| Thymoma is the most common anterior mediastinal primary tumor, originating from the thymic epithelial cells with slow growth. The incidence of thymoma is approximately20%in adult mediastinal tumor,50%in anterior mediastinal tumor,1-5cases out of million population per year. Its etiology is not very clear, and it has complex biological behaviors. Further study of thymoma to reveal the molecular mechanism of occurrence, development and transfer will not only offer specific biomarkers for early diagnosis, also will open up a new approach for treatment, ultimately improves long-term survival of patients with thymoma.Further study of thymoma to reveal the molecular mechanism of occurrence, development and transfer can not be implemented in vivo,yet thymoma cell line is essential experimental material to study the molecular mechanism of occurrence and transfer, and its application made it possible to research tumor cell characteristics and analyse carcinogenesis mechanisms in vitro. This study analyzed the biological characteristics of a thymoma cell line,which had been established, and provided a good experimental material for further study of the pathogenesis of thymoma.Objective:We analyze the biological characteristics of a thymoma cell line which has been established through experimental study,to provide experimental material for future research in the molecular mechanism of occurrence and development and clinical therapeutic approaches.Methods:Thymoma and thymic tissue in patients were resected surgically and cultured by using adhesive culture methods. Two methods including mechanical scraping and enzymatic digestion were used to purify epithelial cells and then isolated tumor cells to culture to in vitro. Tryptic digestion technique was used to passage cells, slow freezing and rapid thawing to cryopreserve and recovery cells, phase contrast microscope to observe cell morphology, and cytometry to performe proliferation experiments. Tumorigenicity in nude mice was observed by transplanting cell suspension, the measurement cell lines Molecular markers (CK7, CK8, CK19, EGFR, EMA, CD20, CD99, TdT, Ki67, P63) were determined by immunohistochemistry and chromosome karyotype analysis was performed after preraring chromosome speciments.Results:The thymoma primary cells have been obtained after adhesive culture, mechanical scraping and enzymatic digestion. Cells have been passaged to120generation in vitro with2-3days generation time for one year staying good condition. Cells were polygonal, large nuclei, atypia, nuclear cytoplasm ratio upside down, clear nucleoli, and megakaryocytes, dual-core or multi-core cell were visible. With cobblestone-like growth, cells covered bottle after the end of overlap and accumulation growth phenomenon with no contact inhibition. Cell growth after the incubation period, the logarithmic growth phase and plateau phase, the population doubling time was37hours. Grown cells were stable after repeated freezing and slow thawing and82%were survival. Karyotype analysis shows the number of chromosomes are distributed between27-138, chromosome number is65-70(80%), trunk lines is hypo triploid structure with the characteristics of human tumor chromosomes, and chromosome structure and number were abnormal, showing characteristics of tumor cells. Immunohistochemistry showed that cells molecular markers (CK7, CK8, CK19, EGFR, EMA, Ki67, P63) were positive and (CD20, CD99, TdT)were negative. Tumor growth can be seen by the14days after transplant experiment. At the first85days, tumor diameter is about14mm. Limited mobility in nude mice showed that cells have tumorigenic ability.Conclusion:The new human thymoma cell lines ThyO517are from thymic epithelial cells.Cell lines have been passaged over1year in vitro. It has become a stable cell line due to its unchanged cell morphology and constant growth cycle and it will provide an experimental model of thymoma for future study. |
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