Objective To study the effect of osgentide (OST) on proliferation of mouse preosteoblast MC3T3-E1 under simulated microgravity ( SMG ) .Methods Under normal conditions , cell proliferation was evaluated by MTT assay to screen an OST compound of an effective concentration after MC 3T3-E1 cells were treated with series OSTs .Furthermore, cell proliferation and cell cycle distribution of MC 3T3-E1 cells were analyzed after treatment with 1 nmol/L OST5 by MTT assay and by flow cytometry ( FCM) scanning under SMG .Results Under normal conditions , 1 nmol/L OST5 was able to significantly promote the proliferation of MC3T3-E1 cells (P<0.01).Under SMG, proliferation of MC3T3-E1 cells was significantly inhibited and more cells entered G 1 than under normal conditions (CN).The proportion of S phase of MC3T3-E1 cells after treatment with 1 nmol/L OST5 ( OST-SMG) for 3 d was higher than that of untreated MC 3T3-E1 cells under SMG,suggesting that OST5 could promote DNA synthesis ( P<0.05 ) .Conclusion OST5 facilitates the proliferation of MC3T3-E1 cells under SMG, which provides a basis for the use of OST5 in the prevention and treatment of bone loss relat-ed to microgravity .

Objective To investigate the inhibition of Eriobotryae Folium from twenty different districts towards phosphodiesterase 4(PDF4) in vitro.Methods The Eriobotryae Folium were extracted with 95％ ethanol reflux and the inhibition rates against PDE4D2 were carried out by liquid scintillation counting method.Results All the samples exhibited inhibitory activities towards PDE4 at 5 mg/L.Among them,nine samples were of the inhibition rate less than 80％,eleven samples were of more than 80％ inhibition and eight samples were of more than 90％ inhibition.Conclusion The Eriobotryae Folium shows significantly different inhibitory activities towards PED4.

Objective To investigate the effects of simulated microgravity by rotary cell culture system (RCCS) on expression profiles of miRNA in mouse fibroblasts L929 cell line.Methods L929 cells were cultured in vitro and divided into simulated microgravity (SMG) group and normal gravity (NG) group according to the simple random method.Samples of two groups were collected on 7th day of culture and the total RNAs were extracted,labeled,and hybridized in sequence.Feature Extraction Software was used to collect the array images and get raw data,which were analyzed by Genespring Software.Differentially expressed miRNAs were identified and then validated by qRT-PCR.Target genes of differentially expressed miRNAs were predicted by the databases of Targetscan and microRNAorg,and the intersections of databases were identified as potential regulatory target genes.Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) analysis were applied to determine the roles of these target genes.Relevant biological functions and/or signaling pathways of the regulated genes especially related with wound healing process were categorized based on their enrichments.Then integration predictions of the miRNA and mRNA expression profiles had been proposed to refine the functional miRNA-mRNA relationships.The miRNA-mRNA functional network and miRNA-mRNA control network were constructed.Results Four miRNA genes were up-regulated significantly including mmumiR-669j,-122-5p,-30a-3p,-6516-3p,among which mmu-miR-669j was up-regulated at 52.84 folds with the greatest significance (P ＜ 0.05).Seventeen miRNA genes were down-regulated significantly including mmu-miR-21a-3p,-miR-28a-5p,-218-5p,-210-3p,-miR-19a-3p,-miR-31-3p,and-miR-19b-3p,among which mmu-miR-28a-5p was down-regulated at 15.47 folds with the greatest significance (P ＜ 0.05).The qRT-PCR showed a high concordance with the microarray results (P ＜ 0.05).Target gene prediction and functional enrichment analysis suggested that a variety of biological processes and signaling pathways involved in wound repair were significantly enriched (P ＜ 0.05).Function network and regulation network of miRNA-mRNA covered all the differentially expressed miRNAs,which suggested that miR-21 a-3p and predicted target gene Smad3 might play an important role in wound healing under microgravity.Conclusions Simulated microgravity by RCCS can significantly affect the expression of stress-related miRNAs in mouse fibroblasts L929.The miRNA target gene prediction and functional enrichment analysis based on gene chip technology may provide theoretical basis for illustrating the mechanism and management of weightlessness stress injury.

Objective To investigate the effects of simulated microgravity by RCCS on proliferation and cell cytoskeleton of human HaCaT keratinocyte. Methods The rotary cell culture system (RCCS) was used to simulate the microgravity environment, and human HaCaT keratinocytes were divided randomly(random number) into the simulated microgravity group (SMG) and normal gravity group (NG). HaCaT cells in the two groups were harvested respectively after 32, 36 and 42 h culture. The HaCaT cells proliferation and cycles were detected by flow cytometry, the concentration of hb-EGF in supernatant was detected by ELISA, and the cell cytoskeleton was observed after 42 hours' culture under laser confocal microscope with FITC-labeled technique. SPSS 23.0 statistical software was used for statistical analysis, and P <0.05 was considered statistically significant. Results The flow cytometry showed that the proportions of human HaCaT keratinocytes in G1 and G2/M phases were increased while the proportion of HaCaT cells in S stage was decreased significantly after 32, 36 and 42 h RCCSculture compared with those in the normal gravity group. The HaCaT cells in G1 stage were declined along with incubation time. ELISA results showed that the hb-EGF concentration in HaCaT supernatant under simulated microgravity culture for 24 and 36 h was lower than that in the normal control group (P<0.01). The laser confocal microscope revealed that the HaCaT fluorescence intensity was decreased,and there were disordered microfilaments, structural ambiguity, pseudopodia reduction and irregularshape among FITC-labeled HaCaT cells cultured 42 h in RSSC compared with the normal gravity group.Conclusions RCCS simulated microgravity environment could inhibit the cell cycle transformation and proliferation of human HaCaT keratinocyte, affect the keratinocyte-secreting function, and induce alterations of the cell cytoskeleton.