| Budget Amount *help |
¥3,302,000 (Direct Cost: ¥2,540,000、Indirect Cost: ¥762,000)
Fiscal Year 2009: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2008: ¥1,742,000 (Direct Cost: ¥1,340,000、Indirect Cost: ¥402,000)
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| Research Abstract |
1. Radioresponse of Human Apical Pulp-Derived Cells (APDCs) : An Implication for Root Hypoplasia of Developing Teeth following Radiotherapy
Purpose : When pediatric patients receive radiotherapy for the head and neck regions, root hypoplasia of developing teeth often occurs. The purpose of this study was to pursue the possible biological mechanisms underlying root hypoplasia following irradiation.
Methods and Materials : Apical pulp-derived cells (APDCs) were isolated from freshly extracted human third molars with immature apices. Multipotent pulpal spheres, which are thought to contain an enriched population of stem/progenitor cells, were formed from the APDCs, using a neurosphere culture technique. After γ-irradiation, pulpal sphere-forming cells (PSFCs) and bulk APDCs were subjected to radiosensitivity and hard tissue-forming assays.
Results : Compared to bulk APDCs, the PSFCs exhibited a radioresistant phenotype and a higher capacity for DNA double strand break repair. Irradiation ind
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uced a significant increase in a senescence-like phenotype in both cell types. Neither type of cells exhibited a significant induction of apoptotic changes, even after 8Gy irradiation. Ability to form hard tissue in vivo was significantly decreased only in PSFCs following 4Gy irradiation.
Conclusions: We conclude that induction of the inhibition of the differentiation process of stem/progenitor cells into mineralized cells could contribute to the root hypoplasia of developing teeth after radiotherapy.
2. Sphere-forming capacity does not relate tumorigenicity or radioresistance in Established Human Oral Cancer Cell lines.
Purpose : Like many normal tissues, solid cancer may be maintained by a rare population of cancer stem cells (CSCs). The objective of this study was to identify and characterize a subpopulation of sphere-forming cancer cells (SFCCs) from human oral cancer cell lines.
Methods and materials : Established human oral squamous cell carcinoma (SCC) cell lines were cultured and subjected to nonadherent spheres. We subjected to tumorigenicity, cell surface markers, differentiation capacity and radioresponse analyses.
Results : CD133 was not expressed both of bulk and SFCCs, and CD44 was expressed all of cell lines. Same results were shown in human oral SCC tumor samples. High degree of tumorigenic HSC-3 and low degree of tumorigenic HSC-7 formed many typical cancer spheres. SFCCs were undifferentiated, and differentiated into mature keratino-cancer cells under appropriate condition. The tumorigenic capacity difference is not recognaized in both cell lines. Although HSC-7 SFCCs were not change radioresistant capability, but the HSC-3 were a radiosensitivity compared to bulk cells. Furthemore, the DNA double strand breaks repair capacity enhances the radioresponse of SFCCs.
Conclusions : Taken together, our findings lead to the thought that the candidate markers were not suitable for oral CSCs and all of the SFCCs did not contribute to tumorigenicity and radioresistance. Less
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