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# How can I use VitroGel for co-culture or sandwich culture (layer by layer)?

The co-culture of two or more different cell types can be performed with the VitroGel system. Besides adding different cell types together with the hydrogel solution for co-culture, each cell type can also be mixed with the hydrogel solution and be added layer by layer. After the first layer of hydrogel become stable, carefully overlay the second layer of cells/hydrogel mixture on top of the first layer of cells/hydrogel.