Page 124 - Physico-Chemical Niche Conditions for Bone Cells

Regulation of bone cell mitochondrial structure and dynamics
Mitochondrial network structure
Numerous mitochondria could be seen clearly in pre-osteoblasts without and with PFF treatment. Visual inspection alone could not reveal differences between mitochondrial network structure of static control and PFF-treated cells (Fig. 4A). To quantify changes in network structure, the mitochondrial network structure was skeletonized (Fig. 4A). After PFF treatment, the mitochondrial network structure became more dense (Fig. 4A). Assessment of the mitochondrial footprint at different time points revealed that at 1, 5, and 10 sec before PFF treatment, the footprint values were similar (Fig. 4B). After the first (13 sec), second (14 sec) and third (15 sec) cycle of PFF (frequency: 1 Hz), the footprint values also remained similar (Fig. 4B). After 30 sec, the footprint values first increased (from 30 to 70 sec), followed by a decrease (from 70 to 110 sec) (Fig. 4B). At 70 sec, a maximal footprint value was obtained, which was significantly higher than at 13, 14, 15, and 30 sec. Analysis of the mean network branch of mitochondria revealed that at 1, 5, and 10 sec before PFF treatment, the values of mean network branch were similar (Fig. 4C). At the first, second, and third cycle of PFF, the values of mean network branch were also similar (Fig. 4C). After 30 sec, the values of mean network branch first increased (from 30 to 50 sec), and then decreased (from 50 to 110 sec) (Fig. 4C). The maximum value was observed at 50 sec, which was significantly different from the values obtained at 1, 5, 10, 13, 14, and 15 sec. The value at 70 sec was also significantly different from 10 and 15 sec (Fig. 4C). Calculation of the mean branch length of mitochondria, i.e. the average length of all branches (Fig. 4D), revealed that these values pre and post PFF treatment did not change.
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