Vasa Vasorum in Saphenous Vein for CABG: A Review of Morphological Characteristics.

This short article discusses selected scanning electron microscope and transmission electron microscope features of vasa vasorum including pericytes and basement membrane of the human saphenous vein (SV) harvested with either conventional (CON) or no-touch (NT) technique for coronary artery bypass grafting. Scanning electron microscope data shows the general damage to vasa vasorum of CON-SV, while the transmission electron microscope data presents ultrastructural features of the vasa in more detail. Hence there are some features suggesting pericyte involvement in the contraction of vasa blood vessels, particularly in CON-SV. Other features associated with the vasa vasorum of both CON-SV and NT-SV preparations include thickened and/or multiplied layers of the basement membrane. In some cases, multiple layers of basement membrane embrace both pericyte and vasa microvessel making an impression of a "unit" made by basement membrane-pericyte-endothelium/microvessel. It can be speculated that this structural arrangement has an effect on the contractile and/or relaxing properties of the vessels involved. Endothelial colocalization of immunoreactive inducible nitric oxide synthase and endothelin-1 can be observed (with laser confocal microscope) in some of the vasa microvessels. It can be speculated that this phenomenon, particularly of the expression of inducible nitric oxide synthase, might be related to structurally changed vasa vessels, e.g., with expanded basement membrane. Fine physiological relationships between vasa vasorum endothelium, basement membrane, pericyte, and perivascular nerves have yet to be uncovered in the detail needed for better understanding of the cells'specific effects in SV preparations for coronary artery bypass grafting.

Pericyte-specific deletion of ninjurin-1 induces fragile vasa vasorum formation and enhances intimal hyperplasia of injured vasculature.

Adventitial abnormalities including enhanced vasa vasorum malformation are associated with development and vulnerability of atherosclerotic plaque. However, the mechanisms of vasa vasorum malformation and its role in vascular remodeling have not been fully clarified. We recently reported that ninjurin-1 (Ninj1) is a crucial adhesion molecule for pericytes to form matured neovessels. The purpose is to examine if Ninj1 regulates adventitial angiogenesis and affects the vascular remodeling of injured vessels using pericyte-specific Ninj1 deletion mouse model. Mouse femoral arteries were injured by insertion of coiled wire. Four weeks after vascular injury, fixed arteries were decolorized. Vascular remodeling, including intimal hyperplasia and adventitial microvessel formation were estimated in a three-dimensional view. Vascular fragility, including blood leakiness was estimated by extravasation of fluorescein isothiocyanate (FITC)-lectin or FITC-dextran from microvessels. Ninj1 expression was increased in pericytes in response to vascular injury. NG2-CreER/Ninj1loxp mice were treated with tamoxifen (Tam) to induce deletion of Ninj1 in pericyte (Ninj1 KO). Tam-treated NG2-CreER or Tam-nontreated NG2-CreER/Ninj1loxp mice were used as controls. Intimal hyperplasia was significantly enhanced in Ninj1 KO compared with controls. Vascular leakiness was significantly enhanced in Ninj1 KO. In Ninj1 KO, the number of infiltrated macrophages in adventitia was increased, along with the expression of inflammatory cytokines. In conclusion, deletion of Ninj1 in pericytes induces the immature vasa vasorum formation of injured vasculature and exacerbates adventitial inflammation and intimal hyperplasia. Thus, Ninj1 contributes to the vasa vasorum maturation in response to vascular injury and to reduction of vascular remodeling.NEW & NOTEWORTHY Although abnormalities of adventitial vasa vasorum are associated with vascular remodeling such as atherosclerosis, the mechanisms of vasa vasorum malformation and its role in vascular remodeling have not been fully clarified. The present study provides a line of novel evidence that ninjurin-1 contributes to adventitial microvascular maturation during vascular injury and regulates vascular remodeling.

Extracellular adenosine enhances pulmonary artery vasa vasorum endothelial cell barrier function via Gi/ELMO1/Rac1/PKA-dependent signaling mechanisms.

The vasa vasorum (VV), the microvascular network around large vessels, has been recognized as an important contributor to the pathological vascular remodeling in cardiovascular diseases. In bovine and rat models of hypoxic pulmonary hypertension (PH), we have previously shown that chronic hypoxia profoundly increased pulmonary artery (PA) VV permeability, associated with infiltration of inflammatory and progenitor cells in the arterial wall, perivascular inflammation, and structural vascular remodeling. Extracellular adenosine was shown to exhibit a barrier-protective effect on VV endothelial cells (VVEC) via cAMP-independent mechanisms, which involved adenosine A1 receptor-mediated activation of Gi-phosphoinositide 3-kinase-Akt pathway and actin cytoskeleton remodeling. Using VVEC isolated from the adventitia of calf PA, in this study we investigated in more detail the mechanisms linking Gi activation to downstream barrier protection pathways. Using a small-interference RNA (siRNA) technique and transendothelial electrical resistance assay, we found that the adaptor protein, engulfment and cell motility 1 (ELMO1), the tyrosine phosphatase Src homology region 2 domain-containing phosphatase-2, and atypical Gi- and Rac1-mediated protein kinase A activation are implicated in VVEC barrier enhancement. In contrast, the actin-interacting GTP-binding protein, girdin, and the p21-activated kinase 1 downstream target, LIM kinase, are not involved in this response. In addition, adenosine-dependent cytoskeletal rearrangement involves activation of cofilin and inactivation of ezrin-radixin-moesin regulatory cytoskeletal proteins, consistent with a barrier-protective mechanism. Collectively, our data indicate that targeting adenosine receptors and downstream barrier-protective pathways in VVEC may have a potential translational significance in developing pharmacological approach for the VV barrier protection in PH.

Adventitial fibroblast-derived vascular endothelial growth factor promotes vasa vasorum-associated neointima formation and macrophage recruitment.

AIMS: Adventitial vasa vasorum provides oxygen and nourishment to the vascular wall, but whether it regulates vascular disease remains unclear. We have previously shown that an increased expression of VEGF (vascular endothelial growth factor) is associated with macrophage infiltration. This study aims to determine whether adventitial fibroblast (AF)-derived VEGF increases the number of vasa vasorum contributing to neointima formation through macrophage recruitment. METHODS AND RESULTS: In rat balloon injury model, vasa vasorum count was increased particularly in the adventitia accompanied by cell proliferation and VEGF expression. Both endogenous and PKH26-labelled exogenous macrophages were mainly distributed in adventitia around vasa vasorum. Interestingly, perivascular delivery of Ranibizumab preferentially concentrated in adventitia resulted in a decrease of neointima formation with concurrent reduction of vasa vasorum count and macrophage infiltration. AFs with adenovirus-mediated VEGF over-expression delivered to the adventitia significantly enhanced these pathological changes after injury. In Tie2-cre/Rosa-LoxP-RFP mice, endothelial cells were increased in the adventitia after wire injury. By using multiphoton laser scanning microscopy, macrophage rolling, adhesion and transmigration were observed in vasa vasorum. Moreover, adoptive transfer of macrophages accelerated injury-induced neointima formation. VEGF-neutralizing antibody administration also attenuated wire injury-induced neointima formation and macrophage infiltration. In primary cultured AFs, exogenous VEGF increased VEGF expression and secretion in a time- and dose-dependent manner. AF-conditioned medium promoted endothelial cell angiogenesis, vascular cell adhesion molecule-1 expression and macrophage adhesion was blocked by VEGF-neutralizing antibody and VEGFR2 inhibitor ZM323881, which also inhibited activation of VEGFR2/ERK1/2 pathway. CONCLUSION: These results demonstrate that AF-derived VEGF plays a significant role in the increase of vasa vasorum count which is involved in macrophage recruitment and neointima formation.

Reduction in Vasa Vasorum Angiogenesis by Lp-PLA2 Selective Inhibitor Through The HIF-1α and VEGF Expression Under Dyslipidemic Conditions in Atherosclerosis Pathogenesis.

BACKGROUND: Atherosclerosis is a chronic inflammatory disease which may lead to major cardiovascular events. The primary cause of atherosclerosis is Dyslipidemia. The increased level of lipid profile triggers endothelial dysfunction. This results in inflammation with the recruitment of monocyte, macrophage, T lymphocyte, and Mast cells secreted by an Lp-PLA2 enzyme which causes binding between macrophage and oxidized LDL. This binding results in the formation of foam cells and also the migration of smooth muscle cells. Following that, an Lp-PLA2 receptor hydrolizes OxPC which results in LysoPC and OxNEFA, bioactive compounds which stimulate the progression of atherosclerosis plaques. This process leads to cell hypoxia, which may result in the increase of HIF-1α and VEGF expressions and induction of vasa vasorum angiogenesis. Employing darapladib as an agent of Lp-PLA2 selective inhibitors, this study aimed to find out the effect of darapladib as an Lp- PLA2 selective inhibitor agent on the formation of vasa vasorum angiogenesis and the decrease of HIF-1α and VEGF expression in aortic tissue of rats with dyslipidemia. METHOD: A true laboratory experiment with a randomized post-test control group design used 30 male spraque dowley rats as animal models which were divided into 6 groups: Normal 8 weeks, Normal 16 weeks, Dyslipidemia (DL) 8 weeks, Dyslipidemia (DL) 16 weeks, Dyslipidemia with darapladib treatment (DLDP) 8 weeks and Dyslipidemia with darapladib treatment (DLDP) 16 weeks. The data measured in this study were the lipid profile (total cholesterol, HDL, and LDL). Using EnzyChrom TM kit, hematoxylin eosin, and double-labelling immunofluorescene, the levels of lipid profile, vasa vasorum, HIF-1α and VEGF were measured. RESULTS: The study results which were analyzed using NOVA test showed that with darapladib administration, there was a significant decrease in vasa vasorum angiogenesis (p=0.000), HIF-1α (p=0.005) and VEGF (p=0.009) expression in each time series. This result proves that Lp-PLA2 inhibitor reduces inflammatory process. CONCLUSION: Darapladib injection as an Lp-PLA2 selective inhibitor correlates with the decreasing vasa vasorum angiogenesis through alteration in HIF-1α and VEGF expressions in the aorta of high fat diet rats. We recommend further experiments to determine the effectiveness of darapladib with earlier time series in the atherosclerosis process.

Vasa Vasorum Angiogenesis: Key Player in the Initiation and Progression of Atherosclerosis and Potential Target for the Treatment of Cardiovascular Disease.

Plaque microvascularization and increased endothelial permeability are key players in the development of atherosclerosis, from the initial stages of plaque formation to the occurrence of acute cardiovascular events. First, endothelial dysfunction and increased permeability facilitate the entry of diverse inflammation-triggering molecules and particles such as low-density lipoproteins into the artery wall from the arterial lumen and vasa vasorum (VV). Recognition of entering particles by resident phagocytes in the vessel wall triggers a maladaptive inflammatory response that initiates the process of local plaque formation. The recruitment and accumulation of inflammatory cells and the subsequent release of several cytokines, especially from resident macrophages, stimulate the expansion of existing VV and the formation of new highly permeable microvessels. This, in turn, exacerbates the deposition of pro-inflammatory particles and results in the recruitment of even more inflammatory cells. The progressive accumulation of leukocytes in the intima, which trigger proliferation of smooth muscle cells in the media, results in vessel wall thickening and hypoxia, which further stimulates neoangiogenesis of VV. Ultimately, this highly inflammatory environment damages the fragile plaque microvasculature leading to intraplaque hemorrhage, plaque instability, and eventually, acute cardiovascular events. This review will focus on the pivotal roles of endothelial permeability, neoangiogenesis, and plaque microvascularization by VV during plaque initiation, progression, and rupture. Special emphasis will be given to the underlying molecular mechanisms and potential therapeutic strategies to selectively target these processes.

C-reactive protein can upregulate VEGF expression to promote ADSC-induced angiogenesis by activating HIF-1α via CD64/PI3k/Akt and MAPK/ERK signaling pathways.

BACKGROUND: Proliferation of the vasa vasorum has been implicated in the pathogenesis of atherosclerosis, and the vasa vasorum is closely associated with resident stem cells within the vasculature. C-reactive protein (CRP) is positively correlated with cardiovascular disease risk, and our previous study demonstrated that it induces inflammatory reactions of perivascular adipose tissue by targeting adipocytes. METHODS: Here we investigated whether CRP affected the proliferation and proangiogenic paracrine activity of adipose-derived stem cells (ADSCs), which may contribute to vasa vasorum angiogenesis. RESULTS: We found that CRP did not affect ADSC apoptosis, cell cycle, or proliferation but did increase their migration by activating the PI3K/Akt pathway. Our results demonstrated that CRP can upregulate vascular endothelial growth factor-A (VEGF-A) expression by activating hypoxia inducible factor-1α (HIF-1α) in ADSCs, which significantly increased tube formation on Matrigel and functional vessels in the Matrigel plug angiogenesis assay. The inhibition of CRP-activated phosphorylation of ERK and Akt can suppress CRP-stimulated HIF-1α activation and VEGF-A expression. CRP can also stimulate proteolytic activity of matrix metalloproteinase-2 in ADSCs. Furthermore, CRP binds activating CD64 on ADSCs, rather than CD16/32. CONCLUSION: Our findings implicate that CRP might play a role in vasa vasorum growth by activating the proangiogenic activity of ADSCs.

Pericoronary Adipose Tissue as Storage and Supply Site for Oxidized Low-Density Lipoprotein in Human Coronary Plaques.

OBJECTIVES: It is generally believed that low-density lipoprotein enters the vascular wall from its lumen and oxidized (oxLDL), after which it plays an important role in atherosclerosis. Because voluminous epicardial adipose tissue is a risk factor for coronary events, there is a possibility that the pericoronary adipose tissue (PCAT), which is a part of epicardial adipose tissue, acts as a risk factor by supplying oxLDL to the coronary arterial wall. The present study was performed whether PCAT stores and supplies oxLDL to the coronary wall. METHODS: Localization of oxLDL in PCAT and its relation to plaque morphology were examined by immunohistochemical techniques in 27 epicardial coronary arteries excised from 9 human autopsy cases. RESULTS: OxLDL deposited in all PCAT of the studied cases. The percent (%) incidence of oxLDL in the intima of 25 normal segment, 19 white plaques, 15 yellow plaques without necrotic core (NC) and 10 yellow plaques with NC, was 32, 84, 93 (p<0.05 vs normal segments and yellow plaques with NC), and 30, respectively. OxLDL deposited either in dotted or diffuse pattern. Double immunohistochemical staining revealed that the dotted oxLDL was that contained in CD68(+)-macrophages. The oxLDL-containing macrophages were observed in the interstitial space but not inside of the vasa vasorum, and they traversed PCAT, adventitia, external and internal elastic laminae, suggesting their migration towards the intima. Diffuse oxLDL deposits were observed in 17 preparations, the majority of which were co-localized with the vasa vasorum in outer or in both inner and outer halves of intima, and rarely in the inner half alone. CONCLUSIONS: The results suggested that PCAT is a supply source of oxLDL to coronary intima and acts as a risk factor for coronary events, that oxLDL increasingly deposits in the intima with plaque growth and decreases after plaque maturation, and therefore molecular therapies targeting the PCAT before plaque growth could be effective in preventing human coronary atherosclerosis.

Vasa vasorum anti-angiogenesis through H2O2, HIF-1α, NF-κB, and iNOS inhibition by mangosteen pericarp ethanolic extract (Garcinia mangostana Linn) in hypercholesterol-diet-given Rattus norvegicus Wistar strain.

BACKGROUND: Oxidative stress in atherosclerosis produces H2O2 and triggers the activation of nuclear factor kappa beta (NF-κB) and increase of inducible nitric oxide synthase (iNOS). The formation of vasa vasorum occurs in atherosclerosis. Vasa vasorum angiogenesis is mediated by VEGFR-1 and upregulated by hypoxia-inducible factor-1α (HIF-1α). The newly formed vasa vasorum are fragile and immature and thus increase plaque instability. It is necessary to control vasa vasorum angiogenesis by using mangosteen pericarp antioxidant. This study aims to demonstrate that mangosteen pericarp ethanolic extract can act as vasa vasorum anti-angiogenesis through H2O2, HIF-1α, NF-κB, and iNOS inhibition in rats given a hypercholesterol diet. METHODS: This was a true experimental laboratory, in vivo posttest with control group design, with 20 Rattus norvegicus Wistar strain rats divided into five groups (normal group, hypercholesterol group, and hypercholesterol groups with certain doses of mangosteen pericarp ethanolic extract: 200, 400, and 800 mg/kg body weight). The parameters of this study were H2O2 measured by using colorimetric analysis, as well as NF-κB, iNOS, and HIF-1α, which were measured by using immunofluorescence double staining and observed with a confocal laser scanning microscope in aortic smooth muscle cell. The angiogenesis of vasa vasorum was quantified from VEGFR-1 level in aortic tissue and confirmed with hematoxylin and eosin staining. RESULTS: Analysis of variance test and Pearson's correlation coefficient showed mangosteen pericarp ethanolic extract had a significant effect (P<0.05) in decreasing vasa vasorum angiogenesis through H2O2, HIF-1α, NF-κB, and iNOS inhibition in hypercholesterol-diet-given R. norvegicus Wistar strain. CONCLUSION: Mangosteen pericarp ethanolic extract 800 mg/kg body weight is proven to decrease vasa vasorum angiogenesis. Similar studies with other inflammatory parameters are encouraged to clarify the mechanism of vasa vasorum angiogenesis inhibition by mangosteen pericarp ethanolic extract.

Adenosine A1 receptors promote vasa vasorum endothelial cell barrier integrity via Gi and Akt-dependent actin cytoskeleton remodeling.

BACKGROUND: In a neonatal model of hypoxic pulmonary hypertension, a dramatic pulmonary artery adventitial thickening, accumulation of inflammatory cells in the adventitial compartment, and angiogenic expansion of the vasa vasorum microcirculatory network are observed. These pathophysiological responses suggest that rapidly proliferating vasa vasorum endothelial cells (VVEC) may exhibit increased permeability for circulating blood cells and macromolecules. However, the molecular mechanisms underlying these observations remain unexplored. Some reports implicated extracellular adenosine in the regulation of vascular permeability under hypoxic and inflammatory conditions. Thus, we aimed to determine the role of adenosine in barrier regulation of VVEC isolated from the pulmonary arteries of normoxic (VVEC-Co) or chronically hypoxic (VVEC-Hyp) neonatal calves. PRINCIPAL FINDINGS: We demonstrate via a transendothelial electrical resistance measurement that exogenous adenosine significantly enhanced the barrier function in VVEC-Co and, to a lesser extent, in VVEC-Hyp. Our data from a quantitative reverse transcription polymerase chain reaction show that both VVEC-Co and VVEC-Hyp express all four adenosine receptors (A1, A2A, A2B, and A3), with the highest expression level of A1 receptors (A1Rs). However, A1R expression was significantly lower in VVEC-Hyp compared to VVEC-Co. By using an A1R-specific agonist/antagonist and siRNA, we demonstrate that A1Rs are mostly responsible for adenosine-induced enhancement in barrier function. Adenosine-induced barrier integrity enhancement was attenuated by pretreatment of VVEC with pertussis toxin and GSK690693 or LY294002, suggesting the involvement of Gi proteins and the PI3K-Akt pathway. Moreover, we reveal a critical role of actin cytoskeleton in VVEC barrier regulation by using specific inhibitors of actin and microtubule polymerization. Further, we show that adenosine pretreatment blocked the tumor necrosis factor alpha (TNF-α)-induced permeability in VVEC-Co, validating its anti-inflammatory effects. CONCLUSIONS: We demonstrate for the first time that stimulation of A1Rs enhances the barrier function in VVEC by activation of the Gi/PI3K/Akt pathway and remodeling of actin microfilament.

Anti-angiogenic activity of rPAI-1(23) and vasa vasorum regression.

The vasa vasorum are unique networks of vessels that become angiogenic in response to changes in the vessel wall. Structural studies, using various imaging modalities, show that the vasa vasorum form a plexus of microvessels during the atherosclerotic disease process. The events that stimulate vasa vasorum neovascularization remain unclear. Anti-angiogenic molecules have been shown to inhibit/regress the neovascularization; they provide significant insight into vasa vasorum function, structure, and specific requirements for growth and stability. This review discusses evidence for and against potential stimulators of vasa vasorum neovascularization. Anti-angiogenic rPAI-123, a truncated isoform of plasminogen activator inhibitor-1 (PAI-1) stimulates a novel pathway for regulating plasmin activity. This mechanism contributes significantly to vasa vasorum regression/collapse and is discussed as a model of regression.

Fibroblast growth factor-2 is required for vasa vasorum plexus stability in hypercholesterolemic mice.

OBJECTIVE: Vasa vasorum are angiogenic in advanced stages of human atherosclerosis and hypercholesterolemic mouse models. Fibroblast growth factor-2 (FGF-2) is the predominant angiogenic growth factor in the adventitia and plaque of hypercholesterolemic low-density lipoprotein receptor-deficient/apolipoprotein B(100/100) mice (DKO). FGF-2 seems to play a role in the formation of a distinct vasa vasorum network. This study examined the vasa vasorum structure and its relationship to FGF-2. METHODS AND RESULTS: DKO mice treated with saline, antiangiogenic recombinant plasminogen activator inhibitor-1(23) (rPAI-1(23)), or soluble FGF receptor 1 were perfused with fluorescein-labeled Lycopersicon esculentum lectin. Confocal images of FGF-2-probed descending aorta adventitia show that angiogenic vasa vasorum form a plexus-like network in saline-treated DKO similar to the FGF-2 pattern of distribution. Mice treated with rPAI-1(23) and soluble FGF receptor 1 lack a plexus; FGF-2 and vasa vasorum density and area are significantly reduced. A perlecan/FGF-2 complex is critical for plexus stability. Excess plasmin produced in rPAI-1(23)-treated DKO mice degrades perlecan and destabilizes the plexus. Plasmin activity and plaque size measured in DKO and DKO/plasminogen activator inhibitor-1(-)(/-) mice demonstrate that elevated plasmin activity contributes to reduced plaque size. CONCLUSIONS: An FGF-2/perlecan complex is required for vasa vasorum plexus stability. Elevated plasmin activity plays a significant inhibitory role in vasa vasorum plexus and plaque development.

Lipopolysaccharide-induced proliferation of the vasa vasorum in a rabbit model of atherosclerosis as evaluated by contrast-enhanced ultrasound imaging and histology.

Whether lipopolysaccharide (LPS) can promote vasa vasorum (VV) proliferation for atherosclerosis in vivo is unclear. Eighteen rabbits with atherosclerosis were randomly assigned into one of three groups of six. Group A received biweekly injections of 10 mL saline after 2 weeks of balloon injury. Groups B and C received biweekly intravenous injections of 3.0 µg LPS in 10 mL saline at weeks 10 and 4, respectively, until study termination. LPS significantly increased the levels of triglycerides and C-reactive protein and decreased the level of high-density lipoprotein cholesterol. Group C had significant larger plaques and more macrophages than group A (p = 0.01 and p < 0.001, respectively). Contrast enhancement ultrasound imaging and histological detection demonstrated that plaques in group C had a significantly higher VV density than that in group A (p = 0.009 and p = 0.002, respectively). In summary, VV proliferation for plaque destabilization can be accelerated by LPS-induced systemic inflammation and changes in lipid profiles.

Antiangiogenic activity of rPAI-1(23) promotes vasa vasorum regression in hypercholesterolemic mice through a plasmin-dependent mechanism.

RATIONALE: The antiangiogenic activity of rPAI-1(23), a truncated plasminogen activator inhibitor-1 (PAI-1) protein, induces vasa vasorum collapse and significantly reduces plaque area and plaque cholesterol in hypercholesterolemic low-density lipoprotein receptor-deficient/apolipoprotein B48-deficient mice. OBJECTIVE: The objective of this study was to examine rPAI-1(23)-stimulated mechanisms that cause vasa vasorum collapse. METHODS AND RESULTS: The rPAI-1(23) protein opposed PAI-1 antiproteolytic function by stimulating a 1.6-fold increase in plasmin activity compared with the saline-treated counterpart. The increased proteolytic activity corresponded to increased activity of matrix metalloproteinase-3 and degradation of fibrin(ogen), nidogen, and perlecan in the adventitia of descending aortas. PAI-1 activity was reduced by 48% in response to rPAI-1(23); however, PAI-1 protein expression levels were similar in the rPAI-1(23)- and saline-treated hypercholesterolemic mice. Coimmunoprecipitation assays demonstrated a novel PAI-1-plasminogen complex in protein from the descending aorta of rPAI-1(23)- and saline-treated mice, but complexed PAI-1 was 1.6-fold greater in rPAI-1(23)-treated mice. Biochemical analyses demonstrated that rPAI-1(23) and PAI-1 binding interactions with plasminogen increased plasmin activity and reduced PAI-1 antiproteolytic activity. CONCLUSIONS: We conclude that rPAI-1(23) causes regression or collapse of adventitial vasa vasorum in hypercholesterolemic mice by stimulating an increase in plasmin activity. The rPAI-1(23)-enhanced plasmin activity was achieved through a novel mechanism by which rPAI-1(23) and PAI-1 bound plasminogen in a cooperative manner to increase plasmin activity and reduce PAI-1 activity.

C-kit-positive cells accumulate in remodeled vessels of idiopathic pulmonary arterial hypertension.

RATIONALE: C-kit(+) cells, including bone marrow (BM)-derived progenitors and mast cells, may participate in vascular remodelling. Because recent studies suggest that c-kit may be a target for innovative therapies in experimental pulmonary hypertension, we investigated the contribution of c-kit(+) cells in human idiopathic pulmonary arterial hypertension (IPAH). OBJECTIVES: To investigate the contribution of c-kit(+) cells in human IPAH. METHODS: Single c-kit, CXCL12/SDF-1α, CXCR4, CD34, and multiple c-kit, α-smooth muscle actin (α-SMA) and tryptase immunostainings were performed in IPAH lungs. C-kit mRNA expression was quantified by real-time polymerase chain reaction in microdissected pulmonary arteries from patients with IPAH and control subjects. Phenotype and function of circulating progenitors were analyzed by flow cytometry. Plasma levels of soluble c-kit and CXCL12/SDF-1α were measured by ELISA. MEASUREMENTS AND MAIN RESULTS: Infiltration of c-kit(+) cells in pulmonary arterial lesions was associated with an increase in c-kit mRNA expression (P < 0.01 compared with control subjects). Both c-kit(+)/tryptase(+) mast cells and c-kit(+)/tryptase(-) BM-derived cells were increased in pulmonary arteries of patients with IPAH compared with control subjects (106.6 ± 54.5 vs. 28 ± 16.8/mm(2) and 143.8 ± 101.1 vs. 23.3 ± 11.9/mm(2); all P<0.01). Plasma-soluble c-kit was increased in IPAH compared with control subjects (27.4 ± 12.4 vs. 19.5 ± 5.8 ng/ml; P<0.05). Two populations of circulating BM-derived cells (lin-CD34(high)CD133(high) [c-kit(high)CXCR4(low)] and lin-CD34(low)CD133(-) [c-kit(low)CXCR4(high)]) were increased in IPAH compared with control subjects (P=0.01). Pulmonary arterial lesions were associated with vasa vasorum expansion expressing CXL12/SDF-1α that may recruit c-kit(+) cells. CONCLUSIONS: In IPAH, c-kit(+) cells infiltrate pulmonary arterial lesions and may participate to vascular remodeling. Therefore, c-kit may represent a potential target for innovative PAH therapy.

OX40 ligand plays an important role in the development of atherosclerosis through vasa vasorum neovascularization.

AIMS: Atherosclerosis is characterized by infiltration of inflammatory cells and enhanced vasa vasorum formation, for which immunological mechanisms may be involved. OX40, a membrane-bound molecule of the tumour necrosis factor-receptor superfamily, is expressed by activated T-cells, while OX40 ligand (OX40L) is expressed in activated macrophages and endothelial cells. In this study, we thus examined whether the OX40/OX40L system is involved in the pathogenesis of atherosclerosis. METHODS AND RESULTS: We examined apolipoprotein E-deficient (ApoE(-/-)) mice and ApoE(-/-)/OX40L-double-deficient (ApoE(-/-)/OX40L(-/-)) mice fed on a high-fat diet for 8 weeks. The extent of aortic atheroma was significantly less in ApoE(-/-)/OX40L(-/-) mice compared with ApoE(-/-) mice. We also treated high-fat-fed ApoE(-/-) mice with or without MGP34 antibody (OX40L-specific neutralizing antibody) for 10 weeks. After the treatment, the extent of aortic atheroma was again significantly less in MGP34-treated mice compared with controls. Importantly, both vascular density in the aortic adventitia and vascular endothelial growth factor-induced angiogenesis in the Matrigel assay in vivo were significantly reduced in ApoE(-/-)/OX40L(-/-) mice compared with ApoE(-/-) mice. Finally, when high-fat-fed ApoE(-/-) mice were transplanted with bone marrow cells from either wild-type or OX40L(-/-) mice, the extent of aortic atheroma was comparable between the two groups. CONCLUSION: These results indicate that the vascular OX40/OX40L system plays an important role in the formation of vasa vasorum and subsequent atherosclerosis, suggesting that the vascular OX40/OX40L system might be a new therapeutic target of atherosclerosis.

Endothelial cell-selective adhesion molecule modulates atherosclerosis through plaque angiogenesis and monocyte-endothelial interaction.

Endothelial cell-selective adhesion molecule (ESAM) is a new member of the immunoglobulin superfamily, which is expressed in vascular endothelial cells. Previous studies have demonstrated that ESAM regulates angiogenesis, endothelial permeability, and leukocyte transmigration. However, little is known concerning the role of ESAM in atherosclerosis. In this study, we assessed the effects of ESAM inactivation on atherosclerosis in mice. ESAM-/- mice were bred with apoE-/- mice to generate double knockout mice, and the aortic lesion size of apoE-/- and ESAM-/-apoE-/- mice was compared histologically. Although plasma cholesterol levels were higher in ESAM-/-apoE-/- mice, the lesion size was markedly smaller than in apoE-/- mice. ESAM-/-apoE-/- mice exhibited a decrease in the number of vasa vasorum and macrophages in the vessel wall. In vitro adhesion assays showed that THP-1 cells, which did not express ESAM, bound to the ESAM-coated culture plates, suggesting that ESAM may interact with heterophilic ligand(s) on monocytes. Moreover, downregulation of ESAM by siRNA in the endothelial monolayer diminished transendothelial migration of THP-1 cells. In conclusion, ESAM inactivation can reduce susceptibility to atherosclerosis by inhibiting plaque neovascularization and macrophage infiltration into the atheroma.

Vagina vasorum dissection during D2 lymphadenectomy for gastric carcinoma.

AIM: To explore the relationship between metastasis and vagina vasorum in the progress of gastric carcinoma and to find some facts and references for gastric surgeons. METHODS: One hundred and seven specimens of left or right gastric arteries (55 left and 52 right) were gathered from 59 patients undergoing radical gastrectomy for gastric carcinoma. All the frozen specimens were cut into 3 microm-thick sections and stained with hematoxylin-eosin (HE) and immunohistochemical method separately. Cytokeratin (CK) and mesothelial cells (MC) were stained with immunohistochemical method. Cancer cells inside vagina vasorum were detected and the structure of artery wall was observed under microscope. RESULTS: Metastatic cancer cells or tubercles were found inside vagina vasorum in some stage III or IV specimens, but not in stage I or II specimens. Tumor cells in vagina vasorum were CK positive in 26 specimens of 14 tumors. Among them, stage III was found in 4 specimens of 2 tumors, and stage IV in 22 specimens of 12 tumors. None of these specimens was positive for MC. The positive rate of CK increased with TNM staging. Compared with the lower part, tumors in the upper and middle parts of stomach were more likely to metastasize into vagina vasorum. CONCLUSION: Vagina vasorum dissection should be performed during D2 lymphadenectomy for TNM stage III or IV gastric carcinoma.

Deposition of amyloid proteins in the epicardial coronary arteries of 58 patients with primary systemic amyloidosis.

INTRODUCTION: We sought to determine the distribution and the effect of amyloid on epicardial coronary arteries in patients with primary cardiac amyloidosis. METHODS: We reviewed pathologic specimens taken after autopsy or cardiac transplantation from 58 patients with primary cardiac amyloidosis. Patients were seen from 1981 to 2000. Multiple sections of epicardial coronary arteries (left anterior descending artery, left circumflex artery, and right coronary artery) were examined to determine the degree of amyloid deposition in the intima, media, adventitia, and vasa vasorum (vasa vasorum are nutrient arteries for the coronary arteries themselves). RESULTS: In 56 of 58 patients (97%), amyloid was present in epicardial coronary arteries. Amyloid was identified in all artery layers (intima, media, and adventitia), and more patients had amyloid in the adventitia. However, amyloid did not cause intraluminal obstruction of epicardial coronary arteries in any patient. The vasa vasorum had considerable deposits and, in many patients, were obstructed by amyloid. Patients with obstruction of the vasa vasorum were significantly more likely to have obstructive intramural coronary amyloidosis than patients without vasa vasorum obstruction (P=.002). CONCLUSIONS: The epicardial coronary arteries of patients with primary cardiac amyloidosis had extensive amyloid deposition. This deposition, however, did not lead to obstruction of epicardial coronary arteries and therefore did not contribute to ischemic syndromes observed in these patients. Obstruction of the vasa vasorum was associated with obstructive intramural coronary amyloidosis.

[Pathogenesis of atherosclerosis in patients with lipid metabolism disturbances: hypothesis on cholesterol utilization and atheromatous plaque formation]. / Patogenez ateroskleroza u bol'nykh bez narusheniia lipidnogo obmena: gipoteza utilizatsii kholesterina i obrazovaniia ateromatoznoi bliashki.

Cholesterol is known to participate in atheromatous plaque formation coming from blood stream and affecting vascular endothelium in environment of elevated low-density lipoproteins (LDL). Nevertheless, the occurrence of single atheromatous plaque evidences the possibility of local lipoprotein accumulation by vascular wall without systemic increase in serum LDLs. The author hypothesizes that in the absence of hypercholesterolemia atheroma can evolve through the utilization of modified LDL and free or etherified cholesterol, that remain in media non-removed by high density lipoproteins (HDL) owing to their structural damage after local vascular wall ischemia caused by vasa vasorum disorders. Disturbances in HDL acceptor function and transport of cholesterol and modified LDL to blood circulation and further into liver are followed by local accumulation of these products in smooth muscle cells. Overloaded by lipids smooth muscle cells move through internal fenestrated membrane thus activating receptor mechanism for transmission of modified lipoproteins to monocytes and capture of endothelial membrane and amorphous lipids by them in local lipid peroxidation area. A framework for hypothesis experimental and clinical testing is suggested.