Graphene oxide upregulates the homeostatic functions of primary astrocytes and modulates astrocyte-to-neuron communication

TL;DR

This study shows that graphene oxide enhances astrocyte functions related to homeostasis and promotes neuronal maturation, suggesting potential for CNS therapy but also indicating significant cellular effects.

Contribution

It reveals how graphene oxide modulates astrocyte physiology and neuron communication, highlighting its potential for CNS therapeutic strategies.

Findings

GO increases inward-rectifying K+ channels

GO enhances Na+-dependent glutamate uptake

GO promotes neuronal maturation and synapse formation

Abstract

Graphene-based materials are the focus of intense research efforts to devise novel theranostic strategies for targeting the central nervous system. In this work, we have investigated the consequences of long-term exposure of primary rat astrocytes to pristine graphene (GR) and graphene oxide (GO) flakes. We demonstrate that GR/GO interfere with a variety of intracellular processes as a result of their internalization through the endo-lysosomal pathway. Graphene-exposed astrocytes acquire a more differentiated morphological phenotype associated with extensive cytoskeletal rearrangements. Profound functional alterations are induced by GO internalization, including the upregulation of inward-rectifying K+ channels and of Na+-dependent glutamate uptake, which are linked to the astrocyte capacity to control the extracellular homeostasis. Interestingly, GO-pretreated astrocytes promote the functional maturation of co-cultured primary neurons by inducing an increase in intrinsic excitability and in the density of GABAergic synapses. The results indicate that graphene nanomaterials profoundly affect astrocyte physiology in vitro, with consequences for neuronal network activity. This work supports the view that GO-based materials could be of great interest to address pathologies of the central nervous system associated to astrocyte dysfunctions.