Transcriptomic profiling of radiopaque nanoparticle-loaded, bioresorbable polymeric perivascular wrap for arteriovenous fistula maturation.

Genetic deficiency of heme oxygenase-1 impairs functionality and form of an arteriovenous fistula in the mouse

Hemodialysis therapy for end-stage kidney disease (ESKD) requires suitable vascular access, most commonly the arteriovenous fistula (AVF). Forty percent of AVFs fail within one year, leading to morbidity and care costs. Failure mechanisms remain unclear and current therapies are inadequate. Cellular senescence may be critical in AVF failure, and ESKD itself may accelerate senescence and subsequent vascular dysfunction. Senescence follows AVF placement in rodents with normal kidney function, but the temporal and spatial features in uremic conditions are unknown. This study aimed to characterize AVF changes in uremic mice over time and versus control vessels. Six- to eight-week-old male C57BL6/J mice underwent 5/6 nephrectomy. Twenty-eight days later an AVF was created by cuff anastomosis (right carotid artery to the right jugular vein). Transcriptomic analysis was performed seven days post-AVF, and further samples were collected at fourteen and twenty-eight days post-AVF creation for histological assessment. AVF outflow vein morphometry showed reduced neointimal cell density. Whole transcriptomic analysis of outflow vs control veins at seven days post-AVF placement revealed 1187 upregulated and 3256 downregulated genes. Differentially expressed genes were significantly enriched in two established senescence related gene sets, SenMayo (a curated panel of ∼125 genes validated across species to capture senescence and associated proteins) and SenSig (a broader panel assessed to represent fibrotic and stress induced cell response). Histologically, senescence markers p16, p21, and phospho53 increased between day 14 and 28. Genes common to our dataset, SenMayo, and SenSig were validated with qPCR. These data support established markers of AVF failure like matrix-metalloproteinases and monocyte chemokines and identify potential novel modulators of AVF survival that may inform senolytic strategies to improve patency. In summary, this study reveals for the first time the chronological progression of vascular senescence in the AVF of uremic mice.

Introduction: Arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis; however, it has a primary failure rate of 20%–60%. Analyzing the factors associated with AVF failure is crucial for planning appropriate management strategies. Objectives: We aimed to identify the AVF outcomes and associated factors along with the role of duplex ultrasound (DUS) in preoperative and postoperative AVF assessment at a tertiary care hospital. Patients and Methods: This prospective observational study was conducted on pre-dialysis patients who underwent AVF creation between January 2020 and December 2021.AVF outcomes and associated clinical and vascular factors were analyzed using pre- and post-operative DUS. Results: Of 171 patients, males were predominant (83.6%), and diabetic nephropathy (42.7%) was the predominant cause of chronic kidney disease (CKD). AVF outcomes showed, 109 (63.7%) had unassisted mature AVF and 29 (16.9%) had AVF failure wherein early dialysis suitability failure was predominant (17; 9.94%). Among clinical factors, only a history of smoking correlated with AVF failure (P=0.04). On pre-and post-operative DUS assessment, the absence of distensibility and immediate post-operative vein diameter strongly correlated with AVF failure (P<0.001). A unit increase (1 mm) in outflow vein diameter immediately after surgery emerged as an independent predictor of AVF outcome in both univariate (OR 0.98, 95% CI: 0.35-3.99; P<0.001) and multivariate analysis (OR: 0.313, 95% CI: 0.148-0.663; P<0.001). Conclusion: Most patients in our setting had unassisted AVF fistula. We additionally found that smoking correlated with AVF failure. Predominant factors determining AVF success were cephalic vein diameter, distensibility, and increase in draining vein diameter and flow volume at six weeks. This study highlights using DUS in pre- and post-operative periods, along with conventional examination to improve AVF outcomes.

Introduction Thrombosis of fistula occurs most frequently in end-stage kidney disease (ESKD) patients receiving hemodialysis. However, the role of thrombophilia in arteriovenous fistula (AVF) failure has not been well established. Hence, this study was aimed at assessing the roles of hereditary and acquired thrombophilic factors in association with AVF failure among patients with ESKD undergoing hemodialysis. Methods A cross-sectional study was conducted on 100 ESKD patients, of whom 50 patients with well-functioning AVFs with no fistula failures earlier were enrolled as Group 1, and 50 patients who have had AVF failure were enrolled as Group 2. The hereditary factors as factor V Leiden, factor XIII, prothrombin, and methylene tetrahydrofolate reductase and the acquired factors as lipoprotein (a), fibrinogen, homocysteine, and anticardiolipin antibodies IgG and IgM were studied. Results Among the hereditary factors, no statistically significant difference was observed in relation to factor V Leiden and Prothrombin (p > 0.05). However, for factor XIII and methylene tetrahydrofolate reductase, a statistically significant difference was observed between patients with well-functioning AVFs and patients who have had AVF failure (p < 0.05). We found a statistically significant increase in all the acquired factors in patients who have had AVF failure in comparison with patients with well-functioning AVFs (p < 0.001). Association between ABO blood groups and thrombophilic factors showed significant association between factor V Leiden, anticardiolipin antibody IgG and IgM and ABO blood groups (p < 0.05), whereas none of the other thrombophilic factors showed significant association (p > 0.05). Conclusion Thus, our study suggests significant role of acquired factors in causing AVF failure.

Patients with end-stage renal failure need arteriovenous fistulas (AVF) to undergo dialysis. However, AVFs present a high rate of failure as a result of excessive venous thickness. Excessive venous thickness may be a consequence of surgical dissection and change in oxygen concentration within the venous wall. We show that venous cells adapt their metabolism and growth depending on oxygen concentration, and drugs targeting the hypoxic response pathway modulate this response in vitro. We used the same drugs on a mouse model of AVF and show that direct or indirect inhibition of the hypoxia-inducible factors (HIFs) help decrease excessive venous thickness. Hypoxia and HIFs can be targets of therapeutic drugs to prevent excessive venous thickness in patients undergoing AVF surgical creation. Because the oxygen concentration changes in the venous wall, surrounding tissue and the blood during surgical creation of arteriovenous fistula (AVF), we hypothesized that hypoxia could contribute to AVF failure as a result of neointimal hyperplasia. We postulated that modulation of the hypoxia-inducible factors (HIF) with pharmacological compounds could promote AVF maturation. Fibroblasts [normal human fibroblasts (NHF)], smooth muscle cells [human umbilical vein smooth muscle cells (HUVSMC)] and endothelial cells [human umbilical vein endothelial cells (HUVEC)], representing the three layers of the venous wall, were tested in vitro for proliferation, cell death, metabolism, reactive oxygen species production and migration after silencing of HIF1/2-α or after treatment with deferioxamine (DFO), everolimus (Eve), metformin (Met), N-acetyl-l-cysteine (NAC) and topoisomerase I (TOPO), which modulate HIF-α stability or activity. Compounds that were considered to most probably modify intimal hyperplasia were applied locally to the vessels in a mouse model of aortocaval fistula. We showed, in vitro, that NHF and HUVSMC can adapt their metabolism and thus their growth depending on oxygen concentration, whereas HUVEC appears to be less flexible. siHIF1/2α, DFO, Eve, Met, NAC and TOPO can modulate metabolism and proliferation depending on the cell type and the oxygen concentration. In vivo, siHIF1/2α, Eve and TOPO decreased neointimal hyperplasia by 32%-50%, 7 days after treatment. Within the vascular wall, hypoxia and HIF-1/2 mediate early failure of AVF. Local delivery of drugs targeting HIF-1/2 could inhibit neointimal hyperplasia in a mouse model of AVF. Such compounds may be delivered during the surgical procedure for AVF creation to prevent early AVF failure.

BackgroundThe incidence of chronic kidney disease (CKD) and end-stage kidney disease (ESKD) is increasing worldwide. Hemodialysis (HD) is the mainstay of renal replacement therapy for patients with ESKD. Risk factors associated with late arteriovenous fistula (AVF) failure in HD patients are poorly investigated. Therefore, the aim of this study was to identify factors associated with late AVF failure in HD patients.MethodsPatients with end-stage renal disease (ESRD) who underwent forearm or upper arm AVF angioplasty at Second Affiliated Hospital of Chongqing Medical University between September 2009 and August 2018 were included. Patients were followed up for 36 months. Baseline characteristics were collected using electronic medical records (EMRs). Variables associated with late AVF failure were identified using Cox proportional hazards models.ResultsThere were 137 patients (64% male, 36% female) included in this study, with 50 (36.5%) experiencing AVF failure. Univariable log-rank analysis showed that age, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), intact parathyroid hormone (iPTH), albumin (ALB), and AVF patency rate were significantly different between patients who did and did not experience AVF failure. Cox regression analysis showed that CRP [P=0.002, hazard ratio (HR) =2.719, 95% confidence interval (CI) for HR: 1.432–5.164], ESR (P=0.030, HR =2.431, 95% CI: 1.088–5.434), iPTH (P=0.013, HR =0.325, 95% CI: 0.133–0.793), and ALB (P=0.040, HR =0.539, 95% CI: 0.299–0.972) were independently associated with AVF failure. Kaplan-Meier survival analysis showed that the cumulative patency rates of AVF at 6, 12, 18, 24, 30, and 36 months were 84%, 74%, 69%, 64%, 64%, and 64%, respectively.ConclusionsCRP, ESR, iPTH, and ALB were associated with AVF failure and should be used as reference in clinical practice.

In the context of arteriovenous fistula (AVF) failure, local delivery enables the release of higher concentrations of drugs that can suppress neointimal hyperplasia (NIH) while reducing systemic adverse effects. However, the radiolucency of polymeric delivery systems hinders long-term in vivo surveillance of safety and efficacy. We hypothesize that using a radiopaque perivascular wrap to deliver anti-NIH drugs could enhance AVF maturation. Through electrospinning, we fabricated multifunctional perivascular polycaprolactone (PCL) wraps loaded with bismuth nanoparticles (BiNPs) for enhanced radiologic visibility and drugs that can attenuate NIH─rosuvastatin (Rosu) and rapamycin (Rapa). The following groups were tested on the AVFs of a total of 24 Sprague-Dawley rats with induced chronic kidney disease: control (i.e., without wrap), PCL-Bi (i.e., wrap with BiNPs), PCL-Bi-Rosu, and PCL-Bi-Rapa. We found that BiNPs significantly improved the wraps' radiopacity without affecting biocompatibility. The drug release profiles of Rosu (hydrophilic drug) and Rapa (hydrophobic drug) differed significantly. Rosu demonstrated a burst release followed by gradual tapering over 8 weeks, while Rapa demonstrated a gradual release similar to that of the hydrophobic BiNPs. In vivo investigations revealed that both drug-loaded wraps can reduce vascular stenosis on ultrasonography and histomorphometry, as well as reduce [18F]Fluorodeoxyglucose uptake on positron emission tomography. Immunohistochemical studies revealed that PCL-Bi-Rosu primarily attenuated endothelial dysfunction and hypoxia in the neointimal layer, while PCL-Bi-Rapa modulated hypoxia, inflammation, and cellular proliferation across the whole outflow vein. In summary, the controlled delivery of drugs with different properties and mechanisms of action against NIH through a multifunctional, radiopaque perivascular wrap can improve imaging and histologic parameters of AVF maturation.

Arteriovenous fistula (AVF) failure can occur in patients undergoing hemodialysis (HD). In this study, we explored the correlation between hyperlipidemia and AVF failure in patients undergoing HD. Moreover, we compared the lipid profiles of patients with chronic kidney disease (CKD) with those of healthy people to provide a basis for lipid-lowering in patients undergoing HD. We searched PubMed, Web of Science, Embase, the Cochrane library, CNKI, CBM, the China Science Periodical Database, and the China Science and Technology Journal Database. The final search was conducted on August 31, 2021, and the search period was restricted between 2000 and August 31, 2021, without publication restrictions. All studies met the inclusion criteria, and the influences of sex, age, geographical location, diagnosis method, and publication year were excluded. The data were analyzed using the random-effects model and the fixed-effects model. Twenty-eight studies were included in the meta-analysis with 121,666 patients in the CKD group and 1714 patients in the AVF failure group. Triglyceride concentration in patients with CKD was higher than in healthy subjects (MD: -31.56, 95% CI: -41.23 to -21.90, p < 0.00001). A high total cholesterol (TC) concentration (MD: 6.97, 95% CI: 2.19-11.74, p = 0.004) and a high low-density lipoprotein cholesterol (LDL-C) concentration (MD: 23.83, 95% CI: 18.48-29.18, p < 0.00001) were associated with AVF failure. Furthermore, HDL-C was lower in the AVF failure group than in the AVF patency group (MD: -2.68, 95% CI: -4.60 to -0.76, p = 0.006). Our analysis indicates that the AVF failure may be related to the increase of TC/LDL-C and the decrease of HDL-C. Although current guidelines do not consider intensive lipid-lowering therapy as necessary in patients undergoing HD, our research indicates that patients with AVF undergoing HD may need regular TC/LDL-C-lowering therapy to prevent AVF failure. However, this issue still needs well designed prospective trials.

Increased Expression of HIF-1α, VEGF-A and Its Receptors, MMP-2, TIMP-1, and ADAMTS-1 at the Venous Stenosis of Arteriovenous Fistula in a Mouse Model with Renal Insufficiency

Bismuth-infused perivascular wrap facilitates delivery of mesenchymal stem cells and attenuation of neointimal hyperplasia in rat arteriovenous fistulas

Introduction: Chronic kidney disease (CKD) is a global public health problem with increasing prevalence and incidence and poor prognosis. As a result, more patients will be in terminal stage kidney failure and require placement of vascular access for hemodialysis. Mature and functional arteriovenous fistula (AVF) is considered the best modality for access to hemodialysis. This study aims to examine the CAVeA2T2 scores in predicting failure of arteriovenous fistula radiocephalic, significant factors related to failure of arteriovenous fistula so that it can be used to predict failure using a scoring system to predict primary failure and secondary failure fistula.Methods: A cross-sectional study was carried out at Sanglah Hospital, Bali, Indonesia, during the study period. This study using diagnostic test evaluation method using ROC curve analysis on months 1 and 3, a total of 50 populations obtained using Purposive sampling quota period April 2018 - December 2018 and failure of Hemodialysis as gold standard. Data were analyzed using Stata version 12 for Windows.Results: Results of the CAVeA2T2 score where the maximum score of 7 was analyzed using the ROC curve, the cutoff point was obtained at month 1 ≥5 with AUC 0.8987 and at 3 months ≥ 4 with AUC 0.3966 sensitivity and specificity CAVeA2T2 score of 91.3% and 75% in month 1, in the 3rd month 85.7% and 87.5% were obtained.Conclusion: Sensitivity and specificity values that provide a good value so that the CAVeA2T2 score can be used to predict failure of arteriovenous radiocephalic fistulas.

Bioresorbable perivascular scaffolds loaded with antiproliferative agents have been shown to enhance arteriovenous fistula (AVF) maturation by inhibiting neointimal hyperplasia (NIH). These scaffolds, which can mimic the three-dimensional architecture of the vascular extracellular matrix, also have an untapped potential for the local delivery of cell therapies against NIH. Hence, an electrospun perivascular scaffold from polycaprolactone (PCL) to support mesenchymal stem cell (MSC) attachment and gradual elution at the AVF's outflow vein is fabricated. Chronic kidney disease (CKD) in Sprague-Dawley rats is induced by performing 5/6th nephrectomy, then AVFs for scaffold application are created. The following groups of CKD rats are compared: no perivascular scaffold (i.e., control), PCL alone, and PCL+MSC scaffold. PCL and PCL+MSC significantly improve ultrasonographic (i.e., luminal diameter, wall-to-lumen ratio, and flow rate) and histologic (i.e., neointima-to-lumen ratio, neointima-to-media ratio) parameters compared to control, with PCL+MSC demonstrating further improvement in these parameters compared to PCL alone. Moreover, only PCL+MSC significantly reduces 18 F-fluorodeoxyglucose uptake on positron emission tomography. These findings suggest that adding MSCs promotes greater luminal expansion and potentially reduces the inflammatory process underlying NIH. The results demonstrate the utility of mechanical support loaded with MSCs at the outflow vein immediately after AVF formation to support maturation by minimizing NIH.

Introduction: The arteriovenous fistula (AVF) is the lifeline for patients with end-stage kidney disease (ESKD) requiring hemodialysis therapy. The mechanism of “arterialization”, by which a vein transforms into an AVF after anastomosis, is one of the most understudied transformative processes in vascular biology despite the urgent need for new interventions to facilitate and accelerate fistula usability to improve the life of these patients. Hypothesis: Dysregulation of type VIII collagen biosynthesis increases the risk for failure in newly created AVFs Methods and Results: We first deciphered the transcriptional transformation of the pre-access vein after arterial anastomosis using paired venous samples from 38 CKD patients undergoing surgeries for two-stage AVF creation. A total of 3,637 transcripts were differentially expressed (DE) between veins and AVFs in pairwise analyses (log2FC ≥ 1 or ≤ -1, FDR &lt;0.05). Gene set enrichment analyses revealed transcriptional activation of genes related to vasculature development, ECM remodeling, SMC migration, and endothelial cell (EC) proliferation and migration. Two hundred and eighty-four DE transcripts belonged to the matrisome family of genes. These included 20 collagens, 52 ECM glycoproteins, 10 proteoglycans, 58 ECM regulators, 27 ECM-affiliated proteins, 26 proteoglycan biosynthetic/modifying enzymes, and 91 secreted factors. Next, we sought to identify the changes in gene expression during the vein to AVF transformation that were relevant to maturation failure. Pairwise differential gene expression analyses conditional to outcome identified 102 DEGs in association with AVF failure (log2FC ≥ 1 or ≤ -1, FDR &lt;0.05). Eight genes in this group increased more in AVFs that failed compared to those that matured. Accumulation of COL8A1 was confirmed around medial SMC by IHC. This finding was further validated using an independent tissue cohort, which demonstrated significantly higher collagen VIII deposition in stenotic areas from resected AVF fragments compared to adjacent non-stenotic tissues. Conclusions: Vascular accumulation of type VIII collagen in the AVF wall after anastomosis strongly increases the risk of failure.

Arteriovenous fistula (AVF) is vascular access created for hemodialysis in end-stage renal disease patients. AVF creation causes increased blood flow in the outflow vein with increased pressure. Increased blood flow, blood volume, and shear stress causes outward remodeling so that the outflow vein can withstand the increased pressure. Outward remodeling of the vein involved in AVF is necessary for AVF maturation, however, inward remodeling due to excessive neointimal hyperplasia (NIH) and chronic inflammation may end up with vessel thrombosis and AVF maturation failure. Early thrombosis of the vessel may be due to the luminal factors including NIH and chronic inflammation or due to chronic inflammation of the adventitial due to perivascular cuffing. Inflammation may either be due to an immune response to the vascular injury during AVF creation or injury to the surrounding muscles and fascia. Several studies have discussed the role of inflammation in vascular thrombosis due to intimal injury during AVF creation, but there is limited information on the role of inflammation due to surrounding factors like a muscle injury. The concept of perivascular cuffing has been reported in the nervous system, but there is no study of perivascular cuffing in AVF early thrombosis. We performed the bulk RNA sequencing of the femoral arterial tissue and contralateral arteries as we found thrombosed arteries after AVF creation. RNA sequencing revealed several significantly differentially expressed genes (DEGs) related to chronic inflammation and perivascular cuffing, including tripartite motif-containing protein 55 (TRIM55). Additionally, DEGs like myoblast determination protein 1 (MYOD1) increased after muscle injury and relates to skeletal muscle differentiation, and network analysis revealed regulation of various genes regulating inflammation via MYOD1. The findings of this study revealed multiple genes with increased expression in the AVF femoral artery and may provide potential therapeutic targets or biomarkers of early thrombosis in AVF maturation failure. Thus, not only the luminal factors but also the surrounding factors mediating vascular cuffing contribute to vessel thrombosis and AVF failure via early thrombosis, and targeting the key regulatory factors may have therapeutic potential.

Introduction The indication of creation arteriovenous fistula(AVF) may be controversial in elderly population with advanced chronic kidney disease (CKD). Postoperative exercises improve maturation. However, sometimes these exercises could be difficult to perform in the elderly CKD patients. The hand grip device is easy to use, inexpensive and able to increase the muscles of the hand and foream. Nevertheless, scarce scientific evidence has been reported about the role of hand grip device on AVF maturation process in elderly population. Objectives To evaluate the efficacy of a hand grip training program on AVF maturation in our patients older than 75 years old with stages 5-5D CKD. Methodology A 15 months prospective study. After surgery, all patients were randomized to hand grip group (HG) or control group (CG). HG performed a training program using a hand grip device. CO received usual care. Demographics data, upper limb muscle strength (ULMS), Doppler ultrasound (DUS), measurements (outflow vein (OV) diameter and humeral artery blood flow rate (BFR), DUS and clinical AVF maturation as well as VA related complications (hematoma, stenosis, thrombosis, pseudoaneurysm, aneurysm) were assessed at 4 and 8 weeks postoperatively. Results 29 patients. 16 HG, 13 CO. 69% men. Mean age 80,5±2,9 years. 41,4% Radiocephalic AVF. Demographic data, ULMS and DUS measurement at baseline were similar. A significant increase was observed in ULMS only in HG at the end of study (18,8±6,5 vs 21,3±7,1Kg, p=0,005). DUS measurements statistically increased for both groups (OV diameter: CG 2,9 ± 0,6 vs. 5,8 ± 1,4mm; HG 2,9 ± 0,8 vs. 7,2 ± 2,2 mm; humeral artery BFR: CG 132,9± 30,3 vs. 1310,2 ± 691,8ml/min; HG 128,1± 28,9 vs. 1530,7 ± 708,9 ml/min) at the end of study. HG group obtained highest clinical (CG 21,4% vs HG 78,6%;p=0,018) and DUS maturation (CG 27,8% vs HG 72,2%; p=0,011) at 4 weeks and highest clinical (CG 20% vs HG 80%;p=0,007) and DUS maturation (CG 25% vs HG 75%; p=0,002) at 8 weeks, significantly. Despite no significant differences, the number of complications was lower in the HG, mainly significant stenosis (CG 60% vs HG 40%; p=0,428). Conclusions The hand grip device is a useful, safety and easy to use training device to improve the AVF maturation in elderly patients. This device results a novel therapeutic option for the AVF maturation in elderly patients. Further studies are required to support these outcomes in this population.