FIGURE 2.

Schematic representation of various 3D co-culture systems. These could be broadly divided into two types: i) Reconstituted TME, in which cells are mechanically and enzymatically dissociated from the primary tumor tissue and sorted and expanded into different cell populations. Tumor cells grown as spheroids or organoids are then reconstituted with stromal cells of choice. ii) Native TME, where primary tumor tissue is mechanically fragmented and grown as tumor spheroids on low attachment plates or cultured in an air-liquid interface, embedded in a collagen gel in an inner transwell dish. The culture media from an outer dish diffuses into the inner dish via a permeable transwell, and the top of the collagen layer is exposed to air via an ALI, allowing cells to oxygenate. Both of these methods can be incorporated into a specifically designed microfluidic system.