Abstract: Abstract： Objective To test the effect of bone marrow mesenehymal stem cells (MSCs) transplantation on oxidative stress and the development of pulmonary emphysema in rats. Methods SD rats (n=26) were randomly divided into three groups： normal control group (group A, n=8)， emphysema group (group B, n=8) and emphysema+MSCs transplantation group (group C, n=10)．Rat models of emphysema was established by exposing rats to cigarette smoking for 14 weeks. Then rats of group C received MSCs transplantation. At the 14th and 28th days after 4 course of MSCs transplantations, one rat in group C was sacrificed at each time point and their lungs were preserved in frozen sections. Survival of MSCs in the lung tissues were observed by fluorescence microscopy. Eight weeks after transplantations, lung sections were stained by hematoxylin and eo⁃ sin (HE) to observe the morphological alterations．Mean linear intercept (MLI) and mean alveolar numbers (MAN) were also measured. Serum and lung malondialdehyde (MDA) levels and superoxide dismutase (SOD) activity were also examined. Re⁃ sults At the 14th day and 28th day after transplantations of MSCs, MSCs successfully localized to lung and survived in rat models of emphysema. Emphysematous changes of lung tissues were observed in both group B and group C. MLI was higher while MAN was lower in group B and C than those in group A (P < 0.05). MLI and MDA levels in serum and lung were high⁃ er while MAN level and SOD activity were lower in group B than those in group C (P < 0.05)．MDA levels in serum and lung was higher while SOD activity was lower in group B and C than those in group A (P < 0.05). Conclusion MSCs transplanta⁃ tions can effectively alleviates pulmonary emphysema in rat models which might through reducing oxidative stress．

Key words: pulmonary emphysema, mesenchymal stem cells, oxidative stress； mesenchymal stem cell transplantation