BACKGROUND:Notch singling pathway is very important for cellproliferation and differentiation, but its role is stil unknown during chondrogenesis of human umbilical cord mesenchymal stem cells. OBJECTIVE:To investigate the effect of N-[N-(3,5-difluorophenacetyl-L-alanyl)]-(S)-phenylglycinet-butyl ester (DAPT) on inducing human umbilical cord mesenchymal stem celldifferentiation into chondrocytes. METHODS:Human umbilical cord mesenchymal stem cells were isolated from human umbilical cord, then were induced to differentiate into chondrocytes. There were four experimental groups:non-induced group, high-glucose Dulbecco’s modified Eagle’s medium containing 5%fetal bovine serum and 1%double antibody;induced group, induced medium containing 6.25 mg/L insulin, 6.25 mg/L transferrin, 10μg/L transforming growth factor beta 1, 0.1μmol/L dexamethasone, 50 mg/L vitamin C, 5%fetal bovine serum and 1%double antibody;dimethyl sulfoxide group, induced medium containing 0.1%dimethyl sulfoxide;DAPT group, induced medium containing 5μmol/L DAPT. RESULTS AND CONCLUSION:After chondrogenic induction, the morphology of human umbilical cord mesenchymal stem cells became polygon and positive for toluidine blue and immunofluorescence staining;the expression of Jag-1, PS-1, Notch-1 and Hes-1 decreased significantly (P<0.01). After the addition of DAPT, compared with the induced group, the relative gene expression of Jag-1, PS-1 and Hes-1 decreased markedly (P<0.01), the relative gene expression of Notch-1 decreased obviously as wel (P<0.05), and the contents of proteoglycan and col agen type II proteins decreased significantly (P<0.01). At the same time, the relative gene expression of proteoglycan decreased obviously (P<0.05), and the relative gene expression of col agen type II decreased in part. Notch signaling pathway exists in human umbilical cord mesenchymal stem cells, once chondrogenesis begins, the signaling strength wil decline rapidly. DAPT may prevent human umbilical cord mesenchymal stem cells from differentiating into chondrocytes by Jag-1-Notch-1-Hes-1 pathway.

ObjectiveTo explore the potential mechanism by which Huangqi Baijiang Yiren decoction （HBY） repairs the intestinal mucosal injury in the rat model of ulcerative colitis （UC） via the miR-21/suppressor of cytokine signaling 1 （SOCS1）/Janus kinase 1 （JAK1）/signal transducer and activator of transcription 6 （STAT6） signaling pathway. MethodsSixty SPF-grade male SD rats were randomly assigned into six groups： blank， model， low-dose （3.68 g·kg^-1） HBY， medium-dose （7.35 g·kg^-1） HBY， high-dose （14.5 g·kg^-1） HBY， and mesalazine （0.035 g·kg^-1）， with 10 rats in each group. The rat model of UC was established in other groups except the blank group by 3% dextran sulfate sodium solution. The rats were administrated with corresponding drugs once a day for 7 consecutive days since the 3th day after modeling. The histopathological changes of the colon were observed by hematoxylin-eosin staining， and the Robarts histopathology index （RHI） was scored. Enzyme-linked immunosorbent assay was employed to measure the levels of pro-inflammatory cytokines ［interleukin （IL）-6， IL-18， IL-1β， and tumor necrosis factor-α （TNF-α）］ in the serum. Real-time PCR was employed to determine the mRNA levels of miR-21， SOCS1， JAK1， and STAT6 in the colon tissue. Western blot was employed to determine the protein levels of SOCS1， JAK1， phosphorylated （p）-JAK1， STAT6， p-STAT6， Occludin， and Claudin-1 in the colon tissue. ResultsCompared with the blank group， the model group showed an increase in disease activity index （DAI） （P<0.01）， shortening of colon length （P<0.01）， severe histopathological damage in the colon tissue， and an increase in RHI， rises in serum levels of IL-6， IL-1β， IL-18， and TNF-α （P<0.01）， up-regulation in mRNA levels of miR-21， JAK1， and STAT6 and protein levels of p-JAK1 and p-STAT6 （P<0.01）， and down-regulation in mRNA and protein levels of SOCS1 and protein levels of Occludin and Claudin-1 （P<0.01）. The treatment with HBY reduced the DAI （P<0.01）， alleviated colon shortening and histopathological damage in the colon tissue， decreased the RHI （P<0.01）， lowered the serum levels of IL-6， IL-1β， IL-18， and TNF-α （P<0.01）， down-regulated the mRNA levels of miR-21， JAK1， and STAT6 （P<0.05， P<0.01）， up-regulated the mRNA level of SOCS1 （P<0.05）， up-regulated the protein levels of SOCS1， Occludin， and Claudin-1 （P<0.05， P<0.01）， and down-regulated the protein levels of p-JAK1 and p-STAT6 （P<0.05， P<0.01）. ConclusionHBY may modulate the miR-21/SOCS1/JAK1/STAT6 signaling pathway to suppress inflammatory responses and restore the intestinal mucosal barrier in UC rats.