Title page for ETD etd-062410-130619

Document Type	thesis
Author Name	Hu, Jason Z
URN	etd-062410-130619
Title	Assessment of Ascorbic Acid Effects on the Properties of Cell-Derived Tissue Rings
Degree	MS
Department	Biomedical Engineering
Advisors	Marsha Rolle, Advisor
Keywords	CDM ascorbic acid tissue engineering collagen RASMCs TEBVs
Date of Presentation/Defense	2010-06-24
Availability	restricted
Abstract We have developed a system to rapidly create three-dimensional tissue rings from aggregated cells. The ability to use cell-derived tissues to screen the effects of culture conditions on tissue mechanical function has not previously been reported. The first goal of this study was to evaluate the mechanical properties of cell-derived tissue rings in response to ascorbic acid, which has been shown to increase collagen content, resulting in increased mechanical strength. The second goal was to develop quantitative methods to evaluate the structure and composition of cell-derived tissue rings. Rat aortic smooth muscle cells (1.33x10^6 cells/ring) were seeded in agarose wells with 4 mm post diameters in DMEM supplemented with 10% FBS and ascorbic acid (0, 50, 150 ug/ml). After 7 days, the average thickness of the constructs reached 0.72 +/- 0.03 mm with no statistical differences between groups. Ultimate tensile strength values were higher in the ascorbic acid-treated groups compared to untreated controls. However, there was no significant difference between tissue rings treated with 50 and 150 ug/ml ascorbic acid. Biochemical analysis showed that ascorbic acid did not significantly affect total protein, collagen content or cell number. Image analysis of polarized light micrographs suggested that collagen fibril coverage increased in response to ascorbic acid treatment, although the differences between groups were insignificant. In addition to ascorbic acid treatment, we also subjected tissue rings to DTPA treatment to prolong ascorbic acid availability in culture medium, which resulted in weak and necrotic tissue rings. Reduced serum was also investigated in order to decrease cell proliferation, which resulted in decreased tissue thickness and increased mechanical strength. Overall, we successfully demonstrated that the mechanical properties of the tissue rings could be altered by ascorbic acid treatment, and developed a series of quantitative methods to measure tissue mechanics, composition and organization. The results of this study further support the potential to use the tissue ring system as a high throughput screening method for studying the functional properties of three-dimensional engineered tissues.
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