On-line analysis of CAL72 cells on two different titanium surfaces in a perfusion micro-bioreactor

The aim of the present experiment was to test a prototype microsensoric measuring system (micro-bioreactor) for the investigation of the biocompatibility of different titanium surfaces in a cell culture model.

Osteosarcoma cells of the cell line CAL72 were seeded onto titanium plates (10mm x 10mm x 1mm) and inserted into the culture chamber of the micro-bioreactor. Titanium plates with two different surface topographies (machined and titanium plasma-sprayed [TPS]) were used for this pilot investigation. Plastic plates served as controls. The online-sensoric device of the micro-bioreactor allowed the continuous monitoring of the metabolism of the cells and the control of the culture conditions. Over a period of 17 h changes in O(2)-consumption in the medium were measured by micro-electrodes and registered by the software of the system. The metabolic activity of the cells was calculated from the difference between the bypass and the chamber values. The cell proliferation and vitality were analyzed before and after the perfusion time in the micro-bioreactor. The cell morphology was studied using scanning electron microscopy.

The cells on the machined surfaces showed the highest oxygen consumption after 15 h, after that it decreased. The cells on the TPS plates showed a lower oxygen consumption, which remained stable after 17 h. The highest oxygen consumption was seen with the cells on the control plastic plates. Concerning cell proliferation analysis, it could be shown that more vital CAL72 cells seeded onto TPS and plastic could be detected after the passage through the micro-bioreactor. Hence, the number of vital cells on the machined surface was reduced after the passage.

Within the limits of this experiment, the presented micro-bioreactor system could offer a valuable method to examine the dynamic interactions of cells and materials under defined in vitro experimental conditions. While the presented system is already successfully used in the ecological/ecotoxicological field, its routine use for investigating dental materials on a cellular level has to be evaluated.