Multistep Fluidic Control Network toward the Automated Generation of Organ-on-a-Chip

Organ-on-a-chip, which mimics physiological functions of organs, is a potential tool for drug development and precision medicine. This chip, accompanied by a suitable culture environment and appropriate culture procedure, allows cells to form functional tissues that can be used in drug tests. Due to difficulties in the maintenance of cells and the complex nature of the tissue development process, it is essential to develop an automated culture platform to avoid contamination and reduce operational errors during long-term tissue culture. In this study, we developed a semiautomatic culture platform that integrates with a multistep fluidic control network, which allows multiple culture steps to be controlled and meets the requirement of the air-liquid interface (ALI), while maintaining a dynamic flow onto the cells. The culture platform was assembled with a culture chip, a reservoir, a miniaturized peristaltic pump, and a fluidic control base to connect each component and to operate the multiple culture steps. To demonstrate the capability of the culture platform, we have successfully controlled the multiple cell culture steps by switching the operation modes, allowing (1) cell proliferation under a liquid-liquid interface, (2) medium change from proliferation medium to differentiation medium, (3) cell differentiation under ALI conditions, and (4) repeated mucus washing. The dynamics and ALI culture conditions can simulate a physiological environment that is capable of maintaining and enabling cell differentiation for tissue-specific functions. The results demonstrate that bronchial tissue develops in the culture chip after 4 weeks of tissue culture. A versatile combination of culture steps makes the tissue culture platform suitable as an in vitro organ-on-a-chip culture model, especially for the tissues that involve the ALI culture, such as lung and skin. This platform, with multilogic control procedures, holds promise for enabling the long-term cultivation of differentiated tissues for advanced pharmacological and toxicological applications.