Synaptic Connectivity in Engineered Neuronal Networks

Temporal Characterization of Neuronal Migration Behavior on Chemically Patterned Neuronal Circuits in a Defined in Vitro Environment

“…Moreover, such cells utilize somal translocation mode migration to respond to extrinsic geometric cues provided by chemical surface patterning. Previous work has demonstrated a neuritic predisposition to follow extrinsic cues. ,,, Data collected in this study builds on this observation by demonstrating that such physical cues are sufficient to initiate neuronal migration and directed neurite outgrowth and that such behavior can occur successfully without additional biochemical cues and gradients or input from supporting cell types, known to influence neuronal migration in vivo . These observations are supported by recently published findings that independently verify the capacity for neurons to exert a somal translocation mechanism when migrating on patterned culture surfaces …”

“…Verification of hippocampal neurons’ ability to respond to extrinsic geometric cues using a biologically relevant migration mechanism is important for the development of more organized and functionally relevant in vitro culture assays for drug development and disease modeling applications. Demonstration of such biologically accurate translocation behavior provides further validation for chemically patterned neuronal network technology, 49,53 as it shows that the self-assembly of such cell systems is achieved using appropriate signaling and motility mechanisms. Critically, the characterization of cell limitations with regards to survival on patterns, effective translocation distances, migration responses to bifurcating patterns, and neurite outgrowth on increasingly hydrophobic surfaces provides valuable data to investigators seeking to adapt current chemical pattern designs to improve in vitro neuronal network formation.…”

“…A two neuron circuit design (Figure A) was selected for use in this study as a means to reduce cell–cell interaction and thereby provide the best chance of studying individual cell behavior in response to geometric cues without confounding influences from surrounding neurons and glia. The two-neuron circuit design was optimized previously as a means to study synaptic connectivity in vitro and was adapted from earlier work on neuronal patterning and the use of geometric cues to establish neuronal polarity in vitro . Dashed lines were used to induce dendritic tree development and comprised two 10 μm strips, each 2 μm wide, separated by a 10 μm gap .…”

“…The aminosilane DETA possesses hydrophilic properties and has been shown previously to promote neuronal adhesion, 38,48,49,53 whereas the fluorinated silane 13F is hydrophobic and cell repellant. 38,53 It has been shown that although ECM proteins adsorb to the 13 F surface in amounts equivalent to DETA, they then tend to denature and this process inhibits a cells ability to attach and survive in the long term. 59 The surface wettability was found to play a substantial role in regulating neurite lengths in these cultures.…”

“…The neuronal circuit design employed in these experiments (Figure 1) was based on an earlier study 53 which sought to analyze synaptic connectivity between two hippocampal neurons. Embryonic hippocampal neurons were found to either adhere directly to the elliptical patterns or migrate to the pattern based upon the differential properties of the chemically treated culture surface.…”