Several groups have developed astrocyte-neuron co-culture systems, using both rodent and human astrocytes with human iPSC-derived neurons, with promising results for maturation and network activity (Tang et al., 2013; Muratore et al., 2014; Odawara et al., 2014; Kuijlaars et al., 2016). Indeed, the notion that astrocytes enhance synapse maturation is well established from rodent cell cultures (Araque and Perea, 2004). Odawara et al. (2014) utilized multiple electrode array (MEA) plates to co-culture rat astrocytes with hiPSC-derived neurons and found increased electrophysiological activity after 3 weeks of plating, with neurons continuing to increase activity for more than 3 months after plating. Muratore et al. (2014) performed a direct comparison of several neuronal differentiation protocols and demonstrated a significant increase in vGLUT1 expression by day 40 in neurons cultured on mouse astrocytes, pointing to accelerated maturation of excitatory neurons. Kuijlaars et al. (2016) were the first to utilize astrocyte co-culture with solely human cells in 2016. Using commercially available fetal astrocytes, the group observed synchronized calcium oscillations in hiPSC-derived neurons 3–4 weeks after final plating, indicating sustained network activity (Kuijlaars et al., 2016).
