This study was designed to investigate the influence of mesenchymal stem cells (MSCs) on osteoblast (OB) differentiation. Rat bone marrow MSCs were cultured either in growth medium that maintained a MSC phenotype or in osteogenic medium that induced differentiation into OBs. Then, cells were grown in two different culture conditions: indirect co-culture of MSCs and OBs and OBs cultured in MSC-conditioned medium. As a control culture condition, OBs were grown in osteogenic medium without the influence of MSCs. We evaluated cell proliferation, the gene expression of key bone markers, alkaline phosphatase (ALP) activity, bone sialoprotein (BSP) expression, and extracellular matrix mineralization. The results showed that, regardless of whether OBs were indirectly co-cultured with MSCs or cultured in MSC-conditioned medium, MSCs repressed OB differentiation, as evidenced by the downregulation of all evaluated bone marker genes, decreased ALP activity, inhibition of BSP protein expression, and reduced extracellular matrix mineralization. Taken together, these results indicate that despite the key role of both MSCs and OBs in the osteogenic process, the repressive effect of MSCs on OB differentiation in an osteogenic environment may represent a barrier to the strategy of using them together in cell-based therapies to induce bone repair.

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In this study, the hygienic handling of leafy vegetables was evaluated in ten selected food establishments located in south-eastern Brazil. A 14-question survey was applied in these establishments, addressing the origin of the vegetables, washing procedures, and temperature conditions during storage and exposure. In addition, 30 samples of leafy vegetables were collected and submitted to the enumeration of total coliforms, coliforms at 45 °C and tested for Salmonella. Based on the responses to the survey, the establishments could be clustered into three groups. Group 1 included four establishments, where the vegetables originated from farms exclusively and were displayed to consumers at room temperature, and where most of the food handlers had participated in courses on good handling practices. Group 2 included two establishments that performed a centrifugation step and where vegetables were not available to consumers in a self-service. Finally, group 3 included four establishments, where vegetables originated from suppliers exclusively, were stored under refrigeration, and displayed to consumers on refrigerated tables. The mean count of total coliforms was 2.5 ± 0.7 log MPN/g, while coliforms at 45 °C were detected in only one sample (0.9 log MPN/g). Salmonella was not found in any sample. Microbiological results obtained for leafy vegetables from establishments clustered in the three groups did not differ significantly. These data contribute to a better understanding of the hygienic handling of leafy vegetables in the surveyed Brazilian food establishments.