now clear that architectures that reproduce tissue organization in 3D are favored for studying function as first shown by Bissell and co-workers nearly 30 years ago. [5,6] Another emerging concept is the capacity for multiple cell types to auto-organize when given the appropriate mechanical cues. [7] A large variety of 3D models have been developed, with the major subtypes being spheroids/organoids, multilayered tissue like models, and scaffold models. [8] 3D tissues are frequently constructed as spheroids using hydrogel-like matrices such as Matrigel, [9] or PuraMatrix, [10] with a highly desirable degree of mechanical softness, however, there can be problems related to cost and inhomogeneity of the materials. [11] Multilayer models hold a lot of promise for applications such as skin toxicology measurements, [12] however, they cannot be easily applied for more complex tissue or organ constructs including vasculature. Considerable attention has thus focused on the development of biocompatible scaffold materials for hosting cells in 3D. A variety of synthetic and bio-derived polymers (some resorbable, some not) have been used to mimic the ECM or connective tissue. In terms of technology integration, the major advances so far for 3D cell biology have been related to materials and methods used for scaffold preparation, and integration of microfabrication techniques, for example for fluidics. As might be expected, a challenge of 3D culture over 2D is associated with the difficulty of oxygenation of tissues in the absence of vasculature. Microfluidics have gained favor for a number of reasons, including for perfusion, reduction in reagent volumes, and the fact that flow induced stress This work reports the design of a live-cell monitoring platform based on a macroporous scaffold of a conducting polymer, poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate). The conducting polymer scaffolds support 3D cell cultures due to their biocompatibility and tissue-like elasticity, which can be manipulated by inclusion of biopolymers such as collagen. Integration of a media perfusion tube inside the scaffold enables homogenous cell spreading and fluid transport throughout the scaffold, ensuring long term cell viability. This also allows for co-culture of multiple cell types inside the scaffold. The inclusion of cells within the porous architecture affects the impedance of the electrically conducting polymer network and, thus, is utilized as an in situ tool to monitor cell growth. Therefore, while being an integral part of the 3D tissue, the conducting polymer is an active component, enhancing the tissue function, and forming the basis for a bioelectronic device with integrated sensing capability.

We report development of the first biomimetic transistor in a tube for continuous monitoring of 3D cell cultures.

This study aims at investigating the behavior in terms of the proliferation and skeletal muscle differentiation capability of two myoblastic cell lines, C2C12 and H9c2, on both isotropic and anisotropic electrospun nanofibrous poly(hydroxybutyrate) (PHB) scaffolds, as well as on PHB films and polystyrene controls. After a careful characterization of the matrices in terms of surface morphology, surface roughness and mechanical properties, the proliferation rate and the capability of the two cell lines to form skeletal myotubes were evaluated. Genetic analyses were also performed in order to assess the differentiation level of the cells on the different substrates. We demonstrated that the aligned nanofibrous mesh decreases the proliferation activity and provides a higher differentiative stimulus. We also clarified how the nanofibrous substrate influences myotube formation, and quantified a series of myotube-related parameters for both C2C12 and H9c2 cells.

Conducting polymer scaffolds can promote cell growth by electrical stimulation, which is advantageous for some specific type of cells such as neurons, muscle, or cardiac cells. As an additional feature, the measure of their impedance has been demonstrated as a tool to monitor cell growth within the scaffold. In this work, we present innovative conducting polymer porous scaffolds based on poly(3,4-ethylenedioxythiophene) (PEDOT):xanthan gum instead of the well-known PEDOT:polystyrene sulfonate scaffolds. These novel scaffolds combine the conductivity of PEDOT and the mechanical support and biocompatibility provided by a polysaccharide, xanthan gum. For this purpose, first, the oxidative chemical polymerization of 3,4-ethylenedioxythiophene was carried out in the presence of polysaccharides leading to stable PEDOT:xanthan gum aqueous dispersions. Then, by a simple freeze-drying process, porous scaffolds were prepared from these dispersions. Our results indicated that the porosity of the scaffolds and mechanical properties are tuned by the solid content and formulation of the initial PEDOT:polysaccharide dispersion. Scaffolds showed interconnected pore structure with tunable sizes ranging between 10 and 150 μm and Young’s moduli between 10 and 45 kPa. These scaffolds successfully support three-dimensional cell cultures of MDCK II eGFP and MDCK II LifeAct epithelial cells, achieving good cell attachment with very high degree of pore coverage. Interestingly, by measuring the impedance of the synthesized PEDOT scaffolds, the growth of the cells could be monitored.