Symposium X—MRS/The Kavli Foundation Frontiers of Materials
November 29, 2023
Róisín Owens, University of Cambridge
Advanced Tissue Engineering for In Vitro Drug Safety and Toxicology Testing
Written by Alison Hatt
In Tuesday’s Symposium X—MRS/The Kavli Foundation Frontiers of Materials, Róisín Owens of the University of Cambridge gave an overview of her work engineering tissues and integrating devices into cell and tissue models to probe electronic and ionic activity. The measurements can detect pathogens, reveal the impact of drug therapies, and interrogate tissue function, and the work broadly aims to improve in vitro models and accelerate drug discovery.
Most of the work Owens discussed involved devices fabricated from conducting polymers, primarily PEDOT:PSS, which have both ion and electron conductivity and so can translate ionic signals to electronic and vice versa. Conducting polymers also have the great advantage of starting as a liquid, allowing Owens and her collaborators to construct devices in all manner of different shapes and sizes.
She described several projects involving cell membranes, modeled by creating a supported lipid bilayer on the surface of a planar device like a multielectrode array, which can measure the membrane’s resistance and capacitance. Her laboratory used this technique to detect the entry of SARS-CoV-2 into a cell membrane, and to detect whether the virus was successfully blocked by a therapeutic antibody. They also used the technique to interrogate disparate parts of neurons, which can have very different morphologies and properties in different parts of the cell, observing the varying resistance due to changes in ion-channel density.
Stepping up a level in complexity, Owens described her work with barrier tissues next, in which ion flow is controlled by groups of cells. When those barriers are compromised in our bodies, pathogens can enter tissues and many diseases are connected to compromised barriers. Using a transistor device, Owens’s lab measured ion flow in a barrier tissue exposed to tumor-derived extracellular vesicles, which can fuse with healthy cells and spread cancer to them. They observed a change in resistance at the time of exposure due to a hypothesized change in cell morphology and could also observe the effect of a drug treatment, screening continuously to monitor its effect.
Owens also described her group’s work making 3D tissue models. Their strategy is to seed fibroblasts into a porous scaffold of PEDOT:PSS, where they excrete extracellular matrix, forming a sort of cyborg tissue. The researchers can then grow a layer of epithelium or endothelium on top of the membrane. In this manner, Owens’s research group has developed models for gut, brain, and lung tissue, building up stratified tissues with multiple components, allowing them to interrogate diseases and functions of those tissues. Using impedance measurements, the team can discern the signature of different tissue types.
Measuring the impedance of intestinal epithelial tissue is useful for studying the gut microbiome and the connection between the gut and the brain. Owens showed results of an experiment where they added two types of live E. coli bacteria to the model and observed an increase in impedance, which indicated that the bacteria had strengthened the barrier.
Owens also discussed ongoing work to try and address human tissues ex vivo or in vivo with multielectrode devices. In one project, group members created an all-planar device for lung and gut models that can be placed atop existing tissue to measure its barrier properties. In another, her team developed a resistive strain gauge using PEDOT:PSS and PDMS to measure gut motility and neuronal activity of the gut’s muscle layer.
Looking forward, among other things, Owens is working toward developing patient-derived models to study diseases like IBS and MS, helping understand the role of the gut-brain axis and testing new therapies.
Symposium X—MRS/The Kavli Foundation Frontiers of Materials features lectures aimed at a broad audience to provide meeting attendees with an overview of leading-edge topics.