Microphysiological systems for realizing microenvironment that mimics human physiology—functional material and its standardization applied to microfluidics

Microphysiological systems (MPS), also known as Organ(s)-on-Chip (OoC), are in vitro cell culture platforms that reproduce the function of cells/tissues/organs in a microenvironment. To closely mimic in vivo physiological functions, MPS must allow the cells to attain three-dimensional arrangements and be supplied with adequate oxygen and growth factors (via microfluidic channels). Furthermore, as MPS are mostly used in cell-based drug development assays, they must ensure easy analysis and high usability. To make MPS which conform to these various requirements, it is crucial to select appropriate materials; oftentimes, MPS-appropriate materials have been developed. Here, we review the functions and properties of materials used to make MPSs and summarize the specifications, considerations, and selection methods employed in choosing appropriate materials and technologies to fabricate MPS that meet standard requirements. Where possible, we give specific examples to explain several important functions. The functions of the chosen material for MPS depend on the context of use (COU) in the drug development process. Because of the diverse COUs, the material selection strategies and the processes used to fabricate required material functionalities are complex. We also discuss the importance of standardizing MPS material and recent international efforts made in this direction.