Recent advances in 3D-printing-based organ-on-a-chip

Organ-on-a-chip (OOC) facilitates precise manipulation of fluids in microfluidic chips and simulation of the physiological, chemical, and mechanical characteristics of tissues, thus providing a promising tool for in vitro drug screening and physiological modeling. In recent decades, this technology has advanced rapidly because of the development of various three-dimensional (3D) printing techniques. 3D printing can not only fabricate microfluidic chips using materials such as resins and polydimethylsiloxane but also construct biomimetic tissues using bioinks such as cell-loaded hydrogels. In this review, recent advances in 3D-printing-based OOC are systematically summarized based on materials used for direct or indirect 3D printing of OOC, 3D printing techniques for the construction of OOC, and applications of 3D-printing-based OOC in models of the heart, blood vessels, intestines, liver, and kidney. In addition, future perspectives and challenges in this area are envisioned to inspire researchers to employ 3D printing techniques to accelerate OOC development.