Table 1.

Comparison of the key features of 3D systems

	Organoids	Organ-on-chip	Bioprinting	Tissue slices
Attainable complexity	Scalable, highly complex cellular composition by the combination of primary cells, stem cells and their progeny possible	Scalable, highly complex cellular composition and culture environments are possible	Highly defined and controlled assembling of cell types and matrices possible	Retain the original tissue architecture and complexity
Cell damage	Low or absent, but necrotic cores possible	Low or absent	Potentially high (temperature, shear stress)	Damage of adjacent cells unavoidable
Long-term culture	Virtually unlimited due to passaging (subcultivation)	Weeks to months, depending on the specific cell turnover and matrix properties	Depends on the specific cell turnover and matrix properties	Usually days to weeks
Non-preparative sampling	Supernatant, 3D imaging. Access to the apical surface may be difficult	Supernatants (compartment-wise, but limited volumes), sensor readouts; 3D imaging challenging	Supernatant, 3D imaging	Supernatant, 3D imaging
User-friendliness	Requires rather complex cell culture medium and additives	Sophisticated culture devices can be quite costly, time-consuming, and challenging to operate	Requires complex technologies, may be challenging in terms of operation and costs	Easy operation but requires recurrent tissue supply