目的：高氧可能通过改变未成熟肺组织正常结构发育而导致肺功能异常。该研究通过观察高氧时体外培养胎儿肺组织结构和细胞分化的变化特点及地塞米松对这些肺组织的作用,旨在了解高氧对胎儿肺组织发育的影响。方法：用培养人假腺体期胎儿肺组织模型分别于高氧(95%O2,5%CO2)及正常氧(21%O2,5%CO2)中培养72 h,两组又分为地塞米松组(10-6M)及无地塞米松组。收获的肺组织以细胞角蛋白(pancytokeratin)确定上皮细胞,K i-67作为增生性细胞标记物。形态学结果用计算机辅助图像分析系统处理,分别计算出平均气道厚度,气道占组织比例(%),平均气道面积及细胞增生指数。结果：正常氧培养72 h,肺结构无明显改变,而高氧组气道明显扩张。高氧组与正常氧组比较,气道面积6 662μm2vs 2 728μm2;气道厚度7.8μm vs 8.1μm;气道所占比例35.2%vs 23.4%,差异有显著性(均P<0.05)。高氧并用地塞米松组气道面积(3 174μm2)及气道所占比例(23.9%)与高氧组比较,均明显降低,P<0.05;气道厚度无明显变化。高氧组上皮增生指数(21.8%)明显高于正常氧组(5.1%)及并用地塞米松组(7.4%),P<0.05。结论：高氧促进假腺体期胎儿肺组织分化为类似囊状期样结构,这种变化与气道上皮细胞异常增生有关;地塞米松具有抑制高氧对胎儿肺组织的损伤作用。

OBJECTIVE: This study aimed to explore the effects of hyperoxia on the development of fetal lung by investigating the changes of morphological and cell proliferation induced by hyperoxia in cultured fetal lungs as well as the effects of dexamethasone on hyperoxia-exposed lungs. METHODS: Human fetal lung explants at the pseudoglandular stage of development were cultured randomly either in normoxia(21% O_2/5% CO_2) or hyperoxia(95% O_2/5% CO_2) for 72 hrs. Dexamethasone was added into the feeding medium at the concentration of 10~(-6) M. Harvested tissues were stained for pancytokeratin to identify epithelial cells, with Ki-67 as a marker of proliferation. The effects of lung morphometry were analyzed using computer assisted image analysis.The mean airway thickness, the proportion of the surface area occupied by airways, the mean airway surface area and the index of the epithelium proliferation were measured. RESULTS: The lung architectures remained unchanged after 72 hrs normoxia culture, whereas hyperoxia culture resulted in significant dilation of airways and thinning of epithelium, with the surface area of airways of 6 662 μm~2 vs 2 728 μm~2 and the thickness of airways of 7.8 μm vs 8.1 μm(P<0.05). Hyperoxia culture also resulted in an increase in the proportion of the surface area occupied by airways than normoxia culture(35.2% vs 23.4%; P<0.05). The surface area of airways(3 174 μm~2) and the proportion of the surface area occupied by airways(23.9%) decreased significantly in hyperoxia-cultured lungs after dexamethasone administration(P<0.05). The epithelium proliferation index in hyperoxia-cultured lungs(21.8%) was higher than that in normoxia-cultured lungs(5.1%) and dexamethasone-treated hyperoxia-cultured lungs(7.4%)(P<0.05). CONCLUSIONS: The exposure of pseudoglandular lungs to hyperoxia modulates the lung architecture to resemble saccular lungs with higher epithelium proliferation index. Dexamethasone may inhibit the effects induced by hyperoxia.