Date of Award

12-2014

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Bioengineering

Committee Member

Dr. Karen J.L. Burg, Committee Chair

Committee Member

Dr. Frank Alexis

Committee Member

Dr. Didier Dréau

Committee Member

Dr. Ken Webb

Abstract

More than 200,000 women are diagnosed with breast cancer each year in the United States, where the majority will undergo a lumpectomy procedure and then radiotherapy as preventative treatment. Both artificial and tissue transplants may obscure the detection of cancer recurrence or limit the effectiveness of radiation treatment. Previous research in our laboratory has been performed to develop injectable lumpectomy void fillers. This body of work seeks to continue and further develop the technology of the void fillers and further investigate the potential of fatty acids in breast tissue engineering.

Literature suggests that lipid peroxidation products from free fatty acids may have anti-cancerous effects. Linoleic acid is in the family of fatty acids associated with lipid peroxidation; however, linoleic acid is also associated with growth promoting eicosanoids which has caused linoleic acid to be considered a cancer promoting agent. Studies shown here suggest that a high concentration, 100 µM, of linoleic acid was effective at limiting cancerous proliferation by day 6, and suggest a complete removal of the cancerous population by day 8, while control cells remained largely unaffected. Further studies confirmed the elevated presence of lipid peroxide products in the inhibited cancerous cell cultures. When linoleic acid was tested in culture with tamoxifen, the observed inhibition of cancerous proliferation was greater than either of the treatments alone. This finding supports the use of linoleic acid in tissue engineered scaffolding.

Additional work was performed to advance the development of a lumpectomy scaffolding. An injectable chitosan scaffolding has previously been developed through the use of a pH shifting technique; however, work described here continued the scaffolding development by adding gelatin, hyaluronic acid, and an acid washing step which resulted in the formation of a distinct bilayer. Cells cultured on the bilayered scaffolding were found to migrate to the boundary between layers where they proliferated at an accelerated rate compared to uniform hydrogels. Fatty acids were able to be incorporated into the production of the hydrogels at a concentration of 400 µM.

Previous researchers in the laboratory had reported adipogenic effects from linoleic acid. These results were not observed upon further investigation. Linoleic acid did result in the swelling of human stem cells but did not otherwise morphologically change the cells. A mixture of conjugated linoleic acid however, was tested and found to upregulate adipogenic specific markers to a level indistinguishable from adipogenic controls.

Through the course of this body of research, several advances were made in the field of test methods for tissue engineering. Work was done towards the improvement of procedures of multiwell plate readers to allow sterile sampling, the cytotoxicity of alamarBlue was found and investigated, improvements to previous lab gas chromatography procedures were made, and analyses of experimental results indicated the importance of recovery periods in cytotoxicity studies.

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