Astrocyte-secreted cues promote neural maturation and augment activity in human forebrain organoids.

Brain organoids have been proposed as suitable human brain model candidates for a variety of applications. However, the lack of appropriate maturation limits the transferability of such functional tools. Here, we present a method to facilitate neuronal maturation by integrating astrocyte-secreted factors into hPSC-derived 2D and 3D neural culture systems. We demonstrate that protein- and nutrient-enriched astrocyte-conditioned medium (ACM) accelerates neuronal differentiation with enlarged neuronal layer and the overproduction of deep-layer cortical neurons. We captured the elevated changes in the functional activity of neuronal networks within ACM-treated organoids using comprehensive electrophysiological recordings. Furthermore, astrocyte-secreted cues can induce lipid droplet accumulation in neural cultures, offering protective effects in neural differentiation to withstand cellular stress. Together, these data indicate the potential of astrocyte secretions to promote neural maturation.