Page 169 - Physico-Chemical Niche Conditions for Bone Cells

bone cells. Moreover, osteocytes are large and elongated in osteoarthritic bone, small and discoid-shaped in osteopetrotic bone, and relatively large and round in osteopenic bone. In response to mechanical loading, the mitochondrial structure and dynamics are also affected during treatment with PFF, indicating that mitochondria may participate in the process of mechanotransduction. Thereafter, we demonstrated that RGD affects osteoblast shape and differentiation when cultured without mechanical loading (Fig. 1). These results may contribute to a better understanding of the interactions between osteoblasts and RGD via integrins, which might provide new insight for improved bone regeneration using biomaterials. The results described in the thesis provide new horizons on how changes in morphology, structure, mitochondrial network, and nuclei of osteoblasts treated by mechanical loading or RGD- functionalized supported lipid bilayers are affected. This could have important implications for the development of new biomaterials or scaffolds for enhanced bone regeneration and/or osteointegration of implants in the fields of orthodontics, orthopedics, implantology, and oral and maxillofacial surgery.
FUTURE PERSPECTIVE
Based on the present thesis, physical and (bio)chemical factors alter cell body, mitochondria, nucleus, and possibly epigenetics in osteoblasts. Several questions should be further considered in the future:
1. How does mechanical loading cause sub-cellular and epigenetic or genetic changes in
osteoblasts? In the thesis, we investigated sub-cellular changes in osteoblasts treated by mechanical loading, since there are existing causalities between sub-cellular and epigenetic or genetic changes in osteoblasts subjected to mechanical loading.
2. How does mechanical loading affect Fgf2 gene expression, and what are the consequences for cell function? Fgf2 is involved in many biological processes, including cell growth, cell morphogenesis, angiogenesis, tissue repair, and tumor development, as well as in the incidence of excessive anxiety. In the thesis, we found that Fgf2 gene expression was significantly increased by mechanical loading.
3. Which methods should be developed to visualize the morphology of a live bone cell treated by mechanical loading for a longer time period (e.g. > 2 min). In this thesis, live bone cell imaging under PFF treatment is only performed for 2 min. Within minutes after mechanical loading, cells can respond with increased Ca2+ release, which might affect the morphology of the cell. The Ca influx and efflux from the cell treated by mechanical loading might be observed by confocal microscopy at a later time point to determine cell morphology or function.
4. Is a physical signal also transmitted from F-actin to the mitochondria in a bone cell? Mitochondria are known to interact with F-actin in many cell types, e.g. fungi, plant cells,
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