Figure 2.

Types of 3D systems. 3D systems fall into two categories either scaffold-free or scaffold-based systems. Scaffold-free systems depend greatly on the plate where the cells are culture whether it is (A) ultra-low attachment plate for the production of cell aggregates as spheroids or (B) Extracellular matrix (ECM) coated plates for cell differentiation into organoids. Scaffold-based systems are manmade microenvironments that can host cells whether they are (C) solid scaffolds that offer a rigid matrix and allow spheroid formation or (D) soft scaffolds like hydrogels that contain an ECM-like complex architecture in which multicellular tumor spheroids (MCTS) are produced similar to solid in vivo tumors.