Analysis of the composite response of shear wave resonators to the attachment of mammalian cells

The suitability of the quartz crystal microbalance (QCM) technique for moni toring the attachment and spreading of mammalian cells has recently been es tablished. Different cell species were shown to generate an individual resp onse of the QCM when they make contact with the resonator surface. Little i s known, however, about the underlying mechanisms that determine the QCM si gnal for a particular cell type. Here we describe our results for different experimental approaches designed to probe the particular contributions of various subcellular compartments to the overall QCM signal. Using AC impeda nce analysis in a frequency range that closely embraces the resonators' fun damental frequency, we have explored the signal contribution of the extrace llular matrix, the actin cytoskeleton, the medium that overlays the cell la yer, as well as the liquid compartment that is known to exist between the b asal plasma membrane and the culture substrate. Results indicate that the Q CM technique is only sensitive to those parts of the cellular body that are involved in cell substrate adhesion and are therefore close to the resonat or surface. Because of its noninvasive nature, sensitivity, and time resolu tion, the QCM is a powerful means of quantitatively studying various aspect s of cell-substrate interactions.