TABLE 1.

Comparison of 2D and 3D cell culture.

Important characteristics	2D cell culture	3D cell culture	References
Cell shape	• Cells shape is flat and elongated since the cells can only grow and expand two dimensionally • Cells grow into a monolayer on the plate	• Natural cell shape is preserved and cell growth • Cells grow into 3D aggregates/spheroids • Spheroids contain multiple layers	Costa et al., 2016; Langhans, 2018
Cell exposure to medium	• All cells in the culture receive the same amount of nutrients and growth factors from the medium in the plate • This causes more cells to be in the same stage of the cell cycle	• Nutrients does not have to be equally divided amongst all cells but can be if needed • The core cells often remain inactive since they receive less oxygen and growth factors from the medium • This process resembles the core cells in tumor cells, making it possible to mimic the behavior and structure of a tumor cell in vivo	Dhaliwal, 2012; Costa et al., 2016; Langhans, 2018
Cell junction	• Cell junctions are less common and less accurately represent real junctions	• Cell junctions are common and allow for cell-to-cell communication • Cells communicate through exchange ions, small molecules, and electrical currents	Pontes Soares et al., 2012; Ravi et al., 2015; Costa et al., 2016; Langhans, 2018; Lang et al., 2019
Cell differentiation	• Cell differentiation is poor	• Cells are well differentiated	Imamura et al., 2015; Costa et al., 2016; Langhans, 2018
Drug sensitivity	• Cells often have little resistance to drugs making it appear as though drugs administered to the cells were a successful treatment • Drugs are not well metabolized	• Cells often have more resistance to drug treatment • Drug metabolism is much better • Gives a more accurate representation of the drug’s effects	Haisler et al., 2015; Imamura et al., 2015; Langhans, 2018
Cell proliferation	• Cells proliferate at an unnaturally rapid pace.	• Proliferation rates are realistic and can be high or low depending on technique and types of cells being studied.	Ravi et al., 2015, Langhans, 2018
Expression levels	• Gene and protein expression levels are often vastly different compared to in vivo models	• Gene and protein expression levels resemble levels found from cells in vivo	Ravi et al., 2015; Costa et al., 2016; Langhans, 2018
Cost	• For large-scale studies, it is much cheaper than using 3D culture	• Are typically more expensive than 2D cell culture techniques and require more time • 3D cell culturing reduces the differences between in vitro and in vivo drug screening, decreasing the likelihood of needing to use animal models	Ravi et al., 2015; Costa et al., 2016; Langhans, 2018
Apoptosis	• Drugs can easily induce apoptosis in cells	• Higher rates of resistance for drug-induced apoptosis	Costa et al., 2016
Response to stimuli	• Inaccurate representation of response to mechanical stimuli of cells • Cells cannot experience gravity since they are unable to expand into the third dimension	• Accurate representation of response to mechanical stimuli of cells • Cells can experience gravity giving a more accurate representation of a cell in vivo	Ravi et al., 2015; Costa et al., 2016
Usage and analysis	• Highly replicable and easily interpretable • Better for long-term cultures	• Can be difficult to replicate experiments • Can be difficult to interpret data	Kapałczyńska et al., 2018