Effect of local anti-vascular endothelial growth factor therapy to prevent the formation of stenosis in outflow vein in arteriovenous fistula

The influence of near-infrared therapy on arteriovenous fistula patency in haemodialysis patients: A multicentre, randomised, controlled clinical trial

BACKGROUND

Arteriovenous fistula (AVF) is the preferred vascular access for patients undergoing haemodialysis (HD). AVF malfunction remains a major clinical problem and is a significant independent risk factor for death. Although far-infrared (FIR) therapy has been shown to reduce complications and improve the patency rate of AVFs in various studies, it has been cautiously recommended by the Kidney Disease Outcome Quality Initiative (KDOQI) guidelines for AVF care due to insufficient evidence. Therefore, it is necessary to identify more effective methods for preventing AVF dysfunction. Many in vitro studies and few clinical studies have examined the effects of near-infrared (NIR) therapy on the vasculature. This study will examine the effects of NIR therapy on AVF.

METHODS

A randomised, controlled, open-label, multicentre trial will compare the effect of NIR on AVF patency after 1 year of therapy with that of a control group of patients with existing AVF. One group of patients received NIR treatment above their AVFs, whereas the control group received regular care. The primary outcome is the primary fistula patency rate within 12 months. In addition, acute changes in inflammatory, vasodilatory and haemodynamic parameters after a single treatment in the first 40 participants will be examined. This study was registered in the Clinical Trials Registry (ChiCTR2300071305) at https://register.clinicaltrials.gov/.

DISCUSSIONS

This study will explore the long-term and acute effects of NIR on AVFs. The study findings will provide information that can be used to develop new technical support for the prevention of AVF dysfunction in patients undergoing haemodialysis.

Differences in vascular endothelial function and serum proteome between obese people with phlegm-dampness constitution and balanced constitution

OBJECTIVE

To evaluate the extent of vascular endothelial dysfunction and preliminary identify serum protein biomarkers associated with obese individuals at risk for cardiovascular disease (CVD).

METHODS

Fifteen obese volunteers with the phlegm-dampness constitution or balanced constitution were recruited for this study respectively. The clinical baseline data was collected, and the vascular endothelial function was evaluated using the EndoPATTM. Blood samples were collected for the serum proteome analysis. The differences in the serum protein expression levels between the two groups were detected and the protein interaction network analysis, correlation analysis, receiver operating characteristic (ROC) curve analysis, and random forest model investigation were conducted.

RESULTS

There were no statistical differences found in the baseline data. For vascular endothelial function, the reactive hyperemia index (RHI) of the phlegm-dampness constitution obese group was significantly lower than that of the balanced constitution obese group (1.46 ± 0.30 vs 2.82 ± 0.78, P < 0.0001), indicating vascular endothelial dysfunction. There are 66 differentially expressed serum proteins between the two groups. apolipoprotein A2 (ApoA2), angiotensin-converting enzyme 2 (ACE-2), interleukin-33 (IL-33), and forkhead box P3 (FoxP3) showed significant differences and area under curve values of their ROC curves were greater than 0.7 and correlated significantly with RHI.

CONCLUSION

Vascular endothelial dysfunction was present in the phlegm-dampness constitution obese group. Thus, alterations in the expression levels of key serum proteins, including ApoA2, ACE-2, IL-33, and FoxP3 could serve as potential biomarkers in the obese population at risk of CVD.

The rodent models of arteriovenous fistula

Arteriovenous fistulas (AVFs) have long been used as dialysis access in patients with end-stage renal disease; however, their maturation and long-term patency still fall short of clinical needs. Rodent models are irreplaceable to facilitate the study of mechanisms and provide reliable insights into clinical problems. The ideal rodent AVF model recapitulates the major features and pathology of human disease as closely as possible, and pre-induction of the uremic milieu is an important addition to AVF failure studies. Herein, we review different surgical methods used so far to create AVF in rodents, including surgical suturing, needle puncture, and the cuff technique. We also summarize commonly used evaluations after AVF placement. The aim was to provide recent advances and ideas for better selection and induction of rodent AVF models. At the same time, further improvements in the models and a deeper understanding of AVF failure mechanisms are expected.

The Potential Roles of CHI3L1 in Failed Autologous Arteriovenous Fistula in End-Stage Renal Disease

Autologous arteriovenous fistula (AVF) is commonly placed for hemodialysis treatment. Recent studies show that increased baseline serum level of Chitinase-3-like protein 1 (CHI3L1) is independently associated with a higher risk of the early failure of forearm AVFs. However, the changes and mechanisms of CHI3LI in local vascular tissues of failed AVF have not be revealed. This study aims to conduct the expression and mechanism of CHI3L1 in vascular tissues from patients. Immunoreactivity of CHI3L1, matrix metalloproteinase 2 (MMP-2) and vascular endothelial growth factor-A (VEGF-A) were detected in vascular tissues collected from nine patients with AVF surgery. Due to the significant stenosis clinically, six of the nine patients received arteriovenous fistula reconstruction. The expression differences of CHI3L1 between the initial vascular tissues and failed AVF are significant (P < 0.05). Failed AVF due to stenosis shows intraluminal thrombus, collagen fiber rupture, fibrous connective tissue hyperplasia, tube wall thickening, neovascularization, scattered inflammatory cell infiltration in the tunica media as well as high CHI3L1 expression level, and the expression of MMP-2 (r = 0.9022, P = 0.0139) and VEGF-A (r = 0.8355, P = 0.0393) was positively correlated with CHI3L1. CHI3L1 expression in vascular tissues possibly plays an important role in AVF failure. MMP-2 and VEGF-A may participate in venous stenosis with CHI3L1.

What Went Wrong with VEGF-A in Peripheral Arterial Disease? A Systematic Review and Biological Insights on Future Therapeutics

BACKGROUND

Of the 200 million patients worldwide affected by peripheral arterial disease (PAD), 4% will inevitably require major limb amputation. Previous systematic reviews presented a conflicting body of evidence in terms of vascular endothelial growth factor (VEGF) family member effects upon PAD natural progression. Despite that, modulation of intrinsic angiogenesis mechanisms targeting the VEGF family members still confers an attractive therapeutic target. The aim of the present study was to evaluate current evidence of VEGF modulation in the context of PAD.

METHODS

This is a systematic literature review conducted according to the PRISMA guidelines and registered under PROSPERO database [CRD42021285988]. Independent literature search was performed up to April 1, 2022, on six databases. A total of 22 eligible studies were identified [N: 3, interventional patient studies; N: 19, animal studies]. Animal studies were appraised by the SYRCLE risk of bias tool, while human participant studies were assessed by the Newcastle Ottawa scale. Overall, quality of evidence was deemed fair for both animal and human studies. Main study outcomes were percentage change of injured vessel lumen stenosis and neointimal area formation upon VEGF modulation (inhibition or activation) in comparison with control group.

FINDINGS

Nineteen animal models and three human participant studies were included in the systematic review and assessed separately. Positive modulation of VEGF-A in animal models resulted in a median decrease of 65.58% [95% CI 45.2; 71.87] in lumen stenosis [14 studies]. Furthermore, positive modulation of VEGF-A was found to reduce neointimal area proliferation by a median decrease of 63.41% [95% CI 41.6; 79.59] [14 studies]. Median end of study duration was 28 days [range: 14-84 days]. Data were insufficient to assess these outcomes with respect to VEGF-B or VEGF-C modulation. The limited number of available human studies presented inadequate outcome assessment despite their overall fair NOS grading.

INTERPRETATION

VEGF-A-positive modulation decreases lumen stenosis and neointimal hyperplasia in PAD simulation animal models. Previously identified variability among outcomes was found to strongly stem from the variability of experimental designs. Clinical applicability and safety profile of VEGF-A in the context of PAD remain to be defined by a robust and uniformly designed body of further animal model-based experiments.

Oxidative stress: An essential factor in the process of arteriovenous fistula failure

For more than half a century, arteriovenous fistula (AVFs) has been recognized as a lifeline for patients requiring hemodialysis (HD). With its higher long-term patency rate and lower probability of complications, AVF is strongly recommended by guidelines in different areas as the first choice for vascular access for HD patients, and its proportion of application is gradually increasing. Despite technological improvements and advances in the standards of postoperative care, many deficiencies are still encountered in the use of AVF related to its high incidence of failure due to unsuccessful maturation to adequately support HD and the development of neointimal hyperplasia (NIH), which narrows the AVF lumen. AVF failure is linked to the activation and migration of vascular cells and the remodeling of the extracellular matrix, where complex interactions between cytokines, adhesion molecules, and inflammatory mediators lead to poor adaptive remodeling. Oxidative stress also plays a vital role in AVF failure, and a growing amount of data suggest a link between AVF failure and oxidative stress. In this review, we summarize the present understanding of the pathophysiology of AVF failure. Furthermore, we focus on the relation between oxidative stress and AVF dysfunction. Finally, we discuss potential therapies for addressing AVF failure based on targeting oxidative stress.

Transcriptional and Epigenetic Factors Associated with Early Thrombosis of Femoral Artery Involved in Arteriovenous Fistula

Arteriovenous fistulas (AVFs), created for hemodialysis in end-stage renal disease patients, mature through the outward remodeling of the outflow vein. However, early thrombosis and chronic inflammation are detrimental to the process of AVF maturation and precipitate AVF maturation failure. For the successful remodeling of the outflow vein, blood flow through the fistula is essential, but early arterial thrombosis attenuates this blood flow, and the vessels become thrombosed and stenosed, leading to AVF failure. The altered expression of various proteins involved in maintaining vessel patency or thrombosis is regulated by genes of which the expression is regulated by transcription factors and microRNAs. In this study, using thrombosed and stenosed arteries following AVF creation, we delineated transcription factors and microRNAs associated with differentially expressed genes in bulk RNA sequencing data using upstream and causal network analysis. We observed changes in many transcription factors and microRNAs that are involved in angiogenesis; vascular smooth muscle cell proliferation, migration, and phenotypic changes; endothelial cell function; hypoxia; oxidative stress; vessel remodeling; immune responses; and inflammation. These factors and microRNAs play a critical role in the underlying molecular mechanisms in AVF maturation. We also observed epigenetic factors involved in gene regulation associated with these molecular mechanisms. The results of this study indicate the importance of investigating the transcriptional and epigenetic regulation of AVF maturation and maturation failure and targeting factors precipitating early thrombosis and stenosis.