Neuron-Astrocyte Co-culture
Materials Required
Principle
Neuron-astrocyte co-culture is used to study how astrocytes regulate neuronal survival, synapse formation, dendritic morphology, neuronal activity, and disease-related neurotoxicity. Indirect “sandwich” or insert-based designs physically separate neurons and astrocytes while allowing soluble astrocyte-derived factors to affect neurons, whereas direct co-culture permits cell-contact and network-level readouts.
MCE has not independently verified the accuracy of these methods. They are for reference only.
Experimental Materials
• Use primary hippocampal or cortical neurons and astrocytes, culture inserts or suspended coverslips for indirect co-culture, poly-D-lysine or poly-L-lysine-coated culture surfaces for neuronal adhesion, and neuron-compatible serum-free medium such as Neurobasal/B27-based medium when reported for primary neuronal culture.
• Use neuronal markers for cell identity and morphology, astrocyte markers such as GFAP for astrocyte identity, and synaptic markers such as synaptophysin and PSD-95 to quantify preand postsynaptic puncta or colocalized synaptic structures.
• Use a biosafety cabinet and CO2 incubator for sterile cell culture, an inverted or confocal fluorescence microscope for morphology and synaptic puncta imaging, and optional multi-electrode arrays when neuronal firing or network activity is the planned readout.
• Use neuronal markers for cell identity and morphology, astrocyte markers such as GFAP for astrocyte identity, and synaptic markers such as synaptophysin and PSD-95 to quantify preand postsynaptic puncta or colocalized synaptic structures.
• Use a biosafety cabinet and CO2 incubator for sterile cell culture, an inverted or confocal fluorescence microscope for morphology and synaptic puncta imaging, and optional multi-electrode arrays when neuronal firing or network activity is the planned readout.
Experimental Procedure
• Prepare astrocytes and neurons separately when the experimental question requires independent manipulation of astrocytes before co-culture;
• Published models used primary mouse or rat astrocytes as feeder, insert, paper, or suspended cultures paired with primary neurons.
• Coat neuronal culture surfaces with poly-D-lysine or poly-L-lysine before plating neurons, and establish astrocytes as a feeder layer, suspended coverslip, insert culture, or paper-supported culture before combining them with neurons.
• Plate neurons on the coated neuronal surface and place astrocytes above or near the neuronal culture using an indirect configuration when soluble astrocyte-derived effects are the target;
• Reported formats include postnatal mouse hippocampal neurons suspended above astrocyte feeders and insert-based systems that maintain neurons and astrocytes as separate populations in shared medium.
• Maintain co-cultures long enough for the selected readout: the mouse hippocampal sandwich protocol reports healthy neurons beyond 3 weeks and increased synapse development compared with neurons without astrocytes, while paper-based astrocyte co-culture improved low-density neuronal survival after 5 days in vitro across 50,000 to 1,000 cells/cm2 neuronal plating densities.
• For disease or perturbation assays, treat astrocytes before or during co-culture only when the study design requires astrocyte-mediated effects;
• An Alzheimer’s disease-related assay pre-exposed astrocytes to Aβ42, Aβ40, or LPS and then assessed neuronal dendritic complexity and synaptic puncta.
• Acquire fluorescence images of neurons and synaptic markers under consistent imaging settings, quantify neurite or dendritic morphology, count synaptophysin-positive and PSD-95-positive puncta, and define putative synapses as colocalized pre- and postsynaptic marker signals when using immunocytochemistry-based synapse quantification.
• Use neuron-only cultures as a negative comparator for astrocyte support, astrocyte-only cultures to confirm astrocyte status after treatment, untreated co-cultures as baseline controls, and matched cell ratios across conditions because astrocyte effects on neuronal morphology and synaptotoxicity can depend on the defined neuron-astrocyte ratio.
• Published models used primary mouse or rat astrocytes as feeder, insert, paper, or suspended cultures paired with primary neurons.
• Coat neuronal culture surfaces with poly-D-lysine or poly-L-lysine before plating neurons, and establish astrocytes as a feeder layer, suspended coverslip, insert culture, or paper-supported culture before combining them with neurons.
• Plate neurons on the coated neuronal surface and place astrocytes above or near the neuronal culture using an indirect configuration when soluble astrocyte-derived effects are the target;
• Reported formats include postnatal mouse hippocampal neurons suspended above astrocyte feeders and insert-based systems that maintain neurons and astrocytes as separate populations in shared medium.
• Maintain co-cultures long enough for the selected readout: the mouse hippocampal sandwich protocol reports healthy neurons beyond 3 weeks and increased synapse development compared with neurons without astrocytes, while paper-based astrocyte co-culture improved low-density neuronal survival after 5 days in vitro across 50,000 to 1,000 cells/cm2 neuronal plating densities.
• For disease or perturbation assays, treat astrocytes before or during co-culture only when the study design requires astrocyte-mediated effects;
• An Alzheimer’s disease-related assay pre-exposed astrocytes to Aβ42, Aβ40, or LPS and then assessed neuronal dendritic complexity and synaptic puncta.
• Acquire fluorescence images of neurons and synaptic markers under consistent imaging settings, quantify neurite or dendritic morphology, count synaptophysin-positive and PSD-95-positive puncta, and define putative synapses as colocalized pre- and postsynaptic marker signals when using immunocytochemistry-based synapse quantification.
• Use neuron-only cultures as a negative comparator for astrocyte support, astrocyte-only cultures to confirm astrocyte status after treatment, untreated co-cultures as baseline controls, and matched cell ratios across conditions because astrocyte effects on neuronal morphology and synaptotoxicity can depend on the defined neuron-astrocyte ratio.
Troubleshooting
Problem: Neuronal survival is poor in low-density cultures.
• Possible cause: Neurons lack sufficient astrocyte-derived support under sparse plating conditions.• Literature-supported solution: Use an indirect astrocyte co-culture format, because paper-supported astrocytes suspended above low-density neuronal networks improved neuronal viability after 5 days in vitro.
Problem: Synaptic puncta are difficult to interpret.
• Possible cause: Single-marker puncta do not distinguish pre- and postsynaptic alignment.• Literature-supported solution: Image paired pre- and postsynaptic markers and quantify colocalized synaptophysin/PSD-95 puncta rather than relying on one marker alone.
Problem: Astrocyte treatment effects on neurons are inconsistent.
• Possible cause: Cell ratio changes alter the magnitude of astrocyte-mediated neuronal effects.• Literature-supported solution: Keep neuron-astrocyte ratios fixed across experimental groups and report the ratio used.
References:
- [1]. Jones EV, et al. A neuron-astrocyte co-culture system to investigate astrocyte-secreted factors in mouse neuronal development. Methods Mol Biol. 2012;814:341-352. [Content Brief]
- [2]. Gottschling C, et al. The indirect neuron-astrocyte coculture assay: an in vitro set-up for the detailed investigation of neuron-glia interactions. J Vis Exp. 2016;(117):54757. [Content Brief]
- [3]. Roqué PJ, et al. Synaptic structure quantification in cultured neurons. Curr Protoc Toxicol. 2014;60:12.22.1-12.22.32.
- [4]. Wasilewski D, et al. Reactive astrocytes contribute to Alzheimer’s disease-related neurotoxicity and synaptotoxicity in a neuron-astrocyte co-culture assay. Front Cell Neurosci. 2022;15:739411. [Content Brief]
- [5]. Ippolito DM, et al. Quantifying synapses: an immunocytochemistry-based assay to quantify synapse number. J Vis Exp. 2010;(45):2270. [Content Brief]
- [6]. Aebersold MJ, Thompson-Steckel G, Joutang A, Schneider M, Burchert C, Forró C, et al. Simple and inexpensive paper-based astrocyte co-culture to improve survival of low-density neuronal networks. Front Neurosci. 2018;12:94. [Content Brief]
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