Event Abstract

Long-term High-density Microelectrode Array Recordings Evidence Stability of Neuron Locations in Organotypic Hippocampus Slices

  • 1 ETH Zurich, Department of Biosystems Science and Engineering, Switzerland
  • 2 University of Ljubljana, Faculty of Electrical Engineering, Slovenia

Motivation Long-term recordings of neural activates in organotypic slice cultures are important for studying chronic drug effects and gene manipulations. However, the existing slice cultivation and recording methods do not allow repeatedly observing of neural electrical activities at action potential level, over long term periods. Here, we present a device and method that allows to directly culture organotypic brain slices on high-density multi-electrode arrays (HD-MEA), so that slice culture electrical activities can be recorded continuously over multiple recording sessions. Our results showed that the preparations based on the current method are reliable, and could successfully observe activities of neural network and individual neurons f organotypic hippocampal slices over several weeks. Material and Methods We developed a roller-tube system for slice cultivation on HD-MEA chips. The roller-system consisted of several culture chambers and a rotation rack. Each culture chamber can accommodate one HD-MEA chip and forms an enclosed environment that includes a defined culturing medium volume. There is an opening on the culture chamber for gas exchange, and a plastic cup with a filter on top can be used to close the gas opening in order to maintain a sterile condition inside the culturing chamber. The culture chambers can be positioned on the roller rack and fixed tightly with two fixing holes. The roller rack continuously rotates at a slow speed of 1.5 min per cycle. A maximum of 8 culture chambers can be used at same time on one roller rack, which is placed inside an incubator with controlled conditions (36 °C, humidity 90%, and CO2 5%). This approach allowed for culturing organotypic brain slices on HD-MEAs over weeks, while HD-MEA electrophysiology recordings could be performed at any time during the cultivation period. Sagittal hippocampal slices (300 µm thickness) were obtained from new-born mice, and affixed to HD-MEA array surfaces with chicken plasma and thrombin. Culture medium (3 ml, contains: 50% BME, 25% HBSS, 25% horse serum, 47.19 mM D-glucose, 1.29 mM GlutaMAX-VP, 100 U/ml penicillin/streptomycin) was added to each slice culture and changed every three days. The slice cultures attached on the HD-MEAs were maintained in the custom-designed culture chambers, which were continuously rotated at 1.5 min per rotation cycle inside an incubator. HD-MEAs provide 11’011 platinum electrodes in an area of 1.99 × 1.75 mm2. There are 126 recording channels that can be simultaneously used for readout. Sequences of 147 high-density block configurations were used to record from the whole electrode array area with overlaps, and each configuration was recorded for 30 seconds. One complete recording session lasted 1.5 hours. The recordings were performed almost every day inside the incubator. Data were analyzed with MATLAB-based software. Neural network activity and single-neuron activity was extracted. Results Organotypic hippocampus slices were cultivated on HD-MEA chips and recorded from over 30 days. Both neural network activity and single neuron activities could be tracked from the same recordings, across multiple days during the cultivation periods. Conclusion The presented method provides technological means to observe organotypic slice neural network and single-neuron activity dynamics from the same preparation, over extended time periods.

Acknowledgements

Financial support through the ERC Advanced Grant 267351 “NeuroCMOS” and individual support for Wei Gong through the FP7-MTN “EngCaBra” (Contract 264417) is acknowledged.

Keywords: new device, Organotypic brain slice, neuron movements, neuron tracking

Conference: MEA Meeting 2016 | 10th International Meeting on Substrate-Integrated Electrode Arrays, Reutlingen, Germany, 28 Jun - 1 Jul, 2016.

Presentation Type: Poster Presentation

Topic: MEA Meeting 2016

Citation: Gong W, Senčar J, Bakkum D and Hierlemann A (2016). Long-term High-density Microelectrode Array Recordings Evidence Stability of Neuron Locations in Organotypic Hippocampus Slices. Front. Neurosci. Conference Abstract: MEA Meeting 2016 | 10th International Meeting on Substrate-Integrated Electrode Arrays. doi: 10.3389/conf.fnins.2016.93.00056

Received: 22 Jun 2016; Published Online: 24 Jun 2016.

* Correspondence: Dr. Wei Gong, ETH Zurich, Department of Biosystems Science and Engineering, Basel, Switzerland, wei.gong@bsse.ethz.ch

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