Figure 1.
Examples of experimental models. On the left, the absence of vascularization in spheroids and organoids causes a heterogeneous distribution of oxygen, waste products and acidosis. These structures are characterized by a well-irrigated proliferating layer in the periphery, a quiescent layer and a necrotic core. On the right, two methods to create a spatiotemporal O2 distribution. At the top, a semipermeable polydimethylsiloxane (PDMS) membrane is able to produce fast changes in O2 in cell culture, and at the bottom, by using microfluidic devices.