Induction of mammalian cell death by simple shear and extensional flows

Abstract

In this work we investigated whether the type of shear flow, to which cells are exposed, influences the initiation of cell death. It is shown that mammalian cells, indeed, distinguish between discrete types of flow and respond differently. Two flow devices were employed to impose accurate hydrodynamic flow fields: uniform steady simple shear flow and oscillating extensional flow. To distinguish between necrotic and apoptotic cell death, fluorescence activated cell sorting and the release of DNA in the culture supernatant was used. Results show that Chinese Hamster Ovaries and Human Embryonic Kidney cells will enter the apoptotic pathway when subjected to low levels of hydrodynamic stress (around 2.0 Pa) in oscillating, extensional flow. In contrast, necrotic death prevails when the cells are exposed to hydrodynamic stresses around 1.0 Pa in simple shear flow or around 500 Pa in extensional flow. These threshold values at which cells enter the respective death pathway should be avoided when culturing cells for recombinant protein production to enhance culture longevity and productivity.

Improving Viability of Stem Cells During Syringe Needle Flow Through the Design of Hydrogel Cell Carriers

“…Previous experiments have shown that cells undergo significant stretching and deformation in extensional flows, leading to cell death. 37,38 Further, extensional flow is commonly used to stretch and fragment DNA for high throughput sequencing. 39,40 HUVEC in a saline carrier subjected to syringe needle flow (which includes extensional and linear shear flows) resulted in 58.7% viability (Fig.…”

Hydrodynamic stress in orbitally shaken bioreactors

“…The maximal shear stress value in a 1-L OSR agitated at 110 rpm with a working volume of 300 mL was one to two orders of magnitude lower than values reported to be harmful for CHO cells [2]. This indicates that standard cultivation conditions in OSRs are safe for sensitive mammalian cells.…”

Dynamic shear-stress-enhanced rates of nutrient consumption in gasliquid semi-continuous-flow suspensions

“…Mammalian cells exhibit different thresholds for shear versus tensile-stress-induced death, initiating apoptosis when they are exposed to approximately 2 Pascals of oscillatory extensional stress [12]. The following stress thresholds initiate undesirable necrotic death; 1 Pascal of steady shear versus 500 Pascals of oscillatory extension [12]. Both types of death mechanisms have been described empirically by the 1st-order rate expression in Eq.…”

“…When vortex formation and bubble entrainment are absent in agitated gas-liquid reactors, Kunas and Papoutsakis [23] demonstrate that suspended hybridoma cells are damaged at impeller speeds above 700 rpm via bulk turbulent stress. Mammalian cells exhibit different thresholds for shear versus tensile-stress-induced death, initiating apoptosis when they are exposed to approximately 2 Pascals of oscillatory extensional stress [12]. The following stress thresholds initiate undesirable necrotic death; 1 Pascal of steady shear versus 500 Pascals of oscillatory extension [12].…”

“…As another alternative to Eq. (1), the maximum positive eigenvalue in the matrix representation of rv C ¹rv º T provides an order-of-magnitude estimate, or characteristic value, of the velocity gradient [12]. Consider 2-dimensional creeping flow around a no-slip spherically shaped cell that is suspended in a Newtonian culture medium.…”