Strontium ranelate promotes osteogenic differentiation of rat bone marrow mesenchymal stem cells by increasing bone morphogenetic protein-7 expression / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the role of bone morphogenetic protein-7 (BMP-7) in strontium ranelate (Sr)-induced osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs).</p><p><b>METHODS</b>BMSCs were isolated from 4-week-old rats and cultured in vitro. The third or fourth passages of BMSCs were examined using alkaline phosphatase kit for changes in ALP activity in response to treatment with different concentrations of Sr. Calcium nodules in the induced cells were detected using alizarin red staining, and the cellular BMP-7 expression was detected by Western blotting.</p><p><b>RESULTS</b>Within the concentration range of 0.1-3.0 mmol/L, Sr dose-dependently increased ALP activity in rat BMSCs. ALP activity reached the highest level after treatment with 3 mmol/L Sr, which also significantly promoted the formation of calcium nodules. Within the range of 0.1-3.0 mmol/L, Sr dose-dependently enhanced the expression of BMP-7, and its peak expression occurred following 3 mmol/L Sr treatment. Noggin (100 ng/ml), an inhibitor of BMP-7, obviously suppressed Sr-induced over-expression of BMP-7 and reduced ALP activity and calcium nodule formation in the BMSCs.</p><p><b>CONCLUSION</b>Sr promotes osteogenic differentiation of rat BMSCs by increasing the expression of BMP-7.</p>

Reactive oxygen species scavenger protects cardiac cells against injuries induced by chemical hypoxia / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the protective effect of reactive oxygen species (ROS) scavenger, N-acetyl-L-cysteine (NAC), against H9c2 cardiomyocytes from injuries induced by chemical hypoxia.</p><p><b>METHODS</b>H9c2 cells were treated with cobalt chloride (CoCl2), a chemical hypoxia-mimetic agent, to establish the chemical hypoxia-induced cardiomyocyte injury model. NAC was added into the cell medium 60 min prior to CoCl2 exposure. The cell viability was evaluated using cell counter kit (CCK-8), and the intercellular ROS level was measured by 2', 7'- dichlorfluorescein-diacetate (DCFH-DA) staining and photofluorography. Mitochondrial membrane potential (MMP) of the cells was observed by Rhodamine123 (Rh123) staining and photofluorography, and the ratio of GSSG/ (GSSG+GSH) was calculated according to detection results of the GSSG kit.</p><p><b>RESULTS</b>Exposure of H9c2 cardiomyocytes to 600 micromol/L CoCl2 for 36 h resulted in significantly reduced cell viability. Pretreatment with NAC at the concentrations ranging from 500 to 2000 micromol/L 60 min before CoCl2 exposure dose-dependently inhibited CoCl2-induced H9c2 cell injuries, and obviously increased the cell viability. NAC at 2000 micromol/L obviously inhibited the oxidative stress induced by CoCl2, decreased the ratio of GSSG/(GSSG+GSH), increased ROS level, and antagonized CoCl2-induced inhibition on MMP.</p><p><b>CONCLUSION</b>NAC offers obvious protective effect on H9c2 cardiomyocytes against injuries induced by chemical hypoxia by decreasing in the ratio of GSSG/(GSSG+GSH) and ROS level and ameliorating MMP.</p>