Introduction: Although exogenous nitric oxide (NO) is used as medicine, in the previous we showed its inhibitory effect on the proliferation ability of rat bone marrow mesenchymal stem cells (BMSCs). In the present investigation, the inhibitory role of exogenous NO on BMSCs cell cycle was studied. Methods: BMSCs after the third passage were treated for one hour every 48 hours with 100μM of sodium nitroprusside as an NO donor. Then, after 5,10,15, and 20 days of treatment, the viability, proliferation, and cell cycle of the BMSCs was investigated. In addition, the expression of the Raf1, CDK2, CDK4, P53, and GAPDH genes was studied. Results: Cell treatment caused a significant reduction in viability and proliferation at 5,10,15, and 20 days. Also, the treatment caused cell cycle arrest at G1 after 20 days. In addition, it was found that the CDK2 and CDK4 expression were down-regulated whereas the P53 expression was up-regulated, but the expression of Raf1 as well as GAPDH remained the same. Conclusion: This study showed that prolonged treatment with a NO donor arrest the BMSCs cell cycle due to overexpression of P53, which inhibits the expression of Cdk2 and Cdk4.
