目的：探讨再生障碍性贫血（再障）患儿骨髓间充质干细胞（MSC）体外生物学特性及与免疫抑制治疗（IST）疗效的关系，评价MSC异常在再障发生、发展中的作用。方法：对29例再障患儿进行了骨髓MSC培养，其中17例患儿接受IST，观察MSC体外生长特点、表面标志、细胞周期、对PHA刺激的外周血淋巴细胞增殖的抑制作用，并与5例正常儿童骨髓作对照；观察再障患儿MSC异常与IST疗效的关系。结果：55%（16/29）的再障患儿表现为不同程度的MSC生长异常，主要为MSC数量减少及增殖能力下降，其中以重型再障（SAA）、病程较长者或放/化疗后再障为多见。培养成功的再障患儿第3代MSC表面标志、细胞周期、转化生长因子-β1（TGF-β1）分泌水平及对PHA刺激的淋巴细胞增殖的抑制作用与对照组比较，差异均无显著性（P>0.05）。在17例接受IST患儿中，9例MSC生长基本正常的再障患儿经IST后8例达完全缓解，而8例MSC生长异常者仅2例达完全缓解，两组比较差异具有显著性（P<0.01）。结论：多数再障患儿骨髓MSC体外生长存在不同程度的异常，其MSC异常对IST后患儿骨髓造血功能恢复具有一定的负面影响。

OBJECTIVE: To study the biological characteristics of bone marrow-derived mesenchymal stem cells（MSC）in children with aplastic anemia (AA) and evaluate the relationship of biological characteristics of MSC with the efficacy of immunosuppressive therapy (IST). METHODS: Bone marrow- derived MSC were cultured and isolated from 29 children with AA and 5 normal controls. Seventeen out of the 29 cases received IST. Surface markers and cell cycle of MSC at passage 3 were analyzed by flow cytometry. The inhibition of lymphocyte proliferation by MSC was evaluated and TGF-β1 level in the supernatant of MSC was detected using ELISA.ResultsGrowth abnormality of MSC was found in 16 children with AA (55%), characterized by deficiency and poor proliferation of MSC, and was frenquently seen in patients with severe AA or in patients with more prolonged disease course or in patients with radiation/chemotherapy-induced AA. Surface markers, cell cycle and TGF-β1 level in the supernatant of MSC at passage 3 and the inhibition of lymphocyte proliferation by MSC in the AA group were similar to those in the control group. Eight out of nine patients with normal MSC growth achieved complete remission (CR) but only 2 out of 8 patients with abnormal MSC growth achieved CR following IST (P<0.01). CONCLUSIONS: Bone marrow-derived MSC growth abnormality occurs in most of children with AA. MSC abnormality may affect adversely hematological recovery following IST.