In Vivo Stability of Polyurethane-Based Electrospun Vascular Grafts in Terms of Chemistry and Mechanics.

Alexander Gostev,Vera Chernonosova,Inna Shundrina,Andrey Karpenko,Vitaliy Pastukhov,Pavel Laktionov,Alexey Shutov

doi:10.3390/polym12040845

Abstract

The biostability of the polyurethanes Tecoflex EG-80A and Pellethane 2363-80A, used as basic polymers of the vascular grafts (VGs) produced by electrospinning, as well as the tensile strength of Tecoflex VGs, are studied. Solutions of Tecoflex or Pellethane with gelatin and bivalirudin in 1,1,1,3,3,3-hexafluoroisopropanol are used for VG production. After 1, 12, and 24 weeks of VG implantation in the infrarenal position of the abdominal aorta of Wistar rats, VGs are explanted, fixed in formalin, freed from outer tissues, dialyzed, and dried. The polyurethanes are extracted from VGs by dispersion/extraction in tetrahydrofuran (THF) and freed from the excess of THF-insoluble biopolymers. The stability of polyurethanes is assessed by IR spectroscopy and gel permeation chromatography. Pellethane has emerged to be stable at all experimental points. Tecoflex loses approximately 10% of its molecular weight (both Mn and Mw) after 3 months and restored its initial value within 6 months of its functioning as a graft. Mechanical testing demonstrates a 30% reduction in the tensile strength after 3 months in VG and a 10% increase after 6 months. The stability and mechanical properties of polyurethane-based VGs demonstrate their utility for the reconstitution of damaged arteries.

Highlights

Polyurethanes are a class of polymers with a wide range of properties, which makes them promising for medical purposes
We have demonstrated that the 3D matrices produced from protein-enriched polyurethanes possess good mechanical properties, and structural stability in vitro, bio- and hemocompatibilities, and are, valuable materials for the production of small-diameter vascular grafts [19,20,21]
The vascular grafts (VGs) were produced of the blends of these polymers with gelatin because we have previously demonstrated that the 3D matrices produced from these blends are well bio- and hemocompatible, stronger than those of pure polyurethanes, and are valuable materials for VG production [19,20]

Summary

Introduction

Polyurethanes are a class of polymers with a wide range of properties, which makes them promising for medical purposes. They are used for manufacturing both manifold medical instruments [1] and grafts [2], and may have different biodegradation rates depending on the structures of their soft and hard segments [3,4]. The stability of thermoplastic polyurethanes in biological systems and the mechanisms underlying their degradation have been studied for films, sheets, or nonporous monolithic type items manufactured, as a rule, by cast molding [6]. A few studies considered the stability of polyurethanes in porous objects [7,8], while these particular materials, including those produced of a mixture of synthetic and natural polymers, are currently regarded as promising for tissue engineering in various organs [9,10,11].

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Conclusion