Electroactive 4D Porous Scaffold Based on Conducting Polymer as a Responsive and Dynamic In Vitro Cell Culture Platform.

In vivo, cells reside in a 3D porous and dynamic microenvironment. It provides biochemical and biophysical cues that regulate cell behavior in physiological and pathological processes. In the context of fundamental cell biology research, tissue engineering, and cell-based drug screening systems, a challenge is to develop relevant in vitro models that could integrate the dynamic properties of the cell microenvironment. Taking advantage of the promising high internal phase emulsion templating, we here designed a polyHIPE scaffold with a wide interconnected porosity and functionalized its internal 3D surface with a thin layer of electroactive conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) to turn it into a 4D electroresponsive scaffold. The resulting scaffold was cytocompatible with fibroblasts, supported cellular infiltration, and hosted cells, which display a 3D spreading morphology. It demonstrated robust actuation in ion- and protein-rich complex culture media, and its electroresponsiveness was not altered by fibroblast colonization. Thanks to customized electrochemical stimulation setups, the electromechanical response of the polyHIPE/PEDOT scaffolds was characterized in situ under a confocal microscope and showed 10% reversible volume variations. Finally, the setups were used to monitor in real time and in situ fibroblasts cultured into the polyHIPE/PEDOT scaffold during several cycles of electromechanical stimuli. Thus, we demonstrated the proof of concept of this tunable scaffold as a tool for future 4D cell culture and mechanobiology studies.

Fabrication Strategies of Scaffolds for Delivering Active Ingredients for Tissue Engineering.

Designing scaffolds with optimum properties is an essential factor for tissue engineering success. They can be seeded with isolated cells or loaded with drugs to stimulate the body ability to repair or regenerate the injured tissues by acting as centers for new tissue formation. Recently, scaffolds gained a significant interest as principal candidates for tissue engineering due to overcoming the autograft or allograft's associated problems. The advancement of the tissue engineering field relies mainly on the introduction of new biomaterials for scaffolds' fabrication. This review presents and criticizes different scaffolds' fabrication techniques with particular emphasis on the fibrous, injectable in situ forming, foam, 3D freeze-dried, 3D printed, and 4D scaffolds. This article highlights on scaffolds' composition which would be beneficial for developing scaffolds that could potentially help to meet the demand for both drug delivery and tissue regeneration.

Biocompatible electrically conductive nanofibers from inorganic-organic shape memory polymers.

A porous shape memory scaffold with both biomimetic structures and electrical conductivity properties is highly promising for nerve tissue engineering applications. In this study, a new shape memory polyurethane polymer which consists of inorganic polydimethylsiloxane (PDMS) segments with organic poly(ε-caprolactone) (PCL) segments was synthesized. Based on this poly(PCL/PDMS urethane), a series of electrically conductive nanofibers were electrospun by incorporating different amounts of carbon-black. Our results showed that after adding carbon black into nanofibers, the fiber diameters increased from 399±76 to 619±138nm, the crystallinity decreased from 33 to 25% and the resistivity reduced from 3.6 GΩ/mm to 1.8 kΩ/mm. Carbon black did not significantly influence the shape memory properties of the resulting nanofibers, and all the composite nanofibers exhibited decent shape recovery ratios of >90% and shape fixity ratios of >82% even after 5 thermo-mechanical cycles. PC12 cells were cultured on the shape memory nanofibers and the composite scaffolds showed good biocompatibility by promoting cell-cell interactions. Our study demonstrated that the poly(PCL/PDMS urethane)/carbon-black nanofibers with shape memory properties could be potentially used as smart 4-dimensional (4D) scaffolds for nerve tissue regeneration.