Advanced liver-on-chip model mimicking hepatic lobule with continuous microvascular network via high-definition laser patterning

There is a great demand for development of advanced <i>in vitro</i> liver models to predict the efficacy and safety of drug candidates accurately in the preclinical drug development. Despite the great efforts to develop biomimetic models, it remains challenging to precisely mimic a functional unit of the liver (i.e., hepatic lobule) with a continuous microvascular network. Recent progress in laser patterning has allowed us to create arbitrary biomimetic structures with high resolution. Here, we propose an advanced liver-on-chip model mimicking the hepatic lobule with a continuous microvascular network, ranging from the microvessels to the central vein of the liver, utilizing femtosecond laser patterning. Firstly, we optimize the laser power to pattern microchannels mimicking the microvessel and central vein of the hepatic lobule by using a femtosecond laser within a collagen-based hydrogel containing hepatic cells. Secondly, we construct continuous microvessels with luminal structures by comparing different microchannel sizes in diameter. Finally, we assemble a millimeter-scale hepatic lobule-like structure with multiple layers of microvascular networks in the liver-on-chip. Furthermore, our liver-on-chip model exhibits major liver functions and drug-induced hepatotoxicity, as evidenced by albumin and urea productions and by a toxic response to acetaminophen, respectively. Our approach provides valuable strategies for the development of advanced physiological and pathological liver-on-chip models for pharmaceutical and toxicological studies.