Influence of substratum wettability on the strength of adhesion of human fibroblasts

To determine the strength of adhesion and the detachment mechanisms of fibroblasts from substrata with different wettability, the behaviour of adhered cells was studied in a parallel-plate flow chamber during exposure to shear. Adhered cells were observed in situ, i.e. in the flow chamber, by phase-contrast microscope and images were analysed semiautomatically. Detachment was found to be dependent both on shear stress and time, although a critical shear stress can be found below which no detachment occurs. On all substrata, cells round up before detachment and are approximately spherical immediately before detachment. The strength of adhesion calculated ranged from 0.6−3.5 × 10 −10 N per cell on FEP-Teflon® (the least wettable material included) to 9.4 × 10 −9 N per cell for glass (the most wettable). Ease of detachment seemed to decrease with increasing wettability. However, cells reacted more strongly with tissue culture polystyrene (TCPS) than expected on the basis of its wettability, probably due to surface chemistry.