Repairing injured nervous systems requires the ability to regenerate axons and to guide growing axons to their targets. To achieve guidance, mechanistic studies in physiological axon guidance in developing neurons will be critical. It is known that the growth cone, the structure at the leading edge of developing axons, responds to chemical and mechanical cues in the environment to steer the axon to its target, and chemotropic cues have been well characterized. However, the mechanotransduction pathways involved in axon guidance are currently not well understood. Photoacoustics offers a means for mechanical stimulation of neurons that can be used to study axon guidance by mechanotransduction. Compared to other methods, photoacoustics offers a non-genetic, extremely high spatial precision method for neuron stimulation that works by converting pulsed light energy into ultrasound waves by light absorption and subsequent thermal expansion and contraction of the photoacoustic material. In this thesis, photoacoustic stimulation of neuronal growth cones was used to study axon guidance mechanisms. First, a photoacoustic device that was previously developed in this lab was fabricated by applying a photoacoustic composite material coating to the tip of an optical fiber. This device was used for targeting the growth cones of Xenopus laevis primary embryonic neurons in vitro, and subsequent growth patterns were analyzed using optical microscopy with a custom-built quantitative model for measuring growth rates and directional changes. Calcium imaging by Fluo-4 fluorescent dye was used to show successful activation of mechanotransduction pathways. This thesis offers the first evidence that photoacoustic stimulation of growth cones is possible and sets up future research to explore axon guidance by mechanotransduction using photoacoustic stimulation.
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/44789 |
| Date | 07 June 2022 |
| Creators | Rosen, Gavin |
| Contributors | Yang, Chen |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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