Journal articles: 'Synthetic vascular grafts'

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Aleksandrov, Viktor Nikolayevich, Genady Grigorievich Khubulava, and Vladimir Victorovich Levanovich. "Tissue-engineered vascular grafts." Pediatrician (St. Petersburg) 6, no. 1 (March 15, 2015): 87–95. http://dx.doi.org/10.17816/ped6187-95.

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There is no doubt that the introduction of synthetic materials was the prerequisite for success of vascular surgery. Biological inertness, durability, eases of sterilization and modeling of synthetic vascular grafts contributed to their widespread use as in aortic and great vessels. However, analysis of the accumulated clinical experience in using of synthetic grafts showed that fascination with them was gradually replaced by cautious attitude, and sometimes by refusing, because in the presence of well-known advantages, synthetic grafts are prone to thrombosis and the development of infection. Thereby, it takes place searching of anticoagulant and antibiotic therapy schemes, and the ways of creation of such grafts which will minimize the risk of thrombus formation and the development of infectious complications. Not without reason one of such ways includes tissue engineering, which allows to create substitute for biological tissues and organs using the principles and methods of engineering and biology. Tissue engineering vascular grafts (TIVG), created on the basis of natural acellular allogeneic or xenogeneic vascular matrices and populated with patient cells, so personalized, are thought to be biocompatible, athrombogenic, and deprived of any deficiencies of synthetic grafts. Being biocompatible products, they will be able to grow and will be suitable not only for adults but also for children with cardiovascular defects. However, a number of questions related to the search of optimal conditions for obtaining TIVG remain open.

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Kanda, Keiichi, Hiromichi Miwa, and Takehisa Matsuda. "Phenotypic Reversion of Smooth Muscle Cells in Hybrid Vascular Prostheses." Cell Transplantation 4, no. 6 (November 1995): 587–95. http://dx.doi.org/10.1177/096368979500400608.

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Our purpose was to evaluate whether or not and when phenotypic modulation of smooth muscle cells (SMCs) in hybrid vascular prostheses preincorporated with SMCs occurs upon implantation. Two types of hybrid vascular grafts incorporated with vascular cells derived from canine jugular veins were prepared: grafts containing a collagen gel layer covered with an endothelial monolayer at the luminal surface (Model I graft) and those containing an endothelial monolayer and SMC multilayer (Model II graft). They were bilaterally implanted into carotid arteries of the same dogs from which the cells had been harvested for 2 wk (n = 3) and 12 wk (n = 3). The time-dependent changes in populations of three SMC phenotypes (synthetic, intermediate, and contractile) in the neoarterial layers were quantified by morphometric evaluation using a transmission electron microscope in hybrid vascular grafts. Before implantation, all the SMCs were of the synthetic phenotype. In Model II grafts at 2 wk, synthetic and intermediate SMCs were dominant especially in the luminal layer. On the other hand, neoarterial layers at 12 wk were dominated by contractile SMCs, which were evenly distributed throughout the entire neoarterial tissues. A markedly delayed phenotypic reversion was noted for the Model I grafts at 12 wk. In the hybrid grafts, during about 3 mo of implantation, neoarterial SMCs transformed from the synthetic to the contractile phenotypes, which was promoted by SMC incorporation.

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Antonova, L. V., E. O. Krivkina, M. Yu Khanova, E. A. Velikanova, V. G. Matveeva, А. V. Mironov, A. R. Shabaev, et al. "Results of preclinical trials in a sheep model of biodegradable small-diameter vascular grafts." Russian Journal of Transplantology and Artificial Organs 24, no. 3 (August 24, 2022): 80–93. http://dx.doi.org/10.15825/1995-1191-2022-3-80-93.

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Surface modification of polymer vascular matrices is a promising development for preventing vascular graft thrombosis, improving long-term patency and accelerating remodeling. Objective: to study the outcomes of long-term patency of PHBV/PCL/GFmix grafts with iloprost (Ilo) and heparin (Hep) implanted into the carotid artery of sheep. Materials and methods. Matrices 04 mm were fabricated by electrospinning from a polymer composition of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(s-caprolactone) (PCL) with incorporation of endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and chemoattractant molecule (SDF-1a). The fabricated matrices were then modified with Ilo and Hep by complexation via polyvinylpyrrolidone (PVP). Synthetic Gore-Tex grafts were used as a comparison group. The physical and mechanical properties of the studied matrix groups were evaluated, the surface structure of vascular grafts before and after implantation was assessed. Vascular grafts were implanted into the carotid artery of a sheep. The explanted samples were studied via histological and immunofluorescence analysis, the elemental composition of the obtained vascular graft samples was also assessed, and the gene expression profile was evaluated. Results. One day after implantation, the patency of PHBV/PCL/GFmixHep/n° vascular grafts was 62.5%, whereas synthetic Gore-Tex grafts had thrombosis in 100% of cases. At the same time, after 18 months of implantation, the patency of biodegradable PHBV/PCL/GFmixHep/n° vascular grafts decreased to 50%. Permeable drug-coated polymer grafts were completely reabsorbed after 18 months of implantation, and aneurysmally dilated newly-formed vascular tissue was formed in their place. Conclusion. Modification of the surface of PHBV/PCL/GFmix polymer grafts with Hep + Ilo coating improved long-term patency outcomes compared to synthetic Gore-Tex grafts.

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Mohr, Lester L., Douglas C. Smith, and Gregory J. Schaner. "Catheterization of synthetic vascular grafts." Journal of Vascular Surgery 3, no. 6 (June 1986): 854–56. http://dx.doi.org/10.1067/mva.1986.avs0030854.

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Mohr, Lester L., Douglas C. Smith, and Gregory J. Schaner. "Catheterization of synthetic vascular grafts." Journal of Vascular Surgery 3, no. 6 (June 1986): 854–56. http://dx.doi.org/10.1016/0741-5214(86)90149-7.

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Yuan, Xingyu, Wen Li, Bin Yao, Zhao Li, Deling Kong, Sha Huang, and Meifeng Zhu. "Tri-Layered Vascular Grafts Guide Vascular Cells’ Native-like Arrangement." Polymers 14, no. 7 (March 28, 2022): 1370. http://dx.doi.org/10.3390/polym14071370.

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Bionic grafts hold great promise for directing tissue regeneration. In vascular tissue engineering, although a large number of synthetic grafts have been constructed, these substitutes only partially recapitulated the tri-layered structure of native arteries. Synthetic polymers such as poly(l-lactide-co-ε-caprolactone) (PLCL) possess good biocompatibility, controllable degradation, remarkable processability, and sufficient mechanical strength. These properties of PLCL show great promise for fabricating synthetic vascular substitutes. Here, tri-layered PLCL vascular grafts (TVGs) composed of a smooth inner layer, circumferentially aligned fibrous middle layer, and randomly distributed fibrous outer layer were prepared by sequentially using ink printing, wet spinning, and electrospinning techniques. TVGs possessed kink resistance and sufficient mechanical properties (tensile strength, elastic modulus, suture retention strength, and burst pressure) equivalent to the gold standard conduits of clinical application, i.e., human saphenous veins and human internal mammary arteries. The stratified structure of TVGs exhibited a visible guiding effect on specific vascular cells including enhancing endothelial cell (EC) monolayer formation, favoring vascular smooth muscle cells’ (VSMCs) arrangement and elongation, and facilitating fibroblasts’ proliferation and junction establishment. Our research provides a new avenue for designing synthetic vascular grafts with polymers.

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Wang, Yadong, Wei Wu, and Robert Allen. "Vitalize synthetic vascular grafts in vivo." Cardiovascular Pathology 22, no. 3 (May 2013): e51. http://dx.doi.org/10.1016/j.carpath.2013.01.075.

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Adipurnama, Iman, Ming Chien Yang, Tomasz Ciach, and Beata Butruk Raszeja. "Surface Modification With Gelatin For Polyurethane Vascular Grafts: A Review." Jurnal Bahan Alam Terbarukan 8, no. 2 (December 23, 2020): 100–117. http://dx.doi.org/10.15294/jbat.v8i2.23170.

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The means for developing synthetic vascular grafts to replace blood vessels is increasing extensively because of the limited supply of autologous vessels. Synthetic polymers as the alternatives still suffer from restenosis and thrombus formation. Natural polymers, on the other hand, are commonly biocompatible and biodegradable, compliment the synthetic ones. Blending, grafting and coating of natural polymers have been proposed to improve surface properties of synthetic polymers. Gelatin is a promising candidate to help improving synthetic vascular grafts surface owing to its ability to promote cell adhesion without promoting platelet aggregation at its surface. In this review, several techniques to incorporate gelatin onto synthetic polymers, mainly polyurethane, for vascular grafts application are summarized, together with the recent updates and potential development in the future.

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Gao, Jingchen, Yaping Wang, Siyuan Chen, Di Tang, Li Jiang, Deling Kong, and Shufang Wang. "Electrospun poly-ε-caprolactone scaffold modified with catalytic nitric oxide generation and heparin for small-diameter vascular graft." RSC Advances 7, no. 30 (2017): 18775–84. http://dx.doi.org/10.1039/c7ra02086d.

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Vascular grafts are significantly needed in peripheral vascular surgery; however, small diameter grafts are not always available, and synthetic grafts perform poorly because of acute thrombosis and neointimal proliferation after implantation.

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Gerrah, Rabin, Rachel E. Sunstrom PA-C, and Alan R. Hohimer. "Pretreatment of synthetic vascular grafts with heparin before implantation, a simple technique to reduce the risk of thrombosis." Vascular 23, no. 5 (November 18, 2014): 513–18. http://dx.doi.org/10.1177/1708538114560455.

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Thrombosis of synthetic grafts commonly used in cardiovascular surgery is a major complication. We examined whether pretreatment of the graft with heparin reduces the risk of early thrombosis. A circuit was assembled to compare two pairs of shunts simultaneously in the same animal. The study shunts were pretreated with heparin. After 2 hours of circulation, clot formation was evaluated by image analysis techniques. The pretreated grafts had fewer blood clots adhered to the surface by direct visual inspection. The image analysis showed 5 vs. 39 clots, 0.01% vs. 1.8% clotted area, and 62 vs. 5630 clot pixel area between the treated and non-treated grafts respectively, p < 0.05. Pretreatment of the synthetic graft with heparin prior to implantation reduces the risk of early clot formation. This simple practice might be helpful to prevent initial thrombosis of the graft and later occlusion.

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Sohn, Sung-Hwa, Tae-Hee Kim, Tae-Sik Kim, Too-Jae Min, Ju-Han Lee, Sung-Mook Yoo, Ji-Won Kim, et al. "Evaluation of 3D Templated Synthetic Vascular Graft Compared with Standard Graft in a Rat Model: Potential Use as an Artificial Vascular Graft in Cardiovascular Disease." Materials 14, no. 5 (March 5, 2021): 1239. http://dx.doi.org/10.3390/ma14051239.

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Although the number of vascular surgeries using vascular grafts is increasing, they are limited by vascular graft-related complications and size discrepancy. Current efforts to develop the ideal synthetic vascular graft for clinical application using tissue engineering or 3D printing are far from satisfactory. Therefore, we aimed to re-design the vascular graft with modified materials and 3D printing techniques and also demonstrated the improved applications of our new vascular graft clinically. We designed the 3D printed polyvinyl alcohol (PVA) templates according to the vessel size and shape, and these were dip-coated with salt-suspended thermoplastic polyurethane (TPU). Next, the core template was removed to obtain a customized porous TPU graft. The mechanical testing and cytotoxicity studies of the new synthetic 3D templated vascular grafts (3DT) were more appropriate compared with commercially available polytetrafluoroethylene (PTFE) grafts (ePTFE; standard graft, SG) for clinical use. Finally, we performed implantation of the 3DTs and SGs into the rat abdominal aorta as a patch technique. Four groups of the animal model (SG_7 days, SG_30 days, 3DT_7 days, and 3DT_30 days) were enrolled in this study. The abdominal aorta was surgically opened and sutured with SG or 3DT with 8/0 Prolene. The degree of endothelial cell activation, neovascularization, thrombus formation, calcification, inflammatory infiltrates, and fibrosis were analyzed histopathologically. There was significantly decreased thrombogenesis in the group treated with the 3DT for 30 days compared with the group treated with the SG for 7 and 30 days, and the 3DT for 7 days. In addition, the group treated with the 3DT for 30 days may also have shown increased postoperative endothelialization in the early stages. In conclusion, this study suggests the possibility of using the 3DT as an SG substitute in vascular surgery.

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Antonova, Larisa, Vladimir Silnikov, Victoria Sevostyanova, Arseniy Yuzhalin, Lyudmila Koroleva, Elena Velikanova, Andrey Mironov, et al. "Biocompatibility of Small-Diameter Vascular Grafts in Different Modes of RGD Modification." Polymers 11, no. 1 (January 18, 2019): 174. http://dx.doi.org/10.3390/polym11010174.

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Modification with Arg-Gly-Asp (RGD) peptides is a promising approach to improve biocompatibility of small-calibre vascular grafts but it is unknown how different RGD sequence composition impacts graft performance. Here we manufactured 1.5 mm poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/poly(ε-caprolactone) grafts modified by distinct linear or cyclic RGD peptides immobilized by short or long amine linker arms. Modified vascular prostheses were tested in vitro to assess their mechanical properties, hemocompatibility, thrombogenicity and endothelialisation. We also implanted these grafts into rat abdominal aortas with the following histological examination at 1 and 3 months to evaluate their primary patency, cellular composition and detect possible calcification. Our results demonstrated that all modes of RGD modification reduce ultimate tensile strength of the grafts. Modification of prostheses does not cause haemolysis upon the contact with modified grafts, yet all the RGD-treated grafts display a tendency to promote platelet aggregation in comparison with unmodified counterparts. In vivo findings identify that cyclic Arg-Gly-Asp-Phe-Lys peptide in combination with trioxa-1,13-tridecanediamine linker group substantially improve graft biocompatibility. To conclude, here we for the first time compared synthetic small-diameter vascular prostheses with different modes of RGD modification. We suggest our graft modification regimen as enhancing graft performance and thus recommend it for future use in tissue engineering.

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Russu, Eliza, Adrian Vasile Mureșan, Bogdan Andrei Cordoș, Constantin Copotoiu, and Ovidiu Simion Cotoi. "Morpho-Pathological Review on the Healing of Synthetic Vascular Grafts." Acta Medica Marisiensis 62, no. 1 (March 1, 2016): 33–40. http://dx.doi.org/10.1515/amma-2015-0098.

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AbstractObjective: Tissue integration of vascular grafts partially depends on the host response to injury, which immediately begins after implantation and restoration of the circulation. In an infected environment, the inflammation changes the incorporation patterns. The aim of the study was to observe the tissue incorporation process, in a normal and an infected environment. Methods: We have created an experimental model by performing subfascial implantation of four types of vascular grafts, in rats (woven Dacron®, knitted Dacron®, silver coated Dacron®and expanded Polytetrafloroethylene - ePTFE) and by infecting some of them with three different bacterial strains. We have retrieved the noninfected grafts at two and four weeks after implantation, whilst the infected ones at one, two and three weeks. Results: Detailed microscopic appearences were analysed. The control and infected groups were compared. Statistical significance was calculated for various corelations. Conclusions: The morphopathological findings showed that the ePTFE graft’s structure was best preserved. Statistical significance existed between the bacterial strain and the degree of inflammation. The silver coated Dacron®was not shown to be superior to the knitted Dacron®. The poorest incorporation was the one of the woven Dacron®.

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Sackman, Jill E., Michael B. Freeman, Mark G. Petersen, Zuhair Allebban, Glenn P. Niemeyer, and Clinton D. Lothrop. "Synthetic Vascular Grafts Seeded with Genetically Modified Endothelium in the Dog: Evaluation of the Effect of Seeding Technique and Retroviral Vector on Cell Persistence in Vivo." Cell Transplantation 4, no. 2 (March 1995): 219–35. http://dx.doi.org/10.1177/096368979500400206.

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Unique characteristics of endothelium make it an attractive target cell for gene transfer. Genetically modified endothelial cells (ECs) seeded on synthetic vascular grafts offer the potential to control neointimal hyperplasia, decrease graft thrombogenicity and improve small diameter graft patency. This study addresses the issue of synthetic vascular graft colonization with endothelial cells transduced with noninducible retroviral marker genes in the dog. Autologous endothelial cells were enzymatically harvested and transduced with either the bacterial NeoR gene or human growth hormone gene using retroviral vectors. All transduced cells were positive by polymerase chain reaction (PCR) amplification for the transduced gene sequence prior to graft seeding. Transduced ECs were seeded on Dacron grafts (n = 3) pre-clotted with autologous blood. These grafts exhibited complete endothelialization at times from 250 to 360 days. Recovered DNA, however, was negative for the transduced gene sequence when analyzed by PCR and Southern blotting. Expanded polytetrafluoroethylene (ePTFE) was evaluated (n = 8) using several different cell seeding protocols. Grafts were seeded at 3 densities (ranging from 6 × 103 to 1.5 × 105 cells/cm2) and 2 different adherence times. Seeding substrate was also evaluated. Grafts were either preclotted with whole blood or incubated with 20 or 120 μg/ml fibronectin for 60 min. Graft biopsies were evaluated from 2 to 52 wk. Limited endothelialization was present in 4 dogs as early as 2 wk, but never progressed to full luminal coverage. The remaining dogs failed to ever exhibit any luminal EC adherence. Two dogs with limited EC coverage had positive DNA by PCR for the NeoR gene sequence at 2 and 3 wk. In contrast to transduced EC's, nontransduced EC colonization of ePTFE was complete at 2 wk when seeded under conditions that transduced cells had failed to persist. Neither seeding density, adherence time, seeding substrate or retroviral vector used influenced the uniformly poor graft coverage seen with transduced cells. Results of this study indicate that despite successful gene transfer using 4 different retroviral vectors, transduced endothelial cells seeded under varying conditions appear altered in their ability to stably adhere and colonize synthetic vascular grafts in vivo.

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Karrer, L., J. Duwe, A. H. Zisch, E. Khabiri, M. Cikirikcioglu, A. Napoli, A. Goessl, et al. "PPS-PEG Surface Coating to Reduce Thrombogenicity of Small Diameter ePTFE Vascular Grafts." International Journal of Artificial Organs 28, no. 10 (October 2005): 993–1002. http://dx.doi.org/10.1177/039139880502801006.

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Aims Patency failure of small vascular synthetic grafts is still a major problem for coronary and peripheral revascularization. Thus, three new surface coatings of small synthetic grafts were tested in an acute pig model to evaluate their thrombogenicity (extracorporeal arterio-venous shunt) and in a chronic rat model to evaluate the tissue reaction they induced (subcutaneous implantation). Methods In five domestic pigs (25–30 kg) an extracorporeal femoro-femoral arterio-venous shunt model was used. The study protocol included first a non-heparinized perfusion sequence followed by graft perfusion after 10,000 UI iv heparin. Grafts were perfused for 3 and 9 minutes. The following coatings were tested on ePTFE grafts: poly-propylene sulphide (PPS) – poly-ethylene glycol (PEG) (wet and dry applications) as well as carbon. Two sets of control were used, one dry and one wet (vehicle only). After perfusion grafts were examined by scanning electron microscopy for semiquantitative assessment (score 0–3) of cellular and microthrombi deposition. To assess tissue compatibility, pieces of each material were implanted subcutaneously in 16 Wistar rats. At 2, 4, 8, 12 weeks four animals each were sacrificed for semi-quantitative (score 0–3) histologic evaluation of tissue reaction. Results In the pig model, cellular deposition and microthrombi formation increased over time. In non-heparinized animals, the coatings did not improve the surface characteristics, since they did not prevent microthrombi formation and cellular deposition. In heparinized animals, thrombogenicity was lowest in coated grafts, especially in PPS–PEG dry (P&0.05), and highest in controls. Cell deposition was lowest in PPS–PEG dry, but this difference was not statistically significant vs. controls. In the rat model, no significant differences of the tissue reaction could be shown between materials. Conclusion While all coatings failed to add any benefit for lowering tissue reaction, surface coating with PPS–PEG (dry application) reduced thrombogenicity significantly (in heparinized animals) and thus appears to be promising for improving graft patency of small synthetic vascular prostheses.

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Chew, Chee Ho, Bo-Long Sheu, Amanda Chen, Wan-Ting Huang, Tsai-Mu Cheng, Chun-Ming Shih, Austin Chang, and Chien-Chung Chen. "Tissue-Engineered Vascular Graft with Co-Culture of Smooth Muscle Cells and Human Endothelial Vein Cells on an Electrospun Poly(lactic-co-glycolic acid) Microtube Array Membrane." Membranes 11, no. 10 (September 27, 2021): 732. http://dx.doi.org/10.3390/membranes11100732.

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Coronary artery disease is one of the major diseases that plagues today’s modern society. Conventional treatments utilize synthetic vascular grafts such as Dacron® and Teflon® in bypass graft surgery. Despite the wide adaptation, these synthetic grafts are often plagued with weaknesses such as low hemocompatibility, thrombosis, intimal hyperplasia, and risks of graft infection. More importantly, these synthetic grafts are not available at diameters of less than 6 mm. In view of these challenges, we strived to develop and adapt the electrospun Poly Lactic-co-Glycolic Acid (PLGA) Microtube Array Membrane (MTAM) vascular graft for applications smaller than 6 mm in diameter. Homogenously porous PLGA MTAMs were successfully electrospun at 5.5–8.5 kV under ambient conditions. Mechanically, the PLGA MTAMs registered a maximum tensile strength of 5.57 ± 0.85 MPa and Young’s modulus value of 1.134 ± 0.01 MPa; while MTT assay revealed that seven-day Smooth Muscle Cells (SMCs) and Human Umbilical Vein Endothelial Cells (HUVECs) registered a 6 times and 2.4 times higher cell viability when cultured in a co-culture setting in medium containing α-1 haptaglobulin. When rolled into a vascular graft, the PLGA MTAMs registered an overall degradation of 82% after 60 days of cell co-culture. After eight weeks of culturing, immunohistochemistry staining revealed the formation of a monolayer of HUVECs with tight junctions on the surface of the PLGA MTAM, and as for the SMCs housed within the lumens of the PLGA MTAMs, a monolayer with high degree of orientation was observed. The PLGA MTAM registered a burst pressure of 1092.2 ± 175.3 mmHg, which was sufficient for applications such as small diameter blood vessels. Potentially, the PLGA MTAM could be used as a suitable substrate for vascular engineering

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Hung, Huey-Shan, and Shan-hui Hsu. "Surface Modification by Nanobiomaterials for Vascular Tissue Engineering Applications." Current Medicinal Chemistry 27, no. 10 (March 27, 2020): 1634–46. http://dx.doi.org/10.2174/0929867325666180914104633.

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Treatment of cardiovascular disease has achieved great success using artificial implants, particularly synthetic-polymer made grafts. However, thrombus formation and restenosis are the current clinical problems need to be conquered. New biomaterials, modifying the surface of synthetic vascular grafts, have been created to improve long-term patency for the better hemocompatibility. The vascular biomaterials can be fabricated from synthetic or natural polymers for vascular tissue engineering. Stem cells can be seeded by different techniques into tissue-engineered vascular grafts in vitro and implanted in vivo to repair the vascular tissues. To overcome the thrombogenesis and promote the endothelialization effect, vascular biomaterials employing nanotopography are more bio-mimic to the native tissue made and have been engineered by various approaches such as prepared as a simple surface coating on the vascular biomaterials. It has now become an important and interesting field to find novel approaches to better endothelization of vascular biomaterials. In this article, we focus to review the techniques with better potential improving endothelization and summarize for vascular biomaterial application. This review article will enable the development of biomaterials with a high degree of originality, innovative research on novel techniques for surface fabrication for vascular biomaterials application.

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Feldman, H. I., S. Kobrin, and A. Wasserstein. "Hemodialysis vascular access morbidity." Journal of the American Society of Nephrology 7, no. 4 (April 1996): 523–35. http://dx.doi.org/10.1681/asn.v74523.

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Complications associated with hemodialysis vascular access represent one of the most important sources of morbidity among ESRD patients in the United States today. In this study, new data on the magnitude and growth of vascular access-related hospitalization in the United States is presented, demonstrating that the costs of this morbidity will soon exceed $1 billion per yr. This study also reviews published literature on the morbidity associated specifically with native arteriovenous fistulae, polytetrafluoroethylene bridge grafts, and permanent central venous catheters. Next, new information on the changing patterns of vascular access type in the United States is presented, demonstrating the continuing evolution of medical practice away from the use of arteriovenous fistulae in favor of more reliance on synthetic bridge grafts. Based on these data, a discussion is provided of the tradeoffs among the most commonly available modalities of vascular access today. Although radial arteriovenous fistulae continue to represent the optimal access modality, the appropriate roles for brachial arteriovenous fistulae, synthetic bridge grafts, and central venous catheters are less certain because of inadequate data on the long-term function of the first and the high rates of complications associated with the latter two. To reduce vascular access-related morbidity, strategies must be developed not only to prevent and detect appropriately early synthetic vascular access dysfunction, but to better identify the patients in a whom radial arteriovenous fistula is a viable clinical option.

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Gage, Shawn M., and Jeffrey H. Lawson. "Bioengineered hemodialysis access grafts." Journal of Vascular Access 18, no. 1_suppl (March 2017): S56—S63. http://dx.doi.org/10.5301/jva.5000692.

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There is a need for bioengineered therapies to improve the overall health of the growing and aging world population. Patients with renal failure have a life-long requirement for a durable form of hemodialysis vascular access. In this article, we review the history of tissue engineering as it pertains to bioengineered grafts and vessels for hemodialysis access. Over the years, various strategies have been utilized to develop ideal, humanized vessels for vascular replacement such as fixation of animal or human vessels, cell seeding of synthetic materials, and the synthesis of completely autologous or allogeneic bioengineered vessels. Tissue engineering technologies from two companies have progressed to reach phase 2 and phase 3 clinical trials, but the prospect of newer strategies on the horizon may offer improved manufacturing efficiency, a greater variety of conduit size and length, and reduce the cost to produce.

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Yalcin Enis, Ipek, and Telem Gok Sadikoglu. "Design parameters for electrospun biodegradable vascular grafts." Journal of Industrial Textiles 47, no. 8 (June 14, 2016): 2205–27. http://dx.doi.org/10.1177/1528083716654470.

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The inadequacies of the currently used small diameter, non-biodegradable synthetic grafts prompt researchers to focus on the design parameters of vascular grafts. Since the purpose is to mimic the native vessel as far as possible, the design parameters are mainly determined by the layout of cell types and proteins in the layers of the vessels and the nano and micro structure of their environments. In consequence of this, the complex structure of native vessels has become a broad source of inspiration for researchers. Electrospun fibrous scaffolds with their well accepted advantages are promising candidates and researchers are able to work with various materials with differing forms, structures, dimensions, and surface modifications according to their requirements. On the other hand, both synthetic biodegradable polymers and natural proteins are the key materials that enable researchers to take one step closer to achieving the goal of creating an autologous vessel at some time after implantation. When the priority and significance of the need for small diameter vascular grafts is considered, the research field to improve vascular grafts is worthy of note. In this regard, the objective of this review is to discuss comparatively the current studies on the design parameters of electrospun vascular grafts, defined as fiber orientation, fiber diameter, pore size and porosity, wall thickness, and material selection, based on the structure of native blood vessels, the requirements of vascular grafts and electrospinning technology, and the advantages of electrospun vascular grafts, to give an outlook for further studies.

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Tatterton, Mark, Stacy-Paul Wilshaw, Eileen Ingham, and Shervanthi Homer-Vanniasinkam. "The Use of Antithrombotic Therapies in Reducing Synthetic Small-Diameter Vascular Graft Thrombosis." Vascular and Endovascular Surgery 46, no. 3 (February 5, 2012): 212–22. http://dx.doi.org/10.1177/1538574411433299.

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Background. Thrombosis of synthetic small-diameter bypass grafts remains a major problem. The aim of this article is to review the antithrombotic strategies that have been used in an attempt to reduce graft thrombogenicity. Methods. A PubMed/MEDLINE search was performed using the search terms “vascular graft thrombosis,” “small-diameter graft thrombosis,” “synthetic graft thrombosis” combined with “antithrombotic,” “antiplatelet,” “anticoagulant,” “Dacron,” “PTFE,” and “polyurethane.” Results. The majority of studies on antithrombotic therapies have used either in vitro models or in vivo animal experiments. Many of the therapies used in these settings do show antithrombotic efficacy against synthetic graft materials. There is however, a distinct lack of human in vivo studies to further delineate the performance and limitations of therapies displaying good antithrombotic characteristics. Conclusion. Very few antithrombotic therapies have translated into clinical use. More human in vivo studies are required to assess the efficacy and safety of such therapies.

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Rosalia, Mariella, Priusha Ravipati, Pietro Grisoli, Rossella Dorati, Ida Genta, Enrica Chiesa, Giovanna Bruni, and Bice Conti. "Tobramycin Supplemented Small-Diameter Vascular Grafts for Local Antibiotic Delivery: A Preliminary Formulation Study." International Journal of Molecular Sciences 22, no. 24 (December 17, 2021): 13557. http://dx.doi.org/10.3390/ijms222413557.

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Peripheral artery occlusive disease is an emerging cardiovascular disease characterized by the blockage of blood vessels in the limbs and is associated with dysfunction, gangrene, amputation, and a high mortality risk. Possible treatments involve by-pass surgery using autologous vessel grafts, because of the lack of suitable synthetic small-diameter vascular prosthesis. One to five percent of patients experience vascular graft infection, with a high risk of haemorrhage, spreading of the infection, amputation and even death. In this work, an infection-proof vascular graft prototype was designed and manufactured by electrospinning 12.5% w/v poly-L-lactic-co-glycolic acid solution in 75% v/v dichloromethane, 23.8% v/v dimethylformamide and 1.2% v/v water, loaded with 0.2% w/wPLGA. Polymer and tobramycin concentrations were selected after viscosity and surface tension and after HPLC-UV encapsulation efficiency (EE%) evaluation, respectively. The final drug-loaded prototype had an EE% of 95.58% ± 3.14%, with smooth fibres in the nanometer range and good porosity; graft wall thickness was 291 ± 20.82 μm and its internal diameter was 2.61 ± 0.05 mm. The graft’s antimicrobic activity evaluation through time-kill assays demonstrated a significant and strong antibacterial activity over 5 days against Staphylococcus aureus and Escherichia coli. An indirect cell viability assay on Normal Human Dermal Fibroblasts (NHDF) confirmed the cytocompatibility of the grafts.

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Schneider, Peter A., Harry F. Kotz[eacute], Anthon du P. Heyns, and Stephen R. Hanson. "Thromboembolic potential of synthetic vascular grafts in baboons." Journal of Vascular Surgery 10, no. 1 (July 1989): 0075–82. http://dx.doi.org/10.1067/mva.1989.vs0100075.

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Schneider, Peter A., Harry F. Kotzé, Anthon du P. Heyns, and Stephen R. Hanson. "Thromboembolic potential of synthetic vascular grafts in baboons." Journal of Vascular Surgery 10, no. 1 (July 1989): 75–82. http://dx.doi.org/10.1016/0741-5214(89)90288-7.

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Stowell, Chelsea E. T., and Yadong Wang. "Quickening: Translational design of resorbable synthetic vascular grafts." Biomaterials 173 (August 2018): 71–86. http://dx.doi.org/10.1016/j.biomaterials.2018.05.006.

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Absood, Afaf, Akira Furutani, Tsutomu Kawamura, and Linda M. Graham. "Differential PDGF secretion by graft and aortic SMC in response to oxidized LDL." American Journal of Physiology-Heart and Circulatory Physiology 283, no. 2 (August 1, 2002): H725—H732. http://dx.doi.org/10.1152/ajpheart.00060.2002.

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Smooth muscle cells (SMC) from prosthetic vascular grafts constitutively secrete higher levels of platelet-derived growth factor-AA (PDGF-AA) than aortic SMC. Lipid oxidation products accumulate in grafts and may stimulate PDGF production. The effect of oxidized low-density lipoprotein (oxLDL) on PDGF-AA secretion by aortic and graft SMC was compared. SMC isolated from canine thoracic aorta or Dacron thoracoabdominal grafts ( n = 10) were incubated with native LDL or oxLDL (0–400 μg/ml) for 72 h. PDGF-AA in the conditioned medium was measured with enzyme-linked immunosorbent assay. OxLDL increased PDGF-AA production by graft SMC from 78 ± 2 to 256 ± 16 pg PDGF/μg DNA and aortic SMC from 21 ± 1 to 40 ± 2 pg PDGF/μg DNA. Native LDL had no effect. N-acetylcysteine inhibited oxLDL-induced PDGF increase. Both superoxide and H2O2 stimulated PDGF secretion by graft SMC had little effect on aortic SMC. Our results suggest that PDGF production by graft (synthetic) SMC is more sensitive to stimulation by oxidative stress than aortic (contractile) SMC. Lipid oxidation products that accumulate in prosthetic vascular grafts can cause an oxidative stress, which stimulates PDGF production by graft SMC. PDGF can induce migration of aortic SMC onto the graft, contributing to the development of intimal hyperplasia.

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Gade, Piyusha S., Keewon Lee, Blaise N. Pfaff, Yadong Wang, and Anne M. Robertson. "Degradation and erosion mechanisms of bioresorbable porous acellular vascular grafts: an in vitro investigation." Journal of The Royal Society Interface 14, no. 132 (July 2017): 20170102. http://dx.doi.org/10.1098/rsif.2017.0102.

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A fundamental mechanism of in situ tissue regeneration from biodegradable synthetic acellular vascular grafts is the effective interplay between graft degradation, erosion and the production of extracellular matrix. In order to understand this crucial process of graft erosion and degradation, we conducted an in vitro investigation of grafts ( n = 4 at days 1, 4, 7, 10 each) exposed to enzymatic degradation. Herein, we provide constitutive relationships for mass loss and mechanical properties based on much-needed experimental data. Furthermore, we formulate a mathematical model to provide a physics-based framework for understanding graft erosion. A novel finding is that despite their porous nature, grafts lost mass exponentially via surface erosion demonstrating a 20% reduction in outer diameter and no significant change in apparent density. A diffusion based, concentration gradient-driven mechanistic model of mass loss through surface erosion was introduced which can be extended to an in vivo setting through the use of two degradation parameters. Furthermore, notably, mechanical properties of degrading grafts did not scale with mass loss. Thus, we introduced a damage function scaling a neo-Hookean model to describe mechanical properties of the degrading graft; a refinement to existing mass-dependent growth and remodelling (G&R) models. This framework can be used to improve accuracy of well-established G&R theories in biomechanics; tools that predict evolving structure–function relationships of neotissues and guide graft design.

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Kielty, Cay M., Simon Stephan, Michael J. Sherratt, Matthew Williamson, and C. Adrian Shuttleworth. "Applying elastic fibre biology in vascular tissue engineering." Philosophical Transactions of the Royal Society B: Biological Sciences 362, no. 1484 (June 22, 2007): 1293–312. http://dx.doi.org/10.1098/rstb.2007.2134.

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For the treatment of vascular disease, the major cause of death in Western society, there is an urgent need for tissue-engineered, biocompatible, small calibre artery substitutes that restore biological function. Vascular tissue engineering of such grafts involves the development of compliant synthetic or biomaterial scaffolds that incorporate vascular cells and extracellular matrix. Elastic fibres are major structural elements of arterial walls that can enhance vascular graft design and patency. In blood vessels, they endow vessels with the critical property of elastic recoil. They also influence vascular cell behaviour through direct interactions and by regulating growth factor activation. This review addresses physiological elastic fibre assembly and contributions to vessel structure and function, and how elastic fibre biology is now being exploited in small diameter vascular graft design.

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Ijima, Hiroshi, Kunihiko Hirabayashi, Yuzura Sakakibara, Tatsuo Tsutsui, Toshio Mitsui, and Motokazu Hori. "Results of Femoro-Femoral Vein Bypass Grafting with Temporary Arteriovenous Fistula for Femoro-Iliac Venous Thrombosis: Differences between Operations in the Acute and Chronic Phases." Phlebology: The Journal of Venous Disease 5, no. 4 (December 1990): 237–44. http://dx.doi.org/10.1177/026835559000500405.

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Femoro-femoral vein bypass operation using a synthetic vascular graft with simultaneous construction of a temporary arteriovenous fistula (A-V f.) was performed in eight patients with acute femoro-iliac venous thrombosis after successful femoral thrombectomy but unsuccessful iliac thrombectomy; this operation was also performed in one patient with subacute thrombosis of the iliac vein and three patients with femoro-iliac post-phlebitic syndrome. Of the first nine patients who underwent the operation in the acute or subacute phase of the disease, the synthetic vascular grafts remained patent after closure of the A-V f. in six (66.7%), and no recurrence of symptoms was observed in any of the nine, including those in whom the graft was occluded. However, the graft remained patent in only one (33.3%) of the three patients who underwent the operation in the chronic phase and no improvement in symptoms was observed in the patients with occluded grafts. These differences in the results of bypass grafting are considered to be due to differences in the development of pelvic venous collaterals. The indications for this operation should be evaluated after close examination of the state of collateral vasculature.

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Malik, Sairish, Subramanian Sundarrajan, Tanveer Hussain, Ahsan Nazir, and Seeram Ramakrishna. "Fabrication of Highly Oriented Cylindrical Polyacrylonitrile, Poly(lactide-co-glycolide), Polycaprolactone and Poly(vinyl acetate) Nanofibers for Vascular Graft Applications." Polymers 13, no. 13 (June 24, 2021): 2075. http://dx.doi.org/10.3390/polym13132075.

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Small-diameter vascular grafts fabricated from synthetic polymers have found limited applications so far in vascular surgeries, owing to their poor mechanical properties. In this study, cylindrical nanofibrous structures of highly oriented nanofibers made from polyacrylonitrile, poly (lactide-co-glycolide) (PLGA), polycaprolactone (PCL) and poly(vinyl acetate) (PVAc) were investigated. Cylindrical collectors with alternate conductive and non-conductive segments were used to obtain highly oriented nanofibrous structures at the same time with better mechanical properties. The surface morphology (orientation), mechanical properties and suture retention of the nanofibrous structures were characterized using SEM, mechanical tester and universal testing machine, respectively. The PLGA nanofibrous cylindrical structure exhibited excellent properties (tensile strength of 9.1 ± 0.6 MPa, suture retention strength of 27N and burst pressure of 350 ± 50 mmHg) when compared to other polymers. Moreover, the PLGA grafts showed good porosity and elongation values, that could be potentially used for vascular graft applications. The combination of PLGA nanofibers with extracellular vesicles (EVs) will be explored as a potential vascular graft in future.

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Kawecka, A., A. DȨbska-Ślizien, G. Korejwo, J. Prajs, E. Król, B. Rutkowski, J. Lasek, and J. Gwoździewicz. "Evaluation of Gore-Tex Graft Patency in Hemodialysis Access." Journal of Vascular Access 4, no. 2 (April 2003): 45–49. http://dx.doi.org/10.1177/112972980300400203.

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Aim The purpose of this retrospective study was to analyze the patency and complications of Gore-Tex grafts used in hemodialysis (HD) access. Methods In the last 16 years, 1649 surgical procedures were performed on 655 patients to ensure and maintain permanent HD access. The study group consisted of 64 HD patients on whom 81 vascular synthetic PTFE Goretex grafts were performed. There were 28 males and 36 females, 3 of them were children (4.7%). Mean age was 54.2 years (range 15–77). Two types of Gore-Tex prosthesis were used: Diastat and Stretch. All grafts were implanted in the upper extremities. Kaplan-Meier survival curves were calculated to determine primary and secondary patency. Log-rank analysis was used to determine differences between curves. Results Primary and secondary patency at 12 months was 52.5% and 67.5%, and at 18 months respectively 41.5% and 58.2%. The Diastat graft had a lower primary and secondary patency compared with the Stretch graft (respectively p = 0.02 and p = 0.008). Factors such as gender, coexisting diabetes and hypertension did not determine graft patency. Thrombosis was one of the most frequent complications. The remaining complications included stenosis, pseudoaneurysms, infection, steal syndrome and seroma. Conclusion On the basis of our experience Stretch grafts appear a better option for creating vascular access for HD than Diastat grafts.

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Kannan, Ruben Y., Sandip Sarkar, Jalaledin Mirzay-Razaz, and Alexander M. Seifalian. "New vessels: Vascular tissue engineering." Biochemist 29, no. 1 (February 1, 2007): 12–15. http://dx.doi.org/10.1042/bio02901012.

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The use of vascular bypass grafts in patients is not new. The high prevalence of atherosclerosis has seen them being used in the treatment of some of the 800 000 cases of myocardial infarction in the UK. So, is there a need for tissue-engineered blood vessels if there is a functional prosthetic alternative? While this may hold true for vessels with high-blood-flow rates1, the patency rates of poly(ethylene terephthalate) (Dacron®) and expanded polytetrafluoroethylene (ePTFE) grafts are less satisfactory at lower flow rates. Given the limitations with synthetic materials alone, a biological or bio-hybrid vascular prosthesis could provide us with the ideal blood-vessel substitute.

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Yalcin Enis, Ipek, Telem Gok Sadikoglu, Jana Horakova, and David Lukas. "The post-morphological analysis of electrospun vascular grafts following mechanical testing." Journal of Polymer Engineering 38, no. 6 (July 26, 2018): 525–35. http://dx.doi.org/10.1515/polyeng-2017-0157.

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AbstractVascular grafts provide promising scaffolds for patients recuperating from cardiovascular diseases. Since it is necessary to mimic the native vessel in order to overcome the limitations of currently employed synthetic prostheses, researchers are tending to focus on the design of electrospun biodegradable multi-layer scaffolds which involves varying either the polymer type or constructional properties in each layer which, in turn, reveals the importance of layer interactions and their composite effect on the final multi-layer graft. This study describes the fabrication of biodegradable single-layer tubular scaffolds from polycaprolactone and poly(L-lactide)caprolactone polymers composed of either randomly distributed or, preferably, radially oriented fibers. Subsequently, bi-layer scaffolds were fabricated with a randomly distributed inner layer and a radially oriented outer layer from various polymer couple variations. The study focuses on vascular graft production technology including its morphology and mechanical properties. The post-morphologies of single-layer and bi-layer tubular scaffolds designed for vascular grafts were investigated as a continuation of a previously performed analysis of their mechanical properties. The results indicate that the mechanical properties of the final bi-layer grafts were principally influenced by the radially oriented outer layers acting as thetunica mediaof the native vessels when the appropriate polymer couples were chosen for the sub-layers.

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Pislaru, S. V. "Magnetic Forces Enable Rapid Endothelialization of Synthetic Vascular Grafts." Circulation 114, no. 1_suppl (July 4, 2006): I—314—I—318. http://dx.doi.org/10.1161/circulationaha.105.001446.

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Cardozo, M. A., A. D. Frankini, and T. P. Bonamigo. "Use of Superficial Femoral Vein in the Treatment of Infected Aortoiliofemoral Prosthetic Grafts." Cardiovascular Surgery 10, no. 4 (August 2002): 304–10. http://dx.doi.org/10.1177/096721090201000403.

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Purpose: To assess the use of the superficial femoral vein for the reconstruction of the aortoiliofemoral sector in the treatment of prosthetic infections. Methods: From December 1995 to November 1999, 12 patients with infection involving a synthetic vascular prosthesis were submitted to thirteen surgical procedures involving partial or total resection of a synthetic vascular prosthesis and restoration of arterial flow with an in situ femoral vein. Results: The overall operative mortality rate was 15.3% (2 out of 3 patients who underwent total graft replacement and 0 out of 9 patients who underwent unilateral graft replacement). Major amputations related to the surgical procedures were performed in two cases (an 87.5% rate of limb salvage). The series was followed up on average for 22 months (range: 6–65 months). No patient presented clinically significant edema or signs of chronic venous insufficiency in the lower limbs used as donors of autogenous venous grafts. All surviving patients presented complete resolution of the infectious signs and symptoms and none of them presented late thrombosis of the venous graft. Conclusion: The use of the superficial femoral vein is a good surgical alternative for the treatment of prosthetic infections with minimal venous morbidity of the lower limbs used as venous graft donors. The autogenous venous grafts present good long-term patency and excellent adaptation to the aortoiliofemoral position.

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Senokosova, E. A., E. O. Krivkina, L. V. Antonova, and L. S. Barbarash. "Biodegradable small-diameter vascular graft: types of modification with bioactive molecules and RGD peptides." Russian Journal of Transplantology and Artificial Organs 22, no. 1 (April 23, 2020): 86–96. http://dx.doi.org/10.15825/1995-1191-2020-1-86-96.

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The need for small-diameter grafts for replacing the damaged area of the blood pool is still very high. These grafts are very popular for coronary artery bypass grafting. Polymeric synthetic grafts are an alternative to autografts. A promising area of tissue engineering is the creation of a biodegradable graft. It can serve as the basis for de novo generation of vascular tissue directly in the patient’s body. Optimization of the polymer composition of products has led to improved physicomechanical and biocompatible properties of the products. However, the improvements are still far from needed. One of the decisive factors in the reliability of a small-diameter vascular graft is the early formation of endothelial lining on its inner surface, which can provide atrombogenic effect and full lumen of the future newly formed vessel. To achieve this goal, grafts are modified by incorporating bioactive molecules or functionally active peptide sequences into the polymer composition or immobilizing on its inner surface. Peptide sequences include cell adhesion site – arginine-glycine-aspartic acid (RGD peptide). This sequence is present in most extracellular matrix proteins and has a tropism for integrin receptors of endothelial cells. Many studies have shown that imitation of the functional activity of the natural extracellular matrix can promote spontaneous endothelization of the inner surface of a vascular graft. Moreover, configuration of the RGD peptide determines the survival and differentiation of endothelial cells. The linker through which the peptide is crosslinked to the polymer surface determines the bioavailability of the RGD peptide for endothelial cells.

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Pecoraro, Felice, Mayur Krishnaswamy, Johnny Steuer, Gilbert Puippe, Nicola Mangialardi, Thomas Pfammatter, Zoran Rancic, Frank J. Veith, Neal S. Cayne, and Mario Lachat. "Predilation technique with balloon angioplasty to facilitate percutaneous groin access of large size sheath through scar tissue." Vascular 25, no. 4 (January 9, 2017): 396–401. http://dx.doi.org/10.1177/1708538116688786.

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Purpose Percutaneous remote access for endovascular aortic repair is an advantageous alternative to open access. Previous surgery in the femoral region and the presence of synthetic vascular grafts in the femoral/iliac arteries represent major limitations to percutaneous remote access. The aim of this study was to evaluate an original technique used for enabling percutaneous remote access for thoracic or abdominal endovascular aortic repair in patients with scar tissue and/or a vascular graft in the groin. Methods Twenty-five consecutive patients with a thoracic (11/25; 44%) or an aortic aneurysm (14/25; 66%) and with a synthetic vascular graft in the groin (16/25; 64%) or a redo groin access (9/25; 36%) were managed through the percutaneous remote access. In all patients, a percutaneous transluminal angioplasty balloon was used to predilate the scar tissue and the femoral artery or the synthetic vascular graft after preclosing (ProGlide®; Abbott Vascular, Santa Clara, CA, USA). In 10 patients, requiring a 20 Fr sheath, a 6 mm percutaneous transluminal angioplasty balloon was used; and in the remaining 15, requiring a 24 Fr sheath, an 8 mm percutaneous transluminal angioplasty balloon. Preclosing was exclusively performed using ProGlide®. Mean follow-up was 15 months. Results In all cases, stent-graft deployment was successful. There was one surgical conversion (4%; 1/25) due to bleeding from a femoral anastomosis. Two cases required additional percutaneous maneuvers (postclosing with another system in one patient and endoluminal shielding with stent-graft in the other patient). No pseudoaneurysm or access complication occurred during the follow-up. Conclusions Percutaneous access in redo groins with scar tissue and/or synthetic vascular graft using ultrasound-guided punction, preclosing with ProGlide® system and predilation with percutaneous transluminal angioplasty balloon to introduce large size sheath as used for endovascular aortic repair showed to be feasible, safe and with few local complications.

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BACALBASA, Nicolae, Irina BALESCU, Claudia STOICA, Lucian POP, Valentin VARLAS, Cristina MARTAC, Andrei VOICHITOIU, and Tarig MASSAWI. "Autologous grafts for vascular resections after extended resections for locally advanced or borderline resectable pancreatic tumors." Romanian Journal of Medical Practice 17, no. 2 (June 30, 2022): 76–79. http://dx.doi.org/10.37897/rjmp.2022.2.6.

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Once the surgical techniques improved, vascular resections have been proposed in order to increase the radicality in borderline or locally advanced pancreatic cancer. Traditionally, vascular reconstructions in such cases have been performed by using synthetic grafts; however, these prostheses have been associated with significant complications such as infection, thrombosis or leaks, leading to a very difficult postoperative recovery. Therefore, attention was focused on replacing these artificial materials with biological ones such as cadaveric grafts, autologous grafts or even animal grafts. These grafts proved to be more efficient when it comes to the rates of perioperative complications, thrombosis, infection or leakage being more rarely reported. The aim of the current paper is to discuss about the most frequently used biological grafts.

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Domínguez-Robles, Juan, Luis Diaz-Gomez, Emilia Utomo, Tingjun Shen, Camila J. Picco, Carmen Alvarez-Lorenzo, Angel Concheiro, Ryan F. Donnelly, and Eneko Larrañeta. "Use of 3D Printing for the Development of Biodegradable Antiplatelet Materials for Cardiovascular Applications." Pharmaceuticals 14, no. 9 (September 11, 2021): 921. http://dx.doi.org/10.3390/ph14090921.

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Small-diameter synthetic vascular grafts are required for surgical bypass grafting when there is a lack of suitable autologous vessels due to different reasons, such as previous operations. Thrombosis is the main cause of failure of small-diameter synthetic vascular grafts when used for this revascularization technique. Therefore, the development of biodegradable vascular grafts capable of providing a localized and sustained antithrombotic drug release mark a major step forward in the fight against cardiovascular diseases, which are the leading cause of death globally. The present paper describes the use of an extrusion-based 3D printing technology for the production of biodegradable antiplatelet tubular grafts for cardiovascular applications. For this purpose, acetylsalicylic acid (ASA) was chosen as a model molecule due to its antiplatelet activity. Poly(caprolactone) and ASA were combined for the fabrication and characterization of ASA-loaded tubular grafts. Moreover, rifampicin (RIF) was added to the formulation containing the higher ASA loading, as a model molecule that can be used to prevent vascular prosthesis infections. The produced tubular grafts were fully characterized through multiple techniques and the last step was to evaluate their drug release, antiplatelet and antimicrobial activity and cytocompatibility. The results suggested that these materials were capable of providing a sustained ASA release for periods of up to 2 weeks. Tubular grafts containing 10% (w/w) of ASA showed lower platelet adhesion onto the surface than the blank and grafts containing 5% (w/w) of ASA. Moreover, tubular grafts scaffolds containing 1% (w/w) of RIF were capable of inhibiting the growth of Staphylococcus aureus. Finally, the evaluation of the cytocompatibility of the scaffold samples revealed that the incorporation of ASA or RIF into the composition did not compromise cell viability and proliferation at short incubation periods (24 h).

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Jeong, YeJin, Yuan Yao, and Evelyn K. F. Yim. "Current understanding of intimal hyperplasia and effect of compliance in synthetic small diameter vascular grafts." Biomaterials Science 8, no. 16 (2020): 4383–95. http://dx.doi.org/10.1039/d0bm00226g.

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Chiu, Yung-Cheng, Yu-Fang Shen, Alvin Kai-Xing Lee, Shu-Hsien Lin, Yu-Chen Wu, and Yi-Wen Chen. "3D Printing of Amino Resin-based Photosensitive Materials on Multi-parameter Optimization Design for Vascular Engineering Applications." Polymers 11, no. 9 (August 24, 2019): 1394. http://dx.doi.org/10.3390/polym11091394.

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Cardiovascular diseases are currently the most common cause of death globally and of which, the golden treatment method for severe cardiovascular diseases or coronary artery diseases are implantations of synthetic vascular grafts. However, such grafts often come with rejections and hypersensitivity reactions. With the emergence of regenerative medicine, researchers are now trying to explore alternative ways to produce grafts that are less likely to induce immunological reactions in patients. The main goal of such studies is to produce biocompatible artificial vascular grafts with the capability of allowing cellular adhesion and cellular proliferation for tissues regeneration. The Design of Experimental concepts is employed into the manufacturing process of digital light processing (DLP) 3D printing technology to explore near-optimal processing parameters to produce artificial vascular grafts with vascular characteristics that are close to native vessels by assessing for the cause and effect relationships between different ratios of amino resin (AR), 2-hydroxyethyl methacrylate (HEMA), dopamine, and curing durations. We found that with proper optimization of fabrication procedures and ratios of materials, we are able to successfully fabricate vascular grafts with good printing resolutions. These had similar physical properties to native vessels and were able to support cellular adhesion and proliferation. This study could support future studies in exploring near-optimal processes for fabrication of artificial vascular grafts that could be adapted into clinical applications.

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Ross, John R. "Insertion of Short Introducer Sheaths into a Polyurethane Vascular Access Graft for Immediate Hemodialysis Access." Journal of Vascular Access 4, no. 2 (April 2003): 62–67. http://dx.doi.org/10.1177/112972980300400206.

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While native AV fistulae are considered the “gold standard” for hemodialysis patients in need of long-term access, synthetic grafts are the best option for patients who are not candidates for an AV fistula. While AV fistulae should be allowed to mature for 3 – 4 months prior to cannulation, PTFE grafts may be cannulated 14 days after placement. Despite the benefit of earlier cannulation in PTFE graft recipients compared to AV fistulae patients, one critical limitation is that immediate post-operative cannulation is not possible. The self-sealing nature of the polyurethane Vectra® Graft overcomes the time restriction until first cannulation, allowing much earlier vascular access than conventional PTFE grafts. We describe here a procedure for insertion of 5-French DialEase™ Introducer Sheaths into the Vectra Graft for immediate, post-operative hemodialysis access. This procedure eliminates time restrictions until first cannulation of the Vectra Graft; the sheath's large diameter side-port ensures high flow for efficient hemodialysis. Moreover, insertion of the sheath into a new or existing Vectra Graft provides vascular access for inspection of the graft anastomoses, angiography, angioplasty, venography, and declotting procedures. The post-operative introduction of DialEase Sheaths into a Vectra Graft for immediate hemodialysis was successfully performed in 35 patients. All patients then immediately received high-flow hemodialysis (400 – 500 ml) with venous pressures ≤ 125 mmHg and negative arterial pressure ∼100 mmHg. To date, there have been no infections, immediate graft thrombosis or other complications associated with this procedure, and all patients have remained free of anastomotic problems.

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Lee, Bob S. L., Nianji Yang, Miguel Santos, Matthew J. Moore, Angus J. Grant, Jun-Hyeog Jang, Behnam Akhavan, Marcela M. Bilek, Richard P. Tan, and Steven G. Wise. "Truncated vascular endothelial cadherin enhances rapid endothelialization of small diameter synthetic vascular grafts." Materials Today Advances 14 (June 2022): 100222. http://dx.doi.org/10.1016/j.mtadv.2022.100222.

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Reddy, Daniel J. "Atherosclerosis in vascular grafts for peripheral vascular disease part 2. Synthetic arterial prostheses." Journal of Vascular Surgery 6, no. 3 (September 1987): 324. http://dx.doi.org/10.1016/0741-5214(87)90263-1.

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Lawson, Jeffrey. "Engineered Blood Vessels." Blood 130, Suppl_1 (December 7, 2017): SCI—12—SCI—12. http://dx.doi.org/10.1182/blood.v130.suppl_1.sci-12.sci-12.

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Abstract The field of tissue engineering has has made significant progress in the past 20 years. Of the many tissues and organs in development, the area of vascular tissue engineering is now one of the most mature. In that regard, we have developed a novel tissue engineered vascular graft (human acellular vessel [HAV]) that addresses many of the limitations of native vein harvest and the performance of both synthetic ePTFE and autologous vein grafts. The HAV is manufactured in a laboratory by culturing human vascular cells within a biodegradable scaffold that forms a mechanically robust tissue engineered blood vessel. The cells are then completely removed (decellularization), leaving behind a non-immunogenic human collagen-based vascular tissue that can be stored on the shelf for months at a time and ready for immediate implantation into any patient. The HAV is currently being evaluated in Phase II and Phase III clinical trials in the U.S., E.U. and Israel as an arteriovenous vascular access graft for hemodialysis in patients with end-stage renal failure and as an arterial substitute for patients in need of vascular bypass for peripheral arterial disease or vascular trauma. Following clinical implantation, we have observed repopulation and remodeling of the manufactured vessel with the hosts' own cells. We hypothesize that the biological composition of the HAV, compared to synthetic vascular grafts, promotes its physiological integration into host tissue including support of normal host cell infiltration and function. Host cells that identify histologically similar to vascular smooth muscle cells appear to repopulate the middle of the vessel and recipient cells characterized as endothelial cells appear to cover the luminal surface of the implanted vessel. Clinical observations of the Phase II trials have demonstrated excellent vessel durability and a freedom from both early and delayed infection. Based on the success of the Phase II studies, a Global Phase III study is underway for patients in need of dialysis access shunts and vascular programs for vascular (arterial) bypass and trauma are expanding. Disclosures Lawson: InnaVasc: Patents & Royalties; Humacyte, Inc.: Employment.

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Porile, J. L., and M. Richter. "Preservation of vascular access." Journal of the American Society of Nephrology 4, no. 4 (October 1993): 997–1003. http://dx.doi.org/10.1681/asn.v44997.

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Preservation of vascular access is critical in the long-term successful management of hemodialysis patients. Dialysis access abnormalities are the most common cause of hospitalization in this patient group, and access problems can increase the morbidity and cost involved in the care of these patients. Native fistulas are preferable to synthetic grafts because of longer survival and a lower complication rate. Venous outflow stenosis is the most common site of obstruction in a failing graft. The pathophysiology of access failure is poorly understood, but it seems to be related to intimal hyperplasia in the native vessel downstream from the anastomosis. The stimulation of local growth factors by needle puncture may also play a role. An assessment of access adequacy includes careful physical examination, laboratory evaluation, and ultimately, angiography. Measurements of recirculation and venous pressure are commonly used to screen for access dysfunction, and their appropriate use will lower the incidence of graft loss in dialysis units. Treatment is usually either angioplasty or surgery, with some centers having success with thrombolytic therapy. New techniques such as atherectomy and stent placement may prove to be beneficial, but this requires further study.

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Meyer, Schweiger, and Lang. "Der extraanatomische Bypass zur Behandlung einer Gefäßprotheseninfektion in der Leiste." Vasa 28, no. 4 (November 1, 1999): 283–88. http://dx.doi.org/10.1024/0301-1526.28.4.283.

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Background: Infection of an alloplastic vascular graft is a serious complication and often involves the groin. We propose a therapeutic concept using extraanatomic bypass to avoid the septic groin in case of an infected alloplastic vascular reconstruction. Patients and methods: The course of 25 patients (18 men, 7 women, mean age 61 years) with a grade III inguinal infection following placement of an aortic or femoro-distal synthetic graft made of Dacron or PTFE was analysed. The treatment consisted of excision of the infected graft material and extraanatomic reconstruction with ringed PTFE grafts in all patients. Mean follow-up after the extraanatomic procedure was 21 months (1–91 months). Results: Direct surgical exploration definitely secured graft infection in almost three-quarters of the cases. The most common organism isolated was Staphylococcus aureus (13/22 = 59%). At the time of infection 60% of the patients had critical limb ischemia necessitating vascular reconstruction simultaneously with total or partial excision of the infected graft. Complications of the extraanatomic bypass occurred in 7 cases (overall morbidity 28%). Postoperatively, one patient required major amputation. Hospital mortality was 8%. Primary patency and secondary patency rates of extraanatomic grafts amounted to 78.0% (± 10.0 SD) and 84.1% (± 8.7 SD) respectively after two years. Limb salvage rated 78.4% (± 11.6 SD) after 2 years, the 2-year-survival rate was 73.8% (± 9.3 SD). Conclusions: According to the favourable long-term limb salvage and survival rates, we support simultaneous vascular reconstruction by extraanatomic bypass and explantation of the infected graft material in case of grade III inguinal infection of alloplastic vascular reconstructions.

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Byrne, Oisín, Fergal Coulter, Ellen T. Roche, and Eoin D. O'Cearbhaill. "In silico design of additively manufacturable composite synthetic vascular conduits and grafts with tuneable compliance." Biomaterials Science 9, no. 12 (2021): 4343–55. http://dx.doi.org/10.1039/d0bm02169e.

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Prendiville, E. J., S. Laliberté Verdon, K. E. Gould, K. Ramberg, R. J. Connolly, and A. D. Callow. "Correlation of γ-radioactivity and Scanning Electron Microscopy in measurement of retention of 111Indium-labeled canine endothelial cells on synthetic vascular grafts." Proceedings, annual meeting, Electron Microscopy Society of America 47 (August 6, 1989): 886–87. http://dx.doi.org/10.1017/s0424820100156419.

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Abstract:

Endothelial cell (EC) seeding is postulated as a mechanism of improving patency in small caliber vascular grafts. However the majority of seeded EC are lost within 24 hours of restoration of blood flow in previous canine studies . We postulate that the cells have insufficient time to fully develop their attachment to the graft surface prior to exposure to hemodynamic stress. We allowed EC to incubate on fibronectin-coated ePTFE grafts for four different time periods after seeding and measured EC retention after perfusion in a canine ex vivo shunt circuit.Autologous canine EC, were enzymatically harvested, grown to confluence, and labeled with 30 μCi 111 Indium-oxine/80 cm 2 flask. Four groups of 5 cm x 4 mm ID ePTFE vascular prostheses were coated with 1.5 μg/cm.2 human fibronectin, and seeded with 1.5 x 105 EC/ cm.2. After seeding grafts in Group 1 were incubated in complete growth medium for 90 minutes, Group 2 were incubated for 24 hours, Group 3 for 72 hours and Group 4 for 6 days. Grafts were then placed in the canine ex vivo circuit, constructed between femoral artery and vein, and subjected to blood flow of 75 ml per minute for 6 hours. Continuous counting of γ-activity was made possible by placing the seeded graft inside the γ-counter detection crystal for the duration of perfusion. EC retention data after 30 minutes, 2 hours and 6 hours of flow are shown in the table.

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Jabłońska, Beata, Robert Król, and Sławomir Mrowiec. "Vascular Resection in Pancreatectomy—Is It Safe and Useful for Patients with Advanced Pancreatic Cancer?" Cancers 14, no. 5 (February 25, 2022): 1193. http://dx.doi.org/10.3390/cancers14051193.

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Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease with poor prognosis and increased incidence. Surgical resection R0 remains the most important treatment to prolong survival in PDAC patients. In borderline and locally advanced cancer, vascular resection and reconstruction during pancreatectomy enables achieving R0 resection. This study is a comprehensive review of the literature regarding the role of venous and arterial resection with vascular reconstruction in the treatment of pancreatic cancer. The literature review is focused on the use of venous and arterial resection with immediate vascular reconstruction in pancreaticoduodenectomy. Different types of venous and arterial resections are widely described. Different methods of vascular reconstructions, from primary vessel closure, through end-to-end vascular anastomosis, to interposition grafts with use autologous veins (internal jugular vein, saphenous vein, superficial femoral vein, external or internal iliac veins, inferior mesenteric vein, and left renal vein or gonadal vein), autologous substitute grafts constructed from various parts of parietal peritoneum including falciform ligament, cryopreserved and synthetic allografts. The most attention was given to the most common venous reconstructions, such as end-to-end anastomosis and interposition graft with the use of an autologous vein. Moreover, we presented mortality and morbidity rates as well as vascular patency and survival following pancreatectomy combined with vascular resection reported in cited articles.

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Journal articles on the topic 'Synthetic vascular grafts'

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