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This study aimed to explore thrombolysis therapy based on ultrasound combined with urokinase and Arg-Gly-Asp sequence (RGDS)-targeted microbubbles by evaluating the histological changes in a thrombotic rabbit model. Forty-two New Zealand rabbits featuring platelet-rich thrombi in the femoral artery were randomized to (n = 6/group): ultrasound alone (US); urokinase alone (UK); ultrasound plus non-targeted microbubbles (US + M); ultrasound plus RGDS-targeted microbubbles (US + R); RGDS-targeted microbubbles plus urokinase (R + UK); ultrasound, non-targeted microbubbles and urokinase (US + M + UK); and ultrasound, RGDS-targeted microbubbles and urokinase (US + R + UK) groups. Diagnostic ultrasound was used transcutaneously over the thrombus for 30 min. We evaluated the thrombolytic effect based on ultrasound thrombi detection, blood flow, and histological observations. Among all study groups, complete recanalization was achieved in the US + R + UK group. Hematoxylin and eosin staining showed that the thrombi were completely dissolved. Scanning electron microscopy examination demonstrated that the fiber network structure of the thrombi was damaged. Transmission electron microscopy showed that the thrombus was decomposed into high electron-dense particles. Histology for von Willebrand factor and tissue factor were both negative in the US + R + UK group. This study revealed that a thrombolytic therapy consisting of diagnostic ultrasound together with RGDS-targeted and urokinase coupled microbubbles.

With suppressed photon scattering and diminished autofluorescence, in vivo fluorescence imaging in the 1,500- to 1,700-nm range of the near-IR (NIR) spectrum (NIR-IIb window) can afford high clarity and deep tissue penetration. However, there has been a lack of NIR-IIb fluorescent probes with sufficient brightness and aqueous stability. Here, we present a bright fluorescent probe emitting at ∼1,600 nm based on core/shell lead sulfide/cadmium sulfide (CdS) quantum dots (CSQDs) synthesized in organic phase. The CdS shell plays a critical role of protecting the lead sulfide (PbS) core from oxidation and retaining its bright fluorescence through the process of amphiphilic polymer coating and transferring to water needed for imparting aqueous stability and compatibility. The resulting CSQDs with a branched PEG outer layer exhibited a long blood circulation half-life of 7 hours and enabled through-skin, real-time imaging of blood flows in mouse vasculatures at an unprecedented 60 frames per second (fps) speed by detecting ∼1,600-nm fluorescence under 808-nm excitation. It also allowed through-skin in vivo confocal 3D imaging of tumor vasculatures in mice with an imaging depth of ∼1.2 mm. The PEG-CSQDs accumulated in tumor effectively through the enhanced permeation and retention effect, affording a high tumor-to-normal tissue ratio up to ∼32 owing to the bright ∼1,600-nm emission and nearly zero autofluorescence background resulting from a large ∼800-nm Stoke's shift. The aqueous-compatible CSQDs are excreted through the biliary pathway without causing obvious toxicity effects, suggesting a useful class of ∼1,600-nm emitting probes for biomedical research., Competing Interests: The authors declare no conflict of interest.

A new Chinese herbal formula called Mai Tong Formulae (MTF) has recently been used to treat lower limb macroangiopathy in type 2 diabetes mellitus (T2DM) patients. In this study, we investigated the effect of MTF on lower limb macroangiopathy in a spontaneous diabetic rat model (GK rats). We found that MTF treatment significantly reduced serum fasting blood glucose (FBG), triglycerides (TG), total cholesterol (TC), IL6, and VEGF and increased serum insulin in this model. Histological and ultrastructural observations showed that MTF treatment significantly reduced vascular endothelial cell shedding and improved endothelium injuries. We further detect proteome alteration following MTF treatment. 25 differential proteins (DPs) abnormally expressed in GK rats were normalized by MTF treatment. These DPs significantly are enriched in biological processes and pathways that regulate muscle contraction and cGMP-PKG signaling pathway and so on. Additional protein-protein interaction (PPI) network analyses of the DPs showed that Fasn and Prkar2a are involved in the AMPK signaling pathway, and Gnas, Myh11, and Myh6 are involved in vascular smooth muscle contraction; these 5 DPs were validated by Western blotting. These results indicate that MTF treatment effectively treats lower limb macroangiopathy by regulating key proteins involved in AMPK signaling pathway and vascular smooth muscle contraction., Competing Interests: The authors declare that they have no competing interests.

Objectives: Extracellular nucleotide release at the site of arterial injury mediates the proliferation and migration of vascular smooth muscle cells. Our aim was to investigate the role of the P2Y2 nucleotide receptor (P2Y2R) in neointimal hyperplasia. Approach and Results: Vascular injury was induced by the implantation of a polyethylene cuff around the femoral artery in wild-type and P2Y2R-deficient mice (P2Y2R-/-). Electron microscopy was used to analyze monocyte and lymphocyte influx to the intima 36 h after injury. Compared to wild-type littermates, P2Y2R-/- mice exhibited a 3-fold decreased number of mononuclear leukocytes invading the intima (p < 0.05). Concomitantly, the migration of smooth muscle cells was decreased by more than 60% (p < 0.05), resulting in a sharp inhibition of intimal thickening formation in P2Y2R-/- mice (n = 15) 14 days after cuff placement. In vitro, loss of P2Y2R significantly impaired monocyte migration in response to nucleotide agonists. Furthermore, transgenic rats overexpressing the P2Y2R developed accelerated intimal lesions resulting in more than 95% luminal stenosis (p < 0.05, n = 10)., Conclusions: Loss- and gain-of-function approaches established direct evidence for P2Y2R involvement in neointimal hyperplasia. Specific anti-P2Y2R therapies may be used against restenosis and bypass graft failure., (© 2016 S. Karger AG, Basel.)

The failure of endovascular treatments of peripheral arterial disease represents a critical clinical issue. Specialized data are required to tailor such procedures to account for the mechanical response of the diseased femoral arterial tissue to medical device deployment. The purpose of this study is to characterize the mechanical response of atherosclerotic femoral arterial tissue to large deformation, the conditions typical of angioplasty and stenting, and also to determine the mechanically induced failure properties and to relate this behaviour to biological content and structural composition using uniaxial testing, Fourier transform infrared spectroscopy and scanning electron microscopy. Mechanical and biological characterization of 20 plaque samples obtained from femoral endarterectomy identified three distinct classifications. "Lightly calcified" samples display linear mechanical responses and fail at relatively high stretch. "Moderately calcified" samples undergo an increase in stiffness and ultimate strength coupled with a decrease in ductility. Structural characterization reveals calcified nodules within this group that may be acting to reinforce the tissue matrix, thus increasing the stiffness and ultimate strength. "Heavily calcified" samples account for the majority of samples tested and exhibit significantly reduced ultimate strength and ductility compared to the preceding groups. Structural characterization of this group reveals large areas of calcified tissue dominating the failure cross-sections of the samples. The frequency and structural dominance of these features solely within this group offers an explanation as to the reduced ultimate strength and ductility and highlights the need for modern peripheral endovascular devices to account for this behaviour during novel medical device design., (Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Aim: Patients with end-stage critical limb ischemia (CLI) survive on borrowed time and amputation is inevitable if an aggressive management stratagem is not instigated. Our primary aim was to equate effectiveness of subintimal angioplasty (SIA) and tibial balloon angioplasty (TBA) in sustaining clinical improvement and amputation free survival (AFS) in patients with CLI TASD II D. Moreover, patients with severe CLI, who were not suitable for revascularization and who were offered therapy with a sequential compression biomechanical device (SCBD) were scrutinised as part of a comprehensive lower limb salvage program., Methods: From 2002-2012, 5876 patients were referred with peripheral vascular disease (PVD); 987 presented with CLI and 798 had intervention; 189 patients presenting with CLI were not candidates for revascularisation, out of which 171 were offered SCBD. We formed a prospective observational group study of 441 patient who had TASC D disease. All of these patients presented as emergencies and were allocated to the next available treatment list. Duplex ultrasound arterial mapping (DUAM) was the sole preoperative investigation tool in 92% of all cases. Of the 441 patients studied, 190 patients (206 procedures) has SIA for TASC D femero-popliteal occlusions, 80 patients (89 procedures) had TBA and cool eximer laser angioplasty (CELA) for tibial artery occlusions and 171 patients with severe CLI were not suitable for revascularization and joined the SCBD program. Mean age (SIA 73±13 years vs. TBA/CELA 74±8 years vs. SCBD 75±13 years), and comorbidity severity scores (P>0.05) were similar between groups., Results: Perioperative mortality within the SIA group was 1.6% vs. 0% within the TBA group and 0.6% in SCBD. Length of hospital stay within the TBA group was 3.8±2 days vs. SIA 14±16 days, P<0.0001. The 5-year freedom from major adverse events (MAE) for the SIA group was 68% that was comparable to the results obtained for both the TBA group; 59%, and SCBD group: 62.5% (P=0.1935). Five-year freedom from target lesion revascularization was 85.9% within the SIA group and 79% within the TBA group. A sustained clinical improvement was seen in 82.8% of primary SIA and 68% of TBA, which mimics the outcome of SCBD at 68% at one year. A total of 83% SCBD patients had no rest pain within one week of starting the program and gangrene remained dry and non-progressive. Ulceration healed in all but 12 patients. There were no device-related complications. Limb salvage was 94% at 5 years. All-cause survival was 69%. Quality time spent without symptoms of disease or toxicity of treatment (Q-TWiST) was 24.7 months for SIA and 8.5 months for TBA and was 38.13 for SCBD for a total of 708 months of usage. Cost per quality adjusted-life years (QALY) for SIA was € 5662.79, € 12,935.18 for TBA and € 2943.56 for SCBD., Conclusion: All treatment pathways augmented patient-specific Q-TWiST with substantial cost reduction. SIA, TBA and SCBD expand AFS and symptom-free survival. All treatment modalities are minimally invasive and allow for a high patient turnover without compromising limb salvage, once they are performed by experienced vascular surgeons in high deliberate practice volume centers.

Aim: The aim of the study was to evaluate the effect of the nutritional supplements Pycnogenol and TECA (total triterpenic fraction of Centella Asiatica) on atherosclerosis progression in low-risk asymptomatic subjects with carotid or femoral non-stenosing plaques., Methods: This was an observational pilot substudy of the San Valentino epidemiological cardiovascular study. The study included 1363 subjects aged 45-60 without any conventional risk factors who had non stenosing atherosclerotic plaques (<50%) in at least one carotid or common femoral bifurcation, allocated into 6 groups: Group 1 (CONTROLS): management was based on education, exercise, diet and lifestyle changes. This same management plan was used in all groups; Group 2 Pycnogenol 50 mg/day; Group 3 Pycnogenol 100 mg/day; Group 4 Aspirin 100 mg/day or Ticlopidine 250 mg/day if intolerant to aspirin; Group 5 Aspirin 100 mg/day and Pycnogenol 100 mg/day; Group 6 Pycnogenol 100 mg/day plus TECA (total triterpenic fraction of Centella Asiatica) 100 mg/day. There was a six monthly follow-up up to 30 months. Plaque progression was assessed using the ultrasonic arterial score based on the arterial wall morphology and the number of plaques that progressed from the non-stenotic to the stenotic group. A secondary endpoint was to evaluate the changes in oxidative stress at baseline and at 30 months., Results: The ultrasonic score increased significantly in groups 1, 2 and 4 but not in groups 3, 5 and 6 suggesting a beneficial effect of Pycnogenol 100 mg. The percentage of plaques that progressed from class IV to class V was 8.4% in group 2, 5.3% in group 3, 4% in group 5 and 1.1% in group 6 (P<0.0001) compared with 16.6% in group 4 (aspirin) and 21.3% in the control group suggesting a beneficial effect of Pycnogenol. The lowest rate of progression was in group 6 (Pycnogenol plus TECA). At 30 months, the oxidative stress in all the Pycnogenol groups was less than in the control group. The oxidative stress was lower in the Pycnogenol 100 mg group than the Pycnogenol 50 mg group (P<0.0001). In the combined group of Pycnogenol and TECA the oxidative stress was less than the Pycnogenol alone (P<0.001)., Conclusion: Pycnogenol and the combination of Pycnogenol+TECA appear to reduce the progression of subclinical arterial lesions in low-risk asymptomatic subjects. The reduction in plaque progression was associated with a reduction in oxidative stress. The results justify a large randomized controlled study to demonstrate the efficacy of the combined Pycnogenol and TECA prophylactic therapy in subclinical atherosclerosis.

Background: Acute limb ischemia is both a limb-threatening and life-threatening disease process. Nontraumatic acute peripheral arterial occlusion is most commonly caused by a thrombosis or an embolism., Objectives: There is limited evidence on the use of bedside ultrasound for the detection of acute limb ischemia, but duplex ultrasonography is standard in the diagnosis and operative planning in chronic limb ischemia. Emergency physicians may use bedside ultrasound in the evaluation of patients with symptoms and signs suggestive of this disease entity., Case Report: A 64-year-old man with a past medical history of hypertension and an ischemic stroke presented to the Emergency Department with <2 h of severe upper left leg pain that radiated down to his foot. A bedside ultrasound of the left lower extremity was emergently performed. On B-mode ultrasound evaluation, echogenic material was visualized in the left common femoral artery, the artery was noncompressible, and there was an absence of Doppler flow signal. He was then directly taken to the operating room for an emergent limb-saving procedure., Conclusion: A focused examination of the aorta, iliac vessels, and femoral artery bifurcation with bedside ultrasonography may help to localize peripheral arterial occlusions and can assist the emergency physician in seeking timely surgical consultation and management., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Objectives: This study was designed to evaluate the pharmacokinetic and vascular healing of a second-generation everolimus-eluting stent (EES) and slow-release zotarolimus-eluting stent (R-ZES)., Background: Second-generation DESs have alleviated the safety concerns of late stent thrombosis by addressing issues of polymer biocompatibility and stent design, and optimizing drug loads and release kinetics. No preclinical comparison study exists between these stents., Methods: Rabbit iliac artery stent implantation was performed using Xience Prime EES and Resolute R-ZES. Histomorphometric evaluation was performed at 28 and 60 days after implantation in an induced atheroma model. Endothelial coverage and maturation were assessed by scanning electron microscopy and immuno-labeling at 14 and 28 days following deployment. For pharmacokinetic studies, arterial tissue and stents were retrieved at 3, 14, 28, and 90 days, and blood samples were obtained during the first 24 hours., Results: Vascular remodeling (percent stenosis, neointimal thickness) was similar in arteries implanted with either stent group. At 28 days, inflammation was significantly less in the EES group as compared to the R-ZES group (inflammation score: 1.59 ± 0.52 vs 2.22 ± 0.69, respectively; P=.044), with no differences observed at 60 days. Endothelial coverage was similar between both groups; however, endothelial maturation above stent struts was significantly higher in the EES group vs R-ZES group at 28 days (33 ± 20% vs 22 ± 21%, respectively; P=.040). Arterial drug level concentrations were also shown to be significantly less in the EES group vs the R-ZES group (P<.0001)., Conclusions: Overall, EES and R-ZES displayed similar remodeling properties with lower arterial drug levels observed in the EES group vs the R-ZES group, which may have led to more rapid endothelial maturation.

Magnesium is an attractive material for use in biodegradable implants due to its low density, non-toxicity and mechanical properties similar to those of human tissue such as bone. Its biocompatibility makes it amenable for use in a wide range of applications from bone to cardiovascular implants. Here we investigated the corrosion rate in simulated body fluid (SBF) of a series of Mg-Sr alloys, with Sr in the range of 0.3-2.5%, and found that the Mg-0.5 Sr alloy showed the slowest corrosion rate. The degradation rate from this alloy indicated that the daily Sr intake from a typical stent would be 0.01-0.02 mg day⁻¹, which is well below the maximum daily Sr intake levels of 4 mg day⁻¹. Indirect cytotoxicity assays using human umbilical vascular endothelial cells indicated that Mg-0.5 Sr extraction medium did not cause any toxicity or detrimental effect on the viability of the cells. Finally, a tubular Mg-0.5 Sr stent sample, along with a WE43 control stent, was implanted into the right and left dog femoral artery. No thrombosis effect was observed in the Mg-0.5 Sr stent after 3 weeks of implantation while the WE43 stent thrombosed. X-ray diffraction demonstrated the formation of hydroxyapatite and Mg(OH)₂ as a result of the degradation of Mg-0.5 Sr alloy after 3 days in SBF. X-ray photoelectron spectroscopy further showed the possibility of the formation of a hydroxyapatite Sr-substituted layer that presents as a thin layer at the interface between the Mg-0.5 Sr alloy and the corrosion products. We believe that this interfacial layer stabilizes the surface of the Mg-0.5 Sr alloy, and slows down its degradation rate over time., (Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Background: The goal of this study was to evaluate the performance of the magnetic pinned-ring device for nonsuture vascular anastomosis., Methods: The magnetic pinned-ring device consists of paired magnetic rings that are coated with titanium nitride and embedded in a polypropylene shell; the rings are equipped with alternately spaced holes and titanium pins. The vascular anastomosis procedure using the novel magnetic pinned-ring device was performed on 14 mongrel dogs, and the traditional hand-sewing technique was used on 14 additional dogs. In situ end-to-end anastomoses were performed in the femoral artery and the inferior vena cava. Patency was confirmed through ultrasonographic scans at different time points as late as 24 weeks after surgery. Gross observation, histological staining, and scanning electron microscopy were used to evaluate the results at 24 weeks postoperatively., Results: The time required to perform the vascular anastomosis was significantly shorter for the magnetic device than for hand sewing. A continuity of re-endothelialization was confirmed in all anastomotic stomas after 24 weeks, and neither formation of aneurysms nor thickening of the vascular wall was noted. The re-endothelialization was smooth at the anastomotic site of the magnetic device, whereas hand sewing resulted in rough and uneven re-endothelialization and the presence of visible sutures. Moreover, the endothelial cells were regularly arranged at the anastomotic site of the magnetic device, whereas different-sized and irregularly aligned endothelial cells were present at the hand-sewn anastomotic site. Use of the magnetic device was associated with significantly decreased deposition of fibrotic collagen and depressed infiltration of inflammatory cells compared with use of the hand-sewing technique., Conclusions: The magnetic pinned-ring device offers a simple, fast, reliable, and efficacious technique for nonsuture vascular anastomosis. Use of this device shortens operation time, maintains a high patency rate, and improves the healing of vascular tissue., (Copyright © 2012 Annals of Vascular Surgery Inc. Published by Elsevier Inc. All rights reserved.)

An in-house built instrument was used to fabricate a small internal diameter (2 mm) artificial vascular prosthesis from biodegradable chitosan. This new artificial vascular prosthesis has shown a good biocompatibility based on the studies of its cell compatibility, inflammatory reaction, and platelet adhesion. In an animal test, the prosthesis was used to replace a 4-cm-long section of femoral artery in each of the seven tested dogs. The patency of the replacement was monitored at regular intervals using Doppler ultrasound diagnostics. Nine months after the implantation, hematoxylin and eosin staining, immunohistochemical study, and scanning electron microscope observation were carried out. Complete decomposition of the prosthesis and replacement by a natural blood vessel were observed. The results suggests that the artificial vascular prosthesis displays many characteristics of the "ideal" small-diameter artificial vascular, and have the biocompatibility that can be tailored to match those desired in vascular replacement application., (Copyright © 2012 Wiley Periodicals, Inc.)

Human femoral arteries were cultured up to 56 days. Samples were processed for light, immunohistochemical, and transmission electron microscopy. Arteries became rapidly depopulated; at day 42, an endothelial lining (CD31(+), Weibel-Palade bodies) developed on the intima; endothelium was in continuity with mesenchymal stromal cells (CD44(+), CD90(low), CD105(low)) placed on adventitia. The media-adventitia area showed heterogeneous cell populations. In long-term organ culture, femoral artery develops a continuous cell coverage that differentiates to endothelium on the intima exclusively. This suggests that distinct topographical factors, such as resident progenitors and/or matrix signals, are able to regulate vascular homeostasis in adult life.

Objective: Constriction of vein grafts with braided external nitinol meshes had previously led to the successful elimination of neointimal tissue formation. We investigated whether pulse compliance, smaller kink-free bending radius, and milder medial atrophy can be achieved by knitting the meshes rather than braiding, without losing the suppressive effect on intimal hyperplasia., Methods: Pulse compliance, bending stiffness, and bending radius, as well as longitudinal-radial deformation-coupling and radial compression, were compared in braided and knitted nitinol meshes. Identical to previous studies with braided mesh grafts, a senescent nonhuman primate model (Chacma baboons; bilateral femoral interposition grafts/6 months) mimicking the clinical size mismatch between vein grafts and runoff arteries was used to examine the effect of knitted external meshes on vein grafts: nitinol mesh-constricted (group 1); nitinol mesh-constricted and fibrin sealant (FS) spray-coated for mesh attachment (group 2); untreated control veins (group 3), and FS spray-coated control veins (group 4)., Results: Compared with braided meshes, knitted meshes had 3.8-times higher pulse compliance (3.43 ± 0.53 vs 0.94 ± 0.12%/100 mm Hg; P = .00002); 30-times lower bending stiffness (0.015 ± 0.002 vs 0.462 ± 0.077 Nmm(2); P = .0006); 9.2-times narrower kink-free bending radius (15.3 ± 0.4 vs 140.8 ± 22.4 mm; P = .0006), and 4.3-times lower radial narrowing caused by axial distension (18.0% ± 1.0% vs 77.0% ± 3.7%; P = .00001). Compared with mesh-supported grafts, neointimal tissue was 8.5-times thicker in group I (195 ± 45 μm) vs group III (23.0 ± 21.0 μm; P < .001) corresponding with a 14.3-times larger neointimal area in group I (4330 ± 957 × 103 μm(2)) vs group III (303 ± 221× 103 μm(2); P < .00004). FS had no significant influence. Medial muscle mass remained at 43.4% in knitted meshes vs the 28.1% previously observed in braided meshes., Conclusion: Combining the suppression of intimal hyperplasia with a more physiologic remodeling process of the media, manifold higher kink-resistance, and lower fraying than in braided meshes makes knitted nitinol an attractive concept in external vein graft protection., (Copyright © 2011 Society for Vascular Surgery. Published by Mosby, Inc. All rights reserved.)

The purpose of this study was to form a standard electrical trauma model in rat, to investigate the pathological changes in vessels, and to determine the best day for performing microsurgery. In the preliminary study, 20 rats were divided into five groups. One was control, and the rats in the other four groups were exposed to 240 V electrical potential for 5, 10, 15, and 20 seconds, respectively. Femoral vessels from each group were biopsied for electron and light microscopy. In the study group, 36 rats were subjected to 240 V electrical trauma for 18 seconds. The rats in the study group were divided into three groups. On days 3, 7, and 21, the femoral artery of nine rats in each group were cut and anastomosed. The anastomoses were followed for thrombus formation. Visible, respectively increasing necroses were seen in all animals in the second, third, and fourth preliminary study groups. Light and electron microscopy revealed degeneration of vessel walls and loss of endothelium. Second and third microsurgery study groups had statistically significantly more thrombus. Although after electrical trauma major vessels seem normal, they have pathological changes, and microsurgery success rates are decreased shortly after electrical trauma.

Purpose: Cerebral vasospasm is the common cause of poor outcome after aneurysmal subarachnoid hemorrhage (aSAH). Although many agents are experimentally and clinicaly used to protect or recover from vasospasm, an effective neurotherapeutic drug is still missing. Erythropoietin (EPO) is recently a promising candidate. The aim of this study is to investigate the dose-dependent effects of recombinant human EPO (rhEPO) on arterial wall in a rat femoral artery vasospasm model., Methods: Thirty two animals were divided into four groups: vasospasm without any treatment (group A), vasospasm +250 IU/kg rhEPO group (group B), vasospasm +500 IU/kg rhEPO group (group C), and control group (group D). Rat femoral artery vasospasm model was used. For groups B and C, 7 days of 250 IU/kg and 500 IU/kg intraperitoneal rhEPO in 0.3 ml saline were administered respectively; and for groups A and D, 0.3 ml saline were administered intraperitoneally without any treatment. After 7 days, histological and morphometric analyses were carried out., Results: Vasospasm alone group demonstrated the highest vessel wall thicknesses, comparing to other groups (p < 0.001). While for groups B and C, vessel wall thickness values were significantly higher than the control group (p < 0.001), between these two groups, there was no significant difference achieved (p > 0.05)., Conclusion: In our study, there was no significant difference between the two rhEPO treatment groups, but rhEPO treatment was shown to be histologically and morphometrically effective in vasospasm. However, if dosage of EPO treatment is augmented, successful results may be achieved.

Many hemodynamic factors have been shown to be associated with increased intimal hyperplasia at the distal anastomosis of arterial bypass graft. However, the relationship between the length of anastomosis and the development of such a complication has not been studied before. The aim of this study was to assess this relationship at the distal anastomosis with a Dacron graft. Iliofemoral bypass using 6 mm Dacron grafts was performed in 10 German shepherd dogs. In accordance with preoperative randomization to individual animal legs, distal anastomoses were reconstructed using four different groups (A, B, C, and D), depending on the length of the arteriotomy: 3.0, 3.5, 4.0, and 4.5 times the internal diameter of the artery, respectively. The vessels were harvested 6 months after the operation, and specimens were processed for histologic and transmission electron microscopic (TEM) studies. Quantitative analysis was performed to assess the extent of intimal hyperplasia at three zones (heel, toe, and midzone of the arterial bed) of the distal anastomosis. Sixteen arterial bypasses were included in this study. Both light and TEM studies revealed evidence of intimal hyperplasia in the four groups. Quantitative analysis showed a significant decrease in intimal hyperplasia with increasing the length of the anastomosis at the heel, toe, or midzone of the arterial bed. Mean (mum +/- SD) intimal hyperplasia of the three zones together was significantly higher in group A than group B (585 +/- 106 vs 423 +/- 8.6, p < .001) and in group B than group C (423 +/- 8.6 vs 202 +/- 15, p < .001). However, the difference between group C and group D (202 +/- 15 vs 162 +/- 8.6; p = .13) was statistically insignificant. The present study showed that the length of the anastomosis is one of the hemodynamic factors involved in the development of intimal hyperplasia. Anastomotic techniques that resulted in the least intimal hyperplasia were end to side, with length 4 or 4.5 times the internal diameter of the artery.

The adductor canal is a conical or pyramid-shaped pathway that contains the femoral vessels, saphenous nerve and a varying amount of fibrous tissue. It is involved in adductor canal syndrome, a claudication syndrome involving young individuals. Our objective was to study modifications induced by aging on the connective tissue and to correlate them to the proposed pathophysiological mechanism. The bilateral adductor canals and femoral vessels of four adult and five fetal specimens were removed en bloc and analyzed. Sections 12 microm thick were obtained and the connective tissue studied with Sirius Red, Verhoeff, Weigert and Azo stains. Scanning electron microscopy (SEM) photomicrographs of the surfaces of each adductor canal were also analyzed. Findings were homogeneous inside each group. The connective tissue of the canal was continuous with the outer layer of the vessels in both groups. The pattern of concentric, thick collagen type I bundles in fetal specimens was replaced by a diffuse network of compact collagen bundles with several transversal fibers and an impressive content of collagen III fibers. Elastic fibers in adults were not concentrated in the thick bundles but dispersed in line with the transversal fiber system. A dynamic compression mechanism with or without an evident constricting fibrous band has been proposed previously for adductor canal syndrome, possibly involving the connective tissue inside the canal. The vessels may not slide freely during movement. These age-related modifications in normal individuals may represent necessary conditions for this syndrome to develop.

Ruptured atherosclerotic plaques, lined with activated platelets, constitute an attractive target for magnetic resonance imaging (MRI). This study evaluated whether microparticles of iron oxide (MPIO) targeting ligand-induced binding sites (LIBS) on the activated conformation of glycoprotein IIb/IIIa could be used to image platelets. MPIO (size: 1 microm) were conjugated to anti-LIBS or control single-chain antibody. Following guidewire injury to mouse femoral artery, platelet adhesion was present after 24 h. Mice were perfused with anti-LIBS-MPIO (or control MPIO) via the left ventricle and 11.7-tesla MRI was performed on femoral arteries ex vivo. A 3D gradient echo sequence attained an isotropic resolution of 25 microm. MPIO binding, quantified by MRI, was 4-fold higher with anti-LIBS-MPIO in comparison to control MPIO (p < 0.01). In histological sections, low signal zones on MRI and MPIO correlated strongly (R(2) = 0.72; p < 0.001), indicating accurate MR quantification. In conclusion, anti-LIBS-MPIO bind to activated platelets in mouse arteries, providing a basis for the use of function-specific single-chain antibody-MPIO conjugates for molecular MRI, and represent the first molecular imaging of a conformational change in a surface receptor. This presents an opportunity to specifically image activated platelets involved in acute atherothrombosis with MRI., (Copyright 2008 S. Karger AG, Basel.)

A living-tissue conduit with strong mechanical properties was used to produce small-diameter vessels. To improve blood compatibility, a shear-resistant confluent monolayer endothelium was formed on the luminal surface of the conduit. Under mechanical stimulation induced by pulsatile flow in a bioreactor, abrupt high-flow shear stress of 15.3 +/- 4.6 dynes/cm2 was applied to endothelial cells (ECs) seeded onto the lumen of a living-tissue conduit after 2 days of static culture. Scanning electron microscopy images revealed that most of the ECs were washed off after 3 days of dynamic culture. When shear stress was increased stepwise from 1.5 +/- 0.8 to 15.3 +/- 4.6 dynes/cm2 and applied to the ECs, scanning electron microscopy images of the luminal surface revealed that the confluent monolayer ECs were highly elongated and oriented to the flow direction, similar to findings in natural arteries in vivo. The results indicated that in vitro flow conditions played a key role in determining the durability of the EC layer. Careful design of the bioreactor and careful selection of the culture conditions will greatly improve the chances of producing a useful anti-thrombogenic surface for tissue-engineered small-diameter vessels.

Background & Objective: What damages 125Iodine (125I) seed implantation will do to normal tissue is an observation topic in clinic. This study was to investigate the impact of 125I seed implantation to the femoral arteries of rabbits., Methods: A total of 30 healthy rabbits were divided into 3 groups. The femoral sheath in the hind leg at one side selected by random was opened and 10 125I seeds at 0.79-0.85 mCi were implanted near the femoral artery according to the treatment planning system (TPS) before operation. In control group, 10 seeds without radioactivity were implanted. After 2 weeks, 2 months and 4 months, the rabbits were killed, the vessel wall nearest to the seeds was taken out and its morphologic changes were observed by gross examination, light microscopy and electron microscopy., Results: In gross observation, the vessel segments of the legs with 125I seed implantation had no apparent abnormality. Under light microscope, a few exfoliative endothelial cells were observed. Under electron microscope, exfoliation of endothelial cells, degeneration of endothelial cells and smooth muscle cells were observed. The ratios of degenerative vessel endothelial cells to all vessel endothelial cells were 60%-70% in 2-week group, 50% in 2-month group and 30% in 4-month group; the ratios of degenerative vessel smooth muscle cells to all vessel smooth muscle cells in the 3 groups were 50%, 30% and 10%., Conclusion: 125I permanent implantation at 0.79-0.85 mCi mainly damages endothelial cells and smooth muscle cells of the normal vessels and this damnification is reversible.

The arteriovenous loop (AV loop) model is gaining importance as a means of initiating and sustaining perfusion in tissue engineering constructs in vivo. This study represents an attempt to dissect the morphology of early arterialization and angiogenesis in the AV loop in a fibrin matrix with special focus on the interpositional venous graft (IVG) segment. An AV loop was constructed in 30 rats using the femoral vessels and an IVG. The AV loop was encased in an isolation chamber filled with a fibrin matrix. Evaluation methods included scanning electron microscopy (SEM) of corrosion casts, immune histology and micro magnetic resonance angiography (MRA). Direct luminal neovascular sprouting was evident between day 10 and day 14 from the vein and the IVG but not from the arterial segment. Arterialization of the IVG manifested itself on the corrosion casts as a gradual reduction in luminal caliber with onset after day 7. Microdissection of the microvascular replicas could demonstrate for the first time the presence of direct luminal sprouts from the IVG. MRA was used to display the shunt pattern of perfusion in the patent AV loop. From the three segments of the vascular axis in the AV loop the IVG is the most versatile for applications in the clinical as well as the experimental setting. Kinetics of angiogenesis warrant further investigation in the IVG.

This study examined the clinical and pathological features after a microvascular anastomosis of a rat femoral artery using four different suture techniques. Sixty Sprage-Dawely rats were divided randomly into 4 groups. Fifteen bisected arteries (one from each animal) in Group I, II, III and IV were sutured with the simple interrupted suture, continuous suture, sleeve suture and cuff suture, respectively. The anastomosis times in Group I, II, III and IV were 28.67, 14.67, 15.47 and 15.93 min, respectively. Immediate bleeding that stopped without intervention (grade I) was observed in 67%, 73% and 60% of the anastomosed vessels in Groups II, III and IV, respectively, while 60% of the vessels in Group I showed light bleeding that was inhibited by gentile pressure (grade II). All vessels examined appeared to be patent at 5 and 15 min after the anastomosis. On the 7th day postoperatively, the vessels of Group I showed the highest patency rate (93%) compared with Groups II (67%), III (73%) and IV (87%). Moreover, there were more pronounced pathological changes in Group I than in the other groups. These changes included endothelial loss, endothelial proliferation, degeneration and necrosis of the tunica media. Suture materials surrounded by an inflammatory reaction were also observed. In conclusion, the simple interrupted suture is preferable for microvascular anastomosis due to its highest patency rate. The other techniques investigated can be good alternatives because of their short anastomotic time and moderate pathological changes.

Thrombospondin-1 (TSP-1) is a multifunctional, extracellular matrix protein that has been implicated in the regulation of smooth muscle cell proliferation, migration and differentiation during vascular development and injury. Vascular injury in wildtype and TSP-1 null mice was carried out by insertion of a straight spring guidewire into the femoral artery via a muscular arterial branch. Blood flow was restored after the muscular branch was ligated. The injury completely denuded the endothelium and caused medial distension of the vessel in a manner similar to coronary artery balloon-angioplasty. After 28 days, wildtype arteries showed consistent neointima formation with smooth muscle cell hyperplasia. Injured arteries from TSP-1 null mice showed similar neointimal lesions with no significant difference in the extent of neointima formation. Unexpectedly, a high incidence of thrombus formation was observed in the TSP-1 null vessels in a region close to the entry point of the guidewire into the femoral artery. Thrombus was never observed in the injured wildtype vessels. These results provide in vivo evidence that the extent of smooth muscle cell proliferation and neointima formation following endothelial denuding injury is not affected by the absence of TSP-1. Furthermore, our results provide novel evidence for the involvement of TSP-1 in controlling thrombus growth following intra-arterial injury in areas of predicted high turbulent flow.

Alimentary hypercholesterolemia, as well as the intensive physical loadings are accompanied diminishing of level of nitrite-anion as compared to the control group of animals. Combination of the intensive physical loadings and hypercholesterolemia results in maximal lowering level of nitrite-anion and more expressed atherosclerotic damage of wall of arteries of experimental rats, and the moderate physical loadings at hypercholesterolemia render an opposite effect.

Sex related differences in cardiovascular function have been reported in oestrogen receptor beta knockout (ERbetaKO) mice. In this study we examined the role of endothelium-derived hyperpolarizing factor (EDHF) in differences in small artery endothelial function between ERbetaKO and wild-type (WT) mice. Small femoral arteries were isolated from ERbetaKO and WT mice and mounted on a wire myograph. Concentration-response curves to ACh were compared before and after incubation with inhibitors of nitric oxide (NO) and prostacyclin (PGI2) synthesis. Comparison of the expression of the principal vascular connexins (Cx37, 40 and 43), implicated in EDHF-mediated dilatation were undertaken by immunohistochemistry. Vascular ultrastructure was studied by transmission and scanning electron microscopy. ACh-induced relaxation of arteries (< 200 microm internal diameter) was greater in WT females versus males and was attributable to a greater EDHF component of relaxation. This sex difference was absent in ERbetaKO mice. Arteries from ERbetaKO males (but not females) were more sensitive to ACh compared to WT. The pharmacological evidence and morphological prerequisite for involvement of gap junctions in EDHF-mediated responses was confirmed in male arteries. The absence of ERbeta had no influence on expression of main Cx subtypes within vascular wall or on ultrastructure and morphology of the endothelium. The data suggest that in WT male mice, ERbeta reduces EDHF-mediated relaxation through gap junction communication.

Objective: Arterial cell and gene therapies are promising strategies for the treatment of cardiovascular diseases; however, the optimal cell type and delivery technique for such treatment remain to be determined. The aim of the present study was to design a new approach for arterial cell and gene therapy in which genetically modified autologous skin fibroblasts are percutaneously delivered in stented rabbit femoral arteries in vivo., Methods: Autologous skin fibroblasts underwent in vitro transfection with the cationic lipid FuGene and plasmids expressing the human form of the tissue inhibitor of metalloproteinase (hTIMP-1) or nls-LacZ reporter genes., Result: Transfection efficiency was about 50% and there were high levels of hTIMP-1 secretion up to 14 days after gene transfer. We demonstrated the feasibility of in vivo percutaneous transplantation of fluorescent fibroblasts in the rabbit femoral artery. Results were confirmed by scanning electron microscopy. In vivo local delivery of hTIMP-1-expressing fibroblasts in stented femoral arteries also resulted in high-levels of hTIMP-1 secretion ex vivo for 7 days. Fibroblast transplantation resulted in a modest increase in intimal hyperplasia at the target site, which was reversed with hTIMP-1-transfected fibroblasts., Conclusion: Percutaneous transplantation of genetically modified autologous fibroblasts could be used as a cellular platform for locoregional secretion of therapeutic proteins to treat either specific arterial diseases or the diseased organ (eg, the heart) supplied by the target artery., Clinical Relevance: Cell and gene therapies are potential new treatments for cardiovascular diseases. We demonstrated that autologous fibroblasts could be easily harvested from a skin biopsy specimen, genetically modified in vitro with nonviral vectors, and percutaneously seeded in vivo in rabbit femoral arteries, leading to locoregional secretion of abundant amounts of recombinant proteins. This new approach has important advantages over alternative approaches that use endothelial cells, viral vectors, and intraoperative cell delivery. Clinical applications may include local treatment of atherosclerotic plaques or aneurysms and also treatment of the diseased organs supplied by the target artery (eg, ischemic or failing heart).

The use of covered stents in children is limited by the need for a large long sheath for delivery and the impossibility of redilation once implanted. The authors developed a reexpandable covered stent implantable in children through a small sheath and evaluated its clinical feasibility in mini piglets. An original Palmaz stent was covered with a polyurethane membrane that could be stretched up to 700%. Under general anesthesia, the authors implanted the covered stents in six mini piglets using a long sheath with a diameter approximately 1 French larger than the recommended size required to deliver an uncovered Palmaz stent. The implantation technique was similar to conventional stent implantation. In six piglets, the stent could be redilated from 7.5 to 8.7 mm 28-70 days after implantation. Macroscopic and microscopic examination showed intimal coverage of the coating with minimal inflammatory reaction around the stent. Our newly designed reexpandable stent covered with a polyurethane membrane is promising for use in children., ((c) 2006 Wiley-Liss, Inc.)

After permanent occlusion of the femoral artery, the survival of ischemic limb tissue depends on collateral artery growth (arteriogenesis). In previous work, we have shown that shear stress triggers arteriogenesis. To test whether increased shear stress results in enhanced arteriogenesis, we compared arteriogenesis in transgenic mice overexpressing erythropoietin (EPO), which possessed increased blood viscosity through the higher hematocrit (thereby providing increased shear stress), with wild-type mice. The right femoral artery was occluded proximal to the origin of the arteria poplitea. Distal blood flow was assessed by laser Doppler imaging, and the growth and remodeling of collateral arteries was examined by light and electron microscopy and morphometry. After occlusion of the femoral artery, EPO mice demonstrated enhanced arteriogenesis: their collateral arteries developed a 1.7-fold diameter and a 2-fold wall thickness compared with wild-type. However, the blood flow recovery in EPO mice was markedly retarded. Structural remodeling and growth of collateral arteries was markedly enhanced in EPO mice, presumably as a result of increased blood viscosity and shear stress.

Objective: To investigate the effect of Quyu Xiaoban Capsule (QYXB) on the regressive treatment of atherosclerosis (AS) with acoustic densitometry (AD) technique., Methods: Eighty patients with AS were randomly divided into two groups, trial group was treated with QYXB and conventional medicine, and control group was treated with conventional medicine alone. Normal arterial wall and different types of atherosclerotic plaques were detected with AD technique before treatment and 10 months later., Results: The corrected averages in intimal echo intensity (AIIc%) were elevated in both groups but without significant difference, AIIc% of fatty plaques were increased in both groups and the value after treatment was significantly higher than that of pre-treatment in the trial group (68.12 +/- 5.54 vs 61.43 +/- 5.37, P < 0.05). The increment rate of AIIc% in trial group was significantly higher than that in control group (10.9 +/- 5.1% vs 2.5 +/- 5.5%, P < 0.05)., Conclusion: QYXB can stabilize the atherosclerotic plaque by increasing its acoustic density. Acoustic densitometry technique can differentiate the different histological plaques and monitor the histological changes of plaques during treatment.

Background: Early reconstitution after injury to the endothelium is an important feature for reducing a number of vessel wall pathologies. We investigated the effect of vascular endothelial growth factor (VEGF) and its impact on the vascular remodeling process and reendothelialization after microsurgery., Methods and Results: Microvascular anastomosis was performed in the rat femoral artery. One group was treated with intraluminal administration of VEGF and the other with vehicle. We investigated morphological, ultrastructural and immunohistochemical changes of the vascular wall and the reendothelialization process. After 10 days, reendothelialization was significantly faster in VEGF-treated rats. Transmission electron microscopy revealed a complete healing in contrast to vehicle-treated vessels. Moreover, extracellular matrix proteins, such as fibronectin, collagen types I, III and IV, were significantly increased. Furthermore, VEGF treatment significantly induced VEGF receptor 2, flk-1, osteopontin and TGF-beta(1) proteins., Conclusions: Our data clearly document for the first time that intraluminal treatment with VEGF is beneficial to the healing process in vascular microsurgery. Osteopontin and TGF-beta(1), both induced by VEGF, may play an important role in the vascular remodeling process. Our results provide clear evidence that VEGF application may represent a useful strategy in accelerating reendothelialization and improving vascular healing after microsurgery., (Copyright (c) 2005 S. Karger AG, Basel.)

Objective: Last decade, the shear stress caused by increased blood flow in collateral circulation after occlusion of main artery was recognized as a trigger of vascular remodeling and collateral growth. The goal of this study was to differentiate whether the on-going increased blood flow is necessary for the vascular remodeling or the remodeling, once in progress, develops independently of flow., Methods: Femoral artery occlusion was performed in C57B1/6 mice. After 1-3 days, the ligature was removed and normal limb perfusion was re-established, monitored by laser Doppler Imaging (LDI). Two weeks after the first occlusion, both femoral arteries were re-occluded to compare collateral growth on the "naive" and "preconditioned" sides. After perfusion fixation, ultrastructural studies and morphometry of the collateral vessels were performed., Results: Blood flow fell after occlusion to about 15% of control levels and recovered to about 40% by day 3. The reperfusion normalized sustainable blood flow. After the second occlusion, blood flow on both sides fell again to about 15% but recovered to 70% in the "preconditioned" compared to 40% in the "naive" side during the following 3 days. 5-Bromo-2'-desoxy-uridine (BrdU) administered during reperfusion was detected mainly in the neointima that, in many cases, had markedly narrowed the lumen. Two to three days after re-occlusion, a statistically significant lumen enlargement on the "preconditioned" side was observed, while neointima disappeared., Conclusion: Cellular proliferation and remodeling of collateral arteries were induced by short period of increased blood flow (occlusion of the femoral artery) but realized mostly during the low blood flow (reperfusion of the femoral artery). The neointima developing as a result of this remodeling can be recruited as a functional part of the arterial wall if the collateral perfusion increases as a result of repetitive occlusion of the femoral artery. The "medialization" of the neointima might cause the observed quicker gain of collateral lumen diameter and conductance, saving distal muscle tissue from the ischemia.

Expanded polytetrafluoroethylene (PTFE) prostheses may be used in peripheral vascular surgery. Due to contradictory results on patency rate and neointimal formation, the effectiveness of this kind of prosthesis in small caliber artery reconstruction is still under discussion. In order to evaluate the effectiveness of this technique 1 mm internal diameter PTFE prosthesis (fibril length 35 microm) interposed in rabbit femoral artery, for 15 and 30 days, were studied functionally and morphologically. Doppler was performed during surgery, at day 2, 15 and 30. Arteriography was carried out at day 1. Light microscopy and scanning electron microscopy were performed on prosthesis sampled at day 15 and 30. Doppler flowmetry showed the full patency in all PTFE prosthesis. Angiography confirmed that all PTFE grafts were patent after 24 h. Doppler flowmetry, performed after 15 and 30 days, showed a reducing patency rate respectively at 70% (21 grafts) and 60% (18 grafts). Morphological studies showed that endothelial lining was not present at 15 day. After 30 days proliferation of blood cells occurred in the graft wall. Lumina presented a fibrous lining and did not show significant endothelial cell growths. These results confirm that PTFE prosthesis represents a suitable alternative to biological graft for the repair of small caliber artery when the latter are not available. Autologous vein is the vascular substitute of choice for peripheral vascular reconstruction, and PTFE prosthesis may be quite successfully used as a secondary choice, when multiple reconstruction are needed and biological grafts are not sufficient.

Aim: To examine changes in the structure of large (carotid and femoral) arteries at an early stage of chronic renal failure (CRF) and factors significant for their development., Material and Methods: Duplex ultrasonography of the common carotid arteries (CCA) and common femoral arteries (CFA), serum biochemical tests, echocardiography were made in 32 patients (15 males and 17 females) with chronic diffuse renal disease at an initial stage of CRF (creatinine 2.7 mg%, CRF duration 2.7 years). Increased thickness of the intima-media complex (IMC) in both vascular territories was found in 72% of the examinees. There was a close correlation between CCA and CFA IMC (chi-square = 14.05; p = 0.0002). Plaques in the carotid arteries correlated with smoking (chi-square = 4.60; p = 0.0320), in the femoral arteries--with male sex (chi-square = 5.18; p = 0.0228). IMC of both arteries correlated with age (r = 0.49 and r = 50, respectively, p < 0.05), body mass index (r = 0.50, p < 0.05), thickness of the left ventricular posterior wall and interventricular septum (r = 0.65 and r = 0.55, respectively, p < 0.05), CFA IMC correlated also with creatinine level (r = 0.39, p < 0.05), hypertriglyceridemia (chi-square = 10.33; p = 0.0013), systolic, pulse and mean arterial pressure (r = 0.45, r = 0.38, r = 0.36, respectively, p < 0.05), smoking (r = 0.48, r = 0.40, respectively, p < 0.05) and family history of cardiovascular diseases (chi-square = 7.16; p = 0.0075). A linear multifactorial regression analysis has detected that an independent factor of increased CCA and CFA IMC in patients under 50 years of age was creatinine, in patients over 50 years--age., Conclusion: Even at early stages of renal failure patients have thicker IMC associated with both standard risk factors (age, hypertension, smoking, lipid disbolism) and development of renal failure itself.

Introduction: Alexis Carrel pioneered the full-thickness triangulated vascular repair technique, which led to a Nobel Prize in 1912. However, microvascular anastomotic techniques that do not violate the intima, such as the VCS microclip repair and partial-thickness suturing, limit trauma to the intima, thus minimizing the potential for thrombosis. Our study compares such techniques with the standard full thickness-anastomotic repair., Methods: Thirty-two end-to-end anastomotic repairs were performed in rat femoral arteries 1 mm or less in diameter. Group I: thirteen full-thickness repairs were completed using 10-0 nylon on a BV75 microm needle. Nineteen extraluminal repairs were performed using either a partial thickness technique with an 11-0 nylon BV50 microm needle (Group II, n = 12) or VCS nonpenetrating clip (Group III, n=7). Casted samples, injected with methylmethacrylate, were harvested at 1 and 3 weeks for histopathological evaluation. The presence of thrombosis, inflammation, endothelialization, angiogenesis and intimal hyperplasia were described for each repair., Results: Statistical analysis revealed no difference between the intraluminal and extraluminal techniques. Patency rates were similar between both groups: 92% (12/13) for Group I and 94% (17/18) for the extraluminal Groups II and III combined. One-hundred per cent of partial thickness suture repairs were patent. Histology revealed localized inflammation to the adventitia and media, as well as endothelialization at 1 week for anastomoses in Groups II and III. The intima of Group I demonstrated proliferative characteristics in contrast to the extraluminal groups, where secretory myofibroblasts were prevalent. The anastomotic microcirculation did not originate from the repaired artery in any of the groups., Conclusion: Patency rates with end-to-end anastomotic repairs using a partial thickness technique are comparable to the standard full-thickness technique. Repairs that do not include the intima revealed focal inflammatory responses to the outer layers and more rapid endothelialization, while neighboring vessels perfuse the healing anastomosis.

Objective: Plaque disruption does not always result in complete thrombotic occlusion. The mechanism of arterial thrombus propagation remains unclear., Methods and Results: We studied how vascular wall thrombogenicity and blood flow reduction affect thrombus propagation using a rabbit model of single and repeated balloon injury. After balloon injury of the normal femoral artery, the blood flow was reduced to 50%, 25%, or 10% (n=5). Small mural thrombi composed of aggregated platelets were produced, but no occlusive thrombi developed in any flow reduction. Three weeks after the first balloon injury, neointima with tissue factor expression and increased procoagulant activity was developed. Balloon injury of the neointima with the same blood flow reduction (n=5) induced fibrin-rich thrombus formation. Additionally, injury with flow reduced to 25% and 10% promoted thrombus propagation resulting in vessel occlusion within 160+/-18 and 71+/-17 seconds, respectively. An injection of anti-von Willebrand factor (vWF) monoclonal antibody (AJW200; 1.0 mg/kg) prevented occlusive thrombus formation., Conclusions: Increased vascular wall thrombogenicity together with a substantial blood flow reduction is crucial for occlusive thrombus formation, and vWF plays an important role in thrombus propagation. Reduced blood flow at plaque disruption sites might contribute to thrombus propagation leading to acute coronary syndromes.

Background: Exuberant smooth muscle cells (SMCs) hyperplasia is the major cause of postangioplasty restenosis. We suggested that circulating smooth muscle progenitor cells might contribute to lesion formation after vascular injury., Methods: We extensively investigated the cellular constituents during neointimal formation after mechanical vascular injury., Results: A large wire was inserted into the mouse femoral artery, causing complete endothelial denudation and marked enlargement of the lumen with massive apoptosis of medial SMCs. At 2 h, the injured artery remained dilated with a thin media containing very few cells. A scanning electron microscopy showed fibrin and platelet deposition at the luminal side. One week after the injury, CD45-positive hematopoietic cells accumulated at the luminal side. Those CD45-positive cells gradually disappeared, whereas neointimal hyperplasia was formed with alpha-smooth muscle actin (SMA) positive cells. Bone marrow cells and peripheral mononuclear cells differentiated into alpha-SMA-positive cells in the presence of PDGF and basic FGF. Moreover, in bone marrow chimeric mice, bone-marrow-derived cells substantially contributed to neointimal hyperplasia after wire injury., Conclusion: These results suggest that early accumulation of hematopoietic cells may play a role in the pathogenesis of SMC hyperplasia under certain circumstances.

Objective: Abbe and Payr introduced vascular techniques and devices to facilitate vessel anastomosis over a century ago. Obora published the idea of a sutureless vascular anastomosis with use of magnetic rings in 1978. The purpose of this study was to assess the performance of a new magnetic device to perform a side-to-side arteriovenous anastomosis in a dog model., Material and Methods: Male fox hounds (25 kg) were treated preoperatively and daily postoperatively with clopidogrel bisulfate (Plavix) and aspirin. The femoral artery and vein were exposed unilaterally in 3 dogs and bilaterally in 4 dogs (n = 11 anastomoses). A 4-mm arteriotomy was performed, and 1 oval magnet 0.5 mm thick was inserted into the lumen of the artery and a second magnet was applied external to the artery, compressing and stabilizing the arterial wall to create a magnetic port. An identical venous magnetic port was created with another pair of oval magnets. When the 2 ports were allowed to approach each other, they self-aligned and magnetically coupled to complete the arteriovenous anastomosis. Patency was assessed for the first hour with direct observation, again after 9 weeks with duplex ultrasound scanning, and at 10 weeks under direct open observation. The anastomoses were explanted after 10 weeks. Hydrodynamic resistance was measured ex vivo on the final 8 anastomoses by measuring the pressure drop across an anastomosis with a known flow rate., Results: After implantation, very high flow created visible turbulence and palpable vibration. All 11 anastomoses were patent under direct observation and palpation. Ten of 11 anastomoses were clearly patent on duplex scans, and patency of 1 anastomosis was questionable. Hydrodynamic resistance averaged 0.73 +/- 0.33 mm Hg min/mL (mean +/- SEM)., Conclusions: Vascular anastomoses performed with magnets demonstrated feasibility; exhibited 100% patency after 10 weeks in a dog arteriovenous shunt model; lacked apparent aneurysm or other potentially catastrophic failure; demonstrated remodeling of the vessel wall after several weeks to incorporate the magnets, making the magnetic force unnecessary; and warrants further study in vessels with different sizes, flow rates, and locations., Clinical Relevance: We present a magnet-based device used to perform side-to-side peripheral vascular anastomoses. Its advantages include the ability to anastomose vessels without requiring circumferential surgical exposure. Vascular anastomosis performed with these magnets demonstrated 100% patency in the dog, lacked apparent aneurysm or other potentially catastrophic failure, and demonstrated remodeling of the vessel wall after several weeks, to incorporate the magnets, making indefinite retention of field strength unnecessary. This technique could enable minimally invasive procedures, such as complex reconstructive and revascularizing surgery, and warrants further study in vessels with different sizes, flow rates, and locations.

Arteriogenesis has been associated with the presence of monocytes/macrophages within the collateral vessel wall. Induced macrophage migration in vivo is driven by the binding of monocyte chemoattractant protein-1 (MCP-1, or CCL2 in the new nomenclature) to the CCR2-chemokine receptor on macrophages. To determine whether the CCL2-CCR2 signaling pathway is involved in the accumulation of macrophages in growing collateral vessels, we used mice that are deficient in CCR2 in a model of experimental arterial occlusion and collateral vessel growth. In an in vitro CCL2-driven chemotaxis assay, mononuclear cells isolated from wild-type BALB/c mice exhibited CCL2 concentration-dependent migration, whereas this migration was abolished in cells from CCR2(-/-) mice on a BALB/c genetic background. In vivo, blood flow recovery as measured by laser Doppler (LDI) and MRI (MRI) was impaired in CCR2(-/-) mice on either the BALB/c or C57BL/6 genetic backgrounds. Three weeks after femoral artery ligation, LDI perfusion ratio of operated versus nonoperated distal hindlimb in BALB/c wild-type mice increased to 0.45+/-0.06 and in CCR2(-/-) animals only to 0.21+/-0.03 (P<0.01). In C57BL/6 mice, ratio increased to 0.96+/-0.09 and 0.85+/-0.08 (P<0.05), respectively. MRI at 3 weeks (0.76+/-0.06 versus 0.62+/-0.01; P<0.05) and hemoglobin oxygen saturation measurements confirmed these findings. Active foot movement score significantly decreased and gastrocnemius muscle atrophy was significantly greater in CCR2(-/-) mice. Morphometric analysis showed a lesser increase in collateral vessel diameters in CCR2(-/-) mice. Importantly, the number of invaded monocytes/macrophages in the perivascular space of collateral arteries of CCR2(-/-) animals was dramatically reduced in comparison to wild-type mice. In conclusion, our results demonstrate that the CCR2 signaling pathway is essential for efficient collateral artery growth.

Apoptosis plays an important role in atherosclerosis. The factors regulating this process are not well defined. We examined the relation of apoptotic cells with the terminal complement complex C5b-9 in human atherosclerotic lesions. The extent of apoptosis was determined using TdT dUTP nick-end labeling (TUNEL) and immunohistochemistry of apoptosis regulators caspase-3, caspase-9, Bax, and Bcl-2. C5b-9 was localized by immunohistochemistry and immunoelectron microscopy. The apoptotic index was higher in fibrous plaques when compared with intimal fatty streaks and intimal thickenings. Bax expression was present in TUNEL+ apoptotic cells, and Bcl-2 was rarely present in the atherosclerotic wall. Active caspase 9 and caspase 3 deposits were present in the same areas, suggesting an involvement of the mitochondrial pathway. C5b-9 deposits colocalized with TUNEL+ cells, and the percent of double-positive cells was 2% in fatty streaks, 12% in intimal thickenings, and 35% in fibrous plaques. Colocalization of apoptotic cells with C5b-9 was also confirmed by immunoelectron microscopy. In conclusion, some apoptotic cells carry C5b-9 deposits, suggesting that complement might be activated by apoptotic cells and involved in the promotion of apoptosis, contributing to the progression of atherosclerotic lesions.

The aim of the study was to evaluate microscopic changes in the wall structures of allogenic arterial grafts, preserved by the method of cold ischemia in relation to the storage period and to test the possibility of the storage period prolongation by allograft freezing at -70 degrees C. The middle layer ultrastructure is well preserved till 30 days from allograft harvesting, however, allograft freezing results in total destruction of elastic and collagen fibres in the arterial wall. An application of allogenic arterial grafts, preserved by the method of cold ischemia till 30 days from their harvesting, seems an efficient therapeutic method in the treatment of patients with synthetic vascular graft infection. Further prolongation of the storage period at -70 degrees C made the allograft useless for implantation.

A new method for directional velocity estimation is presented. The method uses beamformation along the flow direction to generate data in which the correct velocity magnitude can be directly estimated from the shift in position of the received consecutive signals. The shift is found by cross-correlating the beamformed lines. The approach can find the velocity in any direction, including transverse to the traditionally emitted ultrasound beam. The velocity estimation is studied through extensive simulations using Field II. A 128-element, 7-MHz linear array is used. A parabolic velocity profile with a peak velocity of 0.5 m/s is simulated for different beam-to-flow angles and for different emit foci. At 45 degrees the relative standard deviation over the profile is 1.6% for a transmit focus at 40 mm. At 90 degrees the approach gave a relative standard deviation of 6.6% with a transmit focus of 80 mm, when using 8 pulse-echo lines and stationary echo canceling. Pulsatile flow in the femoral artery was also simulated using Womersley's flow model. A purely transverse flow profile could be obtained with a relative standard deviation of less than 10% over the whole cardiac cycle using 8 pulse emissions for each imaging direction, which is sufficient to show clinically relevant transverse color flow images.

Purpose: In humans, cardiac morphological adaptations to athletic training have been exhaustively described, while the existence of morphologic (adaptive) changes in the peripheral vessels are less well known. Therefore, the scope of the present study was 1) to assess the existence of morphologic changes in the peripheral vessels, such as the common femoral artery (CFA), in athletes engaged in different types of sports; and 2) to assess the relationship existing between the cardiac and CFA changes in highly endurance- ( N = 16) and strength-trained athletes ( N = 15), and in sedentary controls ( N = 20)., Methods: The cross-sectional diameters of the left ventricular (LV) posterior wall and cavity and CFA diameter and intima-media thickness were determined by M-mode echocardiography and ultrasound, respectively., Results: CFA intima-media thickness in the endurance-trained (0.33 +/- 0.03 mm.m(-2) ) was similar to the strength-trained athletes (0.34 +/- 0.05 mm.m(-2) ) and both greater (P < 0.01) compared with the controls (0.27 +/- 0.03 mm.m(-2) ). CFA diameter in endurance-trained athletes (5.6 +/- 0.6 mm.m(-2) ) was highest among groups (strength-trained athletes 4.2 +/- 0.4 mm.m(-2), controls 4.2 +/- 0.5 mm.m(-2) ). Thus, the relative CFA wall thickness (2.intima-media thickness/CFA diameter) was significantly higher (P < 0.01) in the strength-trained (0.16 +/- 0.02) than in the endurance-trained athletes (0.13 +/- 0.02) and the controls (0.13 +/- 0.02), respectively. The relative LV posterior wall thickness (2.LV posterior wall thickness/LV diameter) was not significantly different among the groups. LV posterior wall thickness was significantly related to CFA intima-media thickness (r = 0.31, P < 0.05) and LV diameter to CFA diameter (r = 0.55, P < 0.01)., Conclusions: The study shows a physiological relationship between the LV and CFA wall and cavity dimensions in endurance-trained athletes and controls, respectively. The greater relative wall thickness of the strength-trained athletes may be related to different influencing factors, e.g., increased blood pressure.

Objective: To observe the architecture of elastic fiber of anastomosed artery., Methods: The right femoral arteries of 60 Wistar rats were cut off transversely and end-to-end anastomosis were performed. On the 3rd, 7th, 14th, 21st, 30th and 90th days after operation, the anastomosed artery segments were harvested and fixed by 10% formalin. After routine processed, the architecture of elastic fiber of anastomosed artery was observed under scanning electronic microscope and was compared with that of normal artery., Results: On the 3rd and 7th days after anastomosis, there was no the elastic fiber in the middle of the anastomosed area. From 14 to 90 days after anastomosis, the newborn elastic fiber connected the anastomosed area. The reconstruction of elastic fiber could be divided into quiescent stage, proliferation stage, and rebuilding stage., Conclusion: The reconstruction of elastic fiber occurs after arterious anastomosis and newborn elastic fiber originates from endoarterious layer. The structure of elastic fiber can return to normal 30 days after anastomosis.

Purpose: The purpose of this study was to evaluate the extent (luminal coverage) of the endothelial cell (EC) lining/neointimal development and the thromboresistance of electrostatically EC seeded small diameter e-PTFE vascular grafts., Methods: This evaluation consisted of harvesting autologous, canine jugular vein ECs, electrostatically EC seeding the e-PTFE grafts (4 mm GORE-TEX, Length = 6 cm), implanting the grafts in a canine femoral artery model for six weeks, and excising the graft for histological and scanning electron microscopy evaluations., Results: The results of the histological evaluation (mid-graft region only) indicated that the electrostatic EC seeding significantly affected neointimal development (p < 0.01) and the degree of thrombus formation (p < 0.001) within the EC seeded grafts versus the untreated control grafts. Scanning electron microscopy examination demonstrated a mature, confluent endothelium with a "cobblestone" appearance on the EC seeded graft luminal surface. The control grafts demonstrated an equal distribution of SMCs through the graft wall while the electrostatically EC seeded graft sections exhibited an uneven SMC cellular distribution which was skewed toward the graft luminal surface., Conclusions: The presence of electrostatic EC seeding significantly (p < 0.01) enhanced the development of a neointima and reduced the incidence of thrombosis in e-PTFE grafts implanted in a canine femoral artery model. Results of the mid-graft SMC migration measurements indicate that the electrostatic EC seeding had a significant (p < 0.001) impact on the acute healing of the standard wall e-PTFE vascular graft specimens.

The nature of the vasodilator endothelium-derived hyperpolarizing factor (EDHF) is controversial, putatively involving diffusible factors and/or electrotonic spread of hyperpolarization generated in the endothelium via myoendothelial gap junctions (MEGJs). In this study, we investigated the relationship between the existence of MEGJs, endothelial cell (EC) hyperpolarization, and EDHF-attributed smooth muscle cell (SMC) hyperpolarization in two different arteries: the rat mesenteric artery, where EDHF-mediated vasodilation is prominent, and the femoral artery, where there is no EDHF-dependent relaxation. In the rat mesenteric artery, stimulation of the endothelium with acetylcholine (ACh) evoked hyperpolarization of both ECs and SMCs, and characteristic pentalaminar MEGJs were found connecting the two cell layers. In contrast, in the femoral artery, ACh evoked hyperpolarization in only ECs but not in SMCs, and no MEGJs were present. Selective hyperpolarization of ECs or SMCs evoked hyperpolarization in the other cell type in the mesenteric artery but not in the femoral artery. Disruption of gap junctional coupling using the peptide Gap 27 markedly reduced the ACh-induced hyperpolarization in SMCs, but not in ECs, of the mesenteric artery. These results show that transfer of EC hyperpolarization or of a small molecule to SMCs through MEGJs is essential and sufficient to explain EDHF.

Background: Platelet adhesion on components of the extracellular matrix and platelet activation by those components are crucial for the arrest of posttraumatic bleeding, but they can also harm tissue by occluding diseased vessels. Recent studies have shown that the activation of platelets by collagen is mediated through the same pathway used by immune receptors, with an immunoreceptor tyrosine-based activation motif on the Fc receptor gamma chain (FcRgamma) playing a pivotal role., Methods and Results: We examined the role of collagen-stimulated platelets in the development of injury-induced neointimal formation by using mice deficient in FcRgamma. The left femoral arteries of 8- to 12-week-old FcRgamma-deficient mice (n=16) and C57BL/6 (wild-type) mice (n=16) were injured by a straight spring wire (0.35-mm diameter). Segments of the injured and uninjured femoral arteries were excised at 7 days and 28 days after the vascular injury. Arterial segments were examined by immunohistochemistry and electron microscopy. Two hours after injury, electron microscopy showed marked decreases in platelet adhesion and neutrophil attachment to the vascular wall surface in FcRgamma-knockout mice compared with wild-type mice. At 7 days after injury, staining with anti-neutrophil antibody showed fewer neutrophils in FcRgamma-knockout mice than in wild-type mice. Computer-aided morphometry performed to measure the neointimal area, intima/media ratio, and stenotic area at 28 days after injury showed a significantly smaller ratio and area in FcRgamma-knockout mice than in wild-type mice (for neointimal area, 16 635 +/- 1406 versus 31 483 +/- 2309 microm2, respectively; for intima/media ratio, 1.25 +/- 0.40 versus 2.68 +/- 0.04, respectively; and for stenotic area, 26.8 +/- 2.1% versus 49.3 +/- 4.1%, respectively)., Conclusions: These results demonstrate that FcRgamma may play important roles in the initiation and generation of neointimal hyperplasia after balloon injury through the activation of platelets by collagen.

Previously, during blood perfusion over collagen-coated surfaces; soluble or immobilized heparin proteoglycans (HEP-PG) have been shown to block thrombus growth. Our aim was to study the antithrombotic effect of locally applied unfractionated heparin (UFH, 1 mg/ml), or rat mast cell-derived HEP-PG (MW 750 kD, 10 microg/ml) compared with saline in early (10 min) and late (3 days) thrombus formation upon anastomosis of rat common femoral arteries. In both semiquantitative scanning electron microscopy (SEM) and quantitative platelet Indium 111-labeling HEP-PG inhibited thrombus growth in comparison with saline. At 10 min, the extent of thrombosis (scale 1-4) in SEM followed the order: saline (3.2+/-0.8) > UFH (2.8+/-1.0) > HEP-PG (1.8+/-0.8), and also Indium 111-positive platelets (10(6)) accumulated on the anastomosed vessel in the same order 14.2 +/-7.2, 10.3 +/-5.0, and 7.7 +/-3.1 (saline vs. HEP-PG, p = 0.03 and 0.05, respectively). At 3 days all HEP-PG-treated vessels remained patent with only small mural thrombi, whereas 2/7 saline- and 1/7 UFH-treated anastomoses occluded and showed more thrombosis overall. We conclude that locally administered HEP-PG inhibit arterial thrombus growth in anastomosed small-sized arteries and could prevent thrombotic complications in (micro)vascular surgery and arteriovenous shunts.

Objective: This was a dose-finding and effectiveness study of a newly developed contrast-enhancing agent, sulphur hexafluoride (SF(6)), in patients with peripheral arterial disease in whom the therapeutic policy could not be established on the basis of standard color-flow duplex scanning of the leg arteries., Methods: In this open-label, randomized, dose-ranging, crossover design, 14 patients in whom the assessment of vessel patency was difficult because of poor visibility (low-flow state) or extensive wall calcifications were studied. Contrast-enhanced duplex scanning was performed on the upper leg (n = 4), lower leg (n = 6), or pedal (n = 4) arteries after intravenous injection of four different dosages of SF(6). The results were compared with those from selective angiography of the vessel of interest. Contrast duration and agreement about the diagnosis and the confidence in the diagnosis were obtained before and after administration of the contrast agent., Results: No adverse effects of the contrast agent were seen. Overall agreement was reasonable with regard to vessel patency between contrast-enhanced duplex scanning and angiography (71%). Nine of 14 vessels (64%) appeared open when contrast was applied. In four cases this could not be confirmed by angiography; in two of these cases this was due to the presence of collateral vessels. All vessels that appeared occluded with the contrast agent were also occluded on the angiogram. The confidence in the diagnosis increased from 56% to 91% after contrast administration (P <.0001)., Conclusion: SF(6)-enhanced color-flow duplex scanning is a safe method that may improve the assessment of the patency of leg arteries, particularly in low-flow states. The visualization of collateral vessles during (enhanced) duplex scanning may be misleading because they may be regarded as the vessel of interest.

Immunohistochemical light and electron microscopical analysis of surgical biopsies obtained from femoral and iliac arteries of patients with thromboangiitis obliterans (TAO) were performed to investigate the presence of tumour necrosis factor-alpha (TNF-alpha) and expression of the endothelial cell adhesion molecules intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin. Expression of ICAM-1, VCAM-1 and E-selectin was increased on endothelium and some inflammatory cells in the thickened intima in all TAO patients. Ultrastructural immunohistochemistry revealed contacts between mononuclear blood cells and ICAM-1-, and E-selectin-positive endothelial cells. These endothelial cells showed morphological signs of activation. The present data indicate that endothelial cells are activated in TAO and that vascular lesions are associated with TNF-alpha secretion by tissue-infiltrating inflammatory cells, ICAM-1-, VCAM-1- and E-selectin expression on endothelial cells and leukocyte adhesion via their ligands. The preferential expression of inducible adhesion molecules in microvessels and mononuclear inflammatory cells suggests that angiogenesis contributes to the persistence of the inflammatory process in TAO.