OBJECTIVE: To study the gap junction and phenotype of cultured chondrocyte of rabbit, and the gap junction between the chondrocytes in the same cartilage cavities in human femoral head articular cartilage. METHODS: CFDA-AM was added into the medium of the fifth passage of chondrocyte of rabbit in the 96-well plate. The fluorescent in spherical and fibroblast-like chondrocytes was detected separately. The recurrence of the fluorescent in accordant with time in 16 minutes was recorded after blanching the fluorescent with laser. And the fluorescent after blanching of chondrocyte in the cartilage cavities in the proliferative zone of articular cartilage of adult human femoral head was recorded, too. RESULTS: The average fluorescent of the single layer of the fibroblast-like chondrocyte was 83(ranged from 1 to 274), the highest was found in the spherical shaped cell (averaged 2,057, ranged from 340 to 3,538). The recurrence of the fluorescent after the blanching appeared only in the spherical chondrocyte, the gap junctions reappeared only in the spherical chondrocytes, as well as in the cells in the cartilage cavities in the articular cartilage of the human femoral head. CONCLUSION: The appearance of the gap junction is corresponded with the spherical shape, secretion of the cartilage matrix of the chondrocyte. There are gap junctions in the cells in the same cartilage cavities in the articular cartilage of the human femoral head, while no gap junctions in the isolated chondrocytes in the cartilage.
Bone marrow-derived mesenchymal stem cells (BMSCs) for repairing damaged heart tissue are a new kind of important treatment options because of their potential to differentiate into cardiomyocytes. We in this experiment investigated the effect of different electrical stimulation time on the expression of myocardial specificity gene and protein in rat bone marrow mesenchymal stem cells (rBMSCs) in vitro. The rBMSCs of second or third generation were randomly divided into three groups, i.e. electrical stimulation (ES) group, 5-Azacytidine (5-Aza) group and the control group. The rBMSCs in the ES groups with complete medium were exposed to 2 V, 2 Hz, 5 ms electrical stimulation for 0.5 h, 2 h, 4 h, and 6 h respectively every day for 10 days. Those in the 5-Aza group were induced by 5-Aza (10 μmol/L) for 24 h, and then cultured with complete medium for 10 days. Those in the control group were only cultured with complete medium, without any treatment, for 10 days. The rBMSCs' morphological feature in each group was observed with inverted phase microscope. The mRNA expression of myocyte-specific enhancer factor 2C (MEF-2C) and connexin 43 (Cx43) were examined with Real-Time quantitative PCR and the protein expression of MEF-2C, Cx43 were detected with Western Blot method. The results showed that the mRNA expression level of the MEF-2C, Cx43 and the protein expression level of MEF-2C, Cx43 were significantly higher in the ES group and 5-Aza group than those in the relative control group (P < 0.05). It suggests that electrical stimulation could play a part of role in the induction of the rBMSCs to differentiate into the cariomyocyte-like cells in vitro and the effectiveness of the electrical stimulation with 2 h/d had the best in our experiement. But the mechanism how electrical stimulation promotes the differentiation of rBMSC into cardiomyocyte is still unclear.
ObjectiveTo study the effect and mechanism of lipopolysaccharide (LPS) on osteoclasts formation and its bone resorption function.MethodsBone marrow-derived macrophages (BMMs) were extracted from the marrow of femur and tibia of 4-week-old male C57BL/6 mice. Flow cytometry was used to detect BMMs. The effect of different concentrations of LPS (0, 100, 200, 500, 1 000, 2 000 ng/mL) on BMMs activity was examined by cell counting kit 8 (CCK-8) activity test. In order to investigate the effect of LPS on osteoclastogenesis, BMMs were divided into macrophage colony-stimulating factor (M-CSF) group, M-CSF+receptor activator of nuclear factor κB ligand (RANKL) group, M-CSF+RANKL+50 ng/mL LPS group, M-CSF+RANKL+100 ng/mL LPS group. After the completion of culture, tartrate resistant acid phosphatase (TRAP) staining was used to observe the formation of osteoclasts. In order to investigate the effect of LPS on the expression of Connexin43, BMMs were divided into the control group (M-CSF+RANKL) and the LPS group (M-CSF+RANKL+100 ng/mL LPS); and the control group (M-CSF+RANKL), 50 ng/mL LPS group (M-CSF+RANKL+50 ng/mL LPS), and 100 ng/mL LPS group (M-CSF+RANKL+100 ng/mL LPS). The expressions of Connexin43 mRNA and protein were detected by Western blot and real-time fluorescent quantitative PCR, respectively. In order to investigate the effect of LPS on osteoclast bone resorption, BMMs were divided into M-CSF group, M-CSF+RANKL group, M-CSF+RANKL+50 ng/mL LPS group, and M-CSF+RANKL+100 ng/mL LPS group. Bone absorption test was used to detect the ratio of bone resorption area.ResultsThe flow cytometry test confirmed that the cultured cells were BMMs, and CCK-8 activity test proved that the 100 ng/mL LPS could promote the proliferation of BMMs, showing significant differences when compared with the 0, 200, 500, 1 000, and 2 000 ng/mL LPS (P<0.05). TRAP staining showed no osteoclast formation in M-CSF group. Compared with M-CSF+RANKL group, the osteoclasts in M-CSF+RANKL+50 ng/mL LPS group and M-CSF+RANKL+100 ng/mL LPS group were larger with more nuclei, while the osteoclasts in M-CSF+RANKL+100 ng/mL LPS group were more obvious, and the differences in the ratio of osteoclast area between groups were statistically significant (P<0.05). Western blot result showed that the relative expression of Connexin43 protein in LPS group was significantly higher than that in control group (P<0.05). Real-time fluorescent quantitative PCR showed that the relative expression of Connexin43 mRNA in control group, 50 ng/mL LPS group, and 100 ng/mL LPS group increased gradually, and the differences between groups were statistically significant (P<0.05). Bone resorption test showed that osteoclast bone resorption did not form in M-CSF group, but the ratio of bone resorption area increased gradually in M-CSF+RANKL group, M-CSF+RANKL+50 ng/mL LPS group, and M-CSF+RANKL+100 ng/mL LPS group, and the differences between groups were statistically significant (P<0.05).ConclusionLPS at concentration of 100 ng/mL can promote the expression of Connexin43, resulting in increased osteoclastogenesis and enhanced osteoclastic bone resorption.