title: Quantifying cell adhesion through impingement of a controlled microjet.
abstract: The impingement of a submerged, liquid jet onto a cell-covered surface allows assessing cell attachment on surfaces in a straightforward and quantitative manner and in real time, yielding valuable information on cell adhesion. However, this approach is insufficiently characterized for reliable and routine use. In this work, we both model and measure the shear stress exerted by the jet on the impingement surface in the micrometer-domain, and subsequently correlate this to jet-induced cell detachment. The measured and numerically calculated shear stress data are in good agreement with each other, and with previously published values. Real-time monitoring of the cell detachment reveals the creation of a circular cell-free area upon jet impingement, with two successive detachment regimes: 1), a dynamic regime, during which the cell-free area grows as a function of both the maximum shear stress exerted by the jet and the jet diameter; followed by 2), a stationary regime, with no further evolution of the cell-free area. For the latter regime, which is relevant for cell adhesion strength assessment, a relationship between the jet Reynolds number, the cell-free area, and the cell adhesion strength is proposed. To illustrate the capability of the technique, the adhesion strength of HeLa cervical cancer cells is determined ((34 ± 14) N/m(2)). Real-time visualization of cell detachment in the dynamic regime shows that cells detach either cell-by-cell or by collectively (for which intact parts of the monolayer detach as cell sheets). This process is dictated by the cell monolayer density, with a typical threshold of (1.8 ± 0.2) × 10(9) cells/m(2), above which the collective behavior is mostly observed. The jet impingement method presents great promises for the field of tissue engineering, as the influence of both the shear stress and the surface characteristics on cell adhesion can be systematically studied.
authors.affiliation: Physics of Fluids Group, MESA+ Institute, and J. M. Burgers Centre for Fluid Dynamics, University of Twente, Enschede, The Netherlands. Electronic address: c.visser@utwente.nl.
authors.forename: Claas Willem
authors.initials: CW
authors.lastname: Visser
authors.affiliation: Physics of Fluids Group, MESA+ Institute, and J. M. Burgers Centre for Fluid Dynamics, University of Twente, Enschede, The Netherlands.
authors.forename: Marise V
authors.initials: MV
authors.lastname: Gielen
authors.affiliation: BIOS The Lab-on-a-Chip Group, MESA+ & MIRA Institutes, University of Twente, Enschede, The Netherlands; Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, China.
authors.forename: Zhenxia
authors.initials: Z
authors.lastname: Hao
authors.affiliation: BIOS The Lab-on-a-Chip Group, MESA+ & MIRA Institutes, University of Twente, Enschede, The Netherlands.
authors.forename: Séverine
authors.initials: S
authors.lastname: Le Gac
authors.affiliation: Physics of Fluids Group, MESA+ Institute, and J. M. Burgers Centre for Fluid Dynamics, University of Twente, Enschede, The Netherlands.
authors.forename: Detlef
authors.initials: D
authors.lastname: Lohse
authors.affiliation: Physics of Fluids Group, MESA+ Institute, and J. M. Burgers Centre for Fluid Dynamics, University of Twente, Enschede, The Netherlands. Electronic address: c.sun@utwente.nl.
authors.forename: Chao
authors.initials: C
authors.lastname: Sun
mesh_terms: D002448:Cell Adhesion; D003198:Computer Simulation; D003584:Cytological Techniques / Q000295:instrumentation*; D006367:HeLa Cells; D006801:Humans; D055616:Microtechnology / Q000295:instrumentation* / Q000379:methods*; D008954:Models, Biological; D013314:Stress, Mechanical