Investigating oxygen transport efficiencies in precision-cut liver slice-based organ-on-a-chip devices

Microfluidic ‘organ-on-a-chip’ devices hold great potential for better mimicking the continuous flow microenvironment experienced by tissue and cells in vivo, thereby ensuring realistic transport of nutrients and elimination of waste products. However, the mass transport of oxygen, which arguably is the most critical nutrient due to its inherently low solubility in water, is rarely assessed. To this aim, the suitability of various precision-cut liver slice (PCLS) microfluidic devices for the defined maintenance of oxygen mass transport were evaluated using COMSOL simulations, leading to the development of a novel, optimised design to provide defined in vivo oxygenation conditions within an organ-on-a-chip system. Simulations found that the proposed device was capable of maintaining 43% of the tissue slice volume within the physiological range of the liver against 18% for the best performing literature device. The optimal device architecture derived from the modelling was then fabricated and its operation confirmed with an LDH assay. These simulation results form the basis for a greater understanding of not just the challenges involved in designing organ-on-a-chip devices, but also highlight issues that would arise from the incorporation of additional organs, as research progresses towards complete human-on-a-chip model systems