Developments toward a microfluidic system for long-term monitoring of dynamic cellular events in immobilized human cells.

A microfluidic system for long-term real-time monitoring of dynamic cellular events of immobilized human cells was investigated. The luciferase reporter gene activity in the reporter cell line HFF11, based on HeLa cells, was used as the model system. The cells were immobilized on silicon flow-through microchips and continuously supplied with a cell medium at 2 microL/min while maintaining the chip at 37 degrees C. The HFF11 cell line was designed for high-throughput screening of ligands for seven-transmembrane receptors. When a ligand binds, the receptor is activated and a cascade of intracellular reactions starts, ending with the synthesis of the reporter protein Photinus luciferase. The major goal was to develop a microfluidic system for continuous long-term assaying of the intracellular reporter gene activity in real time and determine the conditions, which could minimize cells stress and hence unspecific expression of the reporter gene. In the resulting microfluidic system and assay protocol, the cell microchip could be kept and assayed for a period up to 30 h. The developed system and data outcome was compared with a corresponding microtiter plate performed with the same cell line to highlight the advantages obtained in the microfluidic format.