| Summary: | 碩士 === 國立臺灣海洋大學 === 生物科技研究所 === 95 === Stem cells are undifferentiated cells with properties of self-renew, high proliferation and high potential to differentiate. Adult stem cells were found in many kinds of human tissues and organs. Take the lung as example, lung stem cells were found in trachea, terminal airway, alveolar, bronchiole, and alveolar junction. Lung stem cells with some specific markers such as Oct-4, SSEA-1, and Sca-1 could be cultured successfully with serum-free medium in our laboratory before. Here, we demonstrate that the number of lung stem cell was increased about 2-3 folds by 0.5 ng/ml EGF and with a dose-dependent manner. To investigate the differences between lung stem cell and alveolar epithelial type-II cell, scanning electronic microscopy (SEM) and immunofluorescence staining were utilized. Results of SEM showed that a gibbosity was revealed in the central region of the lung stem cell and the ratio of nucleus to cytoplasm is high; in contrast, the alveolar epithelial type-II cells displayed flat surface. Two specific markers, CXCR4 and CD54 were expressed only in lung stem cells, but not in type-II cells by immunofluorescence staining analysis. Then, the lung stem cells were sorted by using CXCR4 and CD54 as markers, and the purity was about 80％. Furthermore, these isolated cells were cultured in serum-containing DMEM medium, and the cells were able to grow to colonies, and still had potential to differentiate without the assistance of surrounded stroma cells. In conclusion, high purity lung stem cells could be isolated by CXCR4 and CD54, and be cultured further successfully.
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