Abstract
Three-dimensional (3D) printing has been combined with electrospinning to manufacture multi-layered polymer/glass scaffolds that possess multi-scale porosity, are mechanically robust, release bioactive compounds, degrade at a controlled rate and are biocompatible. Fibrous mats of poly (caprolactone) (PCL) and poly (glycerol sebacate) (PGS) have been directly electrospun on one side of 3D-printed grids of PCL-PGS blends containing bioactive glasses (BGs). The excellent adhesion between layers has resulted in composite scaffolds with a Young’s modulus of 240–310 MPa, higher than that of 3D-printed grids (125–280 MPa, without the electrospun layer). The scaffolds degraded in vitro by releasing PGS and BGs, reaching a weight loss of ~14% after 56 days of incubation. Although the hydrolysis of PGS resulted in the acidification of the buffer medium (to a pH of 5.3–5.4), the release of alkaline ions from the BGs balanced that out and brought the pH back to 6.0. Cytotoxicity tests performed on fibroblasts showed that the PCL-PGS-BGs constructs were biocompatible, with cell viability of above 125% at day 2. This study demonstrates the fabrication of systems with engineered properties by the synergy of diverse technologies and materials (organic and inorganic) for potential applications in tendon and ligament tissue engineering.
Highlights
IntroductionIn the field of tissue engineering, combinations of different materials and fabrication approaches are investigated to manufacture scaffolds that are able to satisfy more than one of the following requirements simultaneously [1,2,3]: be biocompatible; offer a biomimetic interface and multiscale porosity to promote cell attachment, migration and proliferation; mimic the mechanical response of the native tissue; and degrade, if required, at a controlled rate to support tissue regeneration.Recently, blends of poly(caprolactone) (PCL), a slow-degrading polyester, and poly(glycerol sebacate) (PGS), a fast-degrading polyester, have been processed by either electrospinning or 3D printing to create porous and biodegradable scaffolds with controlled mechanical properties for heart valve replacement [4,5,6], cardiac patches [7,8,9] and corneal tissue repair [10]
The enhanced secretion of extracellular matrix (ECM) proteins and the control achieved over degradation and mechanical properties of the scaffolds indicate that the poly(glycerol sebacate) (PGS)-PCL electrospun mats can be used for heart valve tissue engineering
The signature bands of PGS are identifiable in the Fourier Transform Infrared (FTIR) spectrum (Figure 1b): the peaks at 2927 and 2851 cm−1 are attributed to alkene (–CH2) groups; the intense peaks at 1732 and 1164 cm−1 are due to C=O and C–O stretching, respectively, and confirm the formation of ester bonds [16,17,18]
Summary
In the field of tissue engineering, combinations of different materials and fabrication approaches are investigated to manufacture scaffolds that are able to satisfy more than one of the following requirements simultaneously [1,2,3]: be biocompatible; offer a biomimetic interface and multiscale porosity to promote cell attachment, migration and proliferation; mimic the mechanical response of the native tissue; and degrade, if required, at a controlled rate to support tissue regeneration.Recently, blends of poly(caprolactone) (PCL), a slow-degrading polyester, and poly(glycerol sebacate) (PGS), a fast-degrading polyester, have been processed by either electrospinning or 3D printing to create porous and biodegradable scaffolds with controlled mechanical properties for heart valve replacement [4,5,6], cardiac patches [7,8,9] and corneal tissue repair [10]. Blending PGS with PCL led to a 16% mass loss of the scaffolds in 7 days, while fibrous mats of just PCL showed a 6% mass loss at the same timepoint. The PGS-PCL scaffolds stimulated VICs to secrete extracellular matrix (ECM) proteins (collagen I, laminin and fibronectin), which contributed to the mechanical properties of the cell-seeded scaffolds. A Young’s modulus of 9.3 MPa was recorded for PGS-PCL scaffolds seeded with VICs after 3 weeks of culture (7.8 MPa at day 0); while acellular scaffolds showed a two-fold decrease in elastic modulus under the same conditions. The enhanced secretion of ECM proteins and the control achieved over degradation and mechanical properties of the scaffolds indicate that the PGS-PCL electrospun mats can be used for heart valve tissue engineering
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