animal model. The biomechanical analysis consisted of uniaxial tensile tests of threads and sutured samples of the animal abdomen. In the latter case, results were analyzed at short- (21days) and long- (180days) term intervals after the surgery. The morphology studies and collagen expression of the samples were also investigated. The results determined that polydioxanone and polypropylene sutures showed a linear elastic behavior, with barbed polydioxanone as the most compliant suture and polyurethane as the stiffest. The sutured samples showed a statistically significant loss of resistance, measured as the load needed to perform a certain stretch, when compared with the corresponding control tissue. Analysis of the stress-stretch curves showed that elastic polyurethane was the only suture able to reproduce the mechanical behavior of healthy tissue in the short term, while the rest of the sutures remained less stiff. This coincides with the expression of type I collagen observed in this group at this point in the study. In the long term, there was no difference among the sutures, and none was able to mimic control behavior.

A structural approach including the behavior of collagen cross-links to model patient-specific human carotid arteries

In this work the mechanical response of the carotid arterial wall is studied. Some limitations of previous models of the arterial wall are overcomed and variability of the fitting problem is reduced. We review some experimental data from the literature and provide a constitutive model to characterize such data. A strain energy function is introduced including the behavior of cross-links between the main collagen fibers. With this function we are able to fit experimental data including information about the microstructure that previous models were not able to do. To demonstrate the applicability of the proposed model a patient-specific carotid artery geometry is reconstructed and simulated in a finite element framework, providing a microstructural description of the arterial wall. Our results qualitatively and quantitatively describe the experimental findings given in the literature fitting macroscopic mechanical tests and improving the features of previously developed models.

Endothelial progenitor cells in acute ischemic stroke

OBJECTIVES

The levels of circulating endothelial progenitor cells (EPCs) in ischemic stroke have not been studied extensively and reported results are inconsistent. We aimed to investigate the time course, the prognostic relevance, and the variables associated with EPC counts in patients with ischemic stroke at different time points.

MATERIAL AND METHODS

We studied prospectively 146 consecutive patients with ischemic stroke within the first 48 h from the onset of symptoms (baseline). We evaluated demographic data, classical vascular risk factors, treatment with thrombolysis and statins, stroke etiology, National Institute of Health and Stroke Scale score and outcome (favorable when Rankin scale score 0-2). Blood samples were collected at baseline, at day 7 after stroke (n = 121) and at 3 months (n = 92). The EPC were measured by flow cytometry.

RESULTS

We included 146 patients with a mean age of 70.8 ± 12.2 years. The circulating EPC levels were higher on day 7 than at baseline or at 3 months (P = 0.045). Pretreatment with statins (odds ratio [OR] 3.11, P = 0.008) and stroke etiology (P = 0.032) were predictive of EPC counts in the baseline sample. EPC counts were not associated with stroke severity or functional outcome in all the patients. However, using multivariate analyses, a better functional outcome was found in patients with higher EPC counts in large-artery atherosclerosis and small-vessel disease etiologic subtypes.

CONCLUSIONS

After acute ischemic stroke, circulating EPC counts peaked at day 7. Pretreatment with statins increased the levels of EPC. In patients with large-artery atherosclerosis and small-vessel disease subtypes, higher counts were related to better outcome at 3 months.

Monomerization of C-reactive protein requires glycoprotein IIb-IIIa activation: pentraxins and platelet deposition

BACKGROUND

Pentraxins are inflammatory mediators linked to cardiovascular disease; however, their role in thrombosis remains to be fully elucidated.

AIMS

We investigated the role of pentraxins in thrombus formation on different vascular substrates under flow conditions.

METHODS

Native C-reactive protein (nCRP) and serum amyloid P (SAP) effects on thrombosis were evaluated under flow conditions on substrates placed in flat perfusion chambers. nCRP and dissociated monomeric CRP (mCRP) distributions were visualized by use of confocal microscopy. The effects of nCRP on vascular substrates were tested in the Badimon chamber.

RESULTS

mCRP, but not nCRP, induced a significant activation in platelet deposition, whereas SAP induced an activation only on fibrinogen-coated substrates. The effects of CRP on platelet deposition were significantly reduced by statin treatment. mCRP resulting from recirculation of blood containing nCRP over a thrombogenic vessel wall induced increased platelet deposition. Blocking glycoprotein IIb-IIIa prevented the effects of CRP dissociation and significantly reduced platelet deposition. Annexin V treatment did not block monomerization of CRP on activated platelets.

CONCLUSIONS

Under flow conditions, platelet deposited on all tested biological substrates support nCRP dissociation into mCRP. The effect is dependent on the thrombogenic potency of the substrate to trigger initial platelet deposition. Exposure of glycoprotein IIb-IIIa in the platelet surface supports nCRP dissociation. CRP monomerization was not dependent on the aminophospholipid exposed on the surface of activated platelets. The dissociated mCRP is trapped in the growing platelet aggregate and stimulates further platelet deposition. SAP increases platelet deposition only on fibrin monolayers. Therefore, pentraxins induce a platelet activation effect linking inflammation and thrombosis.

Tissue factor induces human coronary artery smooth muscle cell motility through Wnt-signalling

BACKGROUND

Tissue factor (TF) is the most relevant physiological trigger of thrombosis contributing to the presentation of clinical ischemic events after plaque rupture. However, the role of human vascular smooth muscle cell (HVSMC) TF in vascular remodeling, restenosis and atherosclerosis is less known. We have hypothesized that TF contributes to atherosclerotic lesion formation, triggering smooth muscle cell migration through a specific yet unknown signaling pathway.

OBJECTIVES

The aim of this study has been to investigate the signal transduction mechanism by which TF may contribute to the transition of resident static contractile HVSMC into a migrating cell that promotes atherosclerotic plaque progression.

METHODS

We have used a system biology discovery approach with gene-engineered HVSMCs to identify genes/proteins involved in the TF-triggered effects in HVSMC obtained from the coronary arteries of human adult hearts.

RESULTS

Analysis of wild-type HVSMC (TF(+) ) and TF(-) silenced HVSMC (TF(-) ) showed that TF is involved in the regulation of Wnt signaling and in the expression of downstream proteins that affect the atherosclerotic process.

CONCLUSIONS

The 'in silico' analysis pointed to specific Wnt-pathway proteins that have been validated in cell culture and also have been found expressed in human advanced atherosclerotic plaques but not in early lesions. TF signals through Wnt to regulate coronary smooth muscle cell migration and vascular remodeling.

UPA promotes lipid-loaded vascular smooth muscle cell migration through LRP-1

AIM

Migration of vascular smooth muscle cells (VSMCs) is a crucial event in atherosclerosis and vascular repair. Low-density lipoprotein (LDL) infiltrated in the vessel wall become aggregated (agLDL) and internalized by VSMC through the LDL receptor-related protein LRP1, deriving in lipid-loaded cells with reduced motility capacity. The urokinase-plasminogen activator (UPA)/UPA receptor (UPAR) system plays a relevant role in vascular remodelling. Here, we investigated whether UPA-ligand binding is involved in the detrimental effects of lipid loading in VSMC migration.

METHODS AND RESULTS

Animals fed a high-fat diet had 10-fold higher cholesterol-LDL plasma levels, >60% decrease in aortic UPA-protein expression, and VSMC showed impaired outgrowth from aortic explants. Angiotensin II infusion significantly increased aortic UPA expression and accelerated VSMC migration. Using an in vitro model of wound repair, we showed that agLDL inhibits UPA-mediated VSMC migration. UPA silencing reduced migration in control cells to levels observed in lipid-loaded VSMC. UPA silencing did not affect migration in lipid-loaded VSMC. UPA expression was significantly decreased in agLDL-exposed VSMC. agLDL also induced changes in the subcellular localization of UPA, with a reduction in colocalization with UPAR strongly evident at the front edge of agLDL-treated migrating cells. Rescue experiments showed that UPA acting as UPAR ligand restored migration capacity of agLDL-VSMC to control levels. The effects of UPA/UPAR on migration of lipid-loaded cells occurred through the binding to LRP-1.

CONCLUSION

UPA-ligand binding regulates VSMC migration, a process that is interfered by LDL. Thus, tissue infiltrated LDL through the abrogation of UPA function reduces VSMC-regulated vascular repair.

Surgical lung biopsy for diffuse lung disease. Our experience in the last 15 years

INTRODUCTION

Surgical lung biopsy is a technique that presents a morbi-mortality rate of considerable importance. We analyze our experience with surgical lung biopsies for the diagnosis of diffuse lung disease and the effect produced on the indications for surgical biopsy in these pathologies after the publication of the consensus of the ATS (American Thoracic Society) and ERS (European Respiratory Society) for Idiopathic Pulmonary Fibrosis (IPF).

PATIENTS AND METHODS

We performed a retrospective review of 171 patients operated between January 1997 and December 2011. We divided the series into 2 groups: group 1 (operated between 1997 and 2002) and group 2 (operated between 2003 and 2011). Suspected preoperative diagnosis, respiratory status, pathological postoperative diagnoses, percentage of thoracotomies, mean postoperative stay and perioperative morbidity and mortality were analyzed.

RESULTS

Group 1 consisted of 99 patients and group two 72. The most frequent postoperative diagnoses were: usual interstitial pneumonia and extrinsic allergic alveolitis. There were ten (5.84%) deaths. Death was caused by progressive respiratory failure that was related to interstitial lung disease in 7 (70%) of 10 cases, alveolar haemorrhage in 2 (20%) and heart failure in 1 (10%).

CONCLUSIONS

Since the publication of the ATS and ERS consensus on the IPF, we have observed a noticeable decrease in the number of indications for surgical lung biopsy. This technique, though simple, has a considerable morbidity and mortality.

Short-term behavior of different polymer structure lightweight meshes used to repair abdominal wall defects

BACKGROUND

While lightweight (LW) polypropylene (PP) meshes are been used for hernia repair, new prosthetic meshes also of low-density and with large pores have recently been introduced composed of other polymer materials. This study compares the behavior in the short-term of two macroporous LW prosthetic materials, PP and non-expanded PTFE.

METHODS

Partial defects were created in the lateral wall of the abdomen in New Zealand White rabbits and then repaired using a LW PP mesh or a new monofile, LW PTFE mesh. At 14 days postimplant, shrinkage and tissue incorporation, gene and protein expression of neo-collagens (qRT-PCR/immunofluorescence), macrophage response (immunohistochemistry) and biomechanical strength were determined.

RESULTS

Both meshes induced good host tissue ingrowth, yet the macrophage response was significantly greater for the PTFE implants (p⟨0.05). Collagen 1/3 mRNA expression was greater for the PP mesh but differences lacked significance. Similar patterns of collagen I and III protein expression were observed in the neoformed tissue infiltrating the two meshes. After 14 days of implant, tensile strengths were also similar, while elastic modulus values were higher for the PTFE mesh (p⟨0.05).

CONCLUSIONS

In the short term, host collagen deposition and biomechanical performance seemed unaffected by the polymer structure of the implanted mesh. In contrast, the inflammatory response to mesh implant produced at this early time point was more intense for the PTFE.

Viscoelastic properties of the passive mechanical behavior of the porcine carotid artery: influence of proximal and distal positions

The viscoelastic properties of porcine carotid tissue are investigated in this work. Experimental uniaxial stress relaxation tests along the longitudinal and circumferential directions of the vessel were performed for carotid strips extracted from 10 vessels. Directional and local differences--distal versus proximal position--in the tissue behavior were investigated. The experimental tests reveal a highly anisotropic, non-linear viscoelastic response and local dependence of the samples. The carotid artery shows anisotropic relaxation behavior for both proximal and distal samples. The highest stress relaxation was found in the circumferential tensile test for the highest applied strain at the distal position. For the circumferential direction, the relaxation stress was higher than in the longitudinal being at its highest in the distal position. These facts show that the stress relaxation is higher in the distal than in the proximal position. However, there are no differences between both positions in the longitudinal direction. In addition, a constitutive law that takes into account the fundamental features, including non-linear viscoelasticity, of the arterial tissue is proposed. The present results are correlated with the purely elastic response and the microstructural analysis of the tissue by means of histological quantification presented in a previous study.

Subcellular localization of tissue factor and human coronary artery smooth muscle cell migration

BACKGROUND

Tissue factor (TF) is the most relevant physiological trigger of thrombosis. Additionally TF is a transmembrane receptor with cell signaling functions.

OBJECTIVES

The aim of this study was to investigate TF subcellular localization, function and signaling in human coronary artery smooth muscle cell migration.

METHODS

Coronary arteries and primary cultures of vascular smooth muscle cells (HVSMC) were obtained from human explanted hearts. Wound repair and Boyden chamber assays were used to measure migration in vitro. TF-pro-coagulant activity (TF-PCA) was measured in extracted cellular membranes. Analysis of TF distribution was performed by confocal microscopy. A nucleofector device was used for TF and protease activated receptor 2 (PAR2) silencing. mRNA levels were analyzed by RT-PCR.

RESULTS

In migrating HVSMC TF translocates to the leading edge of the cells showing an intense patch-like staining in the lamellipodia. In the migrating front TF colocalizes with filamin (FLN) in the polarized lipid rafts. TF-PCA was increased in migrating cells. Silencing of the TF gene inhibits RSK-induced FLN-Ser-2152 phosphorylation, down-regulates CDC42, RhoA, and Rac1 protein expression and significantly inhibits cell migration. Silencing PAR2 also inhibits cell migration; however, silencing both TF and PAR2 induces a significantly higher effect on migration. Smooth muscle cells expressing TF have been identified in non-lipid-rich human coronary artery atherosclerotic plaques.

CONCLUSIONS

TF translocates to the cell front in association with cytoskeleton proteins and regulates HVSMC migration by mechanisms dependent and independent of factor (F)VIIa/PAR2. These results extend the functional role of TF to smooth muscle cell trafficking in vessel wall remodeling.

Aggregated low-density lipoprotein induce impairment of the cytoskeleton dynamics through urokinase-type plasminogen activator/urokinase-type plasminogen activator receptor in human vascular smooth muscle cell

BACKGROUND

Urokinase-type plasminogen activator (UPA) regulates vascular smooth muscle cell (VSMC) functions relevant in vascular remodeling by facilitating proteolysis at the cell surface and inducing cell signaling pathways. Our previous results demonstrated that aggregated low-density lipoprotein (agLDL) impair cytoskeleton dynamics, a key event contributing to VSMC behavior during progression of atherosclerotic plaques.

OBJECTIVES

To investigate whether mechanisms underlying inhibition of cytoskeleton dynamics in lipid-loaded VSMC occurs through a UPA-mediated process.

METHODS

Adhesion assay was performed in lipid-loaded human VSMC after 16-h exposition to agLDL (100 μg mL(-1)). Protein subcellular localization and actin-fiber formation were assessed by confocal microscopy. For analysis of protein expression western blots were carried out. Co-immunoprecipitates of UPAR were examined by one-dimensional- or two-dimensional electrophoresis (1-DE or 2-DE), mass spectrometry MALDI-TOF and western blot.

RESULTS

agLDL induced UPA subcellular delocalization and significantly decreased UPA levels during attachment of VSMC. UPA (enhanced endogenous-expression or exogenous added) acting as a urokinase-type plasminogen activator receptor (UPAR)-ligand restored actin-cytoskeleton organization and adhesion capacity of lipid-loaded cells to control levels. UPAR co-immunoprecipitated with the unphosphorylated form of myosin regulatory light chain (MRLC) in lipid-loaded cells. The detrimental effects of agLDL on MRLC phosphorylation were reversed by high levels of UPA. The UPA effects on VSMC exposed to agLDL involved FAK phosphorylation.

CONCLUSIONS

The detrimental effects of atherogenic LDL on VSMC are mediated by a decrease and delocalization of the UPA-UPAR interaction that result in an impairment of cytoskeleton dynamics and adhesion capacity affecting cell phenotype and function.

Tissue factor-Akt signaling triggers microvessel formation

BACKGROUND

Tissue factor (TF) and its signaling mediators play a crucial role in angiogenesis. We have previously shown that TF-induced endothelial cell (EC) CCL2 release contributes to neovessel formation.

OBJECTIVE

In this study, we have investigated the signaling pathways involved in TF-induced EC tube formation.

METHODS

The human microvascular endothelial cell line (HMEC-1) cultured onto basement membrane-like gel (Matrigel) was used to study TF signaling pathways during neovessels formation.

RESULTS

Inhibition of endogenous TF expression in ECs using siRNA resulted in inhibition of a stable tube-like structure formation in three-dimensional cultures, associated with a down-regulation of Akt activation, an increased phosphorylation of Raf at Ser(259) with a subsequent reduction of Raf kinase and a reduction of ERK1/2 phosphorylation ending up in Ets-1 transcription factor inhibition. Conversely, overexpression of TF resulted in an increase in tube formation and up-regulation of Akt protein. Moreover, immunoprecipitation of Akt and western blotting of the immunoprecipitates with anti-TF antibody revealed a direct interaction between TF and Akt. The effects of silencing TF were partially reversed by a PAR2 agonist that rescued tube formation, indicating that the TF-Akt pathway induces PAR2-independent effector signaling. Finally, enforced expression of Akt in TF-silenced ECs rescued tube formation in a Matrigel assay and induced Ets-1 phosphorylation.

CONCLUSIONS

In EC, TF forms a complex with Akt activating Raf/ERK and Ets-1 signaling induces microvessel formation.

Ets-1 transcription is required in tissue factor driven microvessel formation and stabilization

Tissue factor (TF) has well-recognized roles as initiator of blood coagulation as well as an intracellular signaling receptor. TF signaling regulates gene transcription and protein translation. Recently, we have shown that TF-induced mature neovessel formation is ultimately driven by CCL2 expression. However, the signaling process induced by TF to promote microvessel formation remains to be determined. This study was designed with the objective to investigate the mechanisms involved in TF-induced neovessel formation. Here, we have identified that Ets-1 expression is a downstream effector of TF signaling. TF-siRNA induced a highly significant reduction in Ets-1 expression levels and in Ets-1/DNA binding while inducing abrogation of microvessel formation. Activation of Ets-1 rescued the effect of TF inhibition and restored microvessel formation confirming the critical role of Ets-1 in TF-induced angiogenesis. VE-cadherin expression, a key regulator of endothelial intercellular junctions, and an Ets-1 target molecule was dependent of TF-inhibition. We show that TF signals through ERK1/2 to activate Ets-1 and induce CCL2 gene expression by binding to its promoter region. We conclude that endothelial cell TF signals through ERK1/2 and Ets-1 to trigger microvessel formation.

Platelets derived from the bone marrow of diabetic animals show dysregulated endoplasmic reticulum stress proteins that contribute to increased thrombosis

OBJECTIVE

Patients with diabetes mellitus have an increased risk of suffering atherothrombotic syndromes and are prone to clustering cardiovascular risk factors. However, despite their dysregulated glucose metabolism, intensive glycemic control has proven insufficient to reduce thrombotic complications. Therefore, we aimed to elucidate the determinants of thrombosis in a model of type 2 diabetes mellitus with cardiovascular risk factors clustering.

METHODS AND RESULTS

Intravital microscopy was used to analyze thrombosis in vivo in Zucker diabetic fatty rats (ZD) and lean normoglycemic controls. Bone marrow (BM) transplants were performed to test the contribution of each compartment (blood or vessel wall) to thrombogenicity. ZD showed significantly increased thrombosis compared with lean normoglycemic controls. BM transplants demonstrated the key contribution of the hematopoietic compartment to increased thrombogenicity. Indeed, lean normoglycemic controls transplanted with ZD-BM showed increased thrombosis with normal glucose levels, whereas ZD transplanted with lean normoglycemic controls-BM showed reduced thrombosis despite presenting hyperglycemia. Significant alterations in megakaryopoiesis and platelet-endoplasmic reticulum stress proteins, protein disulfide isomerase and 78-kDa glucose-regulated protein, were detected in ZD, and increased tissue factor procoagulant activity was detected in plasma and whole blood of ZD.

CONCLUSIONS

Our results indicate that diabetes mellitus with cardiovascular risk factor clustering favors BM production of hyperreactive platelets with altered protein disulfide isomerase and 78-kDa glucose-regulated protein expression that can contribute to increase thrombotic risk independently of blood glucose levels.

Tissue distribution and metabolism of guanosine in rats following intraperitoneal injection

Guanosine has long been known as an endogenous purine nucleoside deeply involved in the modulation of several intracellular processes, especially G-protein activity. More recently, it has been reported to act as an extracellular signaling molecule released from neurons and, more markedly, from astrocytes either in basal conditions or after different kinds of stimulation including hypoxia. Moreover, in vivo studies have shown that guanosine plays an important role as both a neuroprotective and neurotrophic agent in the central nervous system. Specific high-affinity binding sites for this nucleoside have been found on membrane preparations from rat brain. The present study was undertaken to investigate the distribution and metabolic profiles of guanosine after administering the nucleoside to gain a better understanding of the biological effects of this potential drug candidate. Rats were given an intraperitonal (i.p.) injection of 2, 4, 8 or 16 mg/kg of guanosine combined with 0.05% of [3H]guanosine. Plasma samples were collected 7.5, 15, 30, 60 and 90 min after the guanosine-mixture administration and analyzed by either a liquid scintillation counter or by HPLC connected to a UV and to an on-line radiochemical detector to measure the levels of guanosine and its metabolic products guanine, xanthine and uric acid. The levels of guanosine, guanine and xanthine were also measured in brain, lung, heart, kidney and liver tissue homogenates at the defined time points after the injection of 8 mg/kg of the guanosine-mixture. We found that the levels of radioactivity in plasma increased linearly in a dose- and time-dependent manner. Guanosine was widely distributed in all tissues examined in the present study, at almost twice its usual levels. In addition, guanine levels dramatically increased in all the organs. Interestingly, enzymatic analysis of the plasma samples showed the presence of a soluble purine nucleoside phosphorylase, a key enzyme in the purine salvage pathway and nucleoside catabolism. Since guanosine has been shown to be neuroprotective and astrocytes have been reported to play critical roles in mediating neuronal survival and functions in different neurodegenerative disorders, we also performed uptake and release.

Proteomic Signature of Thrombin-Activated Platelets After In Vivo Nitric Oxide–Donor Treatment

Objective—

Growing insight into the antiplatelet properties of new nitric oxide (NO) donors has expanded their potential use in cardiovascular diseases. As such, we reported that oral administration of a new exogenous NO donor (LA419) induced significant inhibition of platelet deposition on damaged vascular wall without provoking hypotension in an in vivo experimental model. Thrombin is one of the major triggers of platelet deposition and thrombosis on injured vessels; however, the effects of NO on thrombin-induced platelet activation are not fully known. Here, our aim was to investigate the inhibitory effects of exogenous NO administration on the major changes in platelet proteins induced by thrombin.

Methods and Results—

Platelets were obtained from a group of swine orally treated with LA419 (0.9 mg kg −1 ) or placebo for 8 days. Washed platelets were incubated with thrombin (0.4 NIH U/mL). Platelet proteins were then sequentially extracted based on differential solubility and studied by two-dimensional electrophoresis, mass spectrometry (matrix-assisted laser desorption ionization/time of flight), Western blot, and confocal immunofluorescence. NO treatment abrogated thrombin effects on 24 proteins involved in actin assembly, signaling, and metabolic activity. NO treatment prevented thrombin-induced translocation of gelsolin, filamin, 14-3-3ζ, phosphatidylinositol 3-kinase-γ isoform, and growth factor receptor-bound protein 2 (Grb2).

Conclusion—

Our results show that exogenous NO donor treatment renders platelets less sensitive to thrombin activation and inhibits thrombosis by interfering with the platelet shape change machinery.

Mechanical behaviour of synthetic surgical meshes: finite element simulation of the herniated abdominal wall

The material properties of meshes used in hernia surgery contribute to the overall mechanical behaviour of the repaired abdominal wall. The mechanical response of a surgical mesh has to be defined since the haphazard orientation of an anisotropic mesh can lead to inconsistent surgical outcomes. This study was designed to characterize the mechanical behaviour of three surgical meshes (Surgipro®, Optilene® and Infinit®) and to describe a mechanical constitutive law that accurately reproduces the experimental results. Finally, through finite element simulation, the behaviour of the abdominal wall was modelled before and after surgical mesh implant. Uniaxial loading of mesh samples in two perpendicular directions revealed the isotropic response of Surgipro® and the anisotropic behaviour of Optilene® and Infinit®. A phenomenological constitutive law was used to reproduce the measured experimental curves. To analyze the mechanical effect of the meshes once implanted in the abdomen, finite element simulation of the healthy and partially herniated repaired rabbit abdominal wall served to reproduce wall behaviour before and after mesh implant. In all cases, maximal displacements were lower and maximal principal stresses higher in the implanted abdomen than the intact wall model. Despite the fact that no mesh showed a behaviour that perfectly matched that of abdominal muscle, the Infinit® mesh was able to best comply with the biomechanics of the abdominal wall.

Tissue Factor Regulates Microvessel Formation and Stabilization by Induction of Chemokine (C-C motif) Ligand 2 Expression

Objective—

Tissue factor (TF) triggers arterial thrombosis. TF is also able to initiate cellular signaling mechanisms leading to angiogenesis. Because high cardiovascular risk atherosclerotic plaques show significant angiogenesis, our objective was to investigate whether TF is able to trigger and stabilize atherosclerotic plaque neovessel formation.

Methods and Results—

In this study, we showed, by real-time confocal microscopy in 3-dimensional basement membrane cocultures, that TF in human microvascular endothelial cells (HMEC-1) and in human vascular smooth muscle cells (HVSMCs) plays an important role in the formation of capillary-like networks. TF silencing in endothelial cells and smooth muscle cells inhibits the formation of tube-like structures with stable phenotype. Using an in vivo model, we observed that TF inhibition in either HMEC-1 or HVSMCs reduced their shared ability to form new capillaries. The phenotypic changes induced by TF silencing were linked to reduced chemokine (C-C motif) ligand 2 (CCL2) expression in endothelial cells. Wound healing and chemotactic assays demonstrated that TF-induced release of CCL2 stimulated HVSMC migration to HMEC-1.

Conclusion—

Endogenous TF regulates CCL2 production in endothelial cells. Secreted CCL2 mediates the angiogenic effect of TF by recruiting smooth muscle cells toward endothelial cells and facilitates the maturation of newly formed microvessels.

First Report of Alfalfa mosaic virus Infection in Viburnum tinus in Chile

Viburnum tinus L., commonly known as laurustinus, is an ornamental shrub that is widely used as a garden plant and flower crop. V. tinus is popular because of its desirable characteristics such as evergreen foliage, tolerance to pruning, winter blooms, and its adaptation to cold temperate zones. It is also relatively easy to grow and is commonly used as a windbreak. Infection of this ornamental species by Alfalfa mosaic virus (AMV) has been associated with yellow mottling or variegated leaf coloring, including light green and white, and has been referred to as the "Viburnum Calico" (1,4). In April 2011, at the onset of winter in the Southern Hemisphere, intense yellow spotting and mottling was observed on V. tinus leaves in the San Joaquin Campus at Pontificia Universidad Catolica de Chile. Presence of Aphis spiraecola Patch was observed on the shrubs, however, in the area it is also common to find other aphid species such as Toxoptera aurantii (Boyer de Fonscolombe) and A. fabae Scopoli. Leaf tissue samples from 10 asymptomatic and 10 symptomatic plants were examined for the presence of AMV by tissue-blot immunoassay with a commercially available polyclonal antibody (Agdia Inc., Elkhart, IN) along with the Goat affinity purified anti-rabbit IgG conjugated (Whole Molecule) (Molecular Probes, Invitrogen Corp., Carlsbad, CA). First-strand cDNA synthesis and PCR were performed with specific primers CP-AMV1 and CP-AMV2 (3). AMV was detected in all symptomatic leaves and also in two of the asymptomatic tissue analyzed by tissue blot assay. Reverse transcription (RT)-PCR produced 753-bp amplicons in all samples that were positive to AMV by tissue printing. No amplification product was observed when water control or seronegative samples were used as templates in the RT-PCR assays. Two amplicons were directly sequenced in both directions to confirm the identification of AMV in the leaf samples. The sequences obtained were homologous and BLASTN analysis of the submitted sequence (GenBank Accession No. JN040542) showed 99% nucleotide sequence identity to an AMV isolate described from Nicotiana tabacum L. (GenBank Accession No. FJ527749). These results demonstrate the presence of AMV in V. tinus in Chile. This pathogen has also been described to be affecting V. tinus in France (1) and V. lucidum Mill. in Spain (2). In Chile, V. tinum is increasingly grown as an ornamental plant. Therefore, care should be taken to ensure that the propagative materials of V. tinum are devoid of AMV infection to prevent further spread of this virus. References: (1) L. Cardin et al. Plant Dis. 90:1115, 2006. (2) M. Cebrián et al. Plant Dis. 92:1132, 2008. (3) M. Finetti-Sialer et al. J. Plant Pathol. 79:115, 1997. (4) H. E. Williams et al. Phytopathology 61:1305, 1971.

Monomeric C-reactive protein is prothrombotic and dissociates from circulating pentameric C-reactive protein on adhered activated platelets under flow

AIMS

We previously reported that C-reactive protein bioactivity on thrombogenesis was based on loss of its pentameric symmetry, resulting in formation of monomeric C-reactive protein. Our purpose was to provide mechanistic information on the direct effects of C-reactive protein isoforms on platelet activation and provide a C-reactive protein dissociation mechanism in circulating blood.

METHODS AND RESULTS

C-reactive protein-induced platelet activation was evaluated by flow cytometry. Platelet aggregation, clot properties, and coagulation were also measured. Washed platelets were incubated with C-reactive protein isoforms and vasodilator-stimulated phosphoprotein (VASP) phosphorylation was analysed by western blot and immunofluorescence. C-reactive protein dissociation under flow was evaluated by confocal microscopy on the surface of adhered platelets after perfusing human blood containing pentameric C-reactive protein at different shear rates. Dissociated monomeric C-reactive protein thrombogenicity was measured in flow experiments. Platelet aggregation and flow cytometry analysis revealed that monomeric C-reactive protein significantly induced platelet aggregation, surface P-selectin and CD63 exposure, and glycoprotein IIb-IIIa activation, whereas pentameric C-reactive protein was unable to produce any effect. p38 mitogen-activated protein kinase (MAPK) and Jun N-terminal kinase (JNK) inhibitors, as well as CD36 blocking antibody partially inhibited monomeric C-reactive protein-induced platelet activation and aggregation. Additionally, monomeric C-reactive protein significantly induced VASP dephosphorylation at serine 239. We found that pentameric C-reactive protein dissociated into monomeric C-reactive protein on the surface of activated adhered platelets under flow conditions and that this generated monomeric C-reactive protein promoted further platelet recruitment.

CONCLUSIONS

These data indicate that whereas serum pentameric C-reactive protein may not affect platelet activation, monomeric C-reactive protein, which dissociates from pentameric C-reactive protein on the surface of activated platelets, could contribute to atherothrombotic complications by promoting thrombosis.

Experimental study and constitutive modelling of the passive mechanical properties of the porcine carotid artery and its relation to histological analysis: Implications in animal cardiovascular device trials

The present study focusses on the determination, comparison and constitutive modelling of the passive mechanical properties of the swine carotid artery over very long stretches in both proximal and distal regions. Special attention is paid to the histological and mechanical variations of these properties depending on the proximity to the heart. The results can have clinical relevance, especially in the research field of intravascular device design. Before the final clinical trials on humans, research in the vascular area is conducted on animal models, swine being the most common due to the similarities between the human and swine cardiovascular systems as well as the fact that the swine size is suitable for testing devices, in this case endovascular carotid systems. The design of devices usually involves numerical techniques, and an important feature is the appropriate modelling of the mechanical properties of the vessel. Fourteen carotid swine arteries were harvested just after sacrifice and cyclic uniaxial tension tests in longitudinal and circumferential directions were performed for distal and proximal samples. The stress-stretch curves obtained were fitted with a hyperelastic anisotropic model. Stress-free configuration states were also analyzed. Finally, human and swine samples were processed in a histological laboratory and images were used to quantify their microconstituents. The statistical analysis revealed significant differences between the mechanical behavior of proximal and distal locations in the circumferential but not in the longitudinal direction. Circumferential direction samples show clear differences both in residual stretches and tensile curves between the two locations, while the features of longitudinal specimens are independent of the axial position. The statistical analysis provides significant evidence of changes depending on the position of the sample, mainly in elastin and SMC quantification.

Molecular and cellular mechanisms involved in cardiac remodeling after acute myocardial infarction

The extent of cardiac remodeling determines survival after acute MI. However, the mechanisms driving cardiac remodeling remain unknown. We examined the effect of ischemia and reperfusion (R) on myocardial changes up to 6 days post-MI. Pigs underwent 1.5h or 4h mid-LAD balloon occlusion and sacrificed or 1.5h occlusion followed by R and sacrificed at 2.5h, 1 day, 3 days, and 6 days. Ischemic- (IM) and non-ischemic myocardium (NIM) was obtained for molecular analysis of: 1) apoptosis (P-Bcl2, Bax, P-p53, active-caspase-3); 2) the TLR-4-MyD88-dependent and independent pathways; 3) Akt/mTOR/P70(S6K) axis activation; and, 4) fibrosis (TGF-β, collagen1-A1/A3). Histopathology for inflammation, collagen, and fibroblast content, TUNEL staining, and metalloproteinase activity was performed. Apoptosis is only detected upon R in IM cardiomyocytes and progresses up to 6 days post-R mainly associated with infiltrated macrophages. The Akt/mTOR/P70(s6K) pathway is also activated upon R (IM) and remains elevated up to 6 days-R (P<0.05). Ischemia activates the TLR-4-MyD88-dependent (cytokines/chemokines) and -independent (IRF-3) pathways in IM and NIM and remains high up to 6 days post-R (P<0.05). Accordingly, leukocytes and macrophages are progressively recruited to the IM (P<0.05). Ischemia up-regulates pro-fibrotic TGF-β that gradually rises collagen1-A1/-A3 mRNA with subsequent increase in total collagen fibrils and fibroblasts from 3 days-R onwards (P<0.005). MMP-2 activity increases from ischemia to 3 days post-R (P<0.05). We report that there is a timely coordinated cellular and molecular response to myocardial ischemia and R within the first 6 days after MI. In-depth understanding of the mechanisms involved in tissue repair is warranted to timely intervene and better define novel cardioprotective strategies.

Aggregated low density lipoprotein induces tissue factor by inhibiting sphingomyelinase activity in human vascular smooth muscle cells

BACKGROUND

Our previous results demonstrated that aggregated low density lipoprotein (agLDL) induces tissue factor (TF) expression and activation through Rho A translocation in human vascular smooth muscle cells (VSMC). We also previously demonstrated that membrane sphingomyelin (SM) content is higher in agLDL-exposed VSMC than in control cells. The main enzymes regulating cellular SM content are the family of sphingomyelinases (Smases) that hydrolize SM to phosphorylcholine and ceramide (CER).

OBJECTIVES

We wished to investigate whether agLDL has the ability to modulate acidic- (A-) and neutral (N-) Smase activity and whether or not this effect is related to the upregulatory effect of agLDL on Rho A translocation and TF activation in human VSMC.

METHODS AND RESULTS

By measuring generated [(14)C]-phosphorylcholine, we found that agLDL significantly decreased A-Smase and specially N-Smase activity. Pharmacological Smase inhibitors increased Rho A and TF. Specific loss-of-function of A-Smase or N-Smase 1 (N1-Smase) by siRNA treatment (500 nmol L(-1), 12 hours) dramatically increased membrane Rho A protein levels (5- and 3-fold, respectively). Concomitantly, TF protein expression and TF procoagulant activity were also increased. Inhibition of A-Smase or N-Smase activity by agLDL, siRNA-anti A- or N1-Smase or pharmacological treatment significantly increased the SM content of vascular cells. The inhibition of SM synthesis by fumonisin B(1) (FB(1)) prevented the upregulatory effect of agLDL on TF.

CONCLUSIONS

These results demonstrate that inhibition of both A- and N1-Smase might explain the upregulatory effect of agLDL on TF activation, and suggest that this effect is related, at least in part, to membrane SM enrichment.

Randomized trial comparing the effects of one set vs two sets of resistance exercises for outpatients with chronic low back pain and leg pain

AIM

Progressive resistance exercises (PRE) are prescribed to reverse the deconditioning associated with chronic back pain. The spine rehabilitation program has utilized 2 sets of progressive resistance exercises during each session, with increased resistance between sets, and with successive sessions. Exercise literature has challenged the need for multiple sets of resistance exercises, with a single set producing similar functional benefits. The authors studied whether completing 1 versus 2 sets of resistance exercises would affect strength, pain and disability outcomes in subjects with chronic low back pain (CLBP).

METHODS

The study randomly assigned subjects with CLBP to perform either 1 set or 2 sets of progressive resistance exercises during otherwise identical spine rehabilitation programs. The patient sample included 100 subjects (36 male patients, 64 female patients, mean age 46 years) with chronic back pain referred to spine rehabilitation. Primary outcomes were back strength and progressive isoinertial lifting evaluation (PILE) at discharge. Secondary outcomes were Oswestry disability (0-100) and pain scores (0-10). Exercises consisted of Cybex back extension, rotary torso, pull downs, and multi-hip; lifting of crates from floor-to-waist (lumbar) and waist-to-shoulder (cervical) heights. The maximum levels of exercises were determined using a four repetition to maximum protocol, and the PILE.

RESULTS

At discharge, there was no significant difference in strength, disability or pain measures between subjects completing 1 versus 2 sets of resistance exercises.

CONCLUSION

These findings suggest that there were no added benefits for completing a second set of resistance exercises during therapy sessions for patients with CLBP.