ObjectiveTo investigate the effects of human placental mesenchymal stem cells (hPMSCs) transplantation on pulmonary vascular endothelial permeability and lung injury repair in mice with lipopolysaccharide (LPS)-induced acute lung injury (ALI).MethodsThe hPMSCs were isolated from the human placental tissue by enzyme digestion and passaged. The cell phenotype of the 3rd generation hPMSCs was detected by flow cytometry. Twenty-four 6-week-old healthy male C57BL/6 mice were randomly divided into 3 groups (n=8). The mice were instilled with LPS in the airway to prepare an ALI model in the ALI model group and the hPMSCs treatment group, and with saline in the control group. At 12 hours after LPS infusion, the mice were injected with 3rd generation hPMSCs via the tail vein in hPMSCs treatment group and with saline in the ALI model group and the control group. At 24 hours after injection, the lung tissues of all mice were taken. The pathological changes were observed by HE staining. The wet/dry mass ratio (W/D) of lung tissue was measured. The Evans blue leak test was used to detect the pulmonary vascular endothelial permea bility in mice. The expression of lung tissue permeability-related protein (VE-cadherin) was detected by Western blot.ResultsFlow cytometry examination showed that the isolated cells had typical MSCs phenotypic characteristics. Mice in each group survived. The alveolar structure of the ALI model group significantly collapsed, a large number of inflammatory cells infiltrated, and local alveolar hemorrhage occurred; while the alveolar structure collapse of the hPMSCs treatment group significantly improved, inflammatory cells infiltration significantly reduced, and a few red blood cells were in the interstitial lung. W/D and exudation volume of Evans blue stain were significantly higher in the ALI model group than in the control group and the hPMSCs treatment group (P<0.05), in the hPMSCs treatment group than in the control group (P<0.05). The relative protein expression of VE-cadherin was significantly lower in the ALI model group than in the control group and the hPMSCs treatment group (P<0.05), and in the hPMSCs treatment group than in the control group (P<0.05).ConclusionIntravenous injection of hPMSCs can effectively reduce the increased pulmonary vascular endothelial permeability mediated by LPS, relieve the degree of lung tissue damage, and play a therapeutic role in ALI mice.