Date of Award

Spring 2009

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biomedical Engineering

First Advisor

Ping-Fai Sit

Abstract

Tissue engineering could provide an alternative source of transplant tissue regardless of donor supply and with reduced risk of immune rejection. Engineered tissue requires three critical components for successful development: the cells, growth factors, and the scaffold on which they will initially grow. The scaffold acts as a temporary extracellular matrix (ECM) allowing cell attachment and acclimation to the environment prior to synthesis and construction of the cell's native ECM. Prior to cell seeding, the scaffold must be characterized to determine whether or not the pore geometry is conducive to cell implantation. Electrochemical impedance spectroscopy (EIS) provides a unique and effective tool for scaffold evaluation upon fabrication as well as following modification and cell seeding. Chitosan scaffolds were tested with EIS showing good comparative values to more common and proven characterization methods.

In addition to characterization, modification may be necessary to improve the cell scaffold interaction. Previous attempts to modify chitosan scaffolds with microparticles during the fabrication have shown that these approaches compromise scaffold integrity; however, particles cannot be effectively forced into the scaffold without damaging it. In light of this difficult modification, electrophoretic particle treatment was implemented. Transport of iron oxide microparticles at low voltage was proven an effective modification method and might be capable of modifying a seeded scaffold.

Finally, it is necessary to not only evaluate the scaffold prior to cell seeding but also subsequent to cell seeding. Successful seeding should lead to cellular proliferation, gene expression, and ECM production. EIS has become a common tool for tissue characterization and can, in turn, be used as an evaluative approach for the assessment of engineered tissues. While cell response and volume exclusion requires a large quantity of cells, varying protein concentrations were notable in scaffolds saturated with complete cell media. In summary, electrokinetics has shown its potential for tissue engineering applications from scaffold fabrication to online monitoring.

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