Fluid flow is a complex and dynamic process in the brain, taking place at the macro- and microscopic level. Interstitial fluid in particular flows throughout the interstitial spaces within the tissue, interacting with cells and the extracellular matrix. We are coming to find that this interstitial fluid flow plays an important role in both homeostatic and pathologic conditions. It helps to transport chemokines and other molecules such as extracellular vesicles within the environment, clear waste from the brain, and provide biophysical cues to cells. When this flow is disrupted however, such as in glioblastoma or Alzheimer's disease, profound events can occur, for example the build-up of plaques or an increase in tumor cell invasion. While there has recently been an up-tick in interstitial fluid flow research, there is surprisingly little known about its exact nature within the interstitial space and its effects on brain pathology such as glioblastoma. In particular, ways to manipulate and measure brain IFF magnitude at the cellular level are lacking. In this dissertation, a set of tools is created and used to explore the role that interstitial fluid flow magnitude plays in the brain through the lens of glioma invasion. We developed and implemented a flow device that is used in conjunction with an established in vitro tissue culture insert assay to manipulate fluid flow rates through a 3D matrix of tumor cells. We showed that this flow device is biocompatible and accurately recreates flow rates that have been measured previously through the use of MRI. We quantified tumor cell invasion from several glioma cell lines using this device to show a nonlinear trend of invasion in response to increasing fluid flow magnitudes. In addition, we developed a computational model to explore one potential mechanism that fluid flow magnitude might be modulating: autologous chemotaxis. Through this model we showed that increased flow magnitudes such as those seen in gliomas cause an increase in the distribution of the chemokine gradient around a cell of interest, that the morphology of the cell is important to this gradient formation, that temporal effects should not be overlooked, and that within the tumor environment, a minimum distance is required for the invading cell to develop this gradient. Finally, we developed a novel in vivo surgical technique that allows for the manipulation and measurement of interstitial fluid flow within the brain through simultaneous multiphoton imaging. We showed that this technique can be used to modulate interstitial fluid flow, as a mechanism by which to label cells of interest, and as a means to implant and monitor glioma progression. Through these means we further characterize interstitial fluid flow in the brain, allowing for its manipulation and measurement, and examine the ability of increased interstitial fluid flow magnitudes to impact glioma invasion. / Doctor of Philosophy / Fluid flows throughout brain tissue and plays an important role in creating normal conditions for proper brain function. This fluid can also play a role in brain cancer, such as glioblastoma, by causing cancer cells to travel further into the brain which is not desirable. This dissertation seeks to understand fluid flow better by studying how its speed contributes to cancer cell movement which is accomplished through the development of several tools. One tool is a new surgical technique that allows for the measurement and manipulation of fluid flow speed within the mouse brain and visualization of cells of interest, one tool is a flow device that changes fluid flow speed through cells in a gel, and the last is a computational model that predicts how a cell might move under different flow and environmental conditions. The tools were created and utilized, showing several interesting results. Using the flow device, different cancer cell lines were seen to react differently to increased fluid flow speed with two main trends: 1) increased cancer cell movement with increased fluid flow speed and 2) a peak effect where the cell movement started to increase with increasing fluid flow speed and then decreased after a certain fluid flow speed was surpassed. The surgical technique was successful at introducing fluid flow and allowed for reproducible measurements of fluid flow speed. It also was used to introduce stains that show specific cells of interest. The computational model showed that there are specific time and spatial contributions that effect cancer cell movement and that with increased fluid flow speed, cells might be able to more easily utilize a specific mechanism to move. Altogether, this work presents novel insight into fluid flow speed that can be used to further inform the field. It is our hope that the findings from this dissertation can go towards a more comprehensive treatment of a specific type of brain cancer, glioblastoma.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/110762 |
| Date | 13 June 2022 |
| Creators | Stine, Caleb A. |
| Contributors | Department of Biomedical Engineering and Mechanics, Munson, Jennifer M., Rossmeisl, John H., Kimbrough, Ian, Staples, Anne E., Davalos, Rafael V. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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