Vascular tissue engineering.

Reconstructive surgery using autologous vessels is the conventional approach for substitution of diseased vessels or for generation of bypass to improve blood supply downstream of stenosed vessels. In some circumstances the use of autologous material is not possible due to concomitant diseases or previous use, and artificial grafts must be used. Unfortunately, these grafts cannot substitute small-caliber arterial vessels because of thrombotic complications. The objective of tissue engineering at the vascular level is then to generate biological substitutes of arterial conduits with functional characteristics of native vessels, combining cellular components with biodegradable scaffolds. These research projects started in several laboratories, in the late 1990s, and have expanded in different directions using a number of experimental approaches. The objective of this review is to give an overview of the results so far obtained in this area of research, and to discuss the problems related to these investigations, at the experimental and clinical level. The article provides an overview of different biodegradable scaffolds used, experimental techniques for vessels maturation in vitro under mechanical stimulation, and of differentiated as well as precursors of vascular cells, which opens new opportunities for further development of this form of cell transplantation. Finally, the current available results in clinical research will be discussed

An image-based modeling framework for patient-specific computational hemodynamics

We present a modeling framework designed for patient-specific computational hemodynamics to be performed in the context of large-scale studies. The framework takes advantage of the integration of image processing, geometric analysis and mesh generation techniques, with an accent on full automation and high-level interaction. Image segmentation is performed using implicit deformable models taking advantage of a novel approach for selective initialization of vascular branches, as well as of a strategy for the segmentation of small vessels. A robust definition of centerlines provides objective geometric criteria for the automation of surface editing and mesh generation. The framework is available as part of an open-source effort, the Vascular Modeling Toolkit, a first step towards the sharing of tools and data which will be necessary for computational hemodynamics to play a role in evidence-based medicine

Interleukin-6 stimulates gene expression of extracellular matrix components in bovine mesangial cells in culture

The effect of interleukin-6 (IL-6) on gene expression of extracellular matrix components in bovine mesangial cells in culture has been investigated. IL-6 (100 U/ml) time dependently increased the steady state expression of mRNAs coding for α1 collagen III and fibronectin, both transcripts being 1.5- and 2.5-fold higher than basal level at 24 and 48 h, respectively. In contrast, IL-6 stimulated laminin mRNA expression only after 48 h incubation (2.5-fold upon basal level). These results suggest that IL-6 could favour glomerular matrix accumulation thus contributing to the development of glomerulosclerosis

C-Reactive protein and risk of ESRD: results from the Trial to Reduce Cardiovascular Events With Aranesp Therapy (TREAT)

Background: To better understand a potential association of elevated C-reactive protein (CRP) level with progression of chronic kidney disease (CKD), we examined the relationship of CRP level with the development of end-stage renal disease (ESRD) in the Trial to Reduce Cardiovascular Events With Aranesp Therapy (TREAT). Study Design Post hoc analysis of a randomized controlled trial. Setting & Participants: 4,038 patients with type 2 diabetes, CKD, and anemia in TREAT. Predictor: Baseline serum CRP concentrations. Outcomes: The primary outcome was development of ESRD; secondary outcomes included doubling of serum creatinine level, a composite of ESRD/serum creatinine doubling, and a composite of death or ESRD. Measurements: We fit unadjusted and adjusted Cox regression models to test the association of baseline CRP level with time to the development of the outcomes of interest. Results: Mean age of participants was 67 years, 43% were men, and 64% were white. Approximately half (48%) the patients had CRP levels > 3.0 mg/L; 668 patients developed ESRD, and 1,270 developed the composite outcome of death or ESRD. Compared with patients with baseline CRP levels ≤ 3.0 mg/L, those with moderately/markedly elevated CRP levels (≥6.9 mg/L; 24% of patients) had a higher adjusted risk for ESRD (HR, 1.32; 95% CI, 1.07-1.63) and the composite outcome of death or ESRD (HR, 1.41; 95% CI, 1.21-1.64). Although nonsignificant, similar trends were noted in competing-risk models. Limitations: Results may not be generalizable to nondiabetic CKD or diabetic CKD in the absence of anemia. Conclusions: Elevated baseline CRP levels are common in type 2 diabetic patients with anemia and CKD and are associated with the future development of ESRD and the composite of death or ESRD

Validation of a patient-specific hemodynamic computational model for surgical planning of vascular access in hemodialysis patients

Vascular access dysfunction is one of the main causes of morbidity and hospitalization in hemodialysis patients. This major clinical problem points out the need for prediction of hemodynamic changes induced by vascular access surgery. Here we reviewed the potential of a patient-specific computational vascular network model that includes vessel wall remodeling to predict blood flow change within 6 weeks after surgery for different arteriovenous fistula configurations. For model validation, we performed a multicenter, prospective clinical study to collect longitudinal data on arm vasculature before and after surgery. Sixty-three patients with newly created arteriovenous fistula were included in the validation data set and divided into four groups based on fistula configuration. Predicted brachial artery blood flow volumes 40 days after surgery had a significantly high correlation with measured values. Deviation of predicted from measured brachial artery blood flow averaged 3% with a root mean squared error of 19.5%, showing that the computational tool reliably predicted patient-specific blood flow increase resulting from vascular access surgery and subsequent vascular adaptation. This innovative approach may help the surgeon to plan the most appropriate fistula configuration to optimize access blood flow for hemodialysis, potentially reducing the incidence of vascular access dysfunctions and the need of patient hospitalization

PUK12 COST-EFFECTIVENESS OF ACE INHIBITOR THERAPY TO PREVENT DIALYSIS IN NON-DIABETIC NEPHROPATHY—INFLUENCE OF THE ACE INSERTION / DELETION POLYMORPHISM

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A Novel Strategy to Enhance Mesenchymal Stem Cell Migration Capacity and Promote Tissue Repair in an Injury Specific Fashion

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Two-photon polymerized "nichoid" substrates maintain function of pluripotent stem cells when expanded under feeder-free conditions

BACKGROUND: The use of pluripotent cells in stem cell therapy has major limitations, mainly related to the high costs and risks of exogenous conditioning and the use of feeder layers during cell expansion passages. METHODS: We developed an innovative three-dimensional culture substrate made of “nichoid” microstructures, nanoengineered via two-photon laser polymerization. The nichoids limit the dimension of the adhering embryoid bodies during expansion, by counteracting cell migration between adjacent units of the substrate by its microarchitecture. We expanded mouse embryonic stem cells on the nichoid for 2 weeks. We compared the expression of pluripotency and differentiation markers induced in cells with that induced by flat substrates and by a culture layer made of kidney-derived extracellular matrix. RESULTS: The nichoid was found to be the only substrate, among those tested, that maintained the expression of the OCT4 pluripotency marker switched on and, simultaneously, the expression of the differentiation markers GATA4 and α-SMA switched off. The nichoid promotes pluripotency maintenance of embryonic stem cells during expansion, in the absence of a feeder layer and exogenous conditioning factors, such as the leukocyte inhibitory factor. CONCLUSIONS: We hypothesized that the nichoid microstructures induce a genetic reprogramming of cells by controlling their cytoskeletal tension. Further studies are necessary to understand the exact mechanism by which the physical constraint provided by the nichoid architecture is responsible for cell reprogramming. The nichoid may help elucidate mechanisms of pluripotency maintenance, while potentially cutting the costs and risks of both feed-conditioning and exogenous conditioning for industrial-scale expansion of stem cells. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13287-016-0387-z) contains supplementary material, which is available to authorized users