A novel polymeric fibrous microstructured biodegradable small-caliber tubular scaffold for cardiovascular tissue engineering

Abstract

Increasing morbidity of cardiovascular diseases in modern society has made it crucial to develop artificial small-caliber cardiovascular grafts for surgical intervention of diseased natural arteries, as alternatives to the gold standard autologous implants. Synthetic small-caliber grafts are still not in use due to increased risk of restenosis, lack of lumen re-endothelialization and mechanical mismatch, leading sometimes either to graft failure or to unsuccessful remodeling and pathology of the distal parts of the anastomosed healthy vascular tissues. In this work, we aimed to synthesize small-caliber polymeric (polycaprolactone) tissue-engineered vascular scaffolds that mimic the structure and biomechanics of natural vessels. Electrospinning was implemented to prepare microstructured polymeric membranes with controlled axis-parallel fiber alignment. Consequently, we designed small-caliber multilayer anisotropic biodegradable nanofibrous tubular scaffolds, giving attention to their radial compliance. Polycaprolactone scaffold morphology and mechanical properties were assessed, quantified, and compared with those of native vessels and commercial synthetic grafts. Results showed a highly hydrophobic scaffold material with a three-layered tubular morphology, 4-mm internal diameter/0.25 ± 0.09-mm thickness, consisting of predominantly axially aligned thin (1.156 ± 0.447 μm), homogeneous and continuous microfibers, with adequate (17.702 ± 5.369 μm) pore size, potentially able to promote cell infiltration in vivo. In vitro accelerated degradation showed a 5% mass loss within 17–25 weeks. Mechanical anisotropy was attained as a result, almost one order of magnitude difference of the elastic modulus (18 ± 3 MPa axially/1 ± 0.3 MPa circumferentially), like that of natural arterial walls. Furthermore, a desirable radial compliance (5.04 ± 0.82%, within the physiological pressure range) as well as cyclic stability of the tubular scaffold was achieved. Finally, cytotoxicity evaluation of the polymeric scaffolds revealed that the materials were nontoxic and did not release substances harmful to living cells (over 80% cell viability achieved).

Recent Applications of Electrospun Nanofibrous Scaffold in Tissue Engineering

“…Moreover, an order of magnitude difference in elastic modulus was achieved, resulting in mechanical inhomogeneity. Finally, the polymeric scaffolds' toxicity evaluation revealed that the materials were safe and did not release any toxic and dangerous substances [ 96 ].…”

Recent applications of electrical, centrifugal, and pressurised emerging technologies for fibrous structure engineering in drug delivery, regenerative medicine and theranostics

“…PCL tubular scaffolds have been developed that have the ability to mimic both the structure and the biomechanics of blood vessels. Dimopoulous et al fabricated biodegradable scaffolds which promoted cell infiltration and possessed excellent mechanical properties mirroring those of natural vessels [445]. PCL was also used in conjunction with fibrin to develop electrospun vascular grafts which also found to improve cell infiltration and proliferation [446].…”

Solution-Based Processing for Scaffold Fabrication in Tissue Engineering Applications: A Brief Review

“…On the other hand, PCL scaffolds for vascular tissue engineering were fabricated as support for the creation of a polymer-cell complex in vitro with subsequent implantation in vivo. Dimopoulos et al [ 95 ] verified the in vitro biocompatibility and cytotoxicity of electrospun PCL structures, as well as their significant effect on cellular behavior in vivo, i.e., their capability to induce cell attachment, migration, and differentiation. Additionally, the achieved fiber diameter, as well as mechanical properties of the produced scaffold, resulted comparable to the collagen fibers found in native vessels.…”