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Vascular Grafts (vascular + graft)

Distribution by Scientific Domains

Medical Sciences	87%
Life Sciences	9%

Selected Abstracts

Development of a Composite Degradable/Nondegradable Tissue-Engineered Vascular Graft

ARTIFICIAL ORGANS, Issue 2 2009
Sunil Kanwal MD
No abstract is available for this article. [source]

Basic Fibroblast Growth Factor Coating and Endothelial Cell Seeding of a Decellularized Heparin-coated Vascular Graft

ARTIFICIAL ORGANS, Issue 7 2004
Brian S. Conklin
Abstract:, The objective of this study was to determine the effect of basic fibroblast growth factor (bFGF) coating on endothelial cell seeding and proliferation on a decellularized heparin coated vascular graft and to determine the retention of seeded cells on the graft under flow conditions. Disks of heparin coated decellularized grafts were incubated for 24 h as controls or with bFGF. Human microvascular endothelial cells (HMECs) or canine peripheral blood endothelial progenitor cells (CEPC) were seeded onto the disks and incubated for 96 h or 48 h, respectively. HMECs were also seeded onto the luminal surfaces of two heparin-coated decellularized grafts for 3 h. One graft was placed in a perfusion culture system and cultured for an additional 6 h with flow and pressure. After culturing, there were 4.7 ± 1.4 cells/mm2 HMECs on control grafts and 11.4 ± 1.4 cells/mm2 in bFGF treated grafts (P < 0.05). Likewise, with CEPCs, there were 14.8 ± 4.8 cells/mm2 in control grafts and 33.3 ± 7.3 cells/mm2 in bFGF treated grafts. After only 3 h of cell attachment, 60% of HMECs were retained in the intact graft exposed flow relative to the static control graft, which is an acceptable level. These data demonstrate that bFGF coating on the heparin bound decellularized grafts significantly increases both HMEC and dog EPC proliferation and that seeded cells are stable under perfusion conditions. [source]

Mechanical Properties of Tissue-Engineered Vascular Grafts: Response to Letter to the Editor

ARTIFICIAL ORGANS, Issue 2 2009
Thomas C. Flanagan PhD
No abstract is available for this article. [source]

Engineering of Vascular Grafts With Genetically Modified Bone Marrow Mesenchymal Stem Cells on Poly (Propylene Carbonate) Graft

ARTIFICIAL ORGANS, Issue 12 2006
Jun Zhang
Abstract:, Bone marrow mesenchymal stem cells (MSCs) have demonstrated their pluripotency to differentiate into different cell lineages and may be an alternative cell source for vascular tissue engineering. The objective of this study is to create small diameter vessels by seeding and culture of genetically modified MSCs onto a synthetic polymer scaffold produced by an electrospinning technique. A tubular scaffold (2 mm in diameter) with a microstructure of nonwoven fibers was produced by electrospinning of poly (propylene carbonate) (PPC). Rat MSCs obtained from bone marrow were expanded in culture and modified with vasculoprotective gene endothelial nitric oxide synthase (eNOS) or marker gene green fluorescent protein (GFP). These MSCs were seeded onto the electrospun fibrous grafts (internal diameter = 2 mm), and cultured in 5% CO2 at 37°C. The growth of MSCs in the scaffold was analyzed with scanning electron microscopy (SEM) and hematoxylin and eosin (H&E) staining. The gene transfer and transgenic gene expression were examined with fluorescence-activated cell sorting (FACS), immunochemical staining, reverse transcriptase-polymerase chain reaction (RT-PCR), and western blot. The production of nitric oxide (NO) by the engineered vessels was measured with an NO detection kit. Our data showed that the seeded cells integrated with the microfibers of the scaffold to form a three-dimensional cellular network, indicating a favorable interaction between this synthetic PPC scaffold with MSCs. High transduction efficiency was obtained with the use of concentrated retrovirus in the gene transfection of MSCs. The eNOS gene transcripts and protein were detected in the grafts seeded with eNOS-modified MSCs by RT-PCR and immunochemical staining. The amount of NO produced by grafts seeded with eNOS-modified MSCs was comparable to that produced by native blood vessels, and it was significantly higher than that in the grafts seeded with nonmodified MSCs. In summary, the vascular graft produced by culture of eNOS gene-modified MSCs onto the electrospun tubular scaffolds shows promising results in terms of function. The use of MSCs and therapeutic genes in tissue engineering of blood vessels could be helpful in improving vessel regeneration and patency. [source]

A Novel Technique for Loading of Paclitaxel-PLGA Nanoparticles onto ePTFE Vascular Grafts

BIOTECHNOLOGY PROGRESS, Issue 3 2007
Hyun Jung Lim
The major cause of hemodialysis vascular access dysfunction (HVAD) is the occurrence of stenosis followed by thrombosis at venous anastomosis sites due to the aggressive development of venous neointimal hyperplasia. Local delivery of antiproliferative drugs may be effective in inhibiting hyperplasia without causing systemic side effects. We have previously demonstrated that paclitaxel-coated expanded poly(tetrafluoroethylene) (ePTFE) grafts, by a dipping method, could prevent neointimal hyperplasia and stenosis of arteriovenous (AV) hemodialysis grafts, especially at the graft-venous anastomoses; however, large quntities of initial burst release have remained a problem. To achieve controlled drug release, paclitaxel (Ptx)-loaded poly(lactic- co -glycolic acid) (PLGA) nanoparticles (Ptx-PLGA-NPs) were prepared by the emulsion-solvent evaporation method and then transferred to the luminal surface and inner part of ePTFE vascular grafts through our micro tube pumping and spin penetration techniques. Scanning electron microscope (SEM) images of various stages of Ptx-PLGA-NPs unequivocally showed that micro tube pumping followed by spin penetration effectively transferred Ptx-PLGA-NPs to the inner part, as well as the luminal surface, of an ePTFE graft. In addition, the in vitro release profiles of paclitaxel demonstrated that this new system achieved controlled drug delivery with a reduced initial burst release. These results suggest that loading of Ptx-PLGA-NPs to the luminal surface and the inner part of an ePTFE graft is a promising strategy to ultimately inhibit the development of venous neointimal hyperplasia. [source]

Vascular grafts in the rat model: An anatomic study

MICROSURGERY, Issue 3 2001
Brantley Blain B.S.
Vascular grafts in animal models have been used extensively in the microsurgical laboratory, and the rat offers an excellent source of graft to meet these needs. In this study, we compiled a list of vessels that were previously identified in experimental literature for use as vascular grafts in the rat model. We then dissected and measured both arterial and venous grafts taken from these sites in 12 adult rats. The surgical procedure for approaching each vascular graft was recorded. The diameter and harvestable length, the start and end points, and the number of branches of the graft were tabulated. We believe that these data will provide valuable insight applicable to the use of the rat vascular graft in microsurgical research and training. © 2001 Wiley-Liss, Inc. Microsurgery 21:80,83 2001 [source]

Vascular Stents in the Management of Portal Venous Complications in Living Donor Liver Transplantation

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 5 2010
Y.-F. Cheng
To evaluate the efficacy of stent placement in the treatment of portal vein (PV) stenosis or occlusion in living donor liver transplant (LDLT) recipients, 468 LDLT records were reviewed. Sixteen (10 PV occlusions and 6 stenoses) recipients (age range, 8 months,59 years) were referred for possible interventional angioplasty (dilatation and/or stent) procedures. Stent placement was attempted in all. The approaches used were percutaneous transhepatic (n = 10), percutaneous transsplenic (n = 4), and intraoperative (n = 2). Technical success was achieved in 11 of 16 patients (68.8%). The sizes of the stents used varied from 7 mm to 10 mm in diameter. In the five unsuccessful patients, long-term complete occlusion of the PV with cavernous transformation precluded catherterization. The mean follow-up was 12 months (range, 3,24). The PV stent patency rate was 90.9% (10/11). Rethrombosis and occlusion of the stent and PV occurred in a single recipient who had a cryoperserved vascular graft to reconstruct the PV during the LDLT operation. PV occlusion of >1 year with cavernous transformation seemed to be a factor causing technical failure. In conclusion, early treatment of PV stenosis and occlusion by stenting is an effective treatment in LDLT. Percutaneous transhepatic and transsplenic, and intraoperative techniques are effective approaches depending on the situation. [source]

New Pulsatile Hydrostatic Pressure Bioreactor for Vascular Tissue-engineered Constructs

ARTIFICIAL ORGANS, Issue 2 2010
Faisal M. Shaikh
Abstract Mechanical conditioning represents a potential means to enhance the biochemical and biomechanical properties of tissue-engineered cell constructs. Bioreactors that can simulate physiologic conditions can play an important role in the preparation of tissue-engineered constructs. Although various forms of bioreactor systems are currently available, these have certain limitations, particularly when these are used for the creation of vascular constructs. The aim of the present report is to describe and validate a novel pressure bioreactor system for the creation of vascular tissue. Here, we present and discuss the design concepts, criteria, as well as the development of a novel pressure bioreactor. The system is compact and easily housed in an incubator to maintain sterility of the construct. Moreover, the proposed bioreactor, in addition to mimicking in vivo pressure conditions, is flexible, allowing different types of constructs to be exposed to various physiologic pressure conditions. The core bioreactor elements can be easily sterilized and have good ergonomic assembly characteristics. This system is a fundamental tool, which may enable us to make further advances in bioreactor technology and tissue engineering. The novel system allows for the application of pressure that may facilitate the growth and development of constructs needed to produce a tissue-engineered vascular graft. [source]

Development and Validation of Small-diameter Vascular Tissue From a Decellularized Scaffold Coated With Heparin and Vascular Endothelial Growth Factor

ARTIFICIAL ORGANS, Issue 3 2009
Min Zhou
Abstract To overcome shortcomings of current small-diameter vascular prostheses, we developed a novel allogenic vascular graft from a decellularized scaffold modified through heparin immobilization and vascular endothelial growth factor (VEGF) coating. The VEGF coating and release profiles were assayed by enzyme-linked immunosorbent assay, the biological activity of modified surface was validated by human umbilical vein endothelial cells seeding and proliferation for 10 days in vitro. In vivo, we implanted either a modified or a nonmodified scaffold as bilateral carotid allogenic graft in canines (n = 15). The morphological examination of decellularized scaffolds showed complete removal of cellular components while the extracellular matrix structure remained intact. After modification, the scaffolds possessed local sustained release of VEGF up to 20 days, on which the cells cultured showed significantly higher proliferation rate throughout the time after incubation compared with the cells cultured on nonmodified scaffolds (P < 0.0001). After 6 months of implantation, the luminal surfaces of modified scaffolds exhibited complete endothelium regeneration, however, only a few disorderly cells and thrombosis overlay the luminal surfaces of nonmodified scaffolds. Specifically, the modified scaffolds exhibited significantly smaller hyperplastic neointima area compared with the nonmodified, not only at midportion (0.56 ± 0.07 vs. 2.04 ± 0.12 mm2, P < 0.0001), but also at anastomotic sites (1.76 ± 0.12 vs. 3.67 ± 0.20 mm2, P < 0.0001). Moreover, modified scaffolds had a significantly higher patency rate than the nonmodified after 6 months of implantation (14/15 vs. 7/15, P = 0.005). Overall, this modified decellularized scaffold provides a promising direction for fabrication of small-diameter vascular grafts. [source]

Engineering of Vascular Grafts With Genetically Modified Bone Marrow Mesenchymal Stem Cells on Poly (Propylene Carbonate) Graft

Basic Fibroblast Growth Factor Coating and Endothelial Cell Seeding of a Decellularized Heparin-coated Vascular Graft

Influence of cultivation conditions on mechanical and morphological properties of bacterial cellulose tubes

BIOTECHNOLOGY & BIOENGINEERING, Issue 2 2007
Aase Bodin
Abstract Bacterial cellulose (BC) was deposited in tubular form by fermenting Acetobacter xylinum on top of silicone tubes as an oxygenated support and by blowing different concentrations of oxygen, that is, 21% (air), 35%, 50%, and 100%. Mechanical properties such as burst pressure and tensile properties were evaluated for all tubes. The burst pressure of the tubes increased with an increase in oxygen ratio and reached a top value of 880 mmHg at 100% oxygen. The Young's modulus was approximately 5 MPa for all tubes, irrespective of the oxygen ratio. The elongation to break decreased from 30% to 10,20% when the oxygen ratio was increased. The morphology of the tubes was characterized by Scanning Electron Microscopy (SEM). All tubes had an even inner side and a more porous outer side. The cross section indicated that the tubes are composed of layers and that the amount of layers and the yield of cellulose increased with an increase in oxygen ratio. We propose that an internal vessel wall with high density is required for the tube to sustain a certain pressure. An increase in wall thickness by an increase in oxygen ratio might explain the increasing burst pressure with increasing oxygen ratio. The fermentation method used renders it possible to produce branched tubes, tubes with unlimited length and inner diameters. Endothelial cells (ECs) were grown onto the lumen of the tubes. The cells formed a confluent layer after 7 days. The tubes potential as a vascular graft is currently under investigation in a large animal model at the Centre of Vascular Engineering, Sahlgrenska University Hospital, Gothenburg. Biotechnol. Bioeng. 2007;97: 425,434. © 2006 Wiley Periodicals, Inc. [source]

Management of concomitant hepatic artery injury in patients with iatrogenic major bile duct injury after laparoscopic cholecystectomy

BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 4 2008
J. Li
Background: Concomitant hepatic artery injury is a rare but severe complication associated with bile duct injury during laparoscopic cholecystectomy (LC). Methods: Sixty patients referred with biliary injury after LC between April 1998 and December 2005 were divided into two groups according to the time elapsed between injury and definitive surgical revision; patients in group 1 were referred early (within 4 days) after operation and those in group 2 were referred later. Hepatic rearterialization was performed in addition to biliary reconstruction when technically possible. Results: Damage to the hepatic artery was detected in ten patients. Hepatic rearterialization was carried out in five patients by end-to-end anastomosis (one), or by using an autologous graft (three) or allogeneic vascular graft (one). Three patients in group 2 underwent right hemihepatectomy without arterial reconstruction owing to liver necrosis or lobar atrophy. Three of ten patients died from postoperative complications. Conclusion: Combined bile duct and hepatic artery injury during LC led to a complicated clinical course, with a high mortality rate. Reconstruction of the right hepatic artery might be helpful in reducing hepatic ischaemia, but is usually feasible only if the injury is identified early. Copyright © 2007 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source]

Use of cadaveric superior mesenteric artery as interpositional vascular graft in orthotopic liver transplantation

BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 1 2001
P. Muiesan
Background: Hepatic artery thrombosis remains the most common technical complication that causes graft failure following orthotopic liver transplantation. The development of split liver and living related liver transplantation has led to the use of shorter and smaller arteries for arterial reconstruction to the graft. The present aim was to assess the effectiveness of the superior mesenteric artery as an interpositional graft in arterial reconstruction during liver transplantation. Methods: Cadaveric superior mesenteric artery was used to reconstruct small and short or multiple hepatic arteries in 35 liver transplants including 29 split, three living related, two whole liver transplants and one emergency revascularization post-transplantation. Results and conclusion: A low incidence of hepatic artery thrombosis (one of 35 patients) was achieved utilizing cadaveric superior mesenteric artery as an interpositional vascular graft in liver transplantation. © 2001 British Journal of Surgery Society Ltd [source]

Compliance properties of conduits used in vascular reconstruction,

BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 11 2000
N. R. Tai
Background Compliance mismatch between native artery and prosthetic graft used for infrainguinal bypass is implicated in the aetiology of graft failure. The aim was to quantify the elastic properties of a new compliant poly(carbonate)polyurethane (CPU) vascular graft, and to compare the compliance properties of grafts made from CPU, expanded polytetrafluoroethylene (ePTFE), Dacron and human saphenous vein with that of human muscular artery. Methods A pulsatile flow phantom was used to perfuse vessel and prosthetic graft segments at physiological pulse pressure and flow. Intraluminal pressure was measured using a Millar Mikro-tip catheter transducer and vessel wall motion was determined with duplex ultrasonography using an echo-locked wall-tracking system. Diametrical compliance and a stiffness index were then calculated for each type of conduit over mean pressures ranging from 30 to 100 mmHg by 10-mmHg increments. Results The compliance values of CPU and artery (mean over the pressure range) were similar (mean(s.d.) 8·1(0·4) and 8·0(5·9) per cent per mmHg × 10,2 respectively), although the elastic behaviour of artery was anisotropic unlike CPU, which was isotropic. Dacron and ePTFE grafts had lower compliance values (1·8(1·2) and 1·2(0·3) per cent per mmHg × 10,2 respectively, averaged over the pressure range). In both these cases, compliance and stiffness differed significantly from that of artery over a mean pressure range of 30,90 mmHg. Human saphenous vein exhibited anisotropic behaviour and, although compliant at low pressure (30 mmHg), was markedly incompliant at higher pressures. Conclusion Compliant polyurethane grafts offer a greater degree of compliance match than either ePTFE or Dacron. © 2000 British Journal of Surgery Society Ltd [source]

Peptide-coated vascular grafts: An in vivo study in sheep

HEMODIALYSIS INTERNATIONAL, Issue 4 2004
Cheng Li
Abstract The data on function and patency of prosthetic vascular grafts in various clinical settings are limited. The purpose of this in vivo study was to compare the function and patency of P15-coated expanded polytetrafluoroethylene (ePTFE) vascular grafts to uncoated ePTFE grafts in sheep. The P15 cell-binding peptide was covalently immobilized onto the surface of ePTFE grafts by a novel atmospheric plasma coating method. We evaluated the amount of neointimal tissue ingrowth present at the arterial and venous sides of the anastomoses and the degree of endothelial cell resurfacing of the luminal surface of the graft. Four P15-coated grafts and two control grafts were implanted as arteriovenous grafts between the femoral artery and vein and the carotid artery and jugular vein in two sheep (n = 6). One animal was euthanized after 14 days and the other after 28 days. The study showed the intimal ingrowth was significantly less. The average intimal thickness of P15-coated grafts (658 µm) was approximately two and a half times less than that of uncoated samples (1657 µm). The newly formed endothelial cell lining was thicker and its coverage was more uniform for P15-coated grafts compared to the uncoated controls. [source]

Fibrin Sealants and Glues

JOURNAL OF CARDIAC SURGERY, Issue 6 2003
Thomas E. MacGillivray M.D.
They have been used as an adjunct to hemostasis, wound healing, tissue adhesion, and drug delivery. In cardiac surgery, fibrin glues have emerged as valuable tools to improve hemostasis, decreased blood transfusions, improve tissue handling, and pretreat vascular grafts. Fibrin glues and sealants are now available commercially in the United States. This article will review the history, pharmacology, uses, and toxicity of fibrin sealants and fibrin glues. (J Card Surg 2003;18:480-485) [source]

Progenitor cells in vascular disease

JOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 3 2005
Neil Roberts
Abstract Stem cell research has the potential to provide solutions to many chronic diseases via the field of regeneration therapy. In vascular biology, endothelial progenitor cells (EPCs) have been identified as contributing to angiogenesis and hence have therapeutic potential to revascularise ischaemic tissues. EPCs have also been shown to endothelialise vascular grafts and therefore may contribute to endothelial maintenance. EPC number has been shown to be reduced in patients with cardiovascular disease, leading to speculation that atherosclerosis may be caused by a consumptive loss of endothelial repair capacity. Animal experiments have shown that EPCs reendothelialise injured vessels and that this reduces neointimal formation, confirming that EPCs have an atheroprotective effect. Smooth muscle cell accumulation in the neointimal space is characteristic of many forms of atherosclerosis, however the source of these cells is now thought to be from smooth muscle progenitor cells (SMPCs) rather than the adjacent media. There is evidence for the presence of SMPCs in the adventitia of animals and that SMPCs circulate in human blood. There is also data to support SMPCs contributing to neointimal formation but their origin remains unknown. This article will review the roles of EPCs and SMPCs in the development of vascular disease by examining experimental data from in vitro studies, animal models of atherosclerosis and clinical studies. [source]

Perfluorocarbons: Life sciences and biomedical uses Dedicated to the memory of Professor Guy Ourisson, a true RENAISSANCE man.

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2007
Marie Pierre Krafft
Abstract Perfluorocarbons are primarily characterized by outstanding chemical and biological inertness, and intense hydrophobic and lipophobic effects. The latter effects provide a powerful noncovalent, labile binding interaction that can promote selective self- assembly. Perfluoro compounds do not mimic nature, yet they can offer abiotic building blocks for the de novo design of functional biopolymers and alternative solutions to physiologically vital issues. They offer new tags useful for molecular recognition, selective sorting, and templated binding (e.g., selective peptide and nucleic acid pairing). They also stabilize membranes and provide micro- and nanocompartmented fluorous environments. Perfluorocarbons provide inert, apolar carrier fluids for lab-on-a-chip experiments and assays using microfluidic technologies. Low water solubility, combined with high vapor pressure, allows stabilization of injectable microbubbles that serve as contrast agents for diagnostic ultrasound imaging. High gas solubilities are the basis for an abiotic means for intravascular oxygen delivery. Other biomedical applications of fluorocarbons include lung surfactant replacement and ophthalmologic aids. Diverse colloids with fluorocarbon phases and/or shells are being investigated for molecular imaging using ultrasound or magnetic resonance, and for targeted drug delivery. Highly fluorinated polymers provide a range of inert materials (e.g., fluorosilicons, expanded polytetrafluoroethylene) for contact lenses, reconstructive surgery (e.g., vascular grafts), and other devices. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1185,1198, 2007. [source]

The influence of endothelial cells on the ECM composition of 3D engineered cardiovascular constructs,

JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Issue 1 2009
Rolf A. A. Pullens
Abstract Tissue engineering of small diameter (<5 mm) blood vessels is a promising approach to develop viable alternatives for autologous vascular grafts. Development of a functional, adherent, shear resisting endothelial cell (EC) layer is one of the major issues limiting the successful application of these tissue engineered grafts. The goal of the present study was to create a confluent EC layer on a rectangular 3D cardiovascular construct using human venous cells and to determine the influence of this layer on the extracellular matrix composition and mechanical properties of the constructs. Rectangular cardiovascular constructs were created by seeding myofibroblasts (MFs) on poly(glycolic acid) poly-4-hydroxybutyrate scaffolds using fibrin gel. After 3 or 4 weeks, ECs were seeded and co-cultured using EGM-2 medium for 2 or 1 week, respectively. A confluent EC layer could be created and maintained for up to 2 weeks. The EGM-2 medium lowered the collagen production by MFs, resulting in weaker constructs, especially in the 2 week cultured constructs. Co-culturing with ECs slightly reduced the collagen content, but had no additional affect on the mechanical performance. A confluent endothelial layer was created on 3D human cardiovascular constructs. The layer was co-cultured for 1 and 2 weeks. Although, the collagen production of the MFs was slightly lowered, co-culturing ECs for 1 week results in constructs with good mechanical properties and a confluent EC layer. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Vascular grafts in the rat model: An anatomic study

Time-related Histopathologic Changes in Fresh Frozen Carotid Xenografts in a Pig-to-Goat Implantation Model

ARTIFICIAL ORGANS, Issue 10 2009
Ji M. Chang
Abstract We performed an animal experiment with an emphasis on time-related histopathologic changes to evaluate the clinical feasibility of immunologically nontreated xenogenic vascular grafts. Bilateral porcine carotid arteries were harvested, and then, after short-term freezing at ,70°C, interposed into goats' carotid arteries. An antiplatelet agent was administered orally for 3 months postoperatively. The goats were randomly assigned to five periods of observation (1 week, and 1, 3, 6, and 12 months after implantation); two animals were observed at each of these times. Doppler ultrasonography was performed periodically during the observation period. At predetermined times, grafts were explanted and examined using hematoxylin and eosin, and Masson's trichrome stains. Immunohistochemical evaluations were conducted with T-lymphocyte indicator and von Willebrand factor. Two goats died prematurely, one from respiratory problems related to anesthesia and the other from pneumonia. A total of 16 grafts from the remaining eight animals were evaluated. Grafts were all patent except one at 3 months after transplantation. Histologically, xenogenic arterial grafts showed early endothelial cell loss at 1 week. This was followed by a progressive spread of recipient endothelial cells from the anastomotic site, and re-endothelialization was complete at 1 month. The degree of neointimal and medial thickening increased until 3 months, and then decreased. At 12 months, no additional growth of the intimal or medial layers was observed. Adventitial inflammation became severe at 3 months, but was reduced at 6,12 months. The proportions of CD3-positive T-lymphocytes among inflammatory cell infiltrations were very low. Fresh frozen xenogenic arterial grafts showed acceptable patency throughout the 12-month period and showed no evidence of being unduly influenced by rejection reactions. [source]

Alcohol Pretreatment of Small-diameter Expanded Polytetrafluoroethylene Grafts: Quantitative Analysis of Graft Healing Characteristics in the Rat Abdominal Aorta Interposition Model

ARTIFICIAL ORGANS, Issue 7 2009
Erman Pektok
Abstract Long-term patency rates of small-diameter expanded polytetrafluoroethylene (ePTFE) vascular prostheses are unsatisfactory. Treatment of ePTFE grafts by alcohol before implantation was reported to increase hydrophilic properties, yielding better endothelialization and cellular in-growth, thus improving graft healing. The effect of alcohol pretreatment on ePTFE grafts and postoperative healing characteristics of wet ePTFE grafts were evaluated in this study. Ten sterile ePTFE grafts (2 mm ID, 30 µ thru-pore, 12 mm long) were implanted in the infrarenal aorta of male Sprague-Dawley rats (324,380 g). Five grafts were treated with ethanol 70% and soaked with saline solution before implantation (wet); five nontreated grafts served as control. All rats were sacrificed after digital subtraction angiography and sampling of the graft for histological investigation after 3 weeks. Histomorphometric analysis was performed for endothelial coverage, cellular in-growth, and intimal hyperplasia. All grafts were patent at the end of 3 weeks in both groups. Histological evaluation revealed significantly better endothelial coverage and prominent infiltration by fibroblasts and lymphocytes in the wet group. Endothelial coverage (31.03 ± 10.61% vs. 13.03 ± 9.46%, P = 0.03) and cellular infiltration of grafts (50.91 ± 8.55% vs. 39.29 ± 10.70%, P = 0.11) were higher in the wet group. Area of intimal hyperplasia per graft length was also higher in the wet group (5.32 ± 4.75 µm2/µm vs. 2.69 ± 3.41 µm2/µm, P = 0.36). Wetting of ePTFE grafts with ethanol 70% pretreatment before implantation might have a beneficial effect on long-term patency of small-diameter vascular grafts due to facilitated graft healing. [source]

Development and Validation of Small-diameter Vascular Tissue From a Decellularized Scaffold Coated With Heparin and Vascular Endothelial Growth Factor

In Vitro and In Vivo Study of Ion-Implanted Collagen for the Substrate of Small Diameter Artificial Grafts

ARTIFICIAL ORGANS, Issue 6 2003
Kimi Kurotobi
Abstract: Ion implantation into the collagen-coated inner surface of the grafts was performed and evaluated in vitro and in vivo to develop small diameter artificial vascular grafts. He+ ion implanted collagen-coated grafts with a fluence of 1 × 1014 ions/cm2 inhibited platelet adhesion and demonstrated patency for 240 days in an animal study. The platelet adhesion test using platelet rich plasma (PRP) showed antithrombogenicity at the fluence of 1 × 1014 ions/cm2. Washed platelet adhesion test showed thrombus formation at the fluence of 1 × 1014 ions/cm2. The results suggested that plasma protein adsorption onto the ion-implanted collagen significantly improved performance of these synthetic grafts. [source]