Zugkraftvergleichsanalyse von primären Osteoblasten und Osteosarkomzellen in Ruhe und nach mechanischer Belastung

Reorganization processes of the bone (Remodeling) take place during the complete life. Despite intensive researches in the area of Mechanosensing, passing and reaction, the exact mechanism of the Mechanotransduction is unsolved in wide areas. It was intention of the work to watch the behavior of bone cells with the help of the traction force microscopy in rest and after a mechanical stimulation by stretching. The results should help to understand the mechanisms of the mechanical transduction and represent a comparison between osteoblasts and osteosarcoma cells simultaneously. For the calculation of the traction forces the cells were sowed on malleable polyacrylamide gels. By the fluorescence particles available in the gels the distortion of the gels caused by the cell was determined and the traction forces could be calculated. After observation of the cell lines at rest a stretch stimulus with 6000µStrain (corresponds with a stretching of 0.6%) and a frequency of 10 Hz for 2 seconds was applied and the chronological sequence of the traction forces was observed. At the observation of the cells at rest a significant difference in the traction forces could be proved between the osteoblasts and the osteosarcoma cells. So the watched sarcoma cells generated considerably lower traction forces. After a mechanical stimulation by stretching no clear reaction of the traction forces could be demonstrated in the two cell populations. Four different reaction types could be proved in the group of the osteoblasts (n = 23). Besides a sudden strength loss in 8 cells, further 3 cells showed a slow strength decrease, 4 cells a slow strength increase and 7 cells showed no reaction. In the group of the osteosarcoma cells MG 63 (n = 18) the majority of the cases (n = 13) showed no reaction, 3 cells reacted with a slow strength decrease and 2 cells with a slow strength increase. So both osteoblasts and osteosarcoma cells don't react to an outer mechanical attraction uniformly. Focal adhesions and their composition could play a leading role as a cause for this phenomenon and for the different reactions between the cell populations. A feedback system between external and internally generated forces in the course of the mechanical transduction seems very probable.