Development of a 3D in vitro platform for functional and structural interrogation of neuronal circuits
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1
Natural and Medical Sciences Institute, Germany
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2
Natural and Medical Sciences Institute, Germany
Motivation
Neurodegenerative disorders represent a dramatically growing condition in our aging society, but advances in finding a cure have been to date extremely limited, despite the significant efforts deployed by public and private stakeholders.
In the quest for developing new therapies, researchers are still largely dependent on 2D in vitro experiments and animal models. These approaches poorly represent the multifaceted nature of neurodegenerative processes in the human brain and consequently have shown low predictive value in clinical studies.
To fill this gap, our group is developing a novel organ-on-a-chip (OoC) phenotypic platform based on the integration of microfabrication technologies, electrode arrays and microfluidics to reconstruct, interrogate and image 3D brain circuits in a high-throughput format.
Materials and Methods
Mouse hippocampal neurons isolated from embryos at day 16, grown within hydrogel scaffolds, are employed to recreate 3D multicellular architectures inside microfabricated bioreactors. Arrays of integrated microelectrodes are used to non-invasively monitor the electrical activity of enclosed neuronal cells at different time points. Simultaneously, confocal microscopy can provide 3D structural information with sub-cellular resolution. Due to the compact size of the microfluidic bioreactor, running each assay only requires a few thousand cells and few microliters of test compounds.
Results
The different in-vitro approaches currently available to capture the electrical activity of neuronal networks are very limited in their capability to capture structural and functional information in a non-invasive manner.
The novel ground-breaking architecture of this device allows the multi-site recording of single neuron activity while structural information is captured in parallel by optical methods. This new platform supports the 3D growth of mixed population of primary cells (neurons and glia) for weeks. The morphological and structural information of neurons embedded in hydrogel can be collected at high-resolution after transduction with AAV vector carrying a green fluorescent protein (GFP) (Figure 1). In addition, integrated microelectrodes record the electrical activity of hundreds of single neurons of the 3D neuronal network in a non-invasive way (Figure 2).
With this high-throughput platform more than twelve independent experiments can be carried out at the same time, monitoring the 3D neuronal functional and structural phenotypes.
Discussion and Conclusion
This multidisciplinary approach which combines 3D neuronal cultures, proprietary microelectrode arrays (MEA) and microfluidics technologies in a single high-content platform has the capacity to reconstruct, visualize and interrogate neuronal circuits in 3D.
In combination with the use of iPSCs derived from neurodegenerative patients and healthy subjects, this new platform will provide scientists and industry with a novel, high-throughput, brain-relevant in vitro system for exploring human disease mechanisms and evaluating efficacy and safety of newly developed compounds.
Figure legends
Figure 1: Confocal images of 3D neuronal network labelled with GFP after one week in-vitro. 3D reconstruction of confocal images stacks (A). Neuron growing in 3D high-definition (B). Dendrite with spines of neuron growing in 3D (C).
Figure 2: Exemplary recording of three independent experiments, 5 microelectrodes each, of 3D neuronal network after one week in-vitro (A). Magnification of one burst (B). Magnification of two action potential (C)
Keywords:
Hippocampus,
Neurons,
iPSCs,
organ-on-chip,
In-vitro,
Neuronal activity,
MEA - Multi-electrodes arrays,
Microfluidics
Conference:
MEA Meeting 2018 | 11th International Meeting on Substrate Integrated Microelectrode Arrays, Reutlingen, Germany, 4 Jul - 6 Jul, 2018.
Presentation Type:
Oral Presentation
Topic:
Microphysiological systems
Citation:
Molina
B,
Jones
PD,
Jentsch
L and
Cesare
P
(2019). Development of a 3D in vitro platform for functional and structural interrogation of neuronal circuits.
Conference Abstract:
MEA Meeting 2018 | 11th International Meeting on Substrate Integrated Microelectrode Arrays.
doi: 10.3389/conf.fncel.2018.38.00026
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Received:
27 Mar 2018;
Published Online:
17 Jan 2019.
*
Correspondence:
Dr. Paolo Cesare, Natural and Medical Sciences Institute, Reutlingen, 72770, Germany, paolo.cesare@nmi.de