Particle-tracking-based estimation of shear stress on cell aggregates in shaking vessel with different shaking methods/speeds

Abstract: Suspension cultures are widely used for cell expansion in regenerative medicine and production. Shear stress caused by the flow of medium in cultures causes cell death and delayed growth; thus, the shear stress on the cell surface must be minimized for successful suspension culture. We established a particle tracking system for estimating the shear stress on induced pluripotent stem cell aggregates during shaking culture and utilized it to optimize shaking conditions (orbital and reciprocating shaking). When the average accelerations of aggregates were calculated, high acceleration occurred periodically, and acceleration on the aggregates in orbital shaking was stable. Furthermore, the number of dead cells correlated with the time average of acceleration. In the case of growth, there was optimal acceleration due to various events, such as aggregate formation and cell death. These results indicated that image-based analyses of acceleration are helpful for estimating the shear stress on the aggregates in suspension culture to optimize agitation.