In vivo hyperoxia versus normoxia neonatal rat lung MSCs

Background: Bronchopulmonary dysplasia (BPD), the most common complication of extreme preterm birth, can be caused by oxygen-related lung injury and is characterized by impaired alveolar and vascular development. Mesenchymal stromal cells (MSCs) have lung protective effects. Conversely, BPD is associated with increased MSCs in tracheal aspirates. Objective: To determine whether endogenous lung (L-)MSCs are perturbed in a well-established oxygen-induced rat model mimicking BPD features. Methods: Rat pups were exposed to room air or 95% oxygen from birth to postnatal day 10. On day 12, CD146+ L-MSCs were isolated and characterized according to the International Society for Cellular Therapy criteria. Epithelial and vascular repair potential were tested by scratch assay and endothelial network formation respectively, immune function by mixed lymphocyte reaction assay. Microarray analysis was performed using the Affymetrix GeneChip and gene set enrichment analysis (GSEA) software. Results: CD146+ L-MSCs isolated from rat pups exposed to hyperoxia had decreased CD73 expression and inhibited lung endothelial network formation. CD146+ L-MSCs indiscriminately promoted epithelial wound healing and limited T-cell proliferation. Expression of potent anti-angiogenic genes of the axonal guidance cue and CDC42 pathways was increased after in vivo hyperoxia, whereas genes of the anti-inflammatory JAK/STAT and lung/vascular growth promoting Fibroblast Growth Factor (FGF) pathways were decreased. Conclusions: In vivo hyperoxia exposure alters the pro-angiogenic effects and FGF expression of L-MSCs. Additionally, decreased CD73 and JAK/STAT expression suggest decreased immune function. L-MSC function may be perturbed and contribute to BPD pathogenesis. These findings may lead to improvements in manufacturing exogenous MSCs with superior repair capabilities.背景：支气管肺发育不良（Bronchopulmonary dysplasia, BPD）是极早早产儿最常见的并发症，可由氧相关性肺损伤引发，以肺泡与血管发育受损为特征。间充质基质细胞（Mesenchymal stromal cells, MSCs）具有肺保护作用。与之相反，BPD与气管抽吸物中MSCs增多相关。 目的：本研究旨在明确在模拟BPD特征的经典氧诱导大鼠模型中，内源性肺源性间充质基质细胞（L-MSCs）是否存在功能紊乱。 方法：将新生大鼠于出生后至出生后第10天暴露于空气或95%氧气环境中。于第12天分离CD146+ L-MSCs，并依据国际细胞治疗学会（International Society for Cellular Therapy）标准进行鉴定。分别通过划痕实验检测上皮修复潜能、内皮管形成实验检测血管修复潜能，混合淋巴细胞反应实验检测其免疫功能。采用Affymetrix基因芯片（Affymetrix GeneChip）进行微阵列分析，并使用基因集富集分析（Gene Set Enrichment Analysis, GSEA）软件进行数据分析。 结果：暴露于高氧环境的新生大鼠分离得到的CD146+ L-MSCs，其CD73表达水平降低，且对肺内皮管形成具有抑制作用。CD146+ L-MSCs可无差别促进上皮创面愈合，并抑制T细胞增殖。体内高氧暴露后，轴突导向通路与CDC42通路中的强效抗血管生成基因表达上调，而抗炎JAK/STAT通路以及促肺/血管生长的成纤维细胞生长因子（Fibroblast Growth Factor, FGF）通路相关基因表达下调。 结论：体内高氧暴露可改变L-MSCs的促血管生成活性及FGF表达水平。此外，CD73与JAK/STAT通路表达降低提示其免疫功能受损。L-MSCs功能紊乱可能参与BPD的发病机制。本研究结果可为优化具有优异修复能力的外源性MSCs制备工艺提供新思路。