Endothelial progenitor cell-conditioned medium improves lung structure in neonatal rats exposed to hyperoxia / 中国病理生理杂志

ABSTRACT

AIM: To investigate the therapeutic effect of endothelial progenitor cell-conditioned medium (EPC-CM) on the lung structure of neonatal rat exposed to hyperoxia, and to explore the mechanisms.METHODS: Bone marrow-derived endothelial progenitor cells (EPCs) were collected from new born Sprague-Dawley (SD) rats and the EPCs were identified.The conditioned medium from the passage 3 EPCs was collected.Newborn SD rats (n=40) were randomly divided into 4 groups.The rats in room air group were exposed to the room air (21% O2) for 21 d.The rats in hyperoxia group were exposed to hyperoxia (85% O2) for 21 d.The rats in endothelial cell basal medium (EBM) group were exposed to hyperoxia for 21 d, and received 100 μL EBM on postnatal day 14 (P14) in a single intratracheal (IT) injection.The rats in EPC-CM group were exposed to hyperoxia for 21 d, and received 100 μL EPC-CM on P14 in a singlie IT injection.The rats were sacrified on the 21st day.The left lungs were excised, placed in 4% paraformaldehyde, serially dehydrated in ethanol and embedded by paraffin.Serial sectioning of the paraffin-embedded left lung tissues was prepared for 5 μm thickness, and stained with hematoxylin and eosin.The pulmonary radical alveolar count (RAC) and alveolar mean linear intercept (MLI) were then calculated.The microvascular density was determined by FVIII immunostaining.The mRNA expression of KGF, VEGF, SP-A and SP-C in the right lung tissues was detected by real-time fluorescence quantitative PCR.RESULTS: The cultured cells had typical EPC morphological characteristics, and had the abilities to bind to FITC-UEA-1 and uptake DiI-ac-LDL.The body weight of the rats on day 21, RAC, MLI and microvascular density were significantly lower in hyperoxia group and EBM group than those in room air group (P<0.05).The EPC-CM group had significantly higher RAC and microvascular density than those in hyperoxia group and EBM group (P<0.05), but the body weight and MLI had no significant difference.The mRNA expression levels of KGF, VEGF, SP-A and SP-C in hyperoxia group and EBM group were significantly lower than those in room air group (P<0.05).The mRNA expression levels of KGF, VEGF, SP-A and SP-C in EPC-CM group were significantly higher than those in hyperoxia group and EBM group (P<0.05).CONCLUSION: EPC-CM promotes the lung alveolarization and microvascular formation in neonatal rats exposed to hyperoxia.These benefits may be correlated with the increased KGF and VEGF mRNA expression.