摘要 目的 探讨脐带间充质干细胞(U-MSCs)对早产大鼠支气管肺发育不良（BPD）肺组织DNA甲基化的影响。 方法 提取U-MSCs进行培养，并行表型鉴定与三系分化能力检测。将早产大鼠随机分为BPD建模组（含体积分数0.95氧处理）和对照组（C组，含体积分数0.21氧处理）。处理9 d后将BPD建模组大鼠随机分为PBS治疗组（A组）和U-MSCs治疗组（B组），正常空气中的大鼠作为C组。A组每只大鼠通过尾静脉注射磷酸盐缓冲液（PBS）100 μL，B组每只大鼠通过尾静脉注射含2×108个U-MSCs的悬液100 μL，C组每只大鼠通过尾静脉注射PBS 100 μL，每隔3 d注射1次，共注射2次。治疗8 d以后收集A、B、C组的肺组织进行DNA甲基化的检测。 结果 提取的U-MSCs高度表达U-MSCs表面标记物CD29、CD44、CD73、CD90、CD105和CD166，而不表达CD31、CD45和HLA-DR，并且具有成骨、成脂和成软骨的能力。B组大鼠生长发育水平和活动度明显高于A组，肺组织损伤程度和炎细胞浸润水平显著低于A组。 与C组相比较，A组中A1bg、Guca1b、Hoxa6、LOC500331、 Alox12、Arid4b、Btnl8、Cldn18、Clstn1、Defb22、Gpatch11、Lep、Lsm4、Mboat7、Mgat5、Olr1689、Olr1707、Olr556、Psmb8、Rbm14、RGD1561039 DNA甲基化水平明显下降（F=24.98～1546.46,P＜0.05）,B组与A组相比，以上DNA的甲基化水平明显回升，差异有显著性（P＜0.05）；而B组与C组相比除Hoxa6、LOC500331 DNA甲基化水平下降外，其他基因的甲基化水平比较差异无显著性（P＞0.05）。 结论 BPD模型中存在DNA甲基化情况。U-MSCs可能通过影响BPD肺组织DNA的甲基化水平影响疾病的发展。 Abstract：Objective To investigate the effect of umbilical cord mesenchymal stem cells (UMSCs) on DNA methylation in the lung tissue of preterm rats with bronchopulmonary dysplasia (BPD). Methods UMSCs were extracted for culture, and phenotypic identification and assessment of three-line differentiation ability were performed. Preterm rats were randomly divided into BPD modeling group (treated with oxygen at a volume fraction of 0.95) and control group (treated with oxygen at a volume fraction of 0.21). After 9 days of treatment, the rats in the BPD modeling group were randomly divided into PBS treatment group (group A) and UMSCs treatment group (group B), and the rats in normal air were used as control group (group C). The rats in group A were injected with 100 μL phosphate buffered saline (PBS) via the tail vein, those in group B were injected with 100 μL suspension containing 2×108 UMSCs via the tail vein, and those in group C were injected with 100 μL PBS via the tail vein; injection was performed once every 4 days, with a total of 2 injections. On day 8 after the treatment started, lung tissue samples were collected from groups A, B, and C for DNA methylation detection. Results The extracted UMSCs had high expression of the UMSC surface markers CD29, CD44, CD73, CD90, CD105, and CD166, with no expression of CD31, CD45, and HLA-DR, and had the osteogenic, adipogenic, and chondrogenic abilities. Compared with group A, group B had significantly higher level of growth and development and degree of activities, as well as significantly lower degree of lung tissue damage and level of inflammatory cell infiltration. Compared with group C, group A had significant reductions in the DNA methylation levels of A1bg Guca1b, Hoxa6, LOC500331,
