Date of Award

Fall 2022

Degree Type

Open Access Dissertation

Degree Name

Engineering and Industrial Applied Mathematics Joint PhD with California State University Long Beach, PhD

Program

Institute of Mathematical Sciences

Advisor/Supervisor/Committee Chair

Perla Ayala

Dissertation or Thesis Committee Member

Ga-young Kelly Suh

Dissertation or Thesis Committee Member

Claudia Rangel-Escareño

Dissertation or Thesis Committee Member

Ali Nadim

Terms of Use & License Information

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

Rights Information

© 2022 Pouye Sedighian

Keywords

Cell Migration, Cell Migration in a 3D Collagen Matrix, Confocal Microscopy, Flow Cytometry, Neutrophil Cell Migration, Neutrophil-Like HL-60 Cell Migration

Subject Categories

Computer Sciences | Mathematics

Abstract

It is known that cell migration in innate and adaptive immune system plays a fundamental role in human health. Among the immune cells, neutrophils are one of the most essential cells in protecting the body against invading pathogens. In the presence of chemoattractants, these cells are the first responders that start a directed migration toward the injured area. As neutrophils approach the site of infection, they transmigrate to the tissue and follow the chemoattractant concentration gradient to locate and eliminate the invading pathogens. Understanding the patterns and mechanism of neutrophil migration in the presence of chemoattractants could possibly play an important role in discovering new treatments for various immune dysfunction diseases such as sepsis or severe COVID-19. Here, to study cell migration patterns, we designed a 3D hydrogel model to create a concentration gradient inside a collagen gel that contained neutrophil-like (dHL-60) cells. Our experimental setup and computational analysis allowed us to study the cell migration indicators such as percentage and velocity of motile cells in a 3D environment. Evaluating these cell migration features showed 10 nM Formyl-Met-Leu-Phe (fMLP) was the most suitable initial concentration among 0, 10, and 100 nM fMLP to maximize the cell activity. In addition, as fMLP was invisible under the microscope, we performed experiments with a fluorescent dye that had a similar molecular weight as fMLP to estimate the chemoattractant concentration and its gradient with high spatiotemporal resolution at any location and time inside the collagen gel. Next, we analyzed the correlation between the cell migration patterns and the chemoattractant concentration and its gradient over time. The results showed that the highest levels of cell motility, measured by a variety of indicators, occurred at moderate fMLP concentrations (5 to 7 nM fMLP) and, counterintuitively,not at the highest concentrations. In summary, the combination of our novel experimental design and computational analysis allowed us to improve on previous studies by correlating the dHL-60 migration indicators to the local chemoattractant concentration at the cell location over time, painting a more complex picture of cell migratory behavior in a 3D environment.

ISBN

9798371975010

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