Electrospun vascular grafts with improved compliance matching to native vessels

Abstract

Coronary artery bypass grafting (CABG) is one of the most commonly performed major surgeries in the United States. Autologous vessels such as the saphenous vein are the current gold standard for treatment; however, synthetic vascular prostheses made of expanded poly(tetrafluoroethylene) (ePTFE) or poly(ethylene terephthalate) (PET) are used when autologous vessels are unavailable. These synthetic grafts have a high failure rate in small diameter (<4 mm) applications due to rapid re-occlusion via intimal hyperplasia. Current strategies to improve clinical performance are focused on preventing intimal hyperplasia by fabricating grafts with compliance and burst pressure similar to native vessels. To this end, we have developed an electrospun vascular graft from segmented polyurethanes with tunable properties by altering material chemistry and graft microarchitecture. Relationships between polyurethane tensile properties and biomechanical properties were elucidated to select polymers with desirable properties. Graft thickness, fiber tortuosity, and fiber fusions were modulated to provide additional tools for controlling graft properties. Using a combination of these strategies, a vascular graft with compliance and burst pressure exceeding the saphenous vein autograft was fabricated (compliance = 6.0 ± 0.6 %/mmHg × 10−4, burst pressure = 2260 ± 160 mmHg). This graft is hypothesized to reduce intimal hyperplasia associated with low compliance in synthetic grafts and improve long term clinical success. Additionally, the fundamental relationships between electrospun mesh microarchitecture and mechanical properties identified in this work can be utilized in various biomedical applications.

Human adipose-derived stromal cells for the production of completely autologous self-assembled tissue-engineered vascular substitutes

“…In accordance, histological staining showed wavier collagen fibers in ASC-TEVS than in DF-TEVS. The compliance of ASC-TEVS (3.72%/100 mmHg) was still lower than native arteries, which range from 4.5 to 16%/100 mmHg in the literature [36][37][38], but it was higher than most synthetic material [39,40]. Furthermore, due to the biological nature of the TEVS, an in vivo remodeling is likely to further improve their compliance [31,37].…”

Matching Static and Dynamic Compliance of Small‐Diameter Arteries, with Poly(lactide‐co‐caprolactone) Copolymers: In Vitro and In Vivo Studies

“…Although considerably lower than natural vessels, it was also twice as large as the highest blood pressure recorded in humans (370 mm Hg) 94. Compliance and burst pressure are often inversely related, which underlines the difficulty of engineering vascular prostheses 49. Hence, a compromise was found between compliance and burst strength achieved by 150 µm WT PLC 70:30 tubes.…”

“…The 150 µm WT PLC 70:30 tube, which had the closest compliance match to the porcine arteries, exhibited a burst strength of 769 ± 9 mm Hg. It is often reported that a vascular prosthesis should exceed the value of saphenous veins (1599 ± 877 mm Hg [89] ) or ten times the systolic pressure ( P Syst = 120 mm Hg) 49,92,93. Although considerably lower than natural vessels, it was also twice as large as the highest blood pressure recorded in humans (370 mm Hg) 94.…”

“…In summary, we have evaluated prostheses made of PLC polymers of different monomer ratio for their compliance, creep, and kink resistance. Compliance and creep were studied using two modes: a static mode, where a constant pressure is exerted; and a dynamic mode with repetitive cycles similar to the pulsatile pressure of vascular circulation 9,30,47–52. Therefore, a customized apparatus (including a peristaltic pump, a pressure gauge, and an optical micrometer) was constructed, which allowed the determination of these mechanical properties under static and dynamic conditions.…”

Novel Method to Track Soft Tissue Deformation by Micro-Computed Tomography: Application to the Mitral Valve

“…7, 17, 19 To this end, earlier idealized geometric models are giving way to those with unprecedented structural detail. 9, 17, 25 These pursuits are facilitated by the increased availability of micro-computed tomography (μCT), which, with voxel resolution as fine as 9–17 μm, 11 has rapidly become a gold-standard against which other structural imaging modalities are evaluated.…”