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ePTFE Grafts (eptfe + graft)

Distribution by Scientific Domains
Medical Sciences87%

Selected Abstracts

Evaluation of the Hemodynamics of a Tissue-engineered Hybrid Graft

ARTIFICIAL ORGANS, Issue 1 2010
Kuk Hui Son
Abstract We evaluated the hemodynamics of tissue-engineered hybrid graft in vivo. The hybrid expanded polytetrafluoroethylene (ePTFE) scaffold was fabricated by coating the ePTFE graft with poly (lactide-co-glycolide) (PLGA) solution. This scaffold was turned into an engineered hybrid graft by culturing smooth muscle cells on its surface. Both the ePTFE (n = 6) and the engineered hybrid grafts (n = 8) were implanted in the carotid arteries of mongrel dogs. The length of intima in the engineered hybrid graft was greater than the ePTFE. The neoarterial thickness in the engineered hybrid group was greater, and the foreign body reaction was more severe. We compared the hemodynamics (diameter, flow rate, pulsatile index, mean velocity, shear stress, resistance index, and systolic/diastolic ratio) of the native arteries in the distal anastmosis. The shear rate in the engineered hybrid group was higher immediately after implantation, and the resistance index was lower, but there was no significant difference after 4 weeks. The engineered grafts demonstrated similar hemodynamics with the ePTFE grafts after 4 weeks implantation. [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]

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]

Evaluation of the Hemodynamics of a Tissue-engineered Hybrid Graft

ARTIFICIAL ORGANS, Issue 1 2010
Kuk Hui Son
Abstract We evaluated the hemodynamics of tissue-engineered hybrid graft in vivo. The hybrid expanded polytetrafluoroethylene (ePTFE) scaffold was fabricated by coating the ePTFE graft with poly (lactide-co-glycolide) (PLGA) solution. This scaffold was turned into an engineered hybrid graft by culturing smooth muscle cells on its surface. Both the ePTFE (n = 6) and the engineered hybrid grafts (n = 8) were implanted in the carotid arteries of mongrel dogs. The length of intima in the engineered hybrid graft was greater than the ePTFE. The neoarterial thickness in the engineered hybrid group was greater, and the foreign body reaction was more severe. We compared the hemodynamics (diameter, flow rate, pulsatile index, mean velocity, shear stress, resistance index, and systolic/diastolic ratio) of the native arteries in the distal anastmosis. The shear rate in the engineered hybrid group was higher immediately after implantation, and the resistance index was lower, but there was no significant difference after 4 weeks. The engineered grafts demonstrated similar hemodynamics with the ePTFE grafts after 4 weeks implantation. [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]

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]