Effects of endothelial defects and venous interposition grafts on the acute incidence of thrombus formation within microvascular procedures.

Endothelial defects (ED) and the usage of interposition vein grafts (IVG) are known risk factors for free flap failure. This experimental study aimed to compare both situations of thrombus formation and fluorescence angiographic behavior. Indocyanine green videoangiography (ICGVA) with the FLOW 800 tool was systematically performed in groups I = ED, II = IVG, and III = ED and IVG (each n = 11). ICGVA was able to detect thrombosis in five animals and safely ruled it out in 26 with two false-positive cases (sensitivity, specificity, and positive and negative predictive values were 100%, 90%, 62%, and 100%, respectively). The difference between visually and ICGVA-assisted ED measurements was significant (p = 0.04). The areas of thrombosis showed no significant difference. Moreover, ICGVA detected a decrease of all parameters at the ED area and/or within the IVG section in all groups. The presence of an endothelial defect had a higher impact on thrombus formation than the IVG usage. ICGVA is qualitatively able to detect endothelial defects and clinically evident thrombosis. However, the quantitative values are not yet attributable to one of the clinical scenarios that may jeopardize free flap transfer.

Effects of acute angle, proximal bending, and distal bending in the deployment vessels on incomplete low-profile visualized intraluminal support (LVIS) expansion: an in vitro study.

BACKGROUND: A low-profile visualized intraluminal support (LVIS) device may incompletely expand during stent deployment in tortuous vessels. However, the cause of incomplete expansion remains uninvestigated. We aimed to examine in vitro the factors causing incomplete expansion in LVIS deployment by using various vessel models. METHODS: A linear model group was created by connecting linear silicone tubes (inner diameter 4 mm) at both sides of the LVIS deployment vessel (inner diameter 4 mm) with different curvature angles of 10-140° at 10° intervals. For comparison, proximal and distal bending model groups were created, both with 90° bending on the proximal/distal larger curvature side of the deployment vessel. A single operator macroscopically deployed an LVIS (4.5×32 mm) four times in each model and 56 times in each group. RESULTS: In each model group the LVIS deployment vessel with a narrow curvature angle incompletely expanded. Incomplete expansion occurred significantly more frequently in the distal bending model group (34%, 19/56) compared with that in the linear model group (14.3%, 8/56; p<0.001), as well as in the proximal bending model group (59%, 33/56) compared with that in the distal bending model group (p<0.05). Compared with the linear model group, the proximal bending model group had a significantly reduced angle between the LVIS and the direction of the LVIS pushing force, but no significant change was found in the distal bending model group compared with that in the linear model group. CONCLUSIONS: Factors such as acute angle, distal bending, and proximal bending of the deployment vessel can cause incomplete LVIS expansion.

NF-κB inhibition prevents acute shear stress-induced inflammation in the saphenous vein graft endothelium.

The long saphenous vein (LSV) is commonly used as a conduit in coronary artery bypass grafting. However, long term patency remains limited by the development of vascular inflammation, intimal hyperplasia and accelerated atherosclerosis. The impact of acute exposure of venous endothelial cells (ECs) to acute arterial wall shear stress (WSS) in the arterial circulation, and the subsequent activation of inflammatory pathways, remain poorly defined. Here, we tested the hypothesis that acute exposure of venous ECs to high shear stress is associated with inflammatory responses that are regulated by NF-κB both in-vitro and ex-vivo. Analysis of the LSV endothelium revealed that activation of NF-κB occurred within 30 min after exposure to arterial rates of shear stress. Activation of NF-κB was associated with increased levels of CCL2 production and enhanced binding of monocytes in LSVECs exposed to 6 h acute arterial WSS. Consistent with this, ex vivo exposure of LSVs to acute arterial WSS promoted monocyte interactions with the vessel lumen. Inhibition of the NF-κB pathway prevented acute arterial WSS-induced CCL2 production and reduced monocyte adhesion, both in vitro and in human LSV ex vivo, demonstrating that this pathway is necessary for the induction of the acute arterial WSS-induced pro-inflammatory response. We have identified NF-κB as a critical regulator of acute endothelial inflammation in saphenous vein in response to acute arterial WSS. Localised endothelial-specific inhibition of the NF-κB pathway may be beneficial to prevent vein graft inflammation and consequent failure.

Papillary Endothelial Hyperplasia (Masson Tumor) of the Hand. Surgical and Pathological Consideration from Seven Cases Using New Vascular Markers.

Although papillary endothelial hyperplasia may occur at almost any site, one of the most common sites is the hand. It is generally regarded as a reactive vascular proliferation i.e. exuberant form of organizing thrombus. Diagnosis of Masson tumor can be challenging due to its close clinical, radiological and even histopathological resemblance to angiosarcoma. We present seven cases of Masson tumor of the hand; wanting to reveal its nature using new vascular markers and discuss the treatment options and expected outcomes, present clinical and radiological features that may aid diagnosis and also offer treatment plans. A multicenter retrospective study was performed between January 2014 and November 2019. Immunohistochemical stains of Glut1, WT1, ERG, CD31 and alpha smooth muscle actin (ASMA) were performed on each cases. We found seven cases during the examined period. 4 out of 7 cases were women. All lesions occurred in the hands. 3 out of 7 cases appeared in a previously present vascular malformation. All cases were treated with surgical excision and the diagnosis of papillary endothelial hyperplasia was made by histology. Pre-operative testing (radiograph/MRI/US/fine needle aspiration biopsy) did not suggest the diagnosis of Masson tumor; however, aspiration cytology could rule out malignancy. The proliferative endothelial cells proved to be Glut1 negative and WT1 positive and the accompanying pericytic cells were ASMA positive in all cases. Though Masson tumor is a rare vascular lesion in the hand among other vascular tumors, it should be considered in the differential diagnostics even in the case of previously existing vascular malformation. WT1 positivity of the endothelial cells and the accompanying pericytic cells raises the question whether the initially reactive endothelial proliferation may transform into a true benign vascular tumor.

Endothelin-1, endothelin receptor antagonists, and vein graft occlusion in coronary artery bypass surgery: 20 years on and still no journey from bench to bedside.

The saphenous vein is the most commonly used bypass graft in patients with coronary artery disease. During routine coronary artery bypass, grafting the vascular damage inflicted on the vein is likely to stimulate the release of endothelin-1, a potent endothelium-derived vasoconstrictor that also possesses cell proliferation and inflammatory properties, conditions associated with vein graft failure. In both in vitro and in vivo studies, endothelin receptor antagonists reduce neointimal thickening. The mechanisms underlying these observations are multifactorial and include an effect on cell proliferation and cell/tissue damage. Much of the data supporting the beneficial action of endothelin-1 receptor antagonism at reducing intimal thickening and occlusion in experimental vein grafts were published over 20 years ago. The theme of the recent ET-16 conference in Kobe was "Visiting Old and Learning New". This short review article provides an overview of studies showing the potential of endothelin receptor antagonists to offer an adjuvant therapeutic approach for reducing saphenous vein graft failure and poses the question why this important area of research has not been translated from bench to bedside given the potential benefit for coronary artery bypass patients.

Endothelial loss during the surgical procedure in saphenous veins harvested by open and endoscopic techniques in coronary artery bypass surgery.

The patency of the vein graft in coronary artery bypass grafting could be dependent on the conventional open (vsO) or endoscopic (vsE) harvesting and on the hypoxic damage of endothelial cells. We aimed to evaluate both surgical techniques according to endothelial loss that occurs in the time between harvesting and implantation. Twenty-six saphenous veins were divided into vsO (n = 16) and vsE (n = 10) group. Three samples were taken from each vein. The first sample was taken after removal, the second before implantation of the distal part, and the third before the implantation of the proximal part, and they were stained with HE, Movat, and immunohistochemically with CD31. A significant loss of endothelial cells within both groups was found at the time of implantation of the distal and the proximal part of the vein graft compared to the endothelial cells at the time of harvesting. There were no significant differences in the endothelial loss between vsE and vsO groups at the time of harvesting and at the time before the implantation of the distal part. A higher number of endothelial cells was found in vsE group compared to vsO group at the time just before the implantation of the proximal part. The comparison of the implanted portions of vsE and vsO grafts to mammary arteries revealed a significant loss of endothelial cells only in vsO graft. We conclude that, at the time of implantation, the endothelial layer of the vein graft harvested endoscopically is more preserved than of the vein graft harvested openly.

Intravascular Papillary Endothelial Hyperplasia of the Maxillary Sinus in Patient with Tricuspid Atresia.

Intravascular papillary endothelial hyperplasia (IPEH) is a benign, highly vascularized, endothelial growth that can be mischaracterized as a malignancy. While hundreds of IPEH cases are reported, only four occurred in the maxillary sinus. We present the case of a 28-year-old male who underwent surgical resection of IPEH of the right maxillary sinus. An additional consideration was the patient's condition of univentricular tricuspid atresia which contributed to chronic hypoxemia and polycythemia. After complete resection from the maxillary sinus, post-operational workup determined the lesion to be IPEH. Given the potential for misdiagnosis of IPEH, careful histopathologic evaluation is required in order to avoid improper treatment.

Sex differences in vascular reactivity of coronary artery bypass graft conduits.

Females have increase in-hospital mortality and poorer outcomes following coronary artery bypass grafting (CABG). Biological differences in the reactivity of the graft conduits to circulating catecholamine may contribute to this sex difference. This study examined sex differences in the vasoconstrictor responses of internal mammary artery (IMA) and saphenous vein (SV) conduits to phenylephrine (PE) and endothelin-1 (ET-1). Functional IMA and SV were obtained from 78 male and 50 female patients undergoing CABG (67.7 ± 11 and 69 ± 10 years, respectively) and subjected to the following experimental conditions. (1) Concentration response curves for PE and ET-1 were generated in an intact IMA and SV and endothelium denuded IMA segments, (2) in the presence of the nitric oxide synthase inhibitor (L-NAME) or the cyclooxygenase inhibitor (indomethacin) in an endothelium-intact IMA and (3) the activity state (abundance and phosphorylation) of the α1-adrenergic receptor was investigated using Phos-tag™ western blot analysis. (1) Compared to male, female IMA and SV were hypersensitive to PE but not ET-1 (p < 0.05). The female IMA hypersensitivity response to PE was abolished following endothelial denudation, (2) persisted in the presence of L-NAME but was abolished in the presence of indomethacin and (3) there was no sex differences in the abundance and phosphorylation of the α1-adrenergic receptor in IMA. Female IMA and SV graft conduits are hypersensitive to α1-adrenergic stimuli. This endothelial cyclooxygenase pathway-mediated hypersensitivity may produce excessive IMA and SV graft constriction in females administered catecholamines and could contribute to their poorer CABG outcomes.

Vessel Wall Imaging After Subarachnoid Hemorrhage in Patients with Multiple Intracranial Aneurysms: A Cautionary Case.

BACKGROUND: Almost 30% of patients with subarachnoid hemorrhage (SAH) are found to have multiple aneurysms. This can potentially present a serious management dilemma when planning treatment. Magnetic resonance imaging vessel wall imaging (VWI) has been proposed as a reliable technique in differentiating between ruptured and unruptured aneurysms in patients with multiple intracranial aneurysms who present with SAH. Expert consensus now supports this as a possible use for the technique. CASE DESCRIPTION: Here we present a patient presenting a particular clinical dilemma with SAH and a left third nerve palsy and transient speech disturbance who had circumferential enhancement in the left larger 3.5-mm irregular middle cerebral artery aneurysm and no detectable enhancement in what was angiographically either a 1.5-mm smooth noncompressive left posterior communicating artery aneurysm or infundibulum, but was proved at surgery to be the culprit aneurysm. CONCLUSION: Although a case of concurrent false positive and false negative in the same patient has not previously been reported, the positive predictive value of VWI for rupture status is known to be much lower than its negative predictive value, and a case like this might be expected to occur in 0.6% of patients. Therefore, whereas VWI is a valuable tool, it should be used in conjunction with, and not in lieu of, traditional indicators of aneurysm rupture.

Arteriovenous fistula and pre-surgery mapping: Potential role of physical exercise on endothelial function.

BACKGROUND: The success of the construction of an arteriovenous fistula for haemodialysis is related to the vascular function of the vessels involved in the anastomosis, with particular reference to radial artery distensibility after reactive hyperaemia test and to the fall of resistance index. Only few studies have evaluated the impact of exercise protocols on the endothelial and morphological characteristics of the vessels of the upper limb with inconclusive results. In this pilot longitudinal study, we aimed to evaluate the impact of a standardized exercise protocol on the haemodynamic and resistive index of the arteries of the upper limb of uraemic patients. METHODS: A total of 17 uraemic patients planned to construct arteriovenous fistula at the distal third of the forearm were enrolled and followed up for 30 days. All patients performed repeated handgrips for 30 min/day. The arterial parameters were detected before and after an ischaemic stress of 5 min and radial and brachial artery flow-mediated dilation was evaluated as well as radial artery resistance index. RESULTS: Pre-exercise measurements of radial artery diameter and resistance index and brachial artery diameter were not modified by 30 days hand physical exercise, whereas the post-exercise haemodynamic were improved. Consequently, flow-mediated dilation of the radial artery was improved (21% ± 14% vs 30% ± 19%; p = 0.03) and resistance index of the radial artery was reduced (p = 0.02). CONCLUSION: Exercise has beneficial effects on endothelial function of the radial artery by resistive index and, potentially, on the outcome of the arteriovenous fistula. Further studies with larger sample size are needed to confirm our preliminary data.

A novel histologic grading system based on lymphovascular invasion, perineural invasion, and tumor budding in colorectal cancer.

PURPOSE: This study aimed to evaluate the prognostic significance of lymphovascular (LVI), perineural invasion (PNI), and tumor budding positivity in patients with colorectal cancer. METHODS: From January 2008 to December 2011, 3707 consecutive patients who underwent curative surgery for stage I-III colorectal cancer were assessed. These patients were then categorized into four groups based on LVI, PNI, and tumor budding (risk grouping): all negative (n = 1495), 1 + only (n = 1063), 2 + only (n = 861), and all positive (n = 288). RESULTS: With a median follow-up period of 52 months, the 5-year disease-free survival rates of the risk groups were significantly different in terms of cancer staging (stage I, Stage II, and Stage III: P = 0.006, P < 0.001, and P < 0.001, respectively). In the multivariate analysis, risk grouping was an independent prognostic factor of disease-free survival. Preoperative carcinoembryonic antigen level, tumor size, T category, and N category were independent predictors of LVI, PNI, and tumor budding positivity. CONCLUSION: Risk grouping based on LVI, PNI, and tumor budding positivity is a strong predictor of disease-free survival in patients with colorectal cancer.

Intravascular papillary endothelial hyperplasia along the intrinsic muscle after hand contusion injury: Report of two cases.

Intravascular papillary endothelial hyperplasia (IPEH), also known as Masson's tumor or vegetant intravascular hemangioendothelioma, is a reactive condition representing an exuberant organization and recanalization of a thrombus. It can occur in normal blood vessels or in vascular malformations, perhaps in response to blood vessel injury or thrombosis. In this report, we present the diagnostic and therapeutic courses of a 55 year-old woman and an 18 year-old man, who had a progressive protruding hand mass following a hand contusion. The pathological examination confirmed the diagnosis of IPEH in both patients.

Down-regulation of vascular GLP-1 receptor expression in human subjects with obesity.

It has been thought that incretin signaling prevents arteriosclerosis, and very recently anti-arteriosclerotic effects through GLP-1 receptor were finally demonstrated in clinical human study. The purpose of this study was to investigate how vascular GLP-1 receptor expression is influenced in human subjects. First, we evaluated GLP-1 receptor expression in human arteries in immunostaining. Next, we separated the artery into the intima and media, and evaluated gene expression levels of various factors. We divided the subjects into obesity and non-obesity group and compared their expression levels between them. Finally, we evaluated which factors determine vascular GLP-1 receptor expression. GLP-1 receptor expression in intima and media was lower in obesity group compared to non-obesity group which was correlated with the alteration of TCF7L2 expression. Multiple regression analyses showed that BMI was an independent determining factor for GLP-1 receptor expression in the intima and media. Furthermore, using small interfering RNA method and TCF7L2-EGFP adenovirus, we showed that TCF7L2 was involved in GLP-1 receptor expression in human vascular cells. Taken together, vascular GLP-1 receptor and TCF7L2 expression was significantly down-regulated in human subjects with obesity. In addition, it is likely that TCF7L2 functions as a modulator of vascular GLP-1 receptor expression.

Staged Management of Intracranial Masson Tumor: An Unexpected Gauntlet: Case Report and Review of the Literature.

BACKGROUND: Intravascular papillary endothelial hyperplasia (IPEH), also known as Masson tumor, is a benign lesion consisting of a reactive proliferation of endothelial cells with papillary formations related to thrombi. It has been reported in many different anatomic areas. Gross total resection is the elected treatment. Intracranial IPEH is rare, and only a few cases have been reported. This article reports a complicated case of cavernous sinus Masson tumor. CASE DESCRIPTION: A 51-year-old woman presented because of hemicraneal headache, left facial paresthesia, and diplopia (due to a slight left ocular external rectum muscle paresis) that she had experienced the previous 60 days. She had previously received a diagnosis of neurofibromatosis type I. Contrast-enhanced magnetic resonance imaging showed a 3.5-cm contrast-enhanced tumor adjacent to the left cavernous sinus involving the Meckel cave that extended around the distal petrous portion of the left internal carotid artery. Two possibilities as a differential diagnosis were suggested: meningioma or neurogenic tumor. After a staged surgical procedure, the histopathologic findings were unexpected and showed IPEH (Masson tumor) as the cause of the mass. Despite having benign features, the IPEH showed recurrences over time, so adjuvant 3-dimensional conformal radiation therapy was initiated. CONCLUSIONS: IPEH is prone to recurrences after subtotal resection. In the present case, successful surgical treatment and adjuvant radiotherapy showed an excellent outcome. To date, no adjuvant therapy has been established as a go-to option.

Resveratrol combined with total flavones of hawthorn alleviate the endothelial cells injury after coronary bypass graft surgery.

OBJECTIVE: To explore the preventive and therapeutic effects of Resveratrol combined with total flavones of hawthorn, compatibility of traditional Chinese medicines, on the endothelial cells injury after artery bypass graft surgery. METHODS: The animal model of coronary artery bypass grafting (CABG) was prepared by transplanting a segment of autologous jugular vein onto the transected common carotid artery in rabbits. After CABG surgery, the rabbits were administrated with saline (model group), aspirin (Aspirin group), resveratrol (Res group), total flavones of hawthorn (Haw group) and resveratrol combined with total flavones of hawthorn (Res+Haw group) once a day for eight weeks, respectively. Eight weeks later, the grafting arteries from all group were obtained for the pathomorphism observation, peripheral blood was collected to detect circulating endothelial cells (CECs) by flow cytometry. And the concentration of albumen and mRNA of ICAM-1 in the serum were measured by western blot and quantitative real-time polymerase chain reaction, respectively. RESULTS: Compared with the model group, the level of CECs density and the expressions of albumen and mRNA of ICAM-1 were significantly decreased in the aspirin,resveratrol,total flavones of hawthorn and resveratrol combined with total flavones of hawthorn groups (P < .05). Of note, above all parameters were lower in Res group than aspirin group. CONCLUSION: The Resveratrol combined with total flavones of hawthorn could protect the endothelial cells after coronary artery bypass graft.

New Regenerative Vascular Grafts for Hemodialysis Access: Evaluation of a Preclinical Animal Model.

The purpose of this study was to evaluate a suitable animal model for the in vivo evaluation of patency and vascular tissue regeneration in small intestinal submucosa (SIS) vascular grafts for hemodialysis access. First, a 4-mm U-shaped SIS vascular graft was implanted between the internal carotid artery (CA) and the external jugular vein (JV) in five sheep and six swine. The U-shape grafts remained functional for 53 ± 4 days in sheep and 32 ± 2 days in swine. The sheep model presented exaggerated inflammation, so the swine model was selected for the in vivo study. Based on these initial results, a 4-mm C-shape SIS vascular graft with SIS circumferential reinforcement was developed to mechanically improve the vascular graft and manage complications identified during surgery in both sheep and swine. The C-shape vascular graft was implanted in a swine model (n = 3) between the CA and JV. GORE-TEX® vascular grafts were used as controls in the contralateral side of the neck. C-shape grafts remained patent for 47 ± 4 days, whereas the GORE-TEX® grafts were patent for 30 ± 15 days. The C-shape vascular graft was easier to handle during surgery, and its circumferential reinforcement improved in vivo patency, avoiding kinks in the graft after implantation. Histological results showed neovascularization and some regeneration with the alignment of endothelial cells in the vascular wall of the grafts. The model developed may be helpful in other research involving in vivo studies of vascular grafts for hemodialysis access.

In situ tissue engineering: endothelial growth patterns as a function of flow diverter design.

BACKGROUND: Vascular remodeling in response to implantation of a tissue engineering scaffold such as a flow diverter (FD) leads to the cure of intracranial aneurysms. We hypothesize that the vascular response is dependent on FD design, and CD34+ progenitor cells play an important role in the endothelialization of the implant. METHODS: Sixteen rabbit aneurysms were randomly treated with two different single-layer braided FDs made of cobalt-chrome alloys. The FD-48 and FD-72 devices had 48 and 72 wires, respectively. Aneurysm occlusion rate was assessed during the final digital subtraction angiogram at 10, 20, 30, and 60 days (n=2 per device per time point). Implanted vessels were analyzed with scanning electron microscopy for tissue coverage, endothelialization, and immuno-gold labeling for CD34+ cells. RESULTS: Complete aneurysm occlusion rates were similar between the devices; however, complete or near complete occlusion was more frequently observed in aneurysms with neck ≤4.2 mm (p=0.008). Total tissue coverage at 10 days over the surface of the FD-48 and FD-72 devices was 56.4±11.6% and 76.6±3.6%, respectively. Endothelial cell growth over the surface was time-dependent for the FD-72 device (Spearman's r=0.86, p=0.013) but not for the FD-48 device (Spearman's r=-0.59, p=0.094). The endothelialization score was marginally correlated with the distance from the aneurysm neck for the FD-48 device (Spearman's r=1, p=0.083) but not for the FD-72 device (Spearman's r=0.8, p=0.33). CD34+ cells were present along the entirety of both devices at all time points. CONCLUSIONS: This study gives preliminary evidence that temporal and spatial endothelialization is dependent on FD design. Circulating CD34+ progenitor cells contribute to endothelialization throughout the healing process.

[Ruptured vascular adrenal cyst after being hit by a wave]. / Rupturierte vaskuläre Nebennierenzyste durch Badeunfall.

Endothelial cysts of the adrenal gland are a rare entity of adolescents. We here present the case of a 19-year-old woman, who developed right abdominal pain after trauma. Magnetic resonance imaging showed a tumor in the right adrenal gland with suspicious signs for malignancy. Histopathological examination revealed the diagnosis of an endothelial (vascular) adrenal cyst. In most cases, cysts of the adrenal gland remain clinically inapparent. In cases of clinically manifest symptoms, surgical intervention represents the standard for therapy.

Selective tissue ablation using laser radiation at 355 nm in lead extraction by a hybrid catheter; a preliminary report.

BACKGROUND: Current lead extraction (LE) devices can harm the blood vessel endothelium, increasing the risk of perforation. OBJECTIVE: Proof of concept for using a solid-state pulsed laser at 355 nm with a hybrid catheter in LE. METHODS: A hybrid catheter was used comprising optical fibers for the delivery of 355 nm laser pulses at 30 Hz and 6 J/cm(2) combined with a blunt mechanical blade. Specific parameters were chosen to enable selectivity in ablation, thereby reducing the risk of blood vessel perforation. The design exploits differences in the mechanical properties of the fibrotic tissue and the normal blood vessel. Ex vivo ablation was performed to evaluate a hybrid catheter operation on various tissues. Two ex/in vivo pig studies used a free-floating electrode to which three bovine tendon pieces were glued. Finally, two in vivo dog model studies were performed on specimens with 4-5-year-old pacing lead implants, followed by a histopathology study. RESULTS: Catheter penetration rate in the ex vivo experiments was 0.1 mm/seconds for bovine tendon, 0.025 mm/seconds for porcine superior vena cava and 0.033 mm/seconds for porcine aorta. In the ex/in vivo pig study, the three tissue blocks were successfully dissected. In the in vivo dog study, the two leads were successfully extracted. In all in vivo tests, hemodynamic stability was maintained. Gross histopathology did not reveal any injury. CONCLUSIONS: Ablation using 355 nm laser pulses in combination with a mechanical blunt blade may potentially constitute a viable alternative for LE.

Arterial Vasoreactivity is Equally Affected by In Vivo Cross-Clamping with Increasing Loads in Young and Middle-Aged Mice Aortas.

PURPOSE: To compensate for the lack of haptic feedback by surgical robots, limitation of exerted forces could be implemented. The limits should be based on the observed relationship between tissue load and induced damage. This study examines whether age-related changes influence this relationship. METHODS: Descending thoracic aortas of male C57BL/6J mice of 10, 25 and 40 weeks were clamped in vivo (no clamp, 0.5N or 2.0N) for 2 min. Functional integrity was tested in vitro by studying endothelium-dependent and -independent vasoreactivity. RESULTS: Endothelium-dependent relaxation deteriorated with increased clamping force at all ages. Clamping did not influence endothelium-independent vasodilation. Age (10, 25 and 40 weeks) did not significantly impact on the effect of clamping on endothelium-dependent and independent vasoreactivity. CONCLUSIONS: Within the tested conditions, mechanical clamping induces damage to the vascular endothelium, but not to the smooth muscle cells. Age has no effect on the obtained results in mice from 10 to 40 weeks old.