Abstract: Objective To investigate the mechanism underlying the the response of bone mesenchymal stem cells(BMSCs) to DNA damage agents. Methods The different reponse of cultured bone marrow BMSCs to cisplatin, camptothecin and vincintine and the expression of apoptosis family member p53 and p73 was analyzed by immunofluorescence. Results In comparation to sensitive tumor cell line K562, the cultured human bone marrow BMSCs were more resistant to cisplatin, camptothecin and vincristine; The phenotype, proliferation and differentiation ability of BMSCs were observed not altered after the drug treatment; The drugs application could lead to a incresed p53 activation which was not accompanied by the apoptosis induction. In addion, the physical level of p73 in BMSCs was significantly lower than that of K562 and could not be activated by drug treatment. Conclusion The cultured BMSCs are resistant ro chemotherapeutic drugs induced apoptosis and could remain stem cell characteristics; The expression level of p73 in BMSCs may contribute to the higher resistance to DNA damage agents and further studies are needed to reveal the this actual machnism.

Key words: Bone marrow mesenchymal stem cell, Chemoresistance, Immunofluorescence