Environmentally Controlled Microfluidic System Enabling Immune Cell Flow and Activation in an Endothelialised Skin‐On‐Chip

Integration of reconstructed human skin (RhS) into organ-on-chip (OoC) platforms addresses current limitations imposed by static culturing. This innovation, however, is not without challenges. Microfluidic devices, while powerful, often encounter usability, robustness, and gas bubble issues that hinder large-scale high-throughput setups. This study aims to develop a novel re-usable multi-well microfluidic adaptor (MMA) with the objective to provide a flexible tool for biologists implementing complex 3D biological models (e.g., skin) while enabling simultaneous user control over temperature, medium flow, oxigen (O₂), nitrogen (N₂), and carbon dioxide (CO₂) without the need for an incubator. The presented MMA device is designed to be compatible with standard, commercially available 6-well multi-well plates (6MWPs) and 12-well transwells. This MMA-6MWP setup is employed to generate a skin-on-chip (SoC). RhS viability is maintained under flow for three days and their morphology closely resembles that of native human skin. A proof-of-concept study demonstrates the system's potential in toxicology applications by combining endothelialised RhS with flowing immune cells. This dynamic setting activates the monocyte-like MUTZ-3 cells (CD83 and CD86 upregulation) upon topical exposure of RhS to a sensitizer, revealing the MMA-6MWP's unique capabilities compared to static culturing, where such activation is absent.