Astrocytes regulate neuronal network burst frequency through NMDA receptors species- and donor-specifically

Abstract

BackgroundDevelopment of synaptic activity is a neuronal key characteristic that relies largely on interactions between neurons and astrocytes. Although astrocytes have known roles in regulating synaptic function and malfunction, the use of human or donor-specific astrocytes in disease models is still rare. Rodent astrocytes are routinely used to enhance neuronal activity in cell cultures, but less is known how human astrocytes influence neuronal activity.MethodsWe established human induced pluripotent stem cell (hiPSC)-derived neuron-astrocyte co-cultures and studied their functional development on microelectrode array (MEA). We used cell lines from 5 neurotypical control individuals and 3 pairs of monozygotic twins discordant for schizophrenia. A method combining Ngn2 overexpression and dual SMAD inhibition was used for neuronal differentiation. The neurons were co-cultured with hiPSC-derived astrocytes differentiated from 6-month-old astrospheres or rat astrocytes.ResultsWe found that the hiPSC-derived co-cultures develop complex network bursting activity similarly to neuronal co-cultures with rat astrocytes. However, the effect of NMDA receptors on neuronal network burst frequency (NBF) differed between co-cultures containing human or rat astrocytes. By using co-cultures derived from patients with schizophrenia and unaffected individuals, we found lowered NBF in the affected cells. We continued to demonstrate how astrocytes from an unaffected individual rescue the lowered NBF in the affected neurons by increasing NMDA receptor activity.ConclusionsOur results indicate that astrocytes participate in the regulation of neuronal NBF through a mechanism involving NMDA receptors. These findings shed light on the importance of using human and donor-specific astrocytes in disease modeling.

Navigating Human Astrocyte Differentiation: Direct and Rapid one-step Differentiation of Induced Pluripotent Stem Cells to Functional Astrocytes Supporting Neuronal Network development

“…Interestingly, hiPSC-astrocytes and NPC-astrocytes clustered closely together, confirming minimal differences between these two protocols. Recently, Räsänen et al (2024) also demonstrated neuronal network activity in hiPSC-astrocyte and iNeuron co-cultures, showing a similar developmental trajectory of the human co-culture over time as was shown in this study 90 . This further indicates that skipping of the NPC intermediate stage has minimal effect on in vitro astrocyte development, and subsequent neuronal network development.…”

Human pluripotent stem cells as a translational toolkit in psychedelic research in vitro

“…However, the PSC-derived co-cultures displayed greater magnitudes of change in response to an NMDA antagonist, resulting in reduced bursting at delta and theta frequencies compared to the mixed-species cultures. 113 …”