Thesis
Tumor necrosis factor-[alpha] effects on endothelial cell adhesion strength and traction force on substrates of varied stiffness
Master of Science (M.S.), Drexel University
May 2014
DOI:
https://doi.org/10.17918/etd-4457
Abstract
Hypertension, a cardiovascular disease characterized by high blood pressure, affected 25.8% of American adults in 2008 (59.4 million people). Hypertension is associated with increased vascular stiffness, which historically has been thought to be caused by vascular adaptation to increased pressure. More recently, human and animal studies demonstrated increased vascular stiffness prior to high blood pressure development. Like many cardiovascular diseases, hypertension is also associated with increased inflammation marked by elevated inflammatory cytokines such as tumor necrosis factor-[alpha] (TNF-[alpha]). A combination of early reversible vascular stiffness and TNF-[alpha] may lead to long-term arterial stiffening via vascular remodeling. Both stiff substrates and TNF-[alpha] can alter endothelial cell adhesion and traction forces. However, the impact of TNF-[alpha] on endothelial cell adhesion and traction force has not been studied in endothelial cells on substrates of different stiffness. I designed and tested a procedure to measure endothelial cell adhesion strength on substrates of varied stiffness using a spinning disc apparatus. Polyacrylamide gels were micropatterned with 30 [mu]m diameter fibronectin spots using microfabricated polydimethylsiloxane stamps. Only 50 to 60% of the micropattern transferred onto polyacrylamide gels due to the large stamp size, and subsequent cell seeding covered less than 60% of the patterned spots. Over 15% of the spots with attached cells had multiple cells on each spot. These design challenges could not be overcome and prevented use of the system to test the effects of TNF-[alpha] on endothelial cell adhesion strength. I subsequently used traction force microscopy to quantify single and monolayer endothelial cell-substrate forces with TNF-[alpha] stimulation on 6 and 55 kPa polyacrylamide gels. Single cell traction forces were not significantly different with TNF-[alpha] treatment, possibly due to the lack of cell-cell junctions. In contrast, cell monolayers on soft substrates doubled overall traction force (from 150 to 300 Pa) with TNF-[alpha] stimulation, while cells on stiff substrates doubled traction force (from 500 to 1200 Pa) only at cell-cell junctions. These data suggest that endothelial cell monolayer response to TNF-[alpha] depends on substrate stiffness, which could impact long-term irreversible vascular remodeling. Early arterial stiffness and inflammatory cytokine measurements could prevent hypertension complications in millions of Americans.
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Details
- Title
- Tumor necrosis factor-[alpha] effects on endothelial cell adhesion strength and traction force on substrates of varied stiffness
- Creators
- Isabel Munroe Buckner - DU
- Contributors
- Alisa Morss Clyne (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Master of Science (M.S.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Resource Type
- Thesis
- Language
- English
- Academic Unit
- School of Biomedical Engineering, Science, and Health Systems (1997-2026); Drexel University
- Other Identifier
- 4457; 991014632160604721