Table 2.

The development of co-culture systems in liver organoid research.

Reference	Co-Culture System	Method	Results	Cell Source
[71]	Hollow fiber (HF) in bioreactor	HF membranes compartmentalize human hepatocytes on the external surface and between the fibers and compartmentalize endothelial cells into the fiber lumen	It retained its functional activity at high levels for up to 18 days	ASCs, ECs, hepatocytes
[72]	Spinning bioreactor	The spinning provides a flow suspension environment, enhances nutrient absorption, and promotes the self-assembly of cells into substantial functional	Generated self-assembled functional hepatobiliary organoids	ASCs (hepatocytes)
[67]	MOC	Microfluidic-based cell culture device with a continuous dynamic flow of media	The system produced functional vascularized liver organoids	iPSCs with ECs and MSCs
[73]	Multi-chamber chip	Multi-chamber chip for long-term co-culture of four tissue types	Multi-organoid chips consisting of functional intestine, liver, skin, and kidney organoids	iPSCs
[74]	Perfused tissues via synthetic 3D soft microfluidics	A 3D-printable 2-photon-polymerizable hydrogel formulation uniquely enables a 3D soft microfluidic strategy	The system enhanced tissue growth and differentiation compared to previously reported in vitro tissue vascularization strategies	iPSCs
[75]	In vitro MOC organoids on a microfluidic vascular bed	The microvascular bed consists of 64 microfluidic chips; each chip has a microfluidic chamber, which permits tissue grafting	The platform provided in vitro vascularization of tissues for routine grafting of spheroids, organoids, or (patient-derived) explants	ASCs (hepatocytes)

Abbreviations: HF, hollow fiber membranes; SB, spinning bioreactors; OoC, organ-on-a-chip; MOCs, multi-organ microfluidic chips; ASCs, adult stem cells; iPSCs, induced pluripotent stem cells; ECs, endothelial cells; MSCs, mesenchymal stem cells; (Lgr5+), stem cells expressing leucine-rich repeat-containing G-protein-coupled receptor 5.