Characterization of the radioresponse of human apical papilla-derived cells.
BACKGROUND
The purpose of this study was to characterize the radiobiological properties of stem/progenitor cells derived from apical papilla-derived cells (APDCs) compared to bulk APDCs.


METHODS
APDCs were isolated from freshly extracted human third molars with immature apices. Multipotent 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, papillary 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 induced a significant increase in a senescence-like phenotype in both cell types. Neither type of cells exhibited a significant induction of apoptotic changes after 8 Gy of irradiation. Ability to form hard tissue in vivo was significantly decreased in PSFCs, but not in APDCs following 4 Gy of irradiation.


CONCLUSIONS
We demonstrated for the first time that stem/progenitor cells derived from APDCs exhibit a radioresistant phenotype; however, the hard tissue forming ability in vivo, but not bulk APDCs, was significantly reduced after irradiation.
Oral Radiation Oncology, Department of Oral Restitution, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. masadrad@tmd.ac.jp
Shigehiro
S
Abe
Keiichi
K
Hamada
Satoshi
S
Yamaguchi
Teruo
T
Amagasa
Masahiko
M
Miura
D002454:Cell Differentiation; D002478:Cells, Cultured; D016922:Cellular Senescence; D004247:DNA / Q000378:metabolism / Q000528:radiation effects; D004260:DNA Repair; D005720:Gamma Rays; D006801:Humans; D008964:Molar, Third / Q000166:cytology* / Q000528:radiation effects; D010641:Phenotype; D011836:Radiation Tolerance
D004247:DNA
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