Damaged Mesenchymal Cells Dampen the Inflammatory Response of Macrophages and the Formation of Osteoclasts.

Damage to mesenchymal cells occurs by dental implant drills as a consequence of shear forces and heat generation. However, how the damaged mesenchymal cells can affect the polarization of macrophages and their differentiation into osteoclastogenesis is not fully understood. To simulate cell damage, we exposed suspended ST2 murine bone marrow stromal cells to freeze/thawing or sonication cycles, followed by centrifugation. We then evaluated the lysates for their capacity to modulate lipopolysaccharide-induced macrophage polarization and RANKL-MCSF-TGF-ß-induced osteoclastogenesis. We report that lysates of ST2, particularly when sonicated, greatly diminished the expression of inflammatory IL6 and COX2 as well as moderately increased arginase 1 in primary macrophages. That was confirmed by lysates obtained from the osteocytic cell line IDG-SW3. Moreover, the ST2 lysate lowered the phosphorylation of p65 and p38 as well as the nuclear translocation of p65. We further show herein that lysates of damaged ST2 reduced the formation of osteoclast-like cells characterized by their multinuclearity and the expression of tartrate-resistant phosphatase and cathepsin K. Taken together, our data suggest that thermal and mechanical damage of mesenchymal cells causes the release of as-yet-to-be-defined molecules that dampen an inflammatory response and the formation of osteoclasts in vitro.

The effect of aggregation on the separation performance of bacteria in capillary electrophoresis.

During the last 15 years, methods for the capillary electrophoretic separation of different bacteria species have been developed, which exploit their characteristic cell surface-charge to volume ratio. A special variant, the polymer-based CE of bacteria, includes a focusing step, which forces the bacteria cells to form aggregates at the beginning of the electrophoretic process, resulting in very high apparent efficiencies. Our experiments presented in this article reveal that the migration time of bacteria species in polymer-based CE increases with a growing amount of injected cells. Thus, the electrophoretic mobilities are not characteristic for the single cells of one species, but for the aggregates of the bacteria species, which are formed during the focusing process. Electrophoretic mobility (EM) data are obviously inapplicable for the identification of bacteria if the concentration of the bacteria sample solution is not constant. Fractions taken during the electrophoretic separation of different bacteria species were cultivated and tested for species purity. Interestingly, the electrophoretic bands were never pure, as all of them contained different mixtures of the injected species. We attribute this to the formation of stable mixed-species aggregates during polymer-based focusing. The mixed clusters migrate in the electric field with consistent velocity as a whole and are not separated electrophoretically.