Endothelial  colony-forming cells reduced the lung injury induced by cardiopulmonary bypass in rats

Background: Cardiopulmonary bypass (CPB) results in severe lung injury via inflammation and endothelial injury. The aim of this study was to evaluate the effect of endothelial colony-forming cells (ECFCs) on lung injury in rats subjected to CPB. Methods: Thirty-two rats were randomized into the sham, CPB, CPB/ECFC and CPB/ECFC/L-NIO groups. The rats in the sham group received anaesthesia, and the rats in the other groups received CPB. The rats also received PBS, ECFCs and L-NIO-pretreated ECFCs. After 24 hours of CPB, pulmonary capillary permeability, including the PaO 2 /FiO 2 ratio, protein levels in bronchoalveolar lavage fluid (BALF) and lung tissue wet/dry weight, was evaluated. The cell numbers and cytokines in BALF and peripheral blood were tested. Endothelial injury, lung histological injury and apoptosis were assessed. The oxidative stress response and apoptosis-related proteins were analysed. Results: After CPB, all the data deteriorated compared with those obtained in the S group (sham vs CPB vs CPB/ECFC vs CPB/ECFC/L-NIO: histological score: 1.62±0.51 vs 5.37±0.91 vs 3.37±0.89 vs 4.37±0.74; PaO 2 /FiO 2 : 389±12 vs 233±36 vs 338±28 vs 287±30; wet/dry weight: 3.11±0.32 vs 6.71±0.73 vs 4.66±0.55 vs 5.52±0.57; protein levels: 134±22 vs 442±99 vs 225±41 vs 337±53, all P<0.05). Compared to the CPB treatment, ECFCs significantly improved pulmonary capillary permeability and PaO 2 /FiO 2 . Similarly, ECFCs also decreased the inflammatory cell number and pro-inflammatory factors in BALF and peripheral blood, as well as the oxidative stress response in the lung tissue. ECFCs reduced the lung histological injury score and apoptosis and regulated apoptosis-related proteins in the lung tissue. Compared with CPB/ECFC group, all the indicators were partly reversed by the L-NIO. Conclusions: ECFCs significantly reduced lung injury induced by inflammation after CPB.