Cell damage of microcarrier cultures as a function of local energy dissipation created by a rapid extensional flow

Microcarrier cultures of Chinese hamster ovary cells were subjected to a range of energy dissipations created by an abrupt contraction. These flow conditions can be characterized as a rapidly transient, extensional, and shear flow. Cell damage was measured using a lactate dehydrogenase assay. The laminar flow in the device was modeled using two commercial, computation fluid-dynamic codes: POLYFLOW and FLUENT. Cell damage was correlated to numerical values of energy dissipation. The magnitude of energy dissipation at which cell damage began to be detected, 10(4) ergs cm(-3) s(-1) (10(4) cm(2) s(-3)), is consistent with values of energy dissipation estimated in bioreactors operated under conditions which result in cell damage. This magnitude of energy dissipation is orders of magnitude lower than those values reported to cause damage to suspended animals cells which is also consistent with generally accepted experimental observations. Finally, an analysis and discussion of the presence and relative importance with re- spect to cell damage of shear vs. extensional flow is included.