Fabrication Of Tubular Scaffolds Research Articles

2D imprinted substrates and 3D electrospun scaffolds revolutionize biomedicine.

Momentous advances in engineering in the 1980s and 1990s reduced significantly the manufacturing cost of equipment that can produce nano to low microscale materials. This was a key milestone in the field of biomedicine, as from the early 2000s, we entered the era of nanobiomedicine. Essentially, with very low capital cost, every laboratory in the world could develop cell culture substrates and/or implantable devices with morphological features down to the nanometer scale. The rationale of using such small dimensional features derives from the fact that the extracellular space is comprised of nanoto microscale supramolecular assemblies. Further, cells employ probing filopodia extensions and contractile intracellular machinery to gather topographical, spatial, mechanical and chemical information from the extracellular environment, which consequently determines cell functionality, lineage commitment and fate. Among the various fabrication technologies, lithography constitutes the most popular 2D top-down method, while electrospinning represents the most widely used 3D bottomup method [1–7]. The produced 2D and 3D constructs have enabled the study of cell and tissue responses at previously economical and technological prohibiting small scales and the rational design thereof for a specific application/clinical indication. Key to the design tenant is that topographical features and morphological structures should promote cellular polarization and organized extracellular matrix assembly, resembling the natural conformation of tissues. Using photolithography back in 1983, microscale V-shape grooves were created to study human gingival and porcine epithelial cell response [8]. By 1997, we were in a position to fabricate substrates with feature (square) accuracy down to 14 nm (depth) to study Xenopus neurites outgrowth using electron-beam lithography [9,10]. To date, we have successfully imprinted various gratings and geometric shapes along different scales onto thermoplastic polymers to create biologically relevant topographical interfaces. Data obtained from these and other studies clearly illustrate that topographical features are powerful modulators of cell morphology and differential function [11–15]. Further, nanoand microscale arrays have been shown to be potent tools in maintaining the phenotype fidelity of permanently differentiated cells and in differentiating stem cells toward specific lineages [16,17]. Multiple topographic arrays have also been used as high-throughput systems to elucidate the cell–surface interactions and enable identification of improved surfaces for optimal/required cell response [18,19]. Specifically, topographical features have been shown to directly modulate cell–material interaction and to affect the composition, orientation and conformation of adsorbed extracellular matrix components [20,21]. Further, nanoimprinted materials have been shown to either 2D imprinted substrates and 3D electrospun scaffolds revolutionize biomedicine

Fabrication of Tubular Scaffolds with Controllable Fiber Orientations Using Electrospinning for Tissue Engineering

Tubular scaffolds with controllable fiber orientations are fabricated by electrospinning with a conductive rotating drum in the presence of a parallel or orthogonal conductive wire. A higher rotational speed of the drum results in thinner fibers and a more aligned fibrous structure. The fiber orientation can be further precisely controlled by the design of a conductive wire capable of guiding the deposition of electrospun fibers. Parallel or orthogonal fiber orientations in the tubular scaffolds are achieved using an orthogonal or parallel conductive wire, respectively, at a high rotational speed of the drum. Cell culture on the scaffolds with random, parallel, and orthogonal fiber orientations reveals that the degree of stretching of the fibroblast is highly affected by the fiber orientations.

Design and fabrication of tubular scaffolds via direct writing in a melt electrospinning mode.

Flexible tubular structures fabricated from solution electrospun fibers are finding increasing use in tissue engineering applications. However it is difficult to control the deposition of fibers due to the chaotic nature of the solution electrospinning jet. By using non-conductive polymer melts instead of polymer solutions the path and collection of the fiber becomes predictable. In this work we demonstrate the melt electrospinning of polycaprolactone in a direct writing mode onto a rotating cylinder. This allows the design and fabrication of tubes using 20 μm diameter fibers with controllable micropatterns and mechanical properties. A key design parameter is the fiber winding angle, where it allows control over scaffold pore morphology (e.g. size, shape, number and porosity). Furthermore, the establishment of a finite element model as a predictive design tool is validated against mechanical testing results of melt electrospun tubes to show that a lesser winding angle provides improved mechanical response to uniaxial tension and compression. In addition, we show that melt electrospun tubes support the growth of three different cell types in vitro and are therefore promising scaffolds for tissue engineering applications.Electronic supplementary materialThe online version of this article (doi:10.1007/s13758-011-0013-7) contains supplementary material, which is available to authorized users.