Date of Award

4-2017

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Science

First Advisor

Sherif M. Karam

Second Advisor

Samir Attoub

Third Advisor

Abderrahim Nemmar

Abstract

Even though the stem cells have attracted many scientists because of their unique properties and therapeutic applications, it is not known how the environmental toxic factors could affect their features and functions. This study is focusing on the interaction between environmental diesel exhaust particles (DEP) and the stomach stem cells. In the stomach, the stem cells are responsible for generating and maintaining different types of cells which are organized to form numerous tubular glands. The aim of this study was to examine the effects of DEP on the mouse gastric stem cells. The hypothesis is that DEP could have deleterious effects on the properties of mouse gastric stem cells such as their viability and migration. An immortalized mouse gastric stem cell line was used to develop a simple in vitro model to test the effects of exposure to various concentrations of DEP. Stem cells were cultured using routine tissue culture protocols. The DEP were added to the culture media at different concentrations: 1, 10, and 100 μg/ml for different time points up to 72 hours. Then, stem cells were analyzed using: cell viability assay, wound healing or migration assay, oxidative stress analysis by measurement of reduced glutathione, lipid peroxidation, and nitric oxide, expression analysis of genes specific for cell proliferation, cell death and oxidative stress using quantitative realtime polymerase chain reaction, and expression of stem cell specific proteins using western blotting. While DEP induced a reduction in the growth rate of gastric stem cells only at high concentration, no significant effects were found on cell migration, cell death related genes/proteins. Only minor changes were observed in oxidative stress parameters. However, these findings were interestingly associated with downregulation of Notch 1, 2 and 3 proteins. Since Notch signaling pathways play an important role in development and differentiation of stem cells, it will be interesting to determine which mechanisms and target genes are involved in an animal model of DEP exposure. In conclusion, this study establishes an in vitro model system to investigate the biological feature of gastric stem cells when exposed to environmental pollutants. In addition, demonstrating the effects of DEP on adult stem cells will help in raising public awareness about environmental hazardous agents.

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