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Ill. mounted. Bibliography: 9.1-9.20.

Some mounted ill. Bibliography: leaves 191-226.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 157-161). Also available on the World Wide Web.

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The addition of silicon ions (10-500 μM) to the culture medium of MG63 osteoblast-like cells showed no changes in cell viability, metabolic activity, proliferation or morphology. Silicon ions resulted in a concentration-dependent increase in the expression of vascular endothelial growth factor (VEGF) by the MG63 cells. Addition of magnesium ions (1-50 mM) to the culture medium of MG63 cells caused a dose-dependent decrease in cell viability, metabolic activity and proliferation at each time point. In general, silicon and magnesium ions had no effect on the viability of a human endothelial cell line (HUVEC). A slight decreasing trend to the metabolic activity of the HUVECs was observed with increasing concentrations of silicon ions at all time points, but this decreasing trend was more pronounced with the addition of magnesium ions. The highest magnesium ion concentration studied (50 mM) caused a change in HUVEC morphology from a typical cobblestone appearance to a fibroblast-like shape. Lastly, the effect of silicon ions on angiogenesis <i>in vitro</i> was studied using two different <i>in vitro</i> assays. The first, using Matrigel as an extracellular matrix coating for the guidance of endothelial cells to form tube-like structures (an indicator of angiogenesis), proved unreliable for studying the promotion of angiogenesis. Additionally, tube-like structures were also observed with osteoblasts cells, raising questions about the efficiency of this assay. The second assay, AngioKit, was a suitable model for studying stimulation and inhibition of tube-like formation. Results obtained using this assay showed that silicon ions alone (500 μM) did not stimulate tube-like formation, but a significant increase in tube-like formation was observed with MG63 cell-conditioned media, with (500 μM) and without silicon ions, when compared to the control medium.

"The large number of patients suffering from cardiovascular diseases has led to a high demand for functional arterial replacements. A variety of approaches to vascular graft tissue engineering have shown promise, including seeding cells onto natural and synthetic scaffolds or by culturing cell sheets which are subsequently rolled into a tube without exogenous scaffolds. The goal of this project is to develop and characterize cell-derived, fully biological small diameter tissue engineered tubes by seeding and culturing cells directly on tubular supports. Rat aortic smooth muscle cells were seeded onto collagen-coated silicone mandrels and cultured for 14 days. Cells proliferated on the mandrels to form tubes (1.19 mm inner diameter, 1.68 +/- 0.1 mm outer diameter and 230 +/- 63 microns thick; n=72). Histological analysis of the developed tissue tubes demonstrated circumferential alignment of smooth muscle cells, abundant glycosaminoglycan production and some amount of collagen production. On inflating at a constant rate, it was observed that the tissue tubes dilated to an average burst pressure of 256 +/- 76 mmHg; (n=11). In order to observe the effects of addition of soluble factors on extracellular matrix synthesis and mechanical properties, tissue tubes were grown in culture medium supplemented with 50 microgram/ml sodium ascorbate. A significant decrease in outer diameter and wall thickness (1.57 +/- 0.02 mm and 189 +/- 10 microns; n=6 respectively) in the treated groups was observed as compared to (1.66 +/- 0.06 mm and 234 +/- 32 microns; n=6; p<0.05) for the untreated control groups. A slight increase in collagen production was observed by visual assessment of histological images of the ascorbate-treated tissue tubes. This suggests that by using a direct cell seeding approach, it is possible to develop completely biologic small diameter cell-derived tissue tubes that can withstand handling, and it may also possible to modulate matrix synthesis by optimizing cell culture conditions. "