OBJECTIVETo investigate the influence of high oxygen exposure on signaling pathway of the receptor for advanced glycation end products (RAGE)-NF-κB of lung in newborn rats and the mechanisms of protecting lung injury for human mesenchymal stem cells (hMSC).

METHODSTwenty-four newborn Sprague-Dawley rats from three litters were randomly divided into three groups, as hyperoxia exposed + hMSC group (group A), hyperoxia exposed group (group B), and air-exposed group (group C). The rats from the group A and B were placed in a sealed Plexiglas chamber with a minimal in-and outflow, providing six to seven exchanges per hour of the chamber volume and maintaining O(2) levels above 95%, while rats in the group C only exposed to air simultaneously. Seven days later, rats in the group A were injected intravenously with hMSC (5×10(4)) after hyperoxia exposure, but rats in group B and C received subcutaneous injection with PBS alone at the same time point. Then all the rats were exposed to air, and were sacrificed three days later. Immunohistochemistry was used to evaluate the expression of RAGE in lung tissue. The levels of TNF-α and sRAGE in bronchoalveolar lavage fluid (BALF) and in serum were detected by ELASA, RAGE mRNA and NF-κB mRNA in tissue homogenates were detected by RT-PCR, RAGE and NF-κB by Western blotting; also the value of lung damage score were calculated with histology under light microscope.

RESULTSThere were significant differences among three groups in the fields of lung damage score (F = 51.59, P = 0.000), mRNA and protein of RAGE (F = 37.21, P = 0.000; F = 15.88, P = 0.000) and NF-κB (F = 5.695, P = 0.011; F = 4.223, P = 0.0288) in lung tissue homogenates, and the level of TNF-α (F = 38.29, P = 0.000) in BALF, all these parameters in group A and group B were higher than that in group C. While sRAGE in BALF in group A and group B were less than that in group C (F = 4.804, P = 0.0191). There were also significant differences between group A and group B in these parameters (P < 0.05). There were also no significant differences neither in TNF-α nor in sRAGE in serum among three groups.

CONCLUSIONShMSC protects hyperoxia-induced lung injury via downregulating the signaling pathway of RAGE-NF-κB.