Optimization of Anti-kinking Designs for Vascular Grafts Based on Supramolecular Materials

Abstract

Synthetic vascular grafts to be applied as access grafts for hemodialysis often require anti-kinking properties. Previously, electrospun microporous vascular implants based on synthetic supramolecular materials have been shown to perform adequately as resorbable grafts due to the microstructures, thereby enabling attraction of endogenous cells and consecutive matrix production in situ. Here, we use supramolecular materials based on hydrogen bonding interactions between bisurea (BU) or 2-ureido-4[1H]-pyrimidinones (UPy) to produce microporous anti-kinking tubular structures by combining solution electrospinning with 3D printing. A custom-made rational axis for 3D printing was developed to produce controlled tubular structures with freedom in design in order to print complex tubular architectures without supporting structures. Two different tubular grafts were developed, both composed of a three-layered design with a 3D printed spiral sandwiched in between luminal and adventitial electrospun layers. One tubular scaffold was composed of BU-polycarbonate electrospun layers with 3D printed polycaprolactone (PCL) strands in between for dimensional stability, and the other graft fully consisted of supramolecular polymers, using chain-extended UPy-PCL as electrospun layers and a bifunctional UPy-PCL for 3D printing. Both grafts, with a 3D printed spiral, demonstrated a reproducible dimensional stability and anti-kinking behavior under bending stresses.

Glycosaminoglycans: From Vascular Physiology to Tissue Engineering Applications

“…To improve mechanical properties of electrospun scaffolds, hybrid approaches, combining electrospinning with fused deposition modeling (FDM) ( Centola et al, 2010 ; Wu et al, 2020 ) or melt electrowriting (MEW) ( Brown et al, 2011 ) were explored too. MEW combines electrospinning and FDM, by applying a voltage to a needle and grounding the collecting surface, mostly using molten polymers and avoiding the use of solvents.…”

Silk Vascular Grafts with Optimized Mechanical Properties for the Repair and Regeneration of Small Caliber Blood Vessels

“…The mechanical response of small caliber vascular grafts to bending stresses depends on many factors, including the intrinsic properties of the constituent polymer, the manufacturing process, and the design of the wall of the tube [ 31 ]. Regenerated SF materials, such as films and sponges, may be quite brittle or stiff, thus, being unsuitable for manufacturing kink resistant vascular grafts.…”

Combination of 3D Printing and Electrospinning Techniques for Biofabrication

“…In another work, supramolecular materials based on hydrogen bonding interactions were applied to manufacture microporous anti-kinking tubular structures by electrospinning and 3D printing processes. [136] The tube had a threelayered design with a 3D-printed spiral sandwiched between adventitial and luminal electrospun layers, which presented an anti-kinking behavior and reproducible dimensional stability under bending stresses. A similar structure was adopted by Emechebe et al [137] In their work, antithrombotic drug dipyridamole was incorporated into the graft, and an endothelial progenitor cell adhesive protein was used to functionalize the graft surface to inhibit thrombus and aid faster endothelialization, respectively.…”

“…• Only suitable for fabricating planar and tubular-shaped products Tracheal repair, [58][59][60] nerve repair, [55,56,156] vascular grafts, [57,120,121] bone repair [171] Alternate use of 3D printing and electrospinning Vascular grafts, [122,123,[135][136][137] tracheal repair, [109,112] skin repair, [66] cartilage repair, [29,180,183] tympanic membrane scaffold [34] Electrospun fibers as inks of 3D printing…”