| This study focused on investigating the effects of hydrodynamic forces on mammalian cell cultures and the mechanical cell damage mechanisms. The measured maximum energy dissipation in an agitated bench-scale bioreactor showed that agitation generated much lower energy dissipation than bubble ruptures did. The shear sensitivities of five different cell lines, CHO, HB-24, Sf-9, MCF7, and PER.C6RTM, quantified with a contractional microfluidic device, indicated that all cell lines were able to withstand intensive energy dissipation, which was several orders of magnitude higher than the maximum local energy dissipation rate generated by agitations, but comparable to that generated by the rupture of small gas bubbles.;PER.C6RTM cells became more tolerant to hydrodynamic forces after adenovirus infection. This strengthening effect could be attributed to the reorganization of cytoskeleton network during infection. While the modification of cell membrane with two different surfactants did not significantly change the shear sensitivity of PER.C6RTM cells, cytoskeleton should be more important than membrane in determining the cellular mechanical properties.;The effects of PF-68 concentration, bulk cell concentration, and drainage on cell-bubble interactions were quantitatively studied. At low PF-68 concentrations, cells were highly concentrated in the foam. However, the cell-bubble affiliation was significantly suppressed at PF-68 concentrations higher than 0.1 g/L. As the bulk cell concentration increased, the concentration of cells in the foam increased accordingly. Besides cell damage from bubble ruptures, cell damage was also observed during the entrapment of cells in the foam, which might result from the drainage in the foam and the direct contact of cells with the air-medium interface. Due to drainage, more than 90% of the liquid was lost when a bubble rose from the bottom to the top of the foam. Similarly, the majority of the cells also drained away before bubbles ruptured at the top of the foam. The possibility of the bubble-associated cells to be damaged during bubble ruptures increased at lower PF-68 concentrations.;Overall, the protection mechanisms of PF-68 include (1) preventing cell-bubble attachments, (2) forming a stable foam layer, and (3) decreasing the possibility of bubble-associated cell death during bubble ruptures. |
