LAUSR

Aims: To study the protective effects and mechanisms of human umbilical cord mesenchymal stem cells (hUCMSCs) and overexpression of antioxidant gene SOD2 on lung injury by establishing a rat model of paraquat (PQ)‐induced lung injury. Main methods: The hUCMSCs cell line overexpressed SOD2 was established. After intraperitoneal injection of PQ solution (24mg/kg) 3h later, the different groups of hUCMSCs cell lines were injected through the tail veins of rats. Bronchoalveolar lavage fluid (BALF) was obtained to determine the protein level of inflammatory cytokines. Lung tissues were collected to test the wet/dry weight ratios (W/D), oxidative stress index and lung injury scores. Western blotting was used to detect SOD1, SOD2, HO‐1, Nrf2, NF‐&kgr;Bp65 subunit, and cleaved caspase‐3. Key findings: After treatment with cells built on the basis of hUCMSCs, the protein levels of TNF‐&agr;, IL‐8, and ICAM‐1 in BALF decreased, and meanwhile in lung tissues, MDA content was reduced, GSH‐Px activity was elevated, and lung W/D ratio decreased. Additionally, protein expression of NF‐&kgr;B p65 subunit and activated caspase‐3 in lung tissues was down‐regulated, whereas expression of SOD1, SOD2, HO‐1, and Nrf‐2 were up‐regulated. The results of HE staining showed that lung injury was significantly alleviated in the hUCMSC treated group. It is noticeable that hUCMSCs and SOD2‐overexpressed hUCMSCs effectively reduced PQ‐induced lung injury in rats, and moreover, hUCMSCs overexpressed SOD2 were more effective compared with hUCMSCs only. Significance: Evaluation of the efficacy and analysis of mechanism in the treatment of PQ induced ALI by appliance of SOD2‐overexpressed hUCMSCs will provide the proof from bench to bedside.