Effect of porosity on small-diameter vascular graft healing

Contreras, Mauricio; Quist, William C.; LoGerfo, Frank W.

doi:10.1002/(sici)1098-2752(2000)20:1<15::aid-micr3>3.0.co;2-p

Cited by 35 publications

(24 citation statements)

References 19 publications

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“…Endothelialization has been found limited to the perianastomotic regions of 2-mm ePTFE grafts in the rabbit CCA after study at 3 weeks 142 and at 8 weeks. 141 The wide variation in patency of these studies, however, serves to highlight the difficulties in finding consensus among examples of animal models: 20% at 3 weeks and 100% at 8 weeks, respectively.…”

Section: Small-animal Models For the Assessment Of Novel Vascular Conmentioning

confidence: 99%

“…181 Recognition of these separate mechanisms to achieve endothelial graft coverage has led to targeted approaches, including coating ePTFE with antibodies designed to capture circulating endothelial progenitor cells 129 or implantation of ePTFE with increased porosity to allow transmural ingrowth. 141 However, therapeutic modulation of conduit pore size is additionally complicated by a number of factors. The relationship between porosity and graft healing is strongly influenced by material-specific characteristics such as the actual dimensions available for ingrowth and cellular orientation, such that 30-m ePTFE is unable to support transmural endothelialization.…”

Section: New Challenges In the Assessment Of Tissue-engineered Vasculmentioning

confidence: 99%

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Animal models for the assessment of novel vascular conduits

Byrom

Bannon

White

et al. 2010

Journal of Vascular Surgery

155

132

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The development of an ideal small-diameter conduit for use in vascular bypass surgery has yet to be achieved. The ongoing innovation in biomaterial design generates novel conduits that require preclinical assessment in vivo, and a number of animal models have been used for this purpose. This article examines the rationale behind animal models used in the assessment of small-diameter vascular conduits encompassing the commonly used species: baboons, sheep, pigs, dogs, rabbits, and rodents. Studies on the comparative hematology for these species relative to humans are summarized, and the hydrodynamic values for common implant locations are also compared. The large- and small-animal models are then explored, highlighting the characteristics of each that determine their relative utility in the assessment of vascular conduits. Where possible, the performance of expanded polytetrafluoroethylene is given in each animal and in each location to allow direct comparisons between species. New challenges in animal modeling are outlined for the assessment of tissue-engineered graft designs. Finally, recommendations are given for the selection of animal models for the assessment of future vascular conduits.

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Section: Small-animal Models For the Assessment Of Novel Vascular Conmentioning

confidence: 99%

Section: New Challenges In the Assessment Of Tissue-engineered Vasculmentioning

confidence: 99%

Animal models for the assessment of novel vascular conduits

Byrom

Bannon

White

et al. 2010

Journal of Vascular Surgery

155

132

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“…The resulting graft hemorrhage is troublesome, increasing operative time and need for blood transfusion. Many studies have been done to develop vascular grafts that are blood tight during implantation, thus eliminating the need for preclotting of the graft and sufficiently porous to facilitate the tissue in‐growth and biological healing 7. Most commonly used method includes coating or impregnation of porous graft with a biodegradable component.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of alginate dialdehyde cross‐linked gelatin hydrogel as a biodegradable sealant for polyester vascular graft

et al. 2011

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Vascular grafts are devices intended to replace compromised arteries in the body and grafts made of polyethylene terephthalate (PET) fabric have been used mainly for synthetic grafting procedures involving medium to large diameter vascular grafts. Though porosity of the graft permits tissue in-growth, it would lead to bleeding through the graft walls immediately after implantation. So it is essential to seal the pores either by preclotting with patient's own blood or by other sealing materials prior to implantation in order to prevent blood leakage through the graft wall. Biodegradable hydrogel materials are ideal candidates for this purpose. Apart from sealing the pores, they offer biocompatible and low-thrombogenic surfaces when coated on vascular graft. In the present study, a biodegradable hydrogel, derived from oxidized alginate and gelatin, has been deposited on PET grafts by dip coating and were characterized for its efficacy on sealing the pores of the graft. Water permeability in the static and pulsatile conditions, burst strength, in vitro cell culture cytotoxicity, hemocompatibility, and endothelial cell adhesion and proliferation of the coated grafts were investigated. Results showed that the alginate dialdehyde cross-linked gelatin hydrogel was nontoxic, hemocompatible, and was efficient in sealing the pores of the graft. Blood perfusion study showed that when hydrogel-coated grafts were exposed to blood for 30 min, they showed little affinity toward platelets or leukocytes. Hemolytic potential of PET was significantly reduced when it was coated with hydrogel. Improved adhesion and proliferation of endothelial cells were observed when PET grafts were coated with hydrogel. Results also showed that coating with hydrogel did not affect the burst strength of the PET graft.

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“…There are a few reports that do not support the positive role of a permeable graft wall in neointima formation and endothelialization. Contreras et al implanted 2‐cm long and 2‐mm ID ePTFE grafts in the rabbit common carotid artery for 8 weeks and found no effect of permeability on either patency rate or neointima formation 45. Wong et al reported that porous and impervious ePTFE vascular patches of 10 × 15 mm 2 in size implanted in dogs for 30 and 60 days did not reveal any significant difference in terms of neointima formation and the cellular composition of the neointima 46.…”

Section: Discussionmentioning

confidence: 99%

Transmural communication at a subcellular level may play a critical role in the fallout based‐endothelialization of dacron vascular prostheses in canine

Zhang

Briana

Douville

et al. 2007

J Biomedical Materials Res

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A microporous and permeable wall is important for the healing of vascular prostheses, however, the significance of its permeability to soluble substances at subcellular level has not been demonstrated. Polyester arterial prostheses were prepared in such a way that each of them contained three segments, of which at least one segment was impervious and another segment was permeable to water but impermeable to cells. Twenty graft segments were implanted in 7 dogs as a thoraco-abdominal bypass for 2 months. The prostheses were then harvested, photographed, and treated for histological and morphological studies. The low porosity graft capped by two thrombogenic segments was fully endothelialized, proving the fallout mechanism. The striking contrast with its impermeable counterpart demonstrated that a wall permeable to small substances of subcellular level was critical for the endothelial healing. A wide range of water permeabilities did not reveal advantages of high water permeable segments over low water permeable ones. Endothelial ingrowth from anastomoses was also jeopardized in the absence of wall permeability. In conclusion, transmural communication at a subcellular level may have played a critical role in the fallout based-endothelialization of arterial prostheses in canine. This highlights the potential function of perigraft cytokines and growth factors in endothelial healing.

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Effect of porosity on small-diameter vascular graft healing

Cited by 35 publications

References 19 publications

Animal models for the assessment of novel vascular conduits

Animal models for the assessment of novel vascular conduits

Evaluation of alginate dialdehyde cross‐linked gelatin hydrogel as a biodegradable sealant for polyester vascular graft

Transmural communication at a subcellular level may play a critical role in the fallout based‐endothelialization of dacron vascular prostheses in canine

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