Vascular endothelial growth factor induces contralesional corticobulbar plasticity and functional neurological recovery in the ischemic brain

Vascular endothelial growth factor (VEGF) is a potent angiogenic factor, which also has neuroprotective activity. In view of these dual actions on vessels and neurons, we were interested whether VEGF promotes long distance axonal plasticity in the ischemic brain. Herein, we show that VEGF promotes neurological stroke recovery in mice when delivered in a delayed way starting 3 days after middle cerebral artery occlusion. Using anterograde tract-tracing experiments that we combined with histochemical and molecular biological studies, we demonstrate that although VEGF promoted angiogenesis predominantly in the ischemic hemisphere, pronounced axonal sprouting was induced by VEGF in the contralesional, but not the ipsilesional corticobulbar system. Corticobulbar plasticity was accompanied by the deactivation of the matrix metalloproteinase MMP9 in the lesioned hemisphere and the transient downregulation of the axonal growth inhibitors NG2 proteoglycan and brevican and the guidance molecules ephrin B1/2 in the contralesional hemisphere. The regulation of matrix proteinases, growth inhibitors, and guidance molecules offers insights how brain plasticity is controlled in the ischemic brain.

Concomitant Vascular Reconstruction During Pancreatectomy for Malignant Disease: A Propensity Score-Adjusted, Population-Based Trend Analysis Involving 10 206 Patients

OBJECTIVE To assess trends in the frequency of concomitant vascular reconstructions (VRs) from 2000 through 2009 among patients who underwent pancreatectomy, as well as to compare the short-term outcomes between patients who underwent pancreatic resection with and without VR. DESIGN Single-center series have been conducted to evaluate the short-term and long-term outcomes of VR during pancreatic resection. However, its effectiveness from a population-based perspective is still unknown. Unadjusted, multivariable, and propensity score-adjusted generalized linear models were performed. SETTING Nationwide Inpatient Sample from 2000 through 2009. PATIENTS A total of 10 206 patients were involved. MAIN OUTCOME MEASURES Incidence of VR during pancreatic resection, perioperative in-hospital complications, and length of hospital stay. RESULTS Overall, 10 206 patients were included in this analysis. Of these, 412 patients (4.0%) underwent VR, with the rate increasing from 0.7% in 2000 to 6.0% in 2009 (P < .001). Patients who underwent pancreatic resection with VR were at a higher risk for intraoperative (propensity score-adjusted odds ratio, 1.94; P = .001) and postoperative (propensity score-adjusted odds ratio, 1.36; P = .008) complications, while the mortality and median length of hospital stay were similar to those of patients without VR. Among the 25% of hospitals with the highest surgical volume, patients who underwent pancreatic surgery with VR had significantly higher rates of postoperative complications and mortality than patients without VR. CONCLUSIONS The frequency of VR during pancreatic surgery is increasing in the United States. In contrast with most single-center analyses, this population-based study demonstrated that patients who underwent VR during pancreatic surgery had higher rates of adverse postoperative outcomes than their counterparts who underwent pancreatic resection only. Prospective studies incorporating long-term outcomes are warranted to further define which patients benefit from VR.

The GPVI - Fc Fusion Protein Revacept Reduces Thrombus Formation and Improves Vascular Dysfunction in Atherosclerosis without Any Impact on Bleeding Times

Glycoprotein VI (GPVI) is a key platelet receptor which mediates plaque-induced platelet activation and consecutive atherothrombosis, but GPVI is also involved in platelet-mediated atheroprogression. Therefore, interference in GPVI-mediated platelet activation has the potential to combine short-term and long-term beneficial effects, specificity and safety especially regarding bleeding complications.

Vascular endothelial growth factor-A and aldosterone: relevance to normal pregnancy and preeclampsia

Aldosterone levels are markedly elevated during normal pregnancy but fall even though volume contracts when preeclampsia occurs. The level of aldosterone in either condition cannot be explained solely by the activity of the renin-angiotensin II system. In normal gestation, vascular endothelial growth factor (VEGF) is thought to maintain vascular health, but its role in adrenal hormone production is unknown. We hypothesized that the role of VEGF in the adrenal gland is to maintain vascular health and regulate aldosterone production. Here, we demonstrate that supernatant of endothelial cells grown in the presence of VEGF enhanced aldosterone synthase activity in human adrenocortical cells. VEGF either alone or combined with angiotensin II increased aldosterone production in adrenal cells. These data suggest that endothelial cell-dependent and independent activation of aldosterone is regulated by VEGF. In contrast to angiotensin II, VEGF did not upregulate the steroidogenic acute regulatory protein. Consistent with this observation, angiotensin II stimulated both aldosterone and cortisol synthesis from progesterone, whereas VEGF stimulated selectively aldosterone production. In rats, overexpression of soluble fms-like tyrosine kinase-1, an endogenous VEGF inhibitor, led to adrenocortical capillary rarefaction and fall in aldosterone concentrations that correlated inversely with soluble fms-like tyrosine kinase-1 levels. These findings may explain why aldosterone increases so markedly during normal gestation and why preeclampsia, a condition characterized by high soluble fms-like tyrosine kinase-1, is associated with inappropriately low aldosterone levels in spite of relatively lower plasma volumes.

PA21, a New Iron-Based Noncalcium Phosphate Binder, Prevents Vascular Calcification in Chronic Renal Failure Rats

Chronic renal failure (CRF) is associated with the development of secondary hyperparathyroidism and vascular calcifications. We evaluated the efficacy of PA21, a new iron-based noncalcium phosphate binder, in controlling phosphocalcic disorders and preventing vascular calcifications in uremic rats. Rats with adenine-diet-induced CRF were randomized to receive either PA21 0.5, 1.5, or 5% or CaCO3 3% in the diet for 4 weeks, and were compared with uremic and nonuremic control groups. After 4 weeks of phosphate binder treatment, serum calcium, creatinine, and body weight were similar between all CRF groups. Serum phosphorus was reduced with CaCO3 3% (2.06 mM; P ≤ 0.001), PA21 1.5% (2.29 mM; P < 0.05), and PA21 5% (2.21 mM; P ≤ 0.001) versus CRF controls (2.91 mM). Intact parathyroid hormone was strongly reduced in the PA21 5% and CaCO3 3% CRF groups to a similar extent (1138 and 1299 pg/ml, respectively) versus CRF controls (3261 pg/ml; both P ≤ 0.001). A lower serum fibroblast growth factor 23 concentration was observed in the PA21 5%, compared with CaCO3 3% and CRF, control groups. PA21 5% CRF rats had a lower vascular calcification score compared with CaCO3 3% CRF rats and CRF controls. In conclusion, PA21 was as effective as CaCO3 at controlling phosphocalcic disorders but superior in preventing the development of vascular calcifications in uremic rats. Thus, PA21 represents a possible alternative to calcium-based phosphate binders in CRF patients.

Vascular endothelial cell-specific phosphotyrosine phosphatase (VE-PTP) activity is required for blood vessel development

VE-PTP, a receptor-type phosphotyrosine phosphatase, associates with the tyrosine kinase receptor Tie-2 and VE-cadherin and enhances the adhesive function of the latter. Here, VE-PTP was found to be restricted to endothelial cells, with a preference for arterial endothelium. Mutant mice expressing a truncated, secreted form of VE-PTP lacking the cytoplasmic and transmembrane domains and the most membrane-proximal extracellular fibronectin type III repeat, showed severe vascular malformations causing lethality at 10 days of gestation. Although blood vessels were initially formed, the intraembryonic vascular system soon deteriorated. Blood vessels in the yolk sac developed into dramatically enlarged cavities. In explant cultures of mutant allantoides, endothelial cells were found next to vessel structures growing as cell layers. No signs for enhanced endothelial apoptosis or proliferation were observed. Thus, the activity of VE-PTP is not required for the initial formation of blood vessels, yet it is essential for their maintenance and remodeling.

Post-mortem angiography after vascular perfusion with diesel oil and a lipophilic contrast agent

OBJECTIVE: The objective of our study was to establish optimal perfusion conditions for high-resolution postmortem angiography that would permit dynamic visualization of the arterial and venous systems. MATERIALS AND METHODS: Cadavers of two dogs and one cat were perfused with diesel oil through a peristaltic pump. The lipophilic contrast agent Lipiodol Ultra Fluide was then injected, and angiography was performed. The efficiency of perfusion was evaluated in the chick chorioallantoic membrane. RESULTS: Vessels could be seen up to the level of the smaller supplying and draining vessels. Hence, both the arterial and the venous sides of the vascular system could be distinguished. The chorioallantoic membrane assay revealed that diesel oil enters microvessels up to 50 microm in diameter and that it does not penetrate the capillary network. CONCLUSION: After establishing a postmortem circulation by diesel oil perfusion, angiography can be performed by injection of Lipiodol Ultra Fluide. The resolution of the images obtained up to 3 days after death is comparable to that achieved in clinical angiography.

Rapid endocytosis of copper-zinc superoxide dismutase into human endothelial cells: role for its vascular activity

Cytosolic CuZn-SOD (SOD1) is a dimeric, carbohydrate-free enzyme with a molecular weight of about 32 kDa and also circulates in human blood plasma. Due to its molecular mass it has been believed that the enzyme cannot penetrate the cell membrane. Here we report that rapid endocytosis of FITC-CuZn-SOD into human endothelial cells occurs within 5 min. Moreover, relaxation of rat aortic rings in response to CuZn-SOD is associated with a lag time of 45-60 s and only observed in the presence of intact endothelial cells. The results indicate acute and rapid endothelial cell endocytosis of CuZn-SOD, possibly via activation of a receptor-mediated pathway. Intracellular uptake via endocytosis may contribute to the vascular effects of CuZn-SOD, including vasodilation, and is likely to play a role in regulation of vascular tone and diseases such as atherosclerosis.

Different vascular smooth muscle cell apoptosis in the human internal mammary artery and the saphenous vein. Implications for bypass graft disease

BACKGROUND: The remarkable patency of internal mammary artery (MA) grafts compared to saphenous vein (SV) grafts has been related to different biological properties of the two blood vessels. We examined whether proliferation and apoptosis of vascular smooth muscle cells (VSMC) from human coronary artery bypass vessels differ according to patency rates. METHODS AND RESULTS: Proliferation rates to serum or platelet-derived growth factor (PDGF)-BB were lower in VSMC from MA than SV. Surface expression of PDGF beta-receptor was slightly lower, while that of alpha-receptor was slightly higher in MA than SV. Cell cycle distribution, expression of cyclin E, cdk2, p21, p27, p57, and cdk2 kinase activity were identical in PDGF-BB-stimulated cells from MA and SV. However, apoptosis rates were higher in MA than SV determined by lactate dehydrogenase release, DNA fragmentation, and Hoechst 33258 staining. Moreover, caspase inhibitors (Z-VAD-fmk, Boc-D-fmk) abrogated the different proliferation rates of VSMC from MA versus SV. Western blotting and GSK3-beta kinase assay revealed lower Akt activity in VSMC from MA versus SV, while total Akt expression was identical. Adenoviral transduction of a constitutively active Akt mutant abrogated the different proliferation rates of VSMC from MA versus SV. CONCLUSIONS: Higher apoptosis rates due to lower Akt activity rather than different cell cycle regulation account for the lower proliferation of VSMC from MA as compared to SV. VSMC apoptosis may protect MA from bypass graft disease.

The cytoplasmic domain of the ligand ephrinB2 is required for vascular morphogenesis but not cranial neural crest migration

The transmembrane ligand ephrinB2 and its cognate Eph receptor tyrosine kinases are important regulators of vascular morphogenesis. EphrinB2 may have an active signaling role, resulting in bi-directional signal transduction downstream of both ephrinB2 and Eph receptors. To separate the ligand and receptor-like functions of ephrinB2 in mice, we replaced the endogenous gene by cDNAs encoding either carboxyterminally truncated (ephrinB2(DeltaC)) or, as a control, full-length ligand (ephrinB2(WT)). While homozygous ephrinB2(WT/WT) animals were viable and fertile, loss of the ephrinB2 cytoplasmic domain resulted in midgestation lethality similar to ephrinB2 null mutants (ephrinB2(KO)). The truncated ligand was sufficient to restore guidance of migrating cranial neural crest cells, but ephrinB2(DeltaC/DeltaC) embryos showed defects in vasculogenesis and angiogenesis very similar to those observed in ephrinB2(KO/KO) animals. Our results indicate distinct requirements of functions mediated by the ephrinB carboxyterminus for developmental processes in the vertebrate embryo.

Functional interaction of vascular endothelial-protein-tyrosine phosphatase with the angiopoietin receptor Tie-2

During development of the vertebrate vascular system essential signals are transduced via protein-tyrosine phosphorylation. Null-mutations of receptor-tyrosine kinase (RTK) genes expressed in endothelial cells (ECs) display early lethal vascular phenotypes. We aimed to identify endothelial protein-tyrosine phosphatases (PTPs), which should have similar importance in EC-biology. A murine receptor-type PTP was identified by a degenerated PCR cloning approach from endothelial cells (VE-PTP). By in situ hybridization this phosphatase was found to be specifically expressed in vascular ECs throughout mouse development. In experiments using GST-fusion proteins, as well as in transient transfections, trapping mutants of VE-PTP co-precipitated with the Angiopoietin receptor Tie-2, but not with the Vascular Endothelial Growth Factor receptor 2 (VEGFR-2/Flk-1). In addition, VE-PTP dephosphorylates Tie-2 but not VEGFR-2. We conclude that VE-PTP is a Tie-2 specific phosphatase expressed in ECs, and VE-PTP phosphatase activity serves to specifically modulate Angiopoietin/Tie-2 function. Based on its potential role as a regulator of blood vessel morphogenesis and maintainance, VE-PTP is a candidate gene for inherited vascular malformations similar to the Tie-2 gene.

Roles of ephrinB ligands and EphB receptors in cardiovascular development: demarcation of arterial/venous domains, vascular morphogenesis, and sprouting angiogenesis

Eph receptor tyrosine kinases and their cell-surface-bound ligands, the ephrins, regulate axon guidance and bundling in the developing brain, control cell migration and adhesion, and help patterning the embryo. Here we report that two ephrinB ligands and three EphB receptors are expressed in and regulate the formation of the vascular network. Mice lacking ephrinB2 and a proportion of double mutants deficient in EphB2 and EphB3 receptor signaling die in utero before embryonic day 11.5 (E11.5) because of defects in the remodeling of the embryonic vascular system. Our phenotypic analysis suggests complex interactions and multiple functions of Eph receptors and ephrins in the embryonic vasculature. Interaction between ephrinB2 on arteries and its EphB receptors on veins suggests a role in defining boundaries between arterial and venous domains. Expression of ephrinB1 by arterial and venous endothelial cells and EphB3 by veins and some arteries indicates that endothelial cell-to-cell interactions between ephrins and Eph receptors are not restricted to the border between arteries and veins. Furthermore, expression of ephrinB2 and EphB2 in mesenchyme adjacent to vessels and vascular defects in ephB2/ephB3 double mutants indicate a requirement for ephrin-Eph signaling between endothelial cells and surrounding mesenchymal cells. Finally, ephrinB ligands induce capillary sprouting in vitro with a similar efficiency as angiopoietin-1 (Ang1) and vascular endothelial growth factor (VEGF), demonstrating a stimulatory role of ephrins in the remodeling of the developing vascular system.