Objective:To investigate the possible mechanism of mesenchymal stem cells (MSC) secreting hepatocyte growth factor (HGF).Methods:① C57BL/6 mouse mesenchymal stem cells (mMSC) were cultured in vitro, and mMSC with high expression of chemokine receptor 7 (CXCR7) were transduced by lentivirus plasmid. Blank control group and empty carrier control group were set at the same time. After 20 generations of cell culture, the transfection efficiency was identified by fluorescence microscopy and flow cytometry. The mRNA expression levels of CXCR7 in mMSC were detected by real-time fluorescent quantitative reverse transcription-polymerase chain reaction (RT-PCR). ② mMSC with passage number 4-6 were divided into MSC control group [MSC-blank group, 100 μg/L lipopolysaccharide (LPS) was added to wild-type MSC], highly expressed CXCR7 group (MSC-OE-CXCR7 group, 100 μg/L LPS was added to mMSC transduced by lentivirus plasmid with high expression of CXCR7), highly expressed CXCR7 control group (MSC-OENC-CXCR7 group, 100 μg/L LPS was added to mMSC transduced by no load lentivirus plasmid), CXCR4 inhibitor group (MSC-IE-CXCR4 group, 100 μg/L LPS was added to mMSC after 0.1 mg/L CXCR4 inhibitor TC14012 pretreatment for 24 hours), and CXCR4 inhibitor control group (MSC-IENC-CXCR4 group, 100 μg/L LPS was added to mMSC after DMEM culture medium with equal amount of TC14012 pretreatment for 24 hours). Cells in each group were collected after treatment with LPS, and mRNA expression of inhibitor of differentiation-1 (ID-1) was detected by RT-PCR. The cell supernatant was collected, and the levels of HGF were detected by enzyme linked immunosorbent assay (ELISA). Results:① The high expression of CXCR7 for mMSC which were transduced through lentivirus plasmid were successfully constructed detected by fluorescence microscope and flow cytometry. Compared with the blank control group, the expression of CXCR7 mRNA in the lentivirus with high expression of CXCR7 group was significantly increased (2 -ΔΔCt: 5.81±0.97 vs. 1.02±0.12, P < 0.05). There was no significant difference in CXCR7 mRNA expression between the empty carrier control group and the blank control group (2 -ΔΔCt: 0.95±0.22 vs. 1.02±0.12, P > 0.05). ②Compared with the MSC-blank group, high expression of CXCR7 in MSC-OE-CXCR7 group or inhibition of CXCR4 in MSC-IE-CXCR4 group could induce high expression of ID-1 mRNA in mMSC (2 -ΔΔCt: 5.56±0.66, 2.47±0.58 vs. 1.00±0.10, both P < 0.05) and increase HGF exocrine level (ng/L: 632.02±149.98, 217.21±40.53 vs. 108.53±24.62, both P < 0.05). However, there were no significant differences in ID-1 mRNA expression and HGF exocrine level of mMSC among MSC-OENC-CXCR7 group, MSC-IENC-CXCR4 group and MSC-blank group [ID-1 mRNA (2 -ΔΔCt): 1.01±0.27, 1.21±0.32 vs. 1.00±0.10, HGF (ng/L): 133.56±25.19, 107.11±25.30 vs. 108.53±24.62, both P > 0.05]. Conclusion:High expression of CXCR7 or inhibition of CXCR4 in MSC can increase the expression of ID-1 and promote the secretion of HGF, thus promoting pulmonary microvascular endothelial repair.

Objective:To discuss the effect of parthenolide(PTL)on the apoptosis of the chondrocytes under mechanical stretch stress by regulating the expression of piezo type mechanosensitive ion channel component 1(Piezo1),and to clarify the related mechanism.Methods:The chondrocytes were divided into 0%,5%,10%,15%,and 20%stretch groups according to the stretch variable.Additionally,the chondrocytes were divided into control group,20%stretch group,20%stretch+5 μmol·L-1 PTL group,20%stretch+10 μmol·L-1 PTL group,and 20%stretch+20 μmol·L-1 PTL group.The Piezo1 short hairpin RNA(shRNA)interference lentivirus(sh-Piezo1)or shRNA-NC lentivirus were used to infect the chondrocytes,and the chondrocytes were divided into sh-Piezo1 group and sh-NC group,and also set up blank control group.The chondrocytes were also devided into 20%stretch group,20%stretch+PTL group,20%stretch+sh-Piezo1 group,and 20%stretch+sh-Piezo1+PTL group.Hoechst 33258 fluorescence staining was used to observe the morphology of the nuclear in various groups;flow cytometry was used to detect the apoptotic rates of the cells in various groups;spectrophotometry was used to detect the cysteinyl aspartate specific proteinase(Caspase)-3 activities in the cells in various groups;CCK-8 method was used to detect the proliferation rates of the cells in various groups;Fluo-4/AM fluorescent probe method was used to detect the calicium ion(Ca2+)levels in the cells in various groups;real-time fluorescence quantitative PCR(RT-qPCR)method was used to detect the expression levels of Piezo1 mRNA in the cells in various groups;Western blotting method was used to detect the expression levels of Piezo1 protein in the cells in various groups.Results:The Hoechst 33258 fluorescence staining resuts showed that as the increasing of stretch,the number of the chondrocytes with fragmented and densely stained nuclei in 0%,5%,10%,15%,and 20%stretch groups were gradually increased.The flow cytometry results showed that compared with 0%stretch group,the apoptotic rates of the chondrocytes in 5%,10%,15%,and 20%stretch groups were significantly increased(P<0.01);compared with control group,the apoptotic rate of the chondrocytes in 20%stretch group was significantly increased(P<0.05);compared with 20%stretch group,the apoptotic rates of the chondrocytes in 20%stretch+5 μmol·L-1 PTL group,20%stretch+10 μmol·L-1 PTL group,and 20%stretch+20 μmol·L-1 PTL group were significantly decreased(P<0.05);compared with 20%stretch group,the apoptotic rates of chondrocytes in 20%stretch+PTL group and 20%stretch+sh-Piezo1 group were significantly decreased(P<0.05).The spectrophotometry results showed that compared with 0%stretch group,the Caspase-3 activities in the chondrocytes in 5%,10%,15%,and 20%stretch groups were significantly increased(P<0.01);compared with control group,the Caspase-3 activity in the chondrocytes in 20%stretch group was significantly increased(P<0.05);compared with 20%stretch group,the Caspase-3 activities in the chondrocytes in 20%stretch+5 μmol·L-1 PTL group,20%stretch+10 μmol·L-1 PTL group,and 20%stretch+20 μmol·L-1 PTL group were significantly decreased(P<0.05).Compared with 20%stretch group,the Caspase-3 activities in the chondrocytes in 20%stretch+PTL group and 20%stretch+sh-Piezo1 group were significantly decreased(P<0.05).The CCK-8 method results showed that compared with 0 μmol·L-1 PTL group,the proliferation rates of the chondrocytes in 40.00,80.00,and 160.00 μmol·L-1 PTL groups were significantly decreased(P<0.05),indicating that 20.00 μmol·L-1 PTL was the maximum non-toxic concentration.The Fluo-4/AM fluorescent probe method results showed that compared with control group,the Ca2+level in the chondrocytes in 20%stretch group was significantly increased(P<0.05);compared with 20%stretch group,the Ca2+levels in the chondrocytes in 20%stretch+5 μmol·L-1 PTL group,20%stretch+10 μmol·L-1 PTL group,and 20%stretch+20 μmol·L-1 PTL group were significantly decreased(P<0.05);compared with 20%stretch group,the Ca2+levels in the chondrocytes in 20%stretch+PTL group and 20%stretch+sh-Piezo1 group were significantly decreased(P<0.05).The RT-qPCR results showed that compared with blank control group and sh-NC group,the expression level of Piezo1 mRNA in the chondrocytes in sh-Piezo1 group was significantly decreased(P<0.05).The Western blotting results showed that compared with control group,the expression levels of Piezo1 protein in the chondrocytes in 20%stretch group was significantly increased(P<0.05);compared with 20%stretch group,the expression levels of Piezo1 protein in the chondrocytes in 20%stretch+5 μmol·L-1 PTL group,20%stretch+10 μmol·L-1 PTL group,and 20%stretch+20 μmol·L-1 PTL group were significantly decreased(P<0.05);compared with blank control group and sh-NC group,the expression level of Piezo1 protein in the chondrocytes in sh-Piezo1 group was significantly decreased(P<0.05).Conclusion:PTL can inhibit the apoptosis of the chondrocyte induced by high-intensity cyclic mechanical stretch stress,and its mechanism may be related to inhibiting the Piezo1-mediated Ca2+influx-induced apoptosis.