Smooth muscle cells of human veins show an increased response to injury at valve sites

Long-term outcomes of great saphenous vein harvest techniques for infrainguinal arterial bypass in a Medicare-matched registry database

OBJECTIVE

Long-term outcomes for harvesting techniques for great saphenous vein (GSV) and its impact on the outcomes of infrainguinal arterial bypass remains largely unknown. Endoscopic GSV harvesting (EVH) has emerged as a less invasive alternative to conventional open techniques. Using the Vascular Quality initiative Vascular Implant Surveillance & Interventional Outcomes Network (VQI-VISION) database, we compared the long-term outcomes of infrainguinal arterial bypass using open and endoscopic GSV harvest techniques.

METHODS

Patients who underwent infrainguinal GSV bypass between 2010 and 2019 were identified in the VQI-VISION Medicare linked database. Long-term outcomes of major/minor amputations, and reinterventions up to 5 years of follow-up were compared between continuous incisions, skip incision, and EVH, with continuous incisions being the reference group. Secondary outcomes included 30- and 90-day readmission, in addition to surgical site infections and patency rates at 6 months to 2 years postoperatively. Survival analysis using Kaplan-Meier curves and Cox regression hazard models were utilized to compare outcomes between groups. To adjust for multiple comparisons between the study groups, a P value of 2.5% was considered significant.

RESULTS

Among the 8915 patients included in the study, continuous and skip vein harvest techniques were used in 44.4% and 43.4% of cases each, whereas 12.3% underwent EVH. The utilization of EVH remained relatively stable at around 12% throughout the study period. Compared with GSV harvest using continuous incisions, EVH was associated with higher rates of reintervention at 1 year (46.5% vs 41.3%; adjusted hazard ratio [aHR], 1.22; 95% confidence interval [CI], 1.06-1.41; P = .01]. However, no significant difference was observed between EVH and continuous incisions, and between skip and continuous incisions in terms of long-term reintervention or major and minor amputations on adjusted analysis. Compared with continuous incision vein harvest, both EVH and skip incisions were associated with lower surgical site infection rates within the first 6 months post-bypass (aHR, 0.53; 95% CI, 0.35-0.82 and aHR, 0.68; 95% CI, 0.53-0.87, respectively). Loss of primary, primary-assisted, and secondary patency was higher after EVH compared with continuous incision vein harvest. Among surgeons performing EVH, comparable long-term outcomes were observed regardless of low (<4 cases/year), medium (4-7 cases/year), or high procedural volumes (>7 cases/year).

CONCLUSIONS

Despite higher 1-year reintervention rates, EVH for infrainguinal arterial bypass is not associated with a significant difference in long-term reintervention or amputation rates compared with other harvesting techniques. These outcomes are not influenced by procedural volumes for EVH technique.

Hormonal influence: unraveling the impact of sex hormones on vascular smooth muscle cells

Sex hormones play a pivotal role as endocrine hormones that exert profound effects on the biological characteristics and vascular function of vascular smooth muscle cells (VSMCs). By modulating intracellular signaling pathways, activating nuclear receptors, and regulating gene expression, sex hormones intricately influence the morphology, function, and physiological state of VSMCs, thereby impacting the biological properties of vascular contraction, relaxation, and growth. Increasing evidence suggests that abnormal phenotypic changes in VSMCs contribute to the initiation of vascular diseases, including atherosclerosis. Therefore, understanding the factors governing phenotypic alterations in VSMCs and elucidating the underlying mechanisms can provide crucial insights for refining interventions targeted at vascular diseases. Additionally, the varying levels of different types of sex hormones in the human body, influenced by sex and age, may also affect the phenotypic conversion of VSMCs. This review aims to explore the influence of sex hormones on the phenotypic switching of VSMCs and the development of associated vascular diseases in the human body.

Vicious Circle With Venous Hypertension, Irregular Flow, Pathological Venous Wall Remodeling, and Valve Destruction in Chronic Venous Disease: A Review

Substantial advances occurred in phlebological practice in the last two decades. With the use of modern diagnostic equipment, the patients' venous hemodynamics can be examined in detail in everyday practice. Application of venous segments for arterial bypasses motivated studies on the effect of hemodynamic load on the venous wall. New animal models have been developed to study hemodynamic effects on the venous system. In vivo and in vitro studies revealed cellular phase transitions of venous endothelial, smooth muscle, and fibroblastic cells and changes in connective tissue composition, under hemodynamic load and at different locations of the chronically diseased venous system. This review is an attempt to integrate our knowledge from epidemiology, paleoanthropology and anthropology, clinical and experimental hemodynamic studies, histology, cell physiology, cell pathology, and molecular biology on the complex pathomechanism of this frequent disease. Our conclusion is that the disease is initiated by limited genetic adaptation of mankind not to bipedalism but to bipedalism in the unmoving standing or sitting position. In the course of the disease several pathologic vicious circles emerge, sustained venous hypertension inducing cellular phase transitions, chronic wall inflammation, apoptosis of cells, pathologic dilation, and valvular damage which, in turn, further aggravate the venous hypertension.

Saphenous vein valve assessment utilizing upright CT to potentially improve graft assessment for bypass surgery

Saphenous veins (SVs) are frequently employed as bypass grafts. The SV graft failure is predominantly seen at the valve site. Avoiding valves during vein harvest would help reduce graft failure. We endeavored to detect SV valves, tributaries, and vessel size employing upright computed tomography (CT) for the raw cadaver venous samples and in healthy volunteers. Five cadaver legs were scanned. Anatomical analysis showed 3.0 (IQR: 2.0-3.0) valves and 13.50 (IQR: 10.00-16.25) tributaries. The upright CT completely detected, compared to 2.0 (IQR: 1.5-2.5, p = 0.06) valves and 9.5 (IQR: 7.5-13.0, p = 0.13) tributaries by supine CT. From a total of 190 volunteers, 138 (men:75, women:63) were included. The number of valves from the SF junction to 35 cm were significantly higher in upright CT than in supine CT bilaterally [upright vs. supine, Right: 4 (IQR: 3-5) vs. 2 (IQR:1-2), p < 0.0001, Left: 4 (IQR: 3-5) vs. 2 (IQR: 1-2), p < 0.0001]. The number of tributaries and vessel areas per leg were also higher for upright compared with supine CT. Upright CT enables non-invasive detection of SV valves, tributaries, and vessel size. Although not tested here, it is expected that upright CT may potentially improve graft assessment for bypass surgery.

Characterization of culture from smooth muscle cells isolated from rat middle cerebral arteries

Although human brain represents only 2% of the body mass, it uses around 20 % of the organism energy. Due to the brain's limited energy storage, the oxygen and glucose necessary to support brain functions depends on the correct blood supply. The main components of the arteries are smooth muscle cells, which are considered the main regulators of vascular tone and blood flow distribution. The information currently available on the functioning of the cerebral arteries and their cell constituents is extremely scarce. Thus, the aim of this work was to develop an in vitro model of smooth muscle cells derived from rat middle cerebral artery. Explants were collected from rat middle cerebral artery and adhered to collagen-coated culture dishes. Immunocytochemical analysis showed that the cells present in the culture expressed α-actin, a protein characteristic of the contractile phenotype of these cells. In addition, these cells did not express the endothelial marker, vWF. To evaluate the functionality of these cells the response to contractile agents, serotonin and noradrenaline, and to relaxing agent, sodium nitroprusside was determine by Planar Cell Surface Area analysis. Together the data obtained show that the cell culture obtained through the procedure described resulted in cells presenting the markers characteristic of smooth muscle cells and maintaining the usual contractile response, indicating that the cells obtained through this may be used as a model for characterization and study of functional behavior of the middle cerebral artery, as well as interaction studies between vascular and neuronal system.

Expression profiles of the internal jugular and saphenous veins: Focus on hemostasis genes

INTRODUCTION

Venous bed specificity could contribute to differential vulnerability to thrombus formation, and is potentially reflected in mRNA profiles.

MATERIALS AND METHODS

Microarray-based transcriptome analysis in wall and valve specimens from internal jugular (IJV) and saphenous (SV) veins collected during IJV surgical reconstruction in patients with impaired brain outflow. Multiplex antigenic assay in paired jugular and peripheral plasma samples.

RESULTS

Most of the top differentially expressed transcripts have been previously associated with both vascular and neurological disorders. Large expression differences of HOX genes, organ patterning regulators, pinpointed the vein positional identity. The "complement and coagulation cascade" emerged among enriched pathways. In IJV, upregulation of genes for coagulation inhibitors (TFPI, PROS1), activated protein C pathway receptors (THBD, PROCR), fibrinolysis activators (PLAT, PLAUR), and downregulation of the fibrinolysis inhibitor (SERPINE1) and of contact/amplification pathway genes (F11, F12), would be compatible with a thromboprotective profile in respect to SV. Further, in SV valve the prothrombinase complex genes (F5, F2) were up-regulated and the VWF showed the highest expression. Differential expression of several VWF regulators (ABO, ST3GAL4, SCARA5, CLEC4M) was also observed. Among other differentially expressed hemostasis-related genes, heparanase (HPSE)/heparanase inhibitor (HPSE2) were up-/down-regulated in IJV, which might support procoagulant features and disease conditions. The jugular plasma levels of several proteins, encoded by differentially expressed genes, were lower and highly correlated with peripheral levels.

CONCLUSIONS

The IJV and SV rely on differential expression of many hemostasis and hemostasis-related genes to balance local hemostasis, potentially related to differences in vulnerability to thrombosis.

Inhibitory Effects of PRG4 on Migration and Proliferation of Human Venous Cells

BACKGROUND

Proteoglycan 4 (PRG4; lubricin) is a member of two gene co-expression network modules associated with human vein graft failure. However, little is known about PRG4 and the vascular system. Therefore, we have investigated the effects of recombinant human PRG4 (rhPRG4) on cell migration and proliferation in human veins.

METHODS

Effects of rhPRG4 on cell migration, proliferation, and neointima formation were determined in human venous tissue and cultured venous smooth muscle cells (SMCs), adventitial cells, and endothelial cells. Expression of PRG4 by cultured human saphenous veins, failed vein grafts, and varicose veins was determined by immunostaining or Western blotting.

RESULTS

Limited expression of PRG4 in fresh saphenous veins was dramatically increased around medial SMCs after culture ex vivo. rhPRG4 inhibited the migration of cultured SMCs, adventitial cells, and endothelial cells, as well as the proliferation of endothelial cells. rhPRG4 also inhibited the migration of SMCs and adventitial cells from tissue explants, but there was no effect on cell proliferation or neointima formation in ex vivo whole veins. Finally, PRG4 was largely absent in two examples of venous pathology, that is, failed human vein grafts and varicose veins.

CONCLUSIONS

Although rhPRG4 can inhibit the migration of venous SMCs, endothelial cells, and adventitial cells, and the proliferation of endothelial cells, PRG4 was only increased around medial SMCs in veins after ex vivo culture. PRG4 was not observed around medial SMCs in failed human vein grafts and varicose veins, suggesting the possibility that a failure of PRG4 upregulation may promote these pathologies.

Transmembrane protein 100 is expressed in neurons and glia of dorsal root ganglia and is reduced after painful nerve injury

Introduction

Tmem100 modulates interactions between TRPA1 and TRPV1. The cell specificity of Tmem100 expression in dorsal root ganglia (DRGs) is not well defined, nor is the effect of peripheral nerve injury on Tmem100 expression.

Objective

This study was designed to determine the cell specificity of Tmem100 expression in DRG and its subcellular localization, and to examine how Tmem100 expression may be altered in painful conditions.

Methods

Dorsal root ganglion Tmem100 expression was determined by immunohistochemistry, immunoblot, and quantitative real-time PCR, and compared between various experimental rat pain models and controls.

Results

Tmem100 is expressed in both neurons and perineuronal glial cells in the rat DRG. The plasma membrane and intracellular localization of Tmem100 are identified in 83% ± 6% of IB4-positive and 48% ± 6% of calcitonin gene-related peptide-positive neurons, as well as in medium- and large-sized neurons, with its immunopositivity colocalized to TRPV1 (94% ± 5%) and TRPA1 (96% ± 3%). Tmem100 is also detected in the perineuronal satellite glial cells and in some microglia. Tmem100 protein is significantly increased in the lumbar DRGs in the complete Freund adjuvant inflammatory pain. By contrast, peripheral nerve injury by spinal nerve ligation diminishes Tmem100 expression in the injured DRG, with immunoblot and immunohistochemistry experiments showing reduced Tmem100 protein levels in both neurons and satellite glial cells of DRGs proximal to injury, whereas Tmem100 is unchanged in adjacent DRGs. The spared nerve injury model also reduces Tmem100 protein in the injured DRGs.

Conclusion

Our data demonstrate a pain pathology-dependent alteration of DRG Tmem100 protein expression, upregulated during CFA inflammatory pain but downregulated during neuropathic pain.

Semaphorin-3A protects against neointimal hyperplasia after vascular injury

BACKGROUND

Neointimal hyperplasia is a prominent pathological event during in-stent restenosis. Phenotype switching of vascular smooth muscle cells (VSMCs) from a differentiated/contractile to a dedifferentiated/synthetic phenotype, accompanied by migration and proliferation of VSMCs play an important role in neointimal hyperplasia. However, the molecular mechanisms underlying phenotype switching of VSMCs have yet to be fully understood.

METHODS

The mouse carotid artery ligation model was established to evaluate Sema3A expression and its role during neointimal hyperplasia in vivo. Bioinformatics analysis, chromatin immunoprecipitation (ChIP) assays and promoter-luciferase reporter assays were used to examine regulatory mechanism of Sema3A expression. SiRNA transfection and lentivirus infection were performed to regulate Sema3A expression. EdU assays, Wound-healing scratch experiments and Transwell migration assays were used to assess VSMC proliferation and migration.

FINDINGS

In this study, we found that semaphorin-3A (Sema3A) was significantly downregulated in VSMCs during neointimal hyperplasia after vascular injury in mice and in human atherosclerotic plaques. Meanwhile, Sema3A was transcriptionally downregulated by PDGF-BB via p53 in VSMCs. Furthermore, we found that overexpression of Sema3A inhibited VSMC proliferation and migration, as well as increasing differentiated gene expression. Mechanistically, Sema3A increased the NRP1-plexin-A1 complex and decreased the NRP1-PDGFRβ complex, thus inhibiting phosphorylation of PDGFRβ. Moreover, we found that overexpression of Sema3A suppressed neointimal hyperplasia after vascular injury in vivo.

INTERPRETATION

These results suggest that local delivery of Sema3A may act as a novel therapeutic option to prevent in-stent restenosis.

Versican is differentially regulated in the adventitial and medial layers of human vein grafts

Changes in extracellular matrix proteins may contribute significantly to the adaptation of vein grafts to the arterial circulation. We examined the production and distribution of versican and hyaluronan in intact human vein rings cultured ex vivo, veins perfused ex vivo, and cultured venous adventitial and smooth muscle cells. Immunohistochemistry revealed higher levels of versican in the intima/media compared to the adventitia, and no differences in hyaluronan. In the vasa vasorum, versican and hyaluronan associated with CD34⁺ progenitor cells. Culturing the vein rings for 14 days revealed increased versican immunostaining of 30–40% in all layers, with no changes in hyaluronan. Changes in versican accumulation appear to result from increased synthesis in the intima/media and decreased degradation in the adventitia as versican transcripts were increased in the intima/media, but unchanged in the adventitia, and versikine (the ADAMTS-mediated cleavage product of versican) was increased in the intima/media, but decreased in the adventitia. In perfused human veins, versican was specifically increased in the intima/media in the presence of venous pressure, but not with arterial pressure. Unexpectedly, cultured adventitial cells express and accumulate more versican and hyaluronan than smooth muscle cells. These data demonstrate a differential regulation of versican and hyaluronan in human venous adventitia vs. intima/media and suggest distinct functions for these extracellular matrix macromolecules in these venous wall compartments during the adaptive response of vein grafts to the arterial circulation.