Page 177 - Physico-Chemical Niche Conditions for Bone Cells
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chapter 3. We found that mechanical loading decreased osteoblast cell and nucleus volume and cell surface area, increased the fluorescence intensity of paxillin and integrin-a5, and altered the distribution of F-actin and a-tubulin. These results suggested that mechanical loading alters osteoblast cell and nucleus volume, and that the changed morphology of osteoblasts coincides with changes in cytoskeletal and focal adhesion protein expression after mechanical loading.
Mechanical loading not only alters the bone cell morphology in the short-term, but also affects bone cell behavior and osteogenic differentiation in the long-term. However, the immediate and initial down-stream impact of mechanical loading resulting in short and long- term osteogenic differentiation and bone matrix formation is unknown. In chapter 4, immediate, initial down-stream, short-term down-stream, and long-term down-stream impact of mechanical loading on pre-osteoblast behavior and osteogenic differentiation in a computational and experimental approach were investigated. We found that mechanical loading in the form of pulsating fluid flow has immediate impact on fluid dynamics over the bone cells, and influences their morphology in the short-term. This process might be associated with osteogenic differentiation and matrix production by bone cells in the long-term. This suggests that a short bout of mechanical loading with biochemical factors stimulates bone cell differentiation in the long-term.
Mechanical loading affects bone cell shape or morphology by changing cell area and volume, F-actin, paxillin, integrin-a5, and a-tubulin. However, little is known about organelles in a live bone cell treated by mechanical loading. Therefore, in chapter 5, we investigated the regulation of bone cell mitochondrial structure and dynamics by mechanical loading. We found that mechanical loading changed mitochondrial movement (e.g. track speed and track displacement), footprint (area) and mean network branch during the real-time treatment. This suggests that mechanosensitivity of mitochondria may contribute to the changes in structure and function of a bone cell as a result of mechanical loading.
Physical forces affect bone cell morphology, activity and function. It is interesting to know how (bio)chemical factors affect bone cell behavior without mechanical loading. Therefore, in chapter 6, we investigated the effects of RGD-functionalized supported lipid bilayers on osteoblast adherence and differentiation. We found that RGD-functionalized supported lipid bilayers affect osteoblast adhesion, morphology, and osteogenic differentiation. This suggests that osteoblasts cultured on RGD-functionalized supported lipid bilayers are more osteogenic than cells on poly-L-lysine-coated glass, indicating possible clinical application of RGD-functionalized supported lipid bilayers as coating on biomaterials for enhanced bone regeneration and osteointegration.
General summary
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