Accelerating the Development of Hippocampal Neurons using Nanopillar Structures

Abstract

During the development of a neuron cell, multiple dendrites and a single axon, which have molecularly and functionally distinct domains, will generate from the soma to enable the directional communication between cells. The initiation and extension of such structures are critical to neuron development and neural circuit formation. In vitro neuron culture system has been a major model to study axon initiation and elongation, and many regulating genes have been identified in the in vitro model. However, only a few of the genes have been proven to be required in vivo, which may mainly due to the lack of extracellular cues in the in vitro model. The importance of extracellular cues to axon initiation and outgrowth is therefore emerging as a major theme in neural development. Nanostructures and nanomaterials serve as promising candidates to provide topographical cues to neuronal adhesion and development. Previous studies showed that neuron cells were able to sense nanoscale structures and responded differently in their neurite extension. In the present work, we use patterned nanopillar structures as controllable topographical cues to culture hippocampal neurons, and found that nanopillars have significant guidance effect on neurite outgrowth and elongation. More interestingly, the axon specification occurs in the first 12 hours after cell plating, which is much earlier than the usual time point for cells growing on normal flat surfaces. It indicated that the topographical cues can indeed accelerating neural development. We further studied this topographical influence on axon initiation and elongation by varying the diameter, height, pitch and shape of the nanopillars, and different effects were observed. This work will provide new insights on the role of topographical cues for neuronal development in vivo, as well as the possibility of using nanoscale topographic features to control neuronal development.