Lipid uptake in ePTFE arterial prostheses implanted in humans

Bédard, E.; Marois, M; Guidoin, Robert; Laroche, Gaétan

doi:10.1007/bf00121188

Cited by 6 publications

(13 citation statements)

References 35 publications

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“…7 The findings that treatment of crosslinked xenografts with detergents or oxidants can impair or totally inhibit calcification 20 suggested to us that the use of such inhibitors may affect the interactions between the exposed surface of the xenograft and the surrounding biological environment. The knowledge that calcification in biological systems is usually driven by organic templates 7 and that organic molecules usually adsorb onto biomaterial surfaces 16,17 prompted us to investigate, by an in vitro system, the surface conditioning of differently treated collagen incubated with serum. This in vitro model appeared to be suitable to rule out the influence played by the tissue cells in precipitation events and to highlight the effect of calcification inhibitors on the surface-conditioning composition of the collagen matrices.…”

Section: Discussionmentioning

confidence: 99%

“…7,15 Furthermore, proteins and lipids are able to adsorb onto biomaterial surfaces during the early phases of the implant affecting the biocompatibility of the prosthesis. 16,17 Little information is available concerning the role of proteins in calcification processes when adsorbed onto the surface of bioprosthetic valves, 18 while no study has been carried out to characterize the early phases of the serum conditioning of bioprosthesis pretreated with inhibitors of calcifications.…”

Section: Introductionmentioning

confidence: 99%

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Changes in serum conditioning profiles of glutaraldehyde-crosslinked collagen sponges after their treatment with calcification inhibitors

Santin

Motta²,

Cannas

1998

J. Biomed. Mater. Res.

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The purpose of this study was to evaluate the effects of the calcification inhibitors FeCl3 and sodium dodecyl sulfate (SDS) on the morphology of glutaraldehyde-crosslinked type I collagen sponges and on their serum conditioning. Scanning electron microscopy (SEM) showed that the morphology of the sponges, already modified by glutaraldehyde crosslinking, underwent further changes after treatment of the hydrogels with inhibitors. Coral-like structures were found to branch from the bulk of the material especially in the case of SDS-treated samples. The composition and morphology of the conditioning layers was characterized after 48 h incubation in serum by SDS-polyacrylamide gel electrophoresis-immunoblot of the adsorbed proteins, by energy-dispersive X-ray analysis of the elements (EDX), and by SEM of the conditioned surfaces. All the samples showed the adsorption of proteins with molecular weights ranging from 10 to 203 kD. However, the peculiar adsorption of an approximately 10-kD band (complement C3 fragment) and of fibronectin were detected in the case of glutaraldehyde-crosslinked collagen. On the other hand, glutaraldehyde-crosslinked collagen treated with 0.1M FeCl3 showed the remarkable adsorption of a 29-kD band. The glutaraldehyde-crosslinked hydrogels showed the massive precipitation of crystals on their exposed surfaces, whereas a disordered network structure surrounding the collagen fibrils was found in the case of the samples pretreated with inhibitors. A predominant precipitation of sodium and chloride was detected in all the sponges, although the ratio between the peaks changed from from one hydrogel to another. The results reported in this article clearly indicate that the treatments with SDS and FeCl3 change the surface conditioning of collagen sponges, suggesting a possible role of deposited serum solutes in affecting mineralization processes on bioprosthesis.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Changes in serum conditioning profiles of glutaraldehyde-crosslinked collagen sponges after their treatment with calcification inhibitors

Santin

Motta²,

Cannas

1998

J. Biomed. Mater. Res.

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“…A phospholipid dispersion was selected as the fluid model essentially because we previously demonstrated (13) that unsaturated fatty acids were the only molecules still present in the ePTFE structure following an aqueous washing to remove the fibrous capsule that had developed around the prosthesis during implantation. Moreover, phospholipids are present in a significant proportion in the total lipid concentration of whole human blood and are known to be an influence in the coagulation cascade (26).…”

Section: Methodsmentioning

confidence: 99%

“…In our previous work on expanded polytetrafluoroethylene (ePTFE) vascular prostheses implanted in humans, we demonstrated that lipids were among those molecules that are tightly and rapidly bound to the ePTFE prosthesis structure (13). If lipid uptake in natural vessels is known to be driven by a metabolic process, the phenomenon responsible for lipid uptake in synthetic prostheses remains misunderstood.…”

mentioning

confidence: 99%

Modeling Lipid Uptake in Expanded Polytetrafluoroethylene Vascular Prostheses and Its Effects on Mechanical Properties

Vermette¹,

Fiset²,

Guidoin

et al. 2000

Artificial Organs

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The radial transport across the wall of expanded polytetrafluoroethylene (ePTFE) arterial prostheses has a significant effect on lipid uptake observed in prostheses implanted in humans, which has been postulated to be one of the causes associated with implant failure. The goal of this study was to stimulate radial transport on a lipidic dispersion across the wall of an ePTFE prosthesis and investigate its effects on the circumferential mechanical properties of the prosthesis. An in vitro model was developed to simulate the lipidic radial transport across the wall. Lipids contained in a phosphatidylcholine dispersion were used as the transported molecules. Lipid concentration profiles were obtained after exposing commercial ePTFE prostheses to various transmural pressure and/or lipidic concentration gradients. Phospholipids gradually accumulated up to the external reinforcing wrap of the prosthesis, which clearly acted as a rigid barrier against lipid infiltration. Tensile tests performed on the virgin samples showed that the wrap was much more rigid than the microporous part of the prosthesis. After the lipid simulation, the rigidity of the wrap decreased with respect to what was observed for the virgin prosthesis. Finally, some clinical implications of this phenomena are discussed.

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“…Moreover, our group demonstrated that lipid uptake on the luminal and external surfaces of 367 expanded polytetrafluoroethylene (ePTFE) vascular prostheses explanted from humans occurred during the first days of implantation and depended on the time of implantation, sex of the patients, and on the prostheses' morphological parameters, including diameter. 16,17 In light of this study, we examined the lipid retention on ePTFE vascular grafts exposed to a phospholipid suspension as a function of various flow conditions. 18 Findings from this study indicated that the lipid uptake depended on the transmural pressure and the time of exposure to the model fluid.…”

Section: Introductionmentioning

confidence: 99%

Lipid uptake across the wall of an expanded polytetrafluoroethylene vascular graft

Vermette

Thibault

Lévesque³

et al. 1999

J. Biomed. Mater. Res.

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Previous studies have shown that vascular grafts were prone to inducing an atherosclerosis-like phenomenon, thus possibly jeopardizing their performance. Furthermore, lipid retention, observed in most synthetic arterial prostheses explanted from humans, appears to have an important role in the progression of this atherosclerotic process, therefore hindering the healing process and neo-intima formation of these synthetic conduits. The current study examined lipid concentration profiles across prosthesis membranes exposed to lipid dispersion under various transmural pressures, flow rates, and durations of exposure. It was demonstrated that the lipids rapidly permeated the prosthesis membrane, as lipid advection increased to a maximum, then steadily decreased until the membrane became completely impermeable to the fluid. The concentration of lipids within the grafts was monitored using FT-IR microspectroscopy, then correlated as a function of time in order to evaluate the mass transfer coefficients and lipid saturation concentration. Lipid sorption, as a function of time, was described by a mechanism taking into account two first-order kinetic models. The lipids were first rapidly adsorbed onto the Teflon(R), potentially influenced by the strong affinity of these lipids for the highly hydrophobic polytetrafluoroethylene polymer. This affinity then enhanced the germination of the lipid deposits that filled in the prosthesis wall. For lipid retention as a function of the transmural pressure and flow rate, no clear tendency was established.

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Lipid uptake in ePTFE arterial prostheses implanted in humans

Cited by 6 publications

References 35 publications

Changes in serum conditioning profiles of glutaraldehyde-crosslinked collagen sponges after their treatment with calcification inhibitors

Changes in serum conditioning profiles of glutaraldehyde-crosslinked collagen sponges after their treatment with calcification inhibitors

Modeling Lipid Uptake in Expanded Polytetrafluoroethylene Vascular Prostheses and Its Effects on Mechanical Properties

Lipid uptake across the wall of an expanded polytetrafluoroethylene vascular graft

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