Page 44 - Physico-Chemical Niche Conditions for Bone Cells

Physicochemical niche conditions and mechanosensing
significantly change their behavior in response to external mechanical stimuli. Future investigations will address how SSS or PFF will deform cells with or without glycocalyx.
Figure 5. Live cell images of MC3T3-E1 pre-osteoblast deformation in response to static shear stress (SSS). Pre-osteoblasts were seeded on a glass slide and cultured for 24 h. Cells were stained for F- actin (Sir-actin, red) and nucleic acids (Syto-9, green) for 4 h. Then the cells were subjected to SSS (0.97 Pa) for 3 min [103]. Confocal microscopy was used to record a series of cross-sectional images of the cell (XZ direction). (a) Distribution of F-actin fiber and DNA before SSS treatment. (b) Distribution of F-actin fiber and DNA after SSS-treatment for 7 sec. (c) Structure of F-actin and nucleus in an SSS- treated cell after 12 sec. (d) Structure of F-actin and nucleus in an SSS-treated cell after 13 sec. (e) Structure of F-actin and nucleus in an SSS-treated cell after 13.7 sec. (f) Structure of F-actin and nucleus within an SSS-treated cell after 14.7 sec. (g, h, i, j) are a partial enlargement and correspond to the orange frame of (c, d, e, f), respectively.
Effects of Ageing and Disease on the Osteocyte and MuSC Niche
During ageing, in bone and skeletal muscle osteocyte and MuSC numbers are reduced, respectively [104–107]. Aging does not alter osteocyte mechanosensitivity, but ER stress probably contributes to reduce the anabolic response to mechanical stimuli in old osteocytes, while it might not play a role in the blunted response of aged muscle to anabolic stimuli [108– 110]. Osteocytes located in smaller lacunae will experience lower strains than those in larger lacunae, and will respond less to the same mechanical loading than those in larger lacunae, indicating that smaller lacunae such as found in aged bones are a potential causative factor for the reduced bone mechanoresponsiveness seen with aging [79-81]. These studies will have pivotal implications for a better understanding of the role of osteocyte lacunar
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