Objective To elucidate the etiology of DNA impairment of type Ⅱ alveolar epithelial cells(AT-II) of the rats fed with low selenium and high cadmium fodder，and the effect of Vitamin C.Methods With single cell gel electrophoresis technique，we observed the joint action of selenium，cadmium and vitamin C on DNA damage in AT-II cells of the eight groups of rats fed separately with：normal （2 groups），high Cd，high Cd+high VC，low Se+high Cd，low Se+high Cd+high VC，high Se+high Cd and high Se+high Cd+high VC fodder for 14 weeks.Results Compared with the control，there was no DNA changes have been observed in the high Se+high Cd+high VC group.However，in the high Se+high Cd group and high Cd+high VC group，DNA damage of AT-II cells can be detected clearly；in the low Se+high Cd+high VC group and high Cd group，the degree of the DNA damage is more serious than the above two groups；in the low Se+high Cd group，the extent of the DNA damage was the most serious on all of the groups be studied.Conclusion It is suggested that Se deficiency and simultaneously Cd overabundance may damaged DNA of AT-II cells of the rats significantly，however，Vitamin C may protect AT-II against the injury effectively.
Objective To explore the migration and differentiation of bone marrow mesenchymal stem cells（MSCs） in lung . Methods MSCs were harvested from a male Wister rat. Sixty female Wister rats were randomly divided into four groups. The pulmonary fibrosis model was established by intratracheal instillation of bleomycin in group A-D. Immediately and 7 days after bleomycin administration respectively，the rats in group B and C received infusion with 5-bromodeoxynridine （BrdU） labeled MSCs via tail vein. And the rats in group D were infused MSCs without BrdU labeling serving as a negative control. The sry gene of Y chromosome was detected by polymerase chain reaction （PCR）. Double immunofluorescence staining was used to detected BrdU and surfactant associated protein-C （SP-C） expression in lung tissue，fresh bone marrow，and the 5th generation MSCs. Reverse transcriptipon-PCR was used to detect the expressions of SP-C mRNA and AQP-5 mRNA. Results The sry gene was detected in bleomycin induced lung injury tissues of the rats after MSCs infusion immediately and on the 7th day The MSCs in lung tissue could transformed into cells with ACEⅡ morphological features and molecular phenotype. The transformation rate was higher in the rats received MSCs infusion immediately than the rats received on 7th day. The 5th generation MSCs and fresh bone marrow expressed SP-C mRNA，without AQP-5 mRNA and SP-C expression. Conclusions Exogenous MSCs can be transplanted into injured lung tissues and transform into AECⅡ，especially in early stage of lung injury. The differentiation potential of MSCs can be activated in injury micro-environment.