Cell adhesion dynamics and actin cytoskeleton reorganization in HepG2 cell aggregates

The temporal dependence of cytoskeletal remodelling on cell-cell contact in HepG2 cells has been established here. Cell-cell contact occurred in an ultrasound standing wave trap designed to form and levitate a 2-D cell aggregate, allowing intercellular adhesive interactions to proceed, free from the influences of solid substrata. Membrane spreading at the point of contact and change in cell circularity reached 50% of their final values within 2.2 min of contact. Junctional F-actin increased at the interface but lagged behind membrane spreading, reaching 50% of its final value in 4.4 min. Aggregates had good mechanical stability after 15 min in the trap. The implication of this temporal dependence on the sequential progress of adhesion processes is discussed. These results provide insight into how biomimetic cell aggregates with some liver cell functions might be assembled in a systematic, controlled manner in a 3-D ultrasound trap.