Discussion : Cellular fluid shear stress on implant surfaces (2)
Further on, the simulations indicated that the flow profile in between the two plates was not influenced by peripheral turbulences alongside the peripheral regions. To verify a cellular realignment towards the shear direction, cells were microscopically examined prior and after exposure to shear forces for 24 h upon a spinning disc at a speed level of 200 rpm. Even if not sufficiently meaningful alone, observing changes in osteoblast cell morphology are still appropriate methods to verify the good usability of a flow chamber for the generation of reproducible FSS. Although not statistically significant, a tendency of cellular realignment towards the liquid flow direction was demonstrated. Similarly, several studies have revealed characteristic changes of osteoblast morphology triggered by fluid shear stress, which depends on exposure time and strength.
Likewise to our findings, these changes are characterised by the formation of actin stress fibres, which in turn align towards the longitudinal cell axis and mainly appear near the nucleus. However, the manual approach of analysing the actin fibres’ orientation has to be stated as a drawback of the present study, since it does not meet the requirements of a valid measurement. Immunofluorescence microscopy is largely a qualitative, or semiquantitative, approach with a limited capability of precise fibre differentiation and/or quantification since standard binary thresholds failed to exhaustively segment all fibres because of their wide variations in intensity and background levels. Hence, more objective measurements could be provided by the use of an automated software-assisted processing. In this context, the FibreScore Algorithm by Lichtenstein et al. presents a potential solution for quantification, since it allows the reliable segmentation of each actin fibre. The procedure itself is based on the acquisition of different pixel intensities, whereby it works through the correlation of pixel adjacent regions with synthetic fibre templates at different orientations and their assignment for the central pixel with the highest correlation coefficient among all orientations.
Serial posts:
- Cellular fluid shear stress on implant surfaces
- Methods : Cellular fluid shear stress on implant surfaces (1)
- Methods : Cellular fluid shear stress on implant surfaces (2)
- Methods : Cellular fluid shear stress on implant surfaces (3)
- Results : Cellular fluid shear stress on implant surfaces (1)
- Results : Cellular fluid shear stress on implant surfaces (2)
- Discussion : Cellular fluid shear stress on implant surfaces (1)
- Discussion : Cellular fluid shear stress on implant surfaces (2)
- Discussion : Cellular fluid shear stress on implant surfaces (3)
- Discussion : Cellular fluid shear stress on implant surfaces (4)
- References : Cellular fluid shear stress on implant surfaces
- Figure 1. Three-dimensional illustration and photography
- Figure 2. Side view of a computerized simulation
- Figure 3. Diagram for visualisation of the calculation of shear stress rates
- Figure 4. Randomly orientated osteoblasts without influence of rotation
- Figure 5. Osteoblasts with an orientation tendency after 24 h