Objective      To investigate the anti-inflammatory effect of transplantation of endothelial progenitor cells (EPCs) in rats with acute lung injury.       Methods      Thirty-six clean Sprague Dawley rats with the same genetic background were randomly divided into 3 groups (n=12): phosphate buffer solution (PBS) group

lipopolysaccharide (LPS) group

and EPCs group. The EPCs were isolated and cultured with density gradient centrifugation. The rats in the LPS and EPC groups were intravenously injected with 5 mg/kg LPS to induce lung injury. The rats in the PBS group were treated with only PBS at the same dose. Half an hour later

the rats in the EPC and PBS groups were injected with bone marrow-derived EPCs (2.0×106/0.5 mL) through the tail vein

and the rats in the LPS group were treated with the same dose of PBS. The amount of tumor necrosis factor-α (TNF-α)

interleukin-1β (IL-1β)

neutrophil elastase (NE) and myeloperoxidase (MPO) in the 3 groups were detected on the 7th day after EPCs transplantation.       Results      Compared with the PBS group

the lung injury score and the lung wet-to-dry ratio were increased in the LPS group

and the amount of TNF-α (195.88±10.08 vs 39.40±2.11 pg/mL)

IL-1β (143.33±10.19 vs 49.18±2.52  pg/mL)

NE (3.88±0.02 vs 0.65±0.03 ng/mL)

and MPO (7.11±0.41 vs 1.32±0.09 U/g) were significantly increased (all P0.05). Compared with the LPS group

the lung injury score and lung wet-to-dry ratio were decreased in the EPC group

and the amount of TNF-α (103.52±10.07 vs 195.88±10.08  pg/mL)

  IL-1β (78.04±3.98 vs 143.33±10.19 pg/mL)

NE (1.98±0.05 vs 3.88±0.02 ng/mL)

and MPO (4.63±0.37 vs 7.11±0.41 U/g) were significantly reduced (P0.05).       Conclusion      Transplantation of EPCs can reduce the inflammatory mediators and improve the injured lung tissues in rats with acute lung injury.