Measurement of Cellular Adhesion Ratios Under Shear Flow on Various Substrates

Perfusion culture is an effective method to enhance the oxygen and nutrient mass transfer for the culture of highly metabolic cells and/or the culture at a high cell density. However, the flow rate of culture medium induces a shear stress that may lead to the death of cells if it is too high. In this study, we measured the cellular adhesion ratio on various materials coated with type-I collagen under Poiseuille flow with flow rates in the range 1–21 mL/min. Hepatoma cell line, HepG2 cells, attached better on a polystyrene plate for tissue culture coated with type-I collagen (with τ_0.5, the shear stress required to detach 50% of cells, equal to 42.2 Pa) followed by a collagen coated glass plate (τ_0.5 of 40.5Pa), then a polystyrene plate for tissue culture without collagen coating (τ_0.5 of 33.8Pa), and finally on a PDMS (τ_0.5 of 24.8Pa) plate coated with collagen. The fluorescence staining of the collagen suggests that clumps of cells and collagen were detached from the surface, which implies that the cell-collagen bonds are stronger than collagen-substrate bonds. Accounting these results, it can be concluded that by reinforcing the bonds between collagen and substrate, it might be possible for the cellular monolayer to stay attached on the substrate until τ_0.5 reaches ∼40Pa. This conclusion suggests the importance of carefully choosing the cell substrate, which has a strong binding with the coated extracellular matrix, for the cell culture under a high shear stress.