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Purpose: Evaluation of reendothelialization with a new thin struts cobalt chromium alloy stent coated with a nano-layer of Polyzene™-F (PzF) in a rabbit iliac artery model.Methods: Fifteen stented external rabbit iliac arteries were harvested at Day 7 for electron microscopy analysis following Cobra PzF stents implantation to assess reendothelialization and compare to historical data. Ten additional rabbits were used to assess time course of reendothelialization at 3 and 5 days.Results: At Day 7, almost complete coverage of endothelial cells was observed with a coverage of 99.54 ± 0.25% of the stented area. No thrombus area was noted. At Day 3, more than half of examined pieces was reendothelialized and reached 78.30 ± 3.7% at Day 5 (p < .01 between each group). All stents were well expanded against the arterial wall and no struts were mal-apposed.Conclusions: Reendothelialization was rapid and complete at Day 7. This is the fastest reendothelization process after stenting in this model. No stent occlusion was observed. [ABSTRACT FROM AUTHOR]

This work firstly aimed to synthesize mono- and di- sulfonic derivatives of chitosan by reductive amination reaction using respectively 2-formyl benzene sulfonic acid and 2,4 formyl benzene sulfonic acid sodium salts. The influence of the reactants molar ratio (R), aryl – substituted amino groups versus chitosan free amino groups, on the degree of substitution (DS) of both sulfonated chitosans was assessed by 1 H NMR, elemental analysis, coupled conductometry-potentiometry analysis and UV spectrometry and FTIR. The influence of pH on sulfonated chitosans’ properties in solution were investigated by solubility and zeta potential (ZP) studies, size exclusion chromatography equipped with MALLS detection (SEC-MALLS) and Taylor dispersion analysis (TDA). The polyampholytic character of both series was evidenced and strongly modified the solutions properties compared to chitosan. Then, the anticoagulant properties of mono- and di- sulfonic polymers were investigated by the measurement of the activated partial thromboplastin time (aPTT), Prothrombin-time (PT) and anti-(factor Xa). [ABSTRACT FROM AUTHOR]

OBJECTIVES: It has been demonstrated that both heterotopic and orthotopic transplants of epithelium-denuded cryopreserved tracheal allografts are feasible in immunosuppressant-free rabbits. Validation of these results in large animals is required before considering clinical applications. We evaluated the viability, immune tolerance and strain properties of such tracheal allografts heterotopically transplanted in a pig model. METHODS: Ten tracheal segments, 5 short (5 rings) and 5 long (10 rings), were obtained from male Landrace pigs. The tracheal segments were surgically denuded of their epithelium, then cryopreserved and stored in a tissue bank for 33 to 232 days. After thawing, tracheal segments stented with a silicone tube were wrapped in the omentum in 2 groups of 5 female recipients. The animals did not receive any immunosuppressive drugs. The animals were euthanized from Day 6 to Day 90 in both groups. RESULTS: An effective revascularization of allografts regardless of length was observed. Lymphocyte infiltrate was shown in the early postoperative period and became non-significant after 30 days. Allografts displayed high levels of neoangiogenesis and viable cartilage rings with islets of calcification. Biomechanical measurements demonstrated strain properties similar to those of a fresh tracheal segment from Day 58. CONCLUSIONS: Our results demonstrate the acceptability and satisfactory stiffness of epithelium-denuded cryopreserved tracheal allografts implanted in the omentum, despite the absence of immunosuppressive drugs. Since the omentum has the capability to reach the tracheal region, this approach should be investigated in the setting of orthotopic transplants in a pig model before considering clinical applications. [ABSTRACT FROM AUTHOR]

OBJECTIVES: Results of tracheal transplantation have been disappointing due to of ischaemia and rejection. It has been experimentally demonstrated that results of tracheal autograft/allograft transplantation were correlated with both graft length and revascularization method. Recently, we demonstrated that heterotopic epithelium-denuded-cryopreserved tracheal allograft (TA) displayed satisfactory immune tolerance. We aimed at evaluating the results of such allografts in orthotopic transplantation according to graft length and prior heterotopic or single-stage orthotopic revascularization in a rabbit model. METHODS: Twenty New Zealand rabbits were used. Six females served as donors. Tracheal mucosa was mechanically peeled off and then the TAs were cryopreserved. Male recipients were divided into three groups receiving: (i) long TA segment with prior heterotopic revascularization (10–12 tracheal rings, n = 3); (ii) average TA segment with single-stage orthotopic revascularization (6–8 tracheal rings, n = 4); (iii) short TA segment with single-stage orthotopic revascularization (4–5 tracheal rings, n = 7). No immunosuppressive therapy was administered. Grafts were assessed bronchoscopically and upon death or sacrifice by macroscopic evaluation, histology and immunohistochemical staining for apoptosis. RESULTS: Four animals were sacrificed from Day 33 to Day 220. The survival time of other recipients was 0–47 days (mean 19.6 ± 16.7 days). Aside from three animals that died from complications, all TA segments had satisfactory stiffness, were well vascularized, showed varying levels of neoangiogenesis and inflammatory infiltration devoid of lymphocytes, and showed evidence of only low levels of apoptosis. Varying degrees of fibroblastic proliferation originating from the lamina propria were observed in the lumen of all TAs and evolved over time into collagenized fibrosis in animals surviving over 45 days. Likewise, cartilage tracheal rings exhibited central calcification deposits, which started on Day 16 and increased over time. Epithelial regeneration was constantly observed. Intense fibroblastic proliferation led to stenosis in all animals from Groups (i) and (ii) but only one of seven animals from Group (iii). CONCLUSIONS: Our results suggest that short segments of epithelium-denuded-cryopreserved TA may be reliable for tracheal transplantation in the rabbit model without problems related to graft stiffness or immune rejection. Before considering clinical applications, investigations should be conducted in larger mammals. [ABSTRACT FROM AUTHOR]

Abstract: Background: We recently demonstrated in an experimental model the expression of tissue factor (TF) in aortic valves. Thrombin, generated at the end of the TF-initiated coagulation cascade, has been shown to cleave the anti-calcific osteopontin (OSP) liberating the pro-inflammatory OSP N-half. Objectives: We hypothesized that TF might play an important role in calcific aortic valve stenosis (AS) through thrombin generation and hence evaluated the valvular expression of TF and its inhibitor (TF pathway inhibitor), α-thrombin, OSP and its thrombin-cleaved form (OSP N-half). Methods: Calcified aortic valves were obtained from patients undergoing valve replacement. Protein expression was evaluated by immunostaining and measured using ELISA kits. Transcripts were analyzed by RT-PCR. Results: We included 52 patients (31 men; age 70±10 years; aortic valve area index 0.35±0.13cm2/m2). Immunohistochemistry revealed that TF, OSP and α-thrombin expressions were associated with calcifications at the aortic side of the leaflets. There was an overexpression in calcified regions as compared to non-calcified zones of TF (733.3±70.5pg/mg vs. 429.4±73.2pg/mg; p <0.0001), OSP (88.9±12.7ng/mg vs. 15.0±3.3ng/mg; p <0.0001) and OSP N-half (0.41±0.06pmol/mg vs. 0.056±0.011pmol/mg; p <0.0001). Additionally, both TF and α-thrombin expressions were associated with OSP N-half (r =0.52; p <0.0001 and r =0.33; p =0.019, respectively). Conclusions: Aortic leaflet TF and α-thrombin expressions and their association with the thrombin-cleaved form of OSP, are a new and important feature of AS. We hypothesize that TF may be involved in the mineralization process of aortic valves by enhancing the generation of the pro-inflammatory OSP N-half through thrombin induction. This pathway deserves further studies to address its implication in the aortic valve calcification process. [ABSTRACT FROM AUTHOR]

Background: Expression of the principal initiator of coagulation, tissue factor (TF), by colorectal cancer (CRC) cells is involved in tumoral angiogenesis and metastasis progression, after binding of factor VIIa (FVIIa) to TF and generation of TF-FVIIa activity. We thus hypothesized that inhibition of the TF pathway by active site-blocked FVIIa (FFR-FVIIa) may prevent the development of hepatic metastasis in CRC. Methods: Rat tumoral cells (DHDK12 proB cells) expressing high levels of TF were injected in the portal vein in syngenic BDIX rats. Rats received intraperitoneal injection of either FFR-FVIIa, from d 3 to d 7 (adjuvant treatment) (n = 19), or solvent buffer (n = 18) (control group). Additionally, cancer cells were infused subcutaneously in 20 other rats, which were assigned to FFR-FVIIa adjuvant treatment (n = 10), or buffer treatment (n = 10). Macroscopic and histological analysis was performed at d 14. Results: In the control group, infusion of cancer cells resulted in development of macroscopic hepatic tumors in 17/18 rats. In the adjuvant FFR-FVIIa group, macroscopic hepatic tumors were visible on the liver surface in 3/19 rats (P = 0.002 versus control). All rats with subcutaneous injection of proB cells exhibited macroscopic tumors, with no significant difference between the control and the treated ones. Conclusion: Inhibition of the proteolytic activity of TF-FVIIa complex blunted hematogenous hepatic metastasis, suggesting that TF-FVIIa is a relevant target for the prevention of hepatic metastasis in CRC. TF-blocking agents should be investigated as adjuvant treatment in this setting. [Copyright &y& Elsevier]

Abstract: Background: Aortic valve sclerosis (AVS) shares epidemiological and histological similarities with atherosclerosis. Tissue factor (TF), the main initiator of blood coagulation, is present in atherosclerotic plaques and contributes to their thrombogenicity. We aimed to analyze valvular TF expression in addition to other components of atherosclerosis in two models of AVS. Methods: Forty-five rabbits were randomly assigned to receive either normal chow (Ctrl, n=15), or 1% cholesterol-enriched chow alone (Hyperchol, n=15) or associated with vitamin D2 (VitD, n=15), for 12 weeks. Aortic valve (AV) performance, leaflet structure, cellular and lipid infiltration, and TF expression were assessed using Doppler, histology, and immunohistochemistry, respectively, and TF activity was evaluated in AV leaflets. Results: Hyperchol and VitD animals developed abnormal leaflet thickening, with a significant alteration of AV performance in VitD animals. Leaflet thickening was related to the development of fatty plaque neolesions on the aortic side of the leaflets, displaying extracellular matrix disorganization, lipid and cellular infiltration, and calcification in VitD animals. TF was found on the leaflet aortic side in Ctrl animals and was identified in AVS lesions in both Hyperchol and VitD animals. TF immunostaining area and valvular activity increased significantly across the three groups. Conclusions: Experimental AVS lesions that are present on the aortic side of leaflets display numerous characteristics of vascular atherosclerosis, including TF expression. Identification of TF associated with other components of the atherosclerotic process in AVS lesions strengthens the link between atherosclerosis and AVS. [Copyright &y& Elsevier]

Potentially toxic plasticizers are commonly added to polyvinyl chloride medical devices for transfusion in order to improve their flexibility and workability. As the plasticizers are not chemically bonded to the PVC, they can be released into labile blood products (LBPs) during storage. Ideally, LBPs would be used in laboratory studies of plasticizer migration from the medical device. However, short supply (i.e., limited stocks of human blood in collection centres) has prompted the development of specific simulants for each type of LBP in the evaluation of new transfusion devices. We performed a Delphi study with a multidisciplinary panel of 24 experts. In the first (qualitative) phase, the panel developed consensus definitions of the specification criteria to be met by each migration simulant. Next, we reviewed the literature on techniques for simulating the migration of plasticizers into LBPs. A questionnaire was elaborated and sent out to the experts, and the replies were synthesized in order to obtain a consensus. The qualitative study established specifications for each biological matrix (whole blood, red blood cell concentrate, plasma, and platelet concentrate) and defined the criteria required for a suitable LBP simulant. Ten criteria were suggested: physical and chemical characteristics, opacity, form, stability, composition, ability to mimic a particular clinical situation, ease and safety of use, a simulant–plastic interaction correlated with blood, and compatibility with analytical methods. The questionnaire data revealed a consensus on the use of natural products (such as pig's blood) to mimic the four LBPs. Opinions diverged with regard to synthetic products. However, an isotonic solution and a rheological property modifier were considered to be of value in the design of synthetic simulants. Consensus reached by the Delphi group could be used as a database for the development of simulants used to assess the migration of plasticizers from PVC bags into LBPs. [ABSTRACT FROM AUTHOR]

Current vascular drug-eluting stents based on immuno-proliferative drugs would reduce the rate of in-stent restenosis (ISR) but may be associated with a higher risk of acute stent thrombosis due to non-selective activity. In this paper, we aimed to develop a polydopamine (PDA) coated chromium‑cobalt (CoCr) stent functionalised with EP224283 (Endotis Pharma SA), which combines both a GPIIbIIIa antagonist (tirofiban moiety) and a factor Xa inhibitor (idraparinux moiety) to reduce acute stent thrombosis. PDA-coated chromium‑cobalt (CoCr) samples were first immersed in a polyethylenimine (PEI, pH 8.5) solution to increase amine function density (36.0 ± 0.1 nmol/cm2) on the CoCr surface. In a second step, avidin was grafted onto CoCr-PDA-PEI through the biotin linkage (strategy 1) or directly by coupling reactions (strategy 2). The HABA titration proved the fixation of biotin onto CoCr-PDA-PEI surface with a density of 0.74 nmol/cm2. The fixation of avidin was demonstrated by water contact angle (WCA) and surface plasmon resonance (SPR). SEM micrograph shows the flexibility of the thin layer coated onto the stent after balloon inflation. Independently of the strategy, a qualitative SEM analysis showed a reduction in platelet activation when the molecule EP224283 was immobilised on avidin. In parallel, the measurement of anticoagulant activity (anti-Xa) revealed a higher anti-factor Xa activity (2.24 IU/mL vs. 0.09 IU/mL in control) when EP224283 was immobilised on avidin. Interestingly, after seven days of degradation, the anticoagulant activity was persistent in both strategies and looked more important with the strategy 2 than in strategy 1. Throughout this work, we developed an innovative vascular stent through the immobilisation of EP224283 onto CoCr-PDA-PEI-(avidin) system, which provides a promising solution to reduce ISR and thrombosis after stent implantation. • Avidin was grafted onto CoCr-PDA-PEI through the biotin linkage or directly by coupling reactions. • The molecule EP224283 was successfully immobilised onto functionalized CoCr-PDA-stent. • The anticoagulant activity of the immobilised EP224283 molecule was preserved. • The second anti platelet adhesion activity of the molecule EP224283 was verified. • The biological activity was maintained for 7 days in in vitro conditions. [ABSTRACT FROM AUTHOR]

OBJECTIVES Animal and clinical studies have demonstrated the feasibility of tracheal allograft transplantation after a revascularization period in heterotopy, thus requiring immunosuppressive therapy. Given the key role of the respiratory epithelium in the immune rejection, we investigated the consequence of both epithelium denudation and cryopreservation in immune tolerance of tracheal allograft in a novel rabbit model. METHODS Five adult female New Zealand rabbits served as donors of tracheas that were denuded of their epithelium and then cryopreserved, and 13 males were used as recipients. Following graft wrap using a lateral thoracic fascial flap, allograft segments 20 mm in length with (n = 9) or without (n = 4) insertion of an endoluminal tube were implanted under the skin of the chest wall. The animals did not receive any immunosuppressive drugs. Sacrifices were scheduled up to 91 days. Macroscopic and microscopic examinations and detection of apoptotic cells by immunohistochemical staining (Apostain) were used to study the morphology, stiffness, viability and immune rejection of allografts. RESULTS There were no postoperative complications. Grafted composite allografts displayed satisfactory tubular morphology provided that an endoluminal tube was inserted. All rabbits were found to have an effective revascularization of their allograft and a mild non-specific inflammatory infiltrate with no significant lymphocyte infiltration. Cartilage rings showed early central calcification deposit, which increased over time, ensuring graft stiffness. Apoptosis events observed into the allograft cells were suggestive of minimal chronic rejection. CONCLUSIONS Our results demonstrated that the epithelium-denuded-cryopreserved tracheal allograft implanted in heterotopy displayed satisfactory morphology, stiffness and immune tolerance despite the absence of immunosuppressive drugs. This allograft with a fascial flap transferable to the neck should be investigated in the setting of tracheal replacement in rabbits. Similar studies need to be conducted in bigger mammals before considering clinical applications. [ABSTRACT FROM AUTHOR]