Self-Organizing Circuit Assembly through Spatiotemporally Coordinated Neuronal Migration within Geometric Constraints

Neurons are dynamically coupled with each other through neurite-mediated adhesion during development. Understanding the collective behavior of neurons in circuits is important for understanding neural development. While a number of genetic and activity-dependent factors regulating neuronal migration have been discovered on single cell level, systematic study of collective neuronal migration has been lacking. Various biological systems are shown to be self-organized, and it is not known if neural circuit assembly is self-organized. Besides, many of the molecular factors take effect through spatial patterns, and coupled biological systems exhibit emergent property in response to geometric constraints. How geometric constraints of the patterns regulate neuronal migration and circuit assembly of neurons within the patterns remains unexplored.We established a two-dimensional model for studying collective neuronal migration of a circuit, with hippocampal neurons from embryonic rats on Matrigel-coated self-assembled monolayers (SAMs). When the neural circuit is subject to geometric constraints of a critical scale, we found that the collective behavior of neuronal migration is spatiotemporally coordinated. Neuronal somata that are evenly distributed upon adhesion tend to aggregate at the geometric center of the circuit, forming mono-clusters. Clustering formation is geometry-dependent, within a critical scale from 200 µm to approximately 500 µm. Finally, somata clustering is neuron-type specific, and glutamatergic and GABAergic neurons tend to aggregate homo-philically.We demonstrate self-organization of neural circuits in response to geometric constraints through spatiotemporally coordinated neuronal migration, possibly via mechanical coupling. We found that such collective neuronal migration leads to somata clustering, and mono-cluster appears when the geometric constraints fall within a critical scale. The discovery of geometry-dependent collective neuronal migration and the formation of somata clustering in vitro shed light on neural development in vivo

Cell Microarray Technologies for High-Throughput Cell-Based Biosensors

Due to the recent demand for high-throughput cellular assays, a lot of efforts have been made on miniaturization of cell-based biosensors by preparing cell microarrays. Various microfabrication technologies have been used to generate cell microarrays, where cells of different phenotypes are immobilized either on a flat substrate (positional array) or on particles (solution or suspension array) to achieve multiplexed and high-throughput cell-based biosensing. After introducing the fabrication methods for preparation of the positional and suspension cell microarrays, this review discusses the applications of the cell microarray including toxicology, drug discovery and detection of toxic agents.ope

Engineering and optimizing physiological cell isolation via the secondary anchor targeted cell release system

Cancer treatment regimens, such as chemotherapies are fundamentally limited through patient drug resistance, as patients respond differentially due to these individualized resistances and differences in biomarker expression on cells. Quantification of these biomarkers, then, would allow a methodology for designing personalized treatments and regimens that the patients would no longer be resistant to. However, techniques designed to purify or isolate cells to quantify these biomarkers are not designed to maintain physiological cell expression. In order to develop an isolation modality to preserve receptor numbers, I have developed and optimized the Secondary Anchor Targeted Cell Release (SATCR) system to separate out cells of interest for downstream analysis. The SATCR enables both capture and release of cells through the targeting of the secondary anchor- streptavidin- through the introduction of 4mM biotin into the system. The system has been optimized to preserve physiological wall shear stress, receptor quantity and cell diameter of cells isolated through the system. This allows for our system to create a more physiologically faithful modality for downstream analysis- potentially opening the door to more physiological analyses of purified cell samples for personalized medicine. Surface functionalization allows for the customization and adaption of surfaces for a variety of needs and applications. We have used surface functionalization to adapt glass and PDMS surfaces with the SATCR surface, but there exists a great deal of mineable space for surface functionalization and its adoption in existing modalities. This space includes moving the SATCR surface from static glass based systems into dynamic microfluidic glass and PDMS systems, and possibly even further to non-standard functionalized materials such as polyvinyl chloride. The functionalization of alternate materials would allow further customization and easier adoption of the capture surface into other substrates, further increasing the utility and degrees of freedom for the SATCR capture surface. In addition to substrate alteration, further adaptions and modifications can advance and optimize the SATCR technology to enable more effective and selective isolation of cells through SATCR integration