(74d) Investigation of Stress Protein Expression and Hydrodynamic Conditions in Various Cell Cultures Vessels

Although considerable research has been devoted to the family of stress proteins expressed due to heat shock and nutritional stress, less attention has been paid to stress protein expression due to hydrodynamic stress. In this work we want to explore the expression of stress proteins under mechanical stress. Since these proteins can be related to the proper folding of proteins as well as apoptosis, it is desirable to increase the knowledge of the behavior of these proteins in cell culture under different hydrodynamic conditions and to investigate the effect of the stress proteins on the quality of recombinant proteins. In this work the pattern of expression of the stress proteins HSP70, HSP90 and HSP25 was investigated. A comparison was established under different hydrodynamic conditions: static cultures in T Flasks, spinner flasks, bioreactors and bioreactors with recirculation. Results indicate that HSP70 is expressed at low levels in all the types of culture evaluated. HSP90 and HSP25 show a decreasing expression profile along the culture in bioreactors while its expression was relatively constant in static cultures. Since other possible stress inductors where avoided in the cultures, results indicate that the differences in expression patterns are attributed to different hydrodynamic conditions. Decreasing expression of stress proteins in bioreactors might indicate adaptation and acquired stress tolerance in agitated cultures. The results obtained in this work suggest a relationship between hydrodynamic stress and expression of stress proteins. The type of stress protein and the level of expression seem to be dependent on cell type and even differences can be observed between clones of the same cell line.