The quartz crystal microbalance as a continuous monitoring tool for the study of endothelial cell surface attachment and growth

The quartz crystal microbalance (QCM) was used to monitor endothelial cell CEC) adhesion on the gold surface of an oscillating quartz crystal containe d in a QCM device. A number of parameters were investigated. First, we obse rved differential QCM O-ring toxicities for ECs. Second, appropriate condit ions for cell culture and QCM cell environment were identified that can eli minate large-scale frequency oscillations in the measurements. These artifa cts are not due to added cells but originate in the time-dependent evaporat ion of water. Having eliminated these artifacts, we then demonstrated that the measured steady-state crystal frequency shift, Delta f, and motional re sistance shift, Delta R, were determined by the number of firmly attached E Cs requiring trypsinization from the crystal surface. Last, following stead y-state attachment of ECs, the EC growth stimulation by fibroblast growth f actor was monitored in a continuous fashion by measuring f and R values ove r a 72 h. period. We observed the Delta f values to increase in a way that reflected the increase in EC number bound to the QCM surface. Following add ition of ECs to the QCM, the time-dependent; increase in Delta R can be int erpreted in terms of increase by the ECs of the energy dissipation properti es of the solution at the solution-gold surface interface. This effect is d ue to their rapid surface attachment and the elaboration of their cytoskele tal properties. These results indicate that the QCM technique can be used f or the study of EC attachment and growth and suggest its potential for the real time study of per unit surface area cell mass distribution dynamics an d viscoelastic properties and the cells' responses to stresses or perturbat ions brought about using biologically active molecules.