Association of Circulating Transforming Growth Factor beta, Tumor Necrosis Factor alpha and Basic Fibroblast Growth Factor with Restenosis after Transluminal Angioplasty

Society for Vascular Surgery Clinical Practice Guideline on the management of intermittent claudication: Focused update

Intermittent claudication (IC) is the most common symptom of peripheral artery disease, which is a growing public health burden in the United States and globally. Patients with IC present with a broad spectrum of risk factors, comorbid conditions, range of disability, and treatment goals. Informed shared decision-making hinges on a comprehensive evaluation of these factors, patient education, and knowledge of the latest available evidence. In 2015, the Society for Vascular Surgery published a clinical practice guideline on the management of asymptomatic peripheral artery disease and IC. An expert writing group was commissioned to provide a focused update to this guideline on the management of IC. Based on the available evidence from published research conducted since the prior guideline, six specific key questions were formulated spanning the areas of antithrombotic management, exercise therapy, and revascularization for IC. A systematic review and evidence synthesis of each question was conducted by a dedicated methodology team. The GRADE approach was employed to describe the strength of each recommendation and level of certainty of evidence. The review identified major gaps in evidence particularly in the arena of comparative effectiveness for interventions (exercise, revascularization) across defined clinical subgroups and employing meaningful patient-centered outcomes. Twelve recommendations, among which are two best practice statements, are provided in this focused update. They address the use of dual pathway antithrombotic strategies, the role and type of exercise therapy, endovascular interventions for femoropopliteal and infrapopliteal disease, and the identification of specific risk factors that should be incorporated into shared decision-making around revascularization. A comprehensive and individualized approach to the management of patients with IC, relying first on education, risk factor control, optimal medical therapy, and exercise, is emphasized. A rubric for decision-making that includes a thorough assessment of risk, benefits, degree of impairment, and treatment durability, is considered fundamental to a patient-centered approach in IC. Significant unmet research needs in this field are also enumerated.

A systematic review supporting the Society for Vascular Surgery guideline update on the management of intermittent claudication

OBJECTIVE

This systematic review and meta-analysis evaluates the current evidence on the management of intermittent claudication (IC), a prevalent manifestation of peripheral arterial disease (PAD).

METHODS

We conducted comprehensive searches of MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Scopus. We addressed six questions developed by a guideline committee from the Society for Vascular Surgery, addressing pharmacological treatments, exercise regimens, endovascular interventions, and predictors of major adverse cardiovascular, limb-related events, and mortality.

RESULTS

The search resulted in 5333 citations, from which we included 73 studies (46 randomized trials). In patients with PAD and IC who had one or more high-risk comorbidities, low-dose rivaroxaban and aspirin were associated with lower risk of major adverse limb events and major adverse cardiovascular events than aspirin alone. In patients who have undergone surgical or endovascular interventions for PAD, the addition of low-dose rivaroxaban to aspirin may improve limb outcomes. Of note, rivaroxaban trials excluded patients at high risk of bleeding. Single antiplatelet agents showed no significant efficacy differences head-to-head in ambulatory patients with IC and had a lower bleeding risk compared with combination therapy or anticoagulation. Home exercise programs were feasible and may be an alternative to supervised exercise in ambulatory patients with IC and in those who had revascularization. Several comorbidities increased the risk of adverse outcomes after revascularization for IC, such as advanced age, diabetes, coronary artery disease, chronic obstructive pulmonary disease, previous interventions, congestive heart failure, infrapopliteal artery involvement, and longer lesion lengths. In patients with IC undergoing endovascular intervention for superficial femoral artery disease, plain balloon angioplasty was associated with worse outcomes than drug elution or stent implantation for intermediate or longer lesions (ie, >5 cm).

CONCLUSIONS

This systematic review summarizes the current evidence base for the management of IC, offering insights into the relative benefits and risks of various therapeutic strategies. The findings underscore the need for individualized patient care, considering both the potential benefits and risks associated with different interventions.

Multiscale, patient-specific computational fluid dynamics models predict formation of neointimal hyperplasia in saphenous vein grafts

Stenosis due to neointimal hyperplasia (NIH) is among the major causes of peripheral graft failure. Its link to abnormal hemodynamics in the graft is complex, and isolated use of hemodynamic markers is insufficient to fully capture its progression. Here, a computational model of NIH growth is presented, establishing a link between computational fluid dynamics simulations of flow in the lumen and a biochemical model representing NIH growth mechanisms inside the vessel wall. For all three patients analyzed, NIH at proximal and distal anastomoses was simulated by the model, with values of stenosis comparable to the computed tomography scans.

Transforming Growth Factor-β Protects against Inflammation-Related Atherosclerosis in South African CKD Patients

Background

Transforming growth factor-β (TGF-β) may inhibit the development of atherosclerosis. We evaluated serum levels of TGF-β isoforms concurrently with serum levels of endotoxin and various inflammatory markers. In addition, we determined if any association exists between polymorphisms in the TGF-β1 gene and atherosclerosis in South African CKD patients.

Methods

We studied 120 CKD patients and 40 healthy controls. Serum TGF-β1, TGF-β2, TGF-β3, endotoxin, and inflammatory markers were measured. Functional polymorphisms in the TGF-β1 genes were genotyped using a polymerase chain reaction-sequence specific primer method and carotid intima media thickness (CIMT) was assessed by B-mode ultrasonography.

Results

TGF-β isoforms levels were significantly lower in the patients with atherosclerosis compared to patients without atherosclerosis (p<0.001). Overall, TGF-β isoforms had inverse relationships with CIMT. TGF-β1 and TGF-β2 levels were significantly lower in patients with carotid plaque compared to those without carotid plaque [TGF-β1: 31.9 (17.2 – 42.2) versus 45.9 (35.4 – 58.1) ng/ml, p=0.016; and TGF-β2: 1.46 (1.30 – 1.57) versus 1.70 (1.50 – 1.87) ng/ml, p=0.013]. In multiple logistic regression, age, TGF-β2, and TGF-β3 were the only independent predictors of subclinical atherosclerosis in CKD patients [age: odds ratio (OR), 1.054; 95% confidence interval (CI): 1.003 – 1.109, p=0.039; TGF-β2: OR, 0.996; 95% CI: 0.994–0.999, p=0.018; TGF-β3: OR, 0.992; 95% CI: 0.985–0.999, p=0.029). TGF-β1 genotypes did not influence serum levels of TGF-β1 and no association was found between the TGF-β1 gene polymorphisms and atherosclerosis risk.

Conclusion

TGF-β isoforms seem to offer protection against the development of atherosclerosis among South African CKD patients.

Patient-Specific, Multi-Scale Modeling of Neointimal Hyperplasia in Vein Grafts

Neointimal hyperplasia is amongst the major causes of failure of bypass grafts. The disease progression varies from patient to patient due to a range of different factors. In this paper, a mathematical model will be used to understand neointimal hyperplasia in individual patients, combining information from biological experiments and patient-specific data to analyze some aspects of the disease, particularly with regard to mechanical stimuli due to shear stresses on the vessel wall. By combining a biochemical model of cell growth and a patient-specific computational fluid dynamics analysis of blood flow in the lumen, remodeling of the blood vessel is studied by means of a novel computational framework. The framework was used to analyze two vein graft bypasses from one patient: a femoro-popliteal and a femoro-distal bypass. The remodeling of the vessel wall and analysis of the flow for each case was then compared to clinical data and discussed as a potential tool for a better understanding of the disease. Simulation results from this first computational approach showed an overall agreement on the locations of hyperplasia in these patients and demonstrated the potential of using new integrative modeling tools to understand disease progression.

Magnetic nanosphere-guided site-specific delivery of vascular endothelial growth factor gene attenuates restenosis in rabbit balloon-injured artery

OBJECTIVE

New and efficient strategies to protect endothelium or to enhance endothelial regrowth are important for treatment of restenosis after percutaneous transluminal angioplasty. Magnetic DNA microspheres are used to accelerate vascular endothelial growth factor (VEGF) re-endothelialization and to attenuate intimal hyperplasia in balloon-injured artery. This study aimed to assess DNA-gelatin magnetic nanospheres containing VEGF expression plasmids in vascular restenosis attenuation.

METHODS

Ninety-six rabbits underwent balloon injury and were randomly divided for gene transfer with naked VEGF plasmids (NAK group), magnetic VEGF microspheres (MIC group), and LacZ (CON group: naked LacZ plasmid and LacZ nanosphere subgroups). Serum and tissue VEGF levels were measured. Also, the ratios of intima area to media area were determined to assess neointima formation.

RESULTS

Microsphere gene delivery through the artery by a magnet resulted in VEGF overexpression in transfected arterial segments. Tissue VEGF integral optical densities were significantly increased in MIC rabbits compared with NAK animals. Serum VEGF was below detection in all animals. X-Gal staining showed higher transfection efficiency in the CON group. The impact of neointimal thickening was evaluated by light microscopy as the ratio of intima area to media area in cross sections. Significant differences in the ratio of intima area to media area were obtained between the NAK group (0.12 ± 0.02, 0.41 ± 0.03, 0.61 ± 0.05, and 0.72 ± 0.04 at 1, 2, 3, and 4 weeks, respectively) and the MIC group (0.06 ± 0.03, 0.20 ± 0.05, 0.25 ± 0.04, and 0.26 ± 0.03 at 1, 2, 3, and 4 weeks, respectively) at 2, 3, and 4 weeks (P < .05).

CONCLUSIONS

Intra-arterial VEGF gene delivery by magnetic microspheres significantly increased DNA stability, transfection efficiency, and targeting specificity, resulting in exogenous VEGF overexpression and attenuated intimal hyperplasia in balloon-injured artery.

An agent-based model of the response to angioplasty and bare-metal stent deployment in an atherosclerotic blood vessel

PURPOSE

While animal models are widely used to investigate the development of restenosis in blood vessels following an intervention, computational models offer another means for investigating this phenomenon. A computational model of the response of a treated vessel would allow investigators to assess the effects of altering certain vessel- and stent-related variables. The authors aimed to develop a novel computational model of restenosis development following an angioplasty and bare-metal stent implantation in an atherosclerotic vessel using agent-based modeling techniques. The presented model is intended to demonstrate the body's response to the intervention and to explore how different vessel geometries or stent arrangements may affect restenosis development.

METHODS

The model was created on a two-dimensional grid space. It utilizes the post-procedural vessel lumen diameter and stent information as its input parameters. The simulation starting point of the model is an atherosclerotic vessel after an angioplasty and stent implantation procedure. The model subsequently generates the final lumen diameter, percent change in lumen cross-sectional area, time to lumen diameter stabilization, and local concentrations of inflammatory cytokines upon simulation completion. Simulation results were directly compared with the results from serial imaging studies and cytokine levels studies in atherosclerotic patients from the relevant literature.

RESULTS

The final lumen diameter results were all within one standard deviation of the mean lumen diameters reported in the comparison studies. The overlapping-stent simulations yielded results that matched published trends. The cytokine levels remained within the range of physiological levels throughout the simulations.

CONCLUSION

We developed a novel computational model that successfully simulated the development of restenosis in a blood vessel following an angioplasty and bare-metal stent deployment based on the characteristics of the vessel cross-section and stent. A further development of this model could ultimately be used as a predictive tool to depict patient outcomes and inform treatment options.

Role of TGF-β1/Smad3 signaling pathway in secretion of type I and III collagen by vascular smooth muscle cells of rats undergoing balloon injury

Antisense Smad3 adenoviral vectors were used to transfect vascular smooth muscle cells (VSMCs) from rats with balloon injury or infused into the rat balloon-catheter injured carotid arteries, and the role of TGF-β1/Smad3 signaling pathway in the secretion of type I and III collagen by VSMCs following balloon injury was investigated. Antisense Smad3 adenoviral vectors were used to transfect these VSMCs (antisense Smad3 group). A total 90 rats were randomly assigned into blank control group, experiment group, negative control group. In the in vitro study, the expression of type I and III collagen was markedly reduced in the antisense Smad3 group when compared with the control groups (P < 0.05). In the in vivo study, the expression of type I and III collagen was significantly lower than that in the negative control group at 3 days, 1 week and 2 weeks after injury (P < 0.05). At 2 weeks and 3 months after injury, the lumen area in the antisense Smad3 group was markedly increased but the intimal area dramatically reduced when compared with the negative control (P < 0.05). We conclude that transfection of VSMCs with antisense Smad3 can reduce the secretion of type I and III collagen which then inhibit intimal hyperplasia.

Proteins mediating collagen biosynthesis and accumulation in arterial repair: novel targets for anti-restenosis therapy

Events contributing to restenosis after coronary interventions include platelet aggregation, inflammatory cell infiltration, growth factor release, and accumulation of smooth muscle cells (SMCs) and extracellular matrix (ECM). The ECM is composed of various collagen subtypes and proteoglycans and over time constitutes the major component of the mature restenotic plaque. The pathophysiology of collagen accumulation in the ECM during arterial restenosis is reviewed. Factors regulating collagen synthesis and degradation, including various cytokines and growth factors involved in the process, may be targets for therapies aimed at prevention of in-stent restenosis.

Transforming Growth Factor-β1 as a Common Target Molecule for Development of Cardiovascular Diseases, Renal Insufficiency and Metabolic Syndrome

Transforming growth factor-β1 (TGF-β1) is a polypeptide member of the transforming growth factor β superfamily of cytokines. It is a secreted protein that performs many cellular functions including control of cell growth, cell proliferation, cell differentiation and apoptosis. In the cardiovascular system, TGF-β1 plays pivotal roles in the pathogenesis of hypertension, restenosis after percutaneous coronary intervention, atherosclerosis, cardiac hypertrophy and heart failure. In addition, TGF-β1 has been shown to be increased in adipose tissue of obese subjects with insulin resistance. Furthermore, TGF-β1 is a potent initiator of proliferation of renal mesangial cells leading to chronic kidney disease. Some currently available agents can manipulate TGF-β1 expression leading to amelioration of cardiovascular diseases. Thus, an understanding of interactions between chronic kidney disease and metabolic syndrome and the development of cardiovascular diseases is an important issue, and attention should be given to TGF-β1 as a crucial factor for regulation and modulation of those pathological conditions.

Effect of percutaneous transluminal angioplasty on tissue oxygenation in ischemic diabetic feet

Percutaneous transluminal angioplasty (PTA) has been performed as an alternative to bypass surgery for improving tissue oxygenation in ischemic diabetic feet because the former is less invasive than the latter. The purpose of this study was to evaluate the effect of PTA on tissue oxygenation in ischemic diabetic feet. This study included 29 ischemic diabetic feet, as determined by a transcutaneous oxygen pressure (TcPO(2) )<30 mmHg. The PTA was carried out in 29 limbs. The PTA procedure was considered successful, acceptable, and failed when residual stenosis was<30%, between 30 and 50%, and>50%, respectively. For evaluation of tissue oxygenation, the foot TcPO(2) was measured before PTA and weekly for 6 weeks after PTA. Immediately after PTA, 26 feet were evaluated as being successful and the remaining three as acceptable. Before PTA, the average foot TcPO(2) was 12.7 ± 8.9 mmHg. The TcPO(2) values were increased to 43.6 ± 24.1, 51.0 ± 22.6, 58.3 ± 23.0, 61.3 ± 24.2, 59.0 ± 22.2, and 53.8 ± 21.0 mmHg 1, 2, 3, 4, 5, and 6 weeks after PTA, respectively (p<0.01). The PTA procedure significantly increases tissue oxygenation in ischemic diabetic feet. The maximal level of tissue oxygenation was measured on the fourth week following PTA.

Role of transforming growth factor-beta superfamily signaling pathways in human disease

Transforming growth factor beta (TGF-beta) superfamily signaling pathways are ubiquitous and essential regulators of cellular processes including proliferation, differentiation, migration, and survival, as well as physiological processes, including embryonic development, angiogenesis, and wound healing. Alterations in these pathways, including either germ-line or somatic mutations or alterations in the expression of members of these signaling pathways often result in human disease. Appropriate regulation of these pathways is required at all levels, particularly at the ligand level, with either a deficiency or an excess of specific TGF-beta superfamily ligands resulting in human disease. TGF-beta superfamily ligands and members of these TGF-beta superfamily signaling pathways also have emerging roles as diagnostic, prognostic or predictive markers for human disease. Ongoing studies will enable targeting of TGF-beta superfamily signaling pathways for the chemoprevention and treatment of human disease.