ANIMAL-CELLS IN TURBULENT FLUIDS - DETAILS OF THE PHYSICAL STIMULUS AND THE BIOLOGICAL RESPONSE

Animal cells in large scale bioreactors are subjected to a variety of fluid forces for which they are not adapted by evolution. In severe ca ses the result is cell death, but under more modest agitation conditio ns an increasing number of nonlethal responses affecting growth rate, metabolism, and product formation have been reported. The forces causi ng these responses have not been characterized because particle-turbul ence interactions are extremely complex. The current understanding of the microscopic structure of turbulence in an infinite liquid and in b oundary layers shows that an average shear stress alone is not likely to be adequate to describe the bioreactor environment. Combining knowl edge of the physical stimuli and the biological responses will lead to better ways of limiting cell damage and possibly to using physical st resses as a means of specifically modifying cell behavior.