Long-term reduction of medial and intimal thickening in porcine saphenous vein grafts with a polyglactin biodegradable external sheath

Vijayan, Vikram; Shukla, Nilima; Johnson, Jason L.; Gadsdon, P; Angelini, Gianni; Smith, Frank C T; Baird, R. N.; Jeremy, Jamie Y.

doi:10.1016/j.jvs.2004.08.047

Cited by 69 publications

(87 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, external support may have a role in redirecting vascular smooth muscle cell migration through a reversed chemotactic gradient. Neutrophils and monocytes that aggregate around the external support (in the context of foreign body reactions as also shown in our study) release chemo-attractive proteins that attract smooth muscle cells and fibroblast to the external support [23].…”

Section: Resultssupporting

confidence: 71%

Inhibition of vein graft remodeling and neo-intimal formation using a cobalt chrome external support

Nitecki¹,

Yosef²,

Tozzi³

et al. 2018

Arch Clin Exp Surg

View full text Add to dashboard Cite

IntroductionThe autologous vein bypass remains the most effective and durable revascularization strategy for patients with critical limb ischemia [1]. However, despite significant advances in the understanding of venous pathophysiology post-implantation, little progress was made in the clinical setting in which vein graft failure rate is still 30 -50% within 3 to 5 years [1,2].Early graft occlusion, within one month from implantation, is generally ascribed to technical or procedural related complications (e.g., kinking and twisting) or poor conduit quality. Late vein graft failure is attributed to the structural changes that occur in the conduit immediately post-implantation due to the exposure to Following completion of the first anastomosis, randomization was performed to allocate the experimental and control grafts in each animal. Post-procedure, Doppler US was used to assess grafts lumen diameter at T0 and then 3-5 and 12-14 weeks after surgery. At 12-14 weeks, all sheep underwent angiography to assess grafts patency and lumen uniformity (coefficient of variance -CV) after which they were sacrificed, and all grafts were harvested for microscopic histological analysis. Results: Baseline (T0) internal diameter was not significantly different between the supported and unsupported grafts. At twelve to fourteen weeks, the internal diameter of supported grafts remained unchanged and was significantly lower compared to the non-supported grafts (6.6mm±0.4mm vs. 12.8mm±4.0mm respectively, p= 0.0001). Percentage coefficient of variance (%CV) was 4.6% ± 4.3 in the supported grafts as opposed to average CV% of 14.7% ±6.5 in the non-stented group (p=0.011). Neointimal area was significantly lower in the stented compared to the non-stented group (1.4 mm2± 3.3mm2 versus 9.6mm2 ± 9.7mm2 respectively, p=0.009). Inhibition of vein graft remodeling and neo-intimal formation using a cobalt chrome external support Conclusions:External support of vein grafts using a braided cobalt chrome external stent reduces early vein graft remodeling and mitigates the development of neointimal hyperplasia.

show abstract

Section: Resultssupporting

confidence: 71%

Inhibition of vein graft remodeling and neo-intimal formation using a cobalt chrome external support

Nitecki¹,

Yosef²,

Tozzi³

et al. 2018

Arch Clin Exp Surg

View full text Add to dashboard Cite

show abstract

“…Preventing acute distension of AVGs by adding an external structural support (or sheath) has seemingly improved the patency of vein grafts [26,31,[40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] i) The biodegradation rate of the wrap must be tunable…”

Section: List Of Tablesmentioning

confidence: 99%

“…They showed that the sheath prevented dilatation, that it was well accepted by the host tissue, and that there was no difference in the tensile strength between supported and nonsupported vessels [50]. Karayannacos effects included enhanced neo-vasa-vasorum development over unwrapped controls [51].…”

Section: Previous Attempts To Wrap Arterial Vein Graftsmentioning

confidence: 99%

“…The porcine internal jugular vein (PIJV) was chosen as a model because of its similarity in inner diameter and wall thickness to the human greater saphenous vein, and because this tissue has previously been used to investigate the pathologic response of veins exposed to arterial hemodynamic conditions [43,49,51,81,163,221,248,273,[294][295][296]. The surgical harvest procedure was performed in the manner of a saphenectomy for bypass.…”

Section: Tissue Harvest and Transportmentioning

confidence: 99%

“…Previous attempts to limit CWS using an external sheath have not been fully successful because they were either biodurable and/or loose fitting [31,[40][41][42][43][44][45][46][47][48][49][50][51][52]54,300]. To demonstrate how the wrap may modulate CWS, and how the wrap may be tuned to achieve desired results, we examined the CWS-over-time profile for each of the wrap combinations given in Table 3.1 and compared these to unwrapped vein segments exposed to venous or arterial conditions.…”

Section: Cws Calculation In a Compound Cylindermentioning

confidence: 99%

See 2 more Smart Citations

In Situ Bioengineering of Arterial Vein Grafts

El-Kurdi

Morelli

Hong

et al. 2008

ASME 2008 Summer Bioengineering Conference, Parts a and B

View full text Add to dashboard Cite

The autogenous saphenous vein remains the graft of choice for both coronary (500,000 annually in the US) and peripheral (80,000 annually) arterial bypass procedures. Failure of arterial vein grafts (AVGs) remains a major problem, and patients with failed grafts will die or require reoperation. Intimal hyperplasia (IH) accounts for 20% to 40% of all AVG failures. It is believed that this adverse pathological response by AVGs is largely due to their abrupt exposure to the significantly elevated circumferential wall stress (CWS) associated with the arterial system. We believe that if an AVG is given an ample opportunity to adapt and remodel to the stresses of its new environment, cellular injury may be reduced, thus limiting the initiating mechanisms of IH.The goal of this work was to develop a new mechanical conditioning paradigm, in the form of a peri-adventitially placed, biodegradable polymer wrap, to safely and functionally "arterialize" AVGs in situ. The polymer wrap was tuned so that as it degraded over a desired period of time, the mechanical support offered by it was reduced and the vein was exposed to gradually increasing levels of CWS in situ.To investigate the effects of mechanical conditioning on AVGs, we utilized both our well established, validated ex vivo vascular perfusion system (EVPS) as well as an appropriate preclinical animal model. The "engineering" component of this bioengineering study was to enhance our EVPS capabilities. Enhancements were made in the form of rigorous mathematical modeling, via subspace system identification, and automatic feedback control, via proportional iv integral and derivative control, of the arterial CWS and shear stress waveform generation capabilities of the EVPS. Pairs of freshly harvested porcine internal jugular veins (PIJVs) were perfused ex vivo under several biomechanical conditions. The acute hyperplastic response of PIJVs abruptly exposed to arterial hemodynamic conditions was compared to PIJVs perfused under normal venous conditions. In an attempt to attenuate this acute hyperplastic response, an ex vivo mechanical conditioning paradigm was imposed onto the PIJVs both via manual adjustment of EVPS parameters and via an adventitially placed tuned electrospun biodegradable polymer wrap. Early markers of IH were evaluated post-perfusion, and they included vascular smooth muscle cell apoptosis, proliferation, and phenotypic modulation. Quantification of these markers via immunohistochemical techniques provided the foundation for the final stage of this work. To assess the efficacy of the tuned electrospun biodegradable polymer wrap in attenuating the development of intimal hyperplasia in AVGs, a series of preclinical studies was performed in a pig model. PIJVs abruptly exposed to arterial levels of CWS showed a significant increase in apoptosis and in the number of synthetic smooth muscle cells, as well as a decrease in proliferation. Mechanical conditioning, via both manual adjustment of the EVPS parameters and placement of the biodegradable adventitial wra...

show abstract

Effect of pore size and spacing on neovascularization of a biodegradble shape memory polymer perivascular wrap

Boire

Himmel

et al. 2020

J Biomedical Materials Res

View full text Add to dashboard Cite

Neointimal hyperplasia (NH) is a main source of failures in arteriovenous fistulas and vascular grafts. Several studies have demonstrated the promise of perivascular wraps to reduce NH via promotion of adventitial neovascularization and providing mechanical support. Limited clinical success thus far may be due to inappropriate material selection (e.g., nondegradable, too stiff) and geometric design (e.g., pore size and spacing, diameter). The influence of pore size and spacing on implant neovascularization is investigated here for a new biodegradable, thermoresponsive shape memory polymer (SMP) perivascular wrap. Following an initial pilot, 21 mice were each implanted with six scaffolds: four candidate SMP macroporous designs (a–d), a nonporous SMP control (e), and microporous GORETEX (f). Mice were sacrificed after 4 (N = 5), 14 (N = 8), and 28 (N = 8) days. There was a statistically significant increase in neovascularization score between all macroporous groups compared to nonporous SMP (p < .023) and microporous GORETEX (p < .007) controls at Day 28. Wider‐spaced, smaller‐sized pore designs (223 μm‐spaced, 640 μm‐diameter Design c) induced the most robust angiogenic response, with greater microvessel number (p < .0114) and area (p < .0055) than nonporous SMPs and GORETEX at Day 28. This design also produced significantly greater microvessel density than nonporous SMPs (p = 0.0028) and a smaller‐spaced, larger‐sized pore (155 μm‐spaced, 1,180 μm‐sized Design b) design (p = .0013). Strong neovascularization is expected to reduce NH, motivating further investigation of this SMP wrap with controlled pore spacing and size in more advanced arteriovenous models.

show abstract

Long-term reduction of medial and intimal thickening in porcine saphenous vein grafts with a polyglactin biodegradable external sheath

Cited by 69 publications

References 40 publications

Inhibition of vein graft remodeling and neo-intimal formation using a cobalt chrome external support

Inhibition of vein graft remodeling and neo-intimal formation using a cobalt chrome external support

In Situ Bioengineering of Arterial Vein Grafts

Effect of pore size and spacing on neovascularization of a biodegradble shape memory polymer perivascular wrap

Contact Info

Product

Resources

About