| Summary: | 博士 === 國立清華大學 === 分子醫學研究所 === 96 === In comparison with conventional monolayer cultures, which are unable to generate normal cell-cell interactions found in vivo, cells grown in three-dimensional (3D) environments more closely resemble the situation in real tissues with regard to differentiation patterns and cell-cell and cell-extracellular matrix interactions. In addition, similarities in gene expression, cell behavior, and ultrastructures between 3D cells in culture and in vivo tissues also reveal the potential as models to mimic actual situation in our body. The multicellular spheroidal organoids (spheroids), aggregated from hundreds to thousands of suspended cells, have been exploited widely as the convenient 3D culture models. In this thesis, we first clarified the molecular mechanism involved in the formation of spheroids and identified the roles of integrin and cadherin in the cellular self-assembly process. To extend the applications of spheroid-based 3D culture systems, we also developed novel techniques to manipulate magnetic particle-labeled spheroids to form designed patterns. Furthermore, a new strategy to vascularize engineered thick tissues using heterospheroids was also proposed and demonstrated in an artificial liver system. For certain applications that require high-resolution cellular organizations to study cell-cell interactions, the dielectrophoresis-based cell patterning technique was investigated for efficiency of liver and bone pattern formation with high cell viability and adhesion. Finally, we studied the cell-cell interactions contributing to the critical step of tumor metastaisis − extravasation, by which circulating tumor cells migrate through damaged endothelial barriers. We proposed a model that the contact of tumor and endothelium will induce apoptosis of endothelial cells through ROS-mediated cytotoxicity. The NADPH oxidase was identified as the main source of ROS generation in responding to tumor induction. These data provide a molecular basis to explain how anti-oxidant administration may inhibit tumor metastasis. In summary, we believe that the studies presented in this thesis will greatly contribute to our knowledge on spheroid self-assembly process and efficient generation of the spheroid-based 3D cell culture to meet the increasing demands for 3D cell models in biomedical researches.
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