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Quartz Crystal Microbalance Study of Endothelial Cell Number Dependent Differences in Initial Adhesion and Steady‐State Behavior: Evidence for Cell‐Cell Cooperativity in Initial Adhesion and Spreading
Author(s) -
Marx Kenneth A.,
Zhou Tiean,
Warren Michael,
Braunhut Susan J.
Publication year - 2003
Publication title -
biotechnology progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 129
eISSN - 1520-6033
pISSN - 8756-7938
DOI - 10.1021/bp0201096
Subject(s) - quartz crystal microbalance , chemistry , adhesion , biophysics , analytical chemistry (journal) , cell adhesion , adsorption , chromatography , biology , organic chemistry
The quartz crystal microbalance (QCM) technique has been applied to the real time monitoring of endothelial cell (EC) adhesion and spreading on the QCM gold surface. We previously showed that the measured QCM Δ f and Δ R shifts were due to cells adhering to the gold crystal surface, requiring proteolytic enzyme treatment to be removed from the surface, in order for the Δ f and Δ R shifts to return to zero. In the present report, we demonstrate the quantitative dependence and saturation of the measured Δ f and Δ R shifts on the number of firmly attached ECs as measured by electronic counting of the cells. We demonstrate through a light microscope simulation experiment that the different Δ f and Δ R regions of the QCM temporal response curve correspond to the incident ECs contacting the surface, followed by their adhesion and spreading, which reflect cellular mass distribution and cytoskeletal viscoelasticity changes. Also, we demonstrate that the dose response curve of Δ f and Δ R values versus attached EC number is more sensitive and possesses less scatter for the hydrophilically treated surface compared to the native gold surface of the QCM. For both surfaces, a Δ f and Δ R versus trypsinized, attached EC number plot 1 h post‐seeding exhibits a sigmoid curve shape whereas a similar plot 24 h post‐seeding exhibits a hyperbolic curve shape. This number dependence suggests cell‐cell cooperativity in the initial cell adhesion and spreading processes. These QCM data and our interpretation are corroborated by differences in cell appearance and spreading behavior we observed for ECs in a light microscope fluorescence simulation experiment of the cell density effect. For a stably attached EC monolayer at 24 h post‐addition, steady‐state Δ f and Δ R values are higher and exhibit saturation behavior for both the hydrophilically treated gold surface as compared to the untreated surface. The steady‐state 24 h Δ f and Δ R values of stably attached ECs are shifted from the 1 h attached ECs. The 24 h values are characteristic of a more energy‐dissipative structure. This is consistent with the time‐dependent elaboration of surface contacts in anchorage‐dependent ECs via the attachment of intregrins to underlying extracellular matrix. It is also in agreement with the known energy dissipation function of the ECs that cover the interior of blood vessels and are exposed to continuous pulsatile blood flow.