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. For the microarray analysis, CD146+ L-MSCs (passage 2) were expanded in 5% O2 (physiological oxygen) culture conditions and collected for RNA isolation. The experiment consisted of two groups: L-MSCs isolated from P12 rat pups exposed to 95% O2 from P0 to P10 (n=3) and L-MSCs isolated from P12 room air control pups (n=3).