A three-dimensional neural cell construct for implantable neural interface

Abstract

Purpose: Two-dimensional neuronal cell culture technique has helped study behaviors of neurons and neuronal networks. However, neurons in a living organism are arranged in threedimensional space, rather than tightly attached to a planar culture plate or an electrode. Besides, neurons co-exist with a large number of glial cells. For these reasons, we developed a method of making culture constructs in which neurons and glial cells were three-dimensionally co-cultured and investigated the morphological features of neural cells cultured in three-dimensional space. Additionally, we formed neural interfaces between the three-dimensionally cultured neurons and metal electrodes. Neural recording was attempted to examine possibilities and problems associated with such interfaces. Methods: Primary hippocampal neurons and astrocytes were cultured in a thermos-gelating protein-based hydrogel for more than two weeks. The functionality and the morphology of the neural cells were verified by means of FM1-43 staining and confocal microscopy, respectively. Finally, neural signal recording from neurons cultured by the proposed method was carried out with both a planar multi-electrode array and a probe-type electrode. Results: The presence of functional synapses was confirmed by the uptake and discharge of the dye, FM1-43, during high potassium stimulation. As a result of three-dimensional restoring of the confocal microscopy images, neurons were observed to extend their processes in a straighter line in three-dimensional culture constructs than in planar cultures, and astrocytes were more stellate than polygonal in terms of their shape when cultured in three-dimensional constructs. The signal strength was low or unmeasurable owing to the coarse distribution of the signal sources and the long distance from them. Conclusions: A three-dimensional co-culturing method for neural cells is developed, in which neurons and glial cells are morphologically similar to in vivo cells and functionally active. From the neural signal recording results, a more realistic density of neural cells in culturing construct need to be achieved in order to better simulate a neural interface between three-dimensionally cultured neurons and metal electrodes. © 2016, Korean Society of Medical and Biological Engineering and Springer.