# A quantitative analysis of receptor-mediated cell adhesion to artificial surfaces

#### Abstract

In recent years, the study of cell adhesion to surfaces has been of increasing clinical and research interest. This process is important in events such as cell affinity chromatography, blood clotting and immunological processes. Further, the success of an artificial implant will often depend on the adherence behavior of tissue cells to the implant. However, little fundamental knowledge exists about the kinetics of cell attachment and detachment or the strength of cell-surface adhesion forces and on how these processes depend on the environment. In an attempt to remedy this situation, we pursued a fundamental study on receptor-mediated cell adhesion to surfaces coated with specific binding groups. Liposomes bearing the protein glycophorin were used as cell-like models. Glass microscope slides coated with the protein wheat-germ agglutinin, which possesses a strong affinity for the protein glycophorin, were used as the bottom part of a parallel plate flow chamber (PPFC) apparatus. In order to simulate the shear force which cells might experience in an in vivo situation, a solution was passed over the artificial cells which were attached on the wheat-germ coated surface. The process of shearing glycophorin liposomes from coated-glass surfaces was viewed and recorded through a video-camera/monitor system installed over a Zeiss inverted microscope. This apparatus allowed us to measure the glycophorin liposome detachment kinetics as a function of incubation time, shear flow rate and glycophorin receptor density. From these experiments several conclusions were drawn. First, cell adhesion process is a two-step process, i.e., a cell-transport and a receptor-mediated adhesion rate. Second, if the cell has mobile receptor with a lateral diffusion constant D$\sb{\rm f}\/>$ 10$\sp{-15}$ cm$\sp2$/sec, the adhesion process will be cell transport-controlled. Third, the liposome population appears to be heterogeneous. Although this was not experimentally proven, all mathematical models used in this research seem to agree in the concept of heterogeneity with respect to the cell-surface bond density. Fourth, the PPFC is an ideal set up for the study of the dynamics of the cell detachment process, but unfortunately it suffers from experimental variability when used to assess the critical shear rate. In this respect, the radial flow chamber, the spinning disc or the wedge chamber seems to be better. Fifth, the liposomes were a useful cell-like model. However, the liposome purification protocol still needs further development. And sixth, the image analysis microscopy technique has the potential to analyse very complicated situations during cell detachment studies as demonstrated in this research.

#### Subject Area

Chemical engineering|Biomedical research|Cellular biology

#### Recommended Citation

Torres Diaz, Hirohito, "A quantitative analysis of receptor-mediated cell adhesion to artificial surfaces" (1992). Dissertations available from ProQuest. AAI9235211.
https://repository.upenn.edu/dissertations/AAI9235211

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