Table 1.

Representative differences in cellular properties between 2D and 3D culture systems.

Cellular properties	2D	3D	Refs.
Morphology	Stretched and Sheet-like cells in monolayer	Spheroid and aggregate structure	225,226
Proliferation	Frequently proliferate at a faster rate than in vivo	Proliferate at a faster/slower rate compared to 2D culture	227,228
Response to soluble factors	Cell monolayers are equally exposed to nutrients and growth factors	Nutrients and growth factors may not be able to fully penetrate the 3D structure	229
Gene and protein expression	Gene and protein expression levels often vary from in vivo	Often display gene/protein expressions similar to in vivo	230,231
Nutrient limited physiology	Cells are not nutrient limited	Some cells are quiescent, hypoxic, or necrotic	134,232