Document Type

Dissertation

Degree

Doctor of Philosophy

Department

Biomedical Engineering

Advisor's Name

Anthony J. McGoron

Advisor's Title

Committee Chair

Advisor's Name

Anuradha Godavarty

Advisor's Name

Yen-Chih Huang

Advisor's Name

Fenfei Len

Advisor's Name

Wei-Chiang Lin

Keywords

doxorubicin, indocyanine green, hyperthermia, near infrared laser, necrosis, apoptosis, heat shock protein, synergy, heating rate, multi-drug resistant

Date of Defense

7-14-2010

Abstract

Hyperthermia is usually used at a sub-lethal level in cancer treatment to potentiate the effects of chemotherapy. The purpose of this study is to investigate the role of heating rate in achieving synergistic cell killing by chemotherapy and hyperthermia. For this purpose, in vitro cell culture experiments with a uterine cancer cell line (MES-SA) and its multidrug resistant (MDR) variant MES-SA/Dx5 were conducted. The cytotoxicitiy, mode of cell death, induction of thermal tolerance and P-gp mediated MDR following the two different modes of heating were studied. Doxorubicin (DOX) was used as the chemotherapy drug. Indocyanine green (ICG), which absorbs near infrared light at 808nm (ideal for tissue penetration), was chosen for achieving rapid rate hyperthermia. A slow rate hyperthermia was provided by a cell culture incubator. The results show that the potentiating effect of hyperthermia to chemotherapy can be maximized by increasing the rate of heating as evident by the results from the cytotoxicity assay. When delivered at the same thermal dose, a rapid increase in temperature from 37 °C to 43 °C caused more cell membrane damage than gradually heating the cells from 37 °C to 43 °C and thus allowed for more intracellular accumulation of the chemotherapeutic agents. Different modes of cell death are observed by the two hyperthermia delivery methods. The rapid rate laser-ICG hyperthermia @ 43 °C caused cell necrosis whereas the slow rate incubator hyperthermia @ 43 °C induced very mild apoptosis. At 43 °C a positive correlation between thermal tolerance and the length of hyperthermia exposure is identified. This study shows that by increasing the rate of heating, less thermal dose is needed in order to overcome P-gp mediated MDR.

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