Furthermore, we were able to obtain mature networks using rodent astrocytes in about three weeks after final plating, which is much faster than in previously published work (2 months after final plating)2931. This difference can result from differences in hiPSC lines, passage numbers before final plating, neural differentiation protocols or methods to measure network maturation. Although synchronization of calcium oscillations appeared earlier in mixed co-cultures than in fully human co-cultures, the percentage of active neurons decreased over time reaching levels of monocultures at week 5. This difference might be due to a “species-specific ‘clock’” regulating neuronal maturation for different species with different kinetics21. Rodent astrocytes potentially have faster kinetics than human astrocytes. However, with our aim to generate a fully human model, we only focused on human astrocyte co-cultures.
