CELL-ADHESION TO CRYSTAL-SURFACES - A MODEL FOR INITIAL-STAGES IN THEATTACHMENT OF CELLS TO SOLID SUBSTRATES

This study addresses the mechanism of the chirally-restricted, RGD-ind ependent adhesion of A6 epithelial cells to the {011} faces of calcium (R,R)-tartrate tetrahydrate crystals. The extensive and rapid adhesio n of the cells to these surfaces, in the presence or absence of serum proteins, is distinctly different from the extracellular matrix-mediat ed adhesion to conventional tissue culture surfaces or to the {101} fa ces of the same crystals. The differences are manifested by insensitiv ity to ATP depletion, to disruption of microfilaments and microtubules and even to formaldehyde fixation of the cells. Furthermore, trypsin pretreatment does not affect cell attachment to the {011} faces, nor d oes trypsin posttreatment cause cell detachment from the crystals. We also noticed that the rapid adhesion to the crystal surface bears seve ral lines of similarity to the early temporal stages in cell adhesion to regular tissue culture surfaces. Based on these observations and ad ditional theoretical considerations, it is proposed that the molecular interactions responsible for the cell adhesion to the {011} surfaces may serve as models for an early ''engagement'' stage in cell adhesion which precedes, and may be essential for, the formation of stable and long-term contacts.