Culture of human mesenchymal stem cells on microcarriers in a 5 l stirred-tank bioreactor

This article was published in the journal, Biotechnology Letters [© Springer Science+Business Media] and the definitive version is available at: http://dx.doi.org/10.1007/s10529-013-1211-9For the first time, fully functional human mesenchymal stem cells (hMSCs) have been cultured at the litre-scale on microcarriers in a stirred-tank 5 l bioreactor, (2.5 l working volume) and were harvested via a potentially scalable detachment protocol that allowed for the successful detachment of hMSCs from the cell-microcarrier suspension. Over 12 days, the dissolved O2 concentration was >45 % of saturation and the pH between 7.2 and 6.7 giving a maximum cell density in the 5 l bioreactor of 1.7 × 105 cells/ml; this represents >sixfold expansion of the hMSCs, equivalent to that achievable from 65 fully-confluent T-175 flasks. During this time, the average specific O2 uptake of the cells in the 5 l bioreactor was 8.1 fmol/cell h and, in all cases, the 5 l bioreactors outperformed the equivalent 100 ml spinner-flasks run in parallel with respect to cell yields and growth rates. In addition, yield coefficients, specific growth rates and doubling times were calculated for all systems. Neither the upstream nor downstream bioprocessing unit operations had a discernible effect on cell quality with the harvested cells retaining their immunophenotypic markers, key morphological features and differentiation capacity

The organic food philosophy. A qualitative exploration of the practices, values, and beliefs of Dutch organic consumers within a cultural-historical frame

Food consumption has been identified as a realm of key importance for progressing the world towards more sustainable consumption overall. Consumers have the option to choose organic food as a visible product of more ecologically integrated farming methods and, in general, more carefully produced food. This study aims to investigate the choice for organic from a cultural-historical perspective and aims to reveal the food philosophy of current organic consumers in The Netherlands. A concise history of the organic food movement is provided going back to the German Lebensreform and the American Natural Foods Movement. We discuss themes such as the wish to return to a more natural lifestyle, distancing from materialistic lifestyles, and reverting to a more meaningful moral life. Based on a number of in-depth interviews, the study illustrates that these themes are still of influence among current organic consumers who additionally raised the importance of connectedness to nature, awareness, and purity. We argue that their values are shared by a much larger part of Dutch society than those currently shopping for organic food. Strengthening these cultural values in the context of more sustainable food choices may help to expand the amount of organic consumers and hereby aid a transition towards more sustainable consumption. © 2012 The Author(s)