环磷酰胺对正常小鼠骨髓造血细胞的影响及其作用机制

本研究检测化疗药物环磷酰胺（CTX）对正常小鼠骨髓造血细胞的影响及其可能的作用机制，尤其是在骨髓造血细胞自我更新、定向分化中的作用。首先建立CTX处理的小鼠模型（一次性腹腔注射CTX 200mg／kg），通过定期检测小鼠外周血及骨髓细胞中造血干细胞（HSC，LKS＋）比例，确定小鼠骨髓及外周血细胞数量完全恢复的时间；应用竞争性移植、非竞争性移植、多色流式细胞仪分析等实验，研究CTX对骨髓造血细胞自我更新、定向分化等功能的影响；通过检测连续移植模型小鼠骨髓细胞中p16Ink4a mRNA的相对表达水平及SA-β-半乳糖苷酶（gal）的染色情况，探讨CTX对骨髓造血细胞衰老的影响。结果表明：尽管CTX处理后小鼠骨髓造血细胞数量能够完全恢复正常，但是却导致造血细胞功能的长期损伤，降低骨髓造血细胞的重建能力；并且在连续移植模型中，移植了CTX处理组小鼠骨髓造血细胞的受体小鼠出现骨髓细胞p16Ink4a mRNA高表达和SA-β-gal蓝染。结论：CTX诱发的骨髓造血细胞衰老可能在其骨髓长期损伤中发挥重要的作用。

Effect of Cyclophosphamide on Murine Bone Marrow Hematopoietic Cells and Its Possible Mechanism

This study was purposed to investigate the effect of chemotherapeutic drug cyclophosphamide （CTX） on normal murine bone marrow hematopoietic cells, especially on the self-renewal, proliferation and differentiation of bone marrow hematopoietic cells, and possible mechanisms. The CTX-treated mouse model was established by CTX 200 mg/ kg, ip. The exact time of complete recovery of hematopoiesis was determined by monitoring the recovery level of differential blood counts and the proportion of LKS ＋ cells in bone marrow cells. The function of bone marrow hematopoietic cells such as self-renewal, proliferation and differentiation were assessed by non-competitive and competitive bone marrow transplantation. The potential effect of CTX on senescence of bone marrow hematopoietic cells was analyzed by detecting p16Ink4a mRNA relative expression and SA-βgalactosidase （gal） staining. The results showed that the CTX could induce long-term but latent damage to bone marrow hematopoietic cell function and lead to the decrease in competency of bone marrow hematopoietic cells to reconstitute while seemingly permitting a complete recovery. Furthermore, the serial-transplantation model showed that these mice received transplantation of bone marrow hematopoietic cells from CTX-treated mice exhibited a high expression of p16Ink4a mRNA and SA-β-gal staining. It is concluded that CTX-induced bone marrow cellular senescence may play an important role in CTX-induced long-term injury to bone marrow hematopoietic cells.