Objective To investigate the influence of chondrocytes originating from different source on early chondrogenic differentiation of bone marrow mesenchymal stem cells (MSCs) in isolated co-culture system.Methods We applied hanging cell culture system to culture chondrocytes of different origin (osteoarthritis chondrocyte cells,nomal chondrocyte cells,infant chondrocyte cells) and controls.These chondrocytes and MSCs of the same origin were cultured in the common medium in a separated condition,and observed by microscope at 3,6,9,12 day after co culture.Expression levels of aggrecan,collagen type Ⅱ (Col 2),cartilage-specific transcription factor (Sox-9) in MSCs of different origin were determined by Real-time PCR.Results MSCs showed obviously morphological differentiation induced by chondrocytes of different origin at 12 day after coculture as compared with controls.Real-time PCR analysis showed that SOX9 mRNA level was stimulated by 1.7-fold,1.6-fold and 1.2-fold (all P＜0.05) and aggrecan mRNA level was increased by 2.8-fold,2.2-fold and 1.3-fold (all P＜0.05) in infant chondrocytes group,nomal chondrocytes group,osteoarthritis chondrocytes group respectively as compared with controls while COL2 mRNA level had no significant differences among the four groups.Corresponding protein signal level had obvious differences among the four groups,especially in infant chondrocytes as compared with osteoarthritis chondrocytes and nomal chondrocytes.Conclusions Isolated co-culture system may indirectly promote MSCs differentiation to chondrocytes by local micro-environment regulation.Chondrocytes of different origin have different effects on MSCs differentiation,but they could promote MSCs differentiation to chondrocytes.

ObjectiveBased on the nuclear factor erythroid 2 related factor 2 （Nrf2）/heme oxygenase-1 （HO-1） signaling pathway， this paper explores the effect of Sinisan （SNS） on liver oxidative stress injury in cholestatic hepatitis rats and its mechanism. MethodThirty 6-week-old male SD rats were randomly divided into a control group， model group， low and high dose groups of SNS （2.5 and 5 g·kg^-1） and ursodeoxycholic acid group （UDCA， 63 mg·kg^-1）， with six rats in each group. Rats were administrated for seven consecutive days. On the 5th day， the control group was given olive oil of 10 mL·kg^-1， and the other groups were given alpha-naphthalene isothiocyanate （ANIT） of 80 mg·kg^-1. The serum biochemical indicator levels of cholestasis and the content of antioxidant factors in rat liver were detected by enzyme-linked immunosorbent assay （ELISA）. Hematoxylin-eosin （HE） staining was used to observe the pathological changes in liver tissue. The relative mRNA and protein expressions of Nrf2， HO-1， and quinone oxidoreductase 1 （NQO1） in liver tissue were detected by real-time fluorescence quantitative polymerase chain reaction （Real-time PCR） and Western blot. ResultCompared with the control group， the model group showed a significant increase in the serum biochemical indicator levels of cholestasis and the content of antioxidant factors in liver tissue （P<0.01）. There were obvious pathological changes in the model group such as the disordered arrangement of hepatocytes， obvious congestion and necrosis in the portal area， infiltration of inflammatory cells， and destruction of the interlobular bile duct. The relative mRNA and protein expressions of Nrf2， HO-1， and NQO1 in liver tissue were significantly down-regulated in the model group （P<0.05， P<0.01）. Compared with the model group， the groups of SNS showed a significant decrease in the serum biochemical indicator levels of cholestasis and the content of antioxidant factors in liver tissue （P<0.01）， and the pathological liver injury was obviously improved. The necrotic area was reduced， and the infiltration of inflammatory cells was decreased. In addition， there was a small amount of extravasated blood in the interlobular vein. The relative mRNA and protein expressions of Nrf2， HO-1， and NQO1 in liver tissue were significantly up-regulated （P<0.05， P<0.01）. ConclusionSNS can significantly improve liver injury in cholestatic hepatitis rats， and its mechanism may be related to the inhibition of oxidative stress response mediated by the Nrf2/HO-1 signaling pathway.