Background

Our research group aims to implement various biological questions and models in microphysiological systems (MPS). We have established an iPSC-derived blood-brain barrier on a Mimetas chip (Burgio et al., 2023) and an in vitro kidney model on the Vitrofluid platform (Specioso et al., 2022). Currently, we are developing a plug-and-play MPS to recapitulate the liver fibrosis AOP in vitro. We have already identified several biomarkers and endpoints for key cellular responses. However, we are lacking real-time monitoring of mitochondrial health. The host lab’s liver chip, with integrated oxygen sensors, can be employed to measure oxygen consumption in a manner analogous to that of the Seahorse assay (Schmidt et al. 2022). The implementation of our liver fibrosis model on the liver chip would not only serve to confirm the robustness of the model, independent of the MPS, but would also facilitate a deeper insight into the mechanisms of fibrosis.

Aims

• Learn to fabricate microphysiological systems in-house, rather than depending on commercial chips or on collaborators to make them.
• Run the home lab’s liver fibrosis model on the host lab’s liver chip, which has oxygen sensors built in.
• Add real-time monitoring of mitochondrial health to the model, by measuring how much oxygen the cells consume.
• Confirm that the fibrosis model behaves consistently when moved onto a different system.

Outcome

Saskia Schmidt came back able to make the chips herself. At the host lab she learned the full process: adapting the technical drawings, cutting the layers, and assembling them under particle-free conditions, including fitting the membranes and bonding the layers together. She also learned the steps that follow, from sterilising a finished chip to preparing its surfaces so that liquid flows through properly and the cell spheroids can be loaded.

She learned to build the oxygen sensors into the chips and to read them, which was the measurement the fibrosis model had been missing. Alongside this came training in automated valve control and in high-speed confocal imaging, which captures a stack of images through the depth of a sample fast enough to follow living tissue.

Some of this transferred to Muttenz immediately. The connection between the chip and its tubing has been improved, and the host lab’s sterilisation protocol adopted, both of which have made the prototype more reliable to run.

Fabrication is the harder part to bring home. Making chips of this kind needs a UV laser cutter, a hot press and a clean room, and the home lab has none of these on hand. Buying them for a single project would be difficult to justify, so the realistic routes are shared facilities or continued collaboration. Meanwhile the work at the host lab continues: a master’s student Schmidt supervised is running experiments there, and the two groups have submitted a joint conference abstract and are preparing a publication.

A wider connection also came out of the stay. The host institution’s 3R centre proposed collaboration between the Swiss 3RCC community and the 3R Network Baden-Württemberg, with the aim of building cross-border links in alternative methods.