Browsing by Author "Shahidi, Sahar"

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    Designing a novel 3-D in-Vitro scaffold to define mechanisms underlying neuronal myelination
    (2018-11-28) Shahidi, Sahar; Syed, Naweed I.; Sanati Nezhad, Amir; Ousman, Shalina S.; Yusuf, Kamran
    All nervous system functions in animals require neuronal assembly during development and the ensuing communications between large networks of neurons, which are often difficult to monitor in the intact brain. As such, most labs around the globe have opted to use and explore in vitro model systems where neurons are generally grown on two-dimensional, plane glass substrates, which limit the ability to decipher fundamental understanding of the mechanisms underlying neuronal growth, polarity and synapse specificity. Most approaches used today employ 2-D models where neurons are cultured on the Poly-D-lysine (PDL) coated substrate which does not mimic the 3-D configuration of the intact mammalian brain – thus limiting a direct comparison between in vivo and in vitro conditions. Assessing cellular and molecular mechanisms of neuronal myelination are critical to determine how myelination and demyelination processes occur in vertebrate models so as to understand developmental and neurodegenerative diseases such as multiple sclerosis. However, there are no suitable in vitro models available to date whereby the process of axon myelination could be studied directly at the level of individual central and peripheral neurons. In contrast to PDL, collagen offers a 3-D structure in which neurons can be suspended in a 3-D configuration, allowing glia to gain access to axonal membrane to exhibit myelination. However, we still lack a reliable 3-D model where mechanisms of neuronal polarity and myelination could be studied at the level of individual peripheral and central neurons. In this study, I designed a 3D substrate comprising of a gelatin base hydrogel with tunable chemical mechanical properties. Using rat Dorsal Root Ganglia Cells (DRG) and their corresponding Schwann cells (SC), I compared and contrasted the effectiveness of GelMA with PDL and Collagen substrates and provide the first direct evidence that the former is more conducive to studying myelination than the later two. Moreover, I also demonstrate that both DRG growth and SC behavior on GelMA resembles to what is seen in vivo thus validating further the usefulness of this substrate for future studies.