[Mechanism of radiation induced premature senescence of bone marrow stromal cells: experiment with murine bone marrow stromal cells].
OBJECTIVE
To investigate the mechanism of radiation induced premature senescence of bone marrow stromal cells induced by gamma-radiation.


METHODS
Bone marrow stromal cells were isolated from the bones of mice, cultured, and divided into 2 groups: control group and irradiation group. The cells of the irradiation group were exposed to 60Co gamma-rays of the dose of 8.0 Gy. 24 h, 72 h, 1 week, and 2 weeks after irradiation MTT method was used to test the proliferation of the cells, Giemsa staining was used to observe the morphology, the percentage of cells positive in beta-galactosidase (SA-beta-Gal), a senescence associated biomarker, was detected by cytochemistry, and RT-PCR was used to detect the mRNA expression of p21(Cip1/Waf1) and p53 gene, both associated with senescence. One week after the irradiation flow cytometry was used to analyze the cell cycle distribution.


RESULTS
Characteristics of mature senescence were seen in the cells of the irradiation group. One week after the irradiation the percentage of G0/G1 of the irradiation group was 89.83% +/- 0.05%, significantly higher than that of the control group (66.95% +/- 0.36%, P < 0.01). 24 h, 72 h, 1 week, and 2 weeks after irradiation the percentages of SA-beta-gal positive cells in the irradiation group were 20.33% +/- 0.03%, 34.33% +/- 0.03%, 86.33% +/- 0.02%, and 95.67% +/- 0.02% respectively, significantly higher than those of the control group (2.33% +/- 0.006%, 14.33% +/- 0.02%, 24.67% +/- 0.02%, and 45.00% +/- 0.02% respectively, all P < 0.01). The mRNA expression of p53 and p21(Cip1/Waf1) mRNA expressions in the irradiation group increased 24 h after the irradiation and lasted for two weeks.


CONCLUSIONS
Gamma-radiation induces changes of premature senescence in bone marrow stromal cells in which p53-p21(Cip1/Waf1) manner pathways may play an important role.
Zhang
Ke-jie
KJ
Department of Hematology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
Zhu
Yan
Y
Sun
Han-ying
HY
Huang
Li-fang
LF
Fu
Jin-rong
JR
Liu
Wen-li
WL
D000818:Animals; D001854:Bone Marrow Cells / Q000378:metabolism / Q000528:radiation effects*; D049109:Cell Proliferation / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000528:radiation effects*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics; D004307:Dose-Response Relationship, Radiation; D005434:Flow Cytometry; D005720:Gamma Rays; D015870:Gene Expression / Q000528:radiation effects; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011833:Radiation Injuries, Experimental; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016159:Tumor Suppressor Protein p53 / Q000235:genetics
D050759:Cyclin-Dependent Kinase Inhibitor p21; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53