Construction and Application of 3D Microfluidic Liver-On-A-Chip

As the largest internal organ in the human body, the liver plays an essential role in the metabolism. The liver or relevant diseases are one of the leading causes of death in the world, with the number of cases surging each year. Therefore, an in-depth understanding of the physiological and biochemical processes and pathological mechanisms of the liver is of great significance for the research, prevention, diagnosis, and treatment of liver-related or metabolism-related diseases. The in vitro liver culture model is an important experimental platform for the study of liver-related biological mechanisms. However, the traditional two-dimensional in vitro cell culture model makes it difficult to reproduce the complex physiological structure and microenvironment of the liver, and lack of disease characteristics. More importantly, the cell structure, gene expression, substance metabolism, and so on in the process of planar culture are significantly different from those in vivo. Microfluidic technology can simulate the physiological structure of liver by designing appropriate micro- structure, providing a microenvironment more like that in vivo by combining with three-dimensional liver tissue culture. Therefore, this paper summarizes the methods and latest progress in constructing 3D liver chips in vitro based on microfluidic technology, including porous membrane culture, hydrogel culture, cell spheroid-based culture, and 3D bioprinting. The applications of 3D cultured liver microchips in remodeling liver physiological structure, exploring mechanism and pathological mechanism, drug screening, and toxicity testing are further summarized. Finally, the potential value and challenges of 3D liver-on-a-chip are discussed.