Background : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up [1]
Cells can be influenced by different mechanostimuli, which lead to an activation of cellular and inter-cellular responses. These reactions may be caused by either a direct stimulation of the cell body (mechanoreception) or indirect cellular stimulation (response) [1,2,3]. Extracellular fluid movement induces fluid shear stress (FSS) that can result in different cellular processes including proliferation, migration and gene expression [4].
There are two different ways of cell stimulation by FSS, where both lead to extracellular signalling. First, fluid-induced cell stimulation occurs when the cell surface is in direct contact with the moving extracellular fluid as seen in the vascular endothelium. Second, it has been hypothesised that indirect stimulation occurs via fluid flow through the lacunar network as seen in bones such as close to loaded dental endosseous implants [1,2,3]. This extracellular cell stimulation leads to an altered cell morphology as well as altered intracellular signal cascades such as changed gene and protein expression pattern [4,5,6,7]. A reorganisation of actin fibres in accordance with the flow direction could be observed as well [8].
To prove the theory of a FSS-triggered effect on different cell lines, several in vitro investigations using different flow chambers were conducted [5, 9,10,11,12]. In osteoblasts, biochemical responses on FSS in form of an increased intracellular calcium production [13,14,15] and an increased release of prostaglandins were reported [15,16,17,18,19]. FSS stimulation of osteoblasts also improved the cell adhesion by enhancing the affinity of intracellular integrins to extracellular matrix ligands as well as to biomaterial surfaces [20, 21]. Shear forces’ triggered effects on osteoblasts could be detected at a value of 10 dyn/cm2, which almost reflects the in vivo situation [4, 22, 23]. Todays’ frequently used flow chambers mainly simulate the in vivo formed shear forces. However, it is difficult to ensure the required reproducibility and linear flow conditions. The most distinctive feature of currently used flow chambers is a liquid flow along rigidly fixed cell-bearing surfaces. Some of the above mentioned flow devices are either operating with a constant flow velocity or using pulsating flow profiles, which should be applied in case of analysing blood flow characteristics [9, 24]. Computerised investigations of flow chambers by Anderson et al. [4] have shown that deviating shear forces occur in the same flow chamber after repeating the same experiment twice. Consequently, different results of stimulation and cells response are obtained. Another downside of reported flow chambers is the inability to simultaneously set different shear forces in a single experiment.
Serial posts:
- Background : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up [1]
- Background : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up [2]
- Methods : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up [1]
- Methods : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up [2]
- Results : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up [1]
- Results : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up [2]
- Discussion : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up [1]
- Discussion : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up [2]
- Discussion : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up [3]
- Conclusions : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up
- Abbreviations : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up
- References : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up [1]
- References : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up [2]
- References : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up [3]
- References : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up [4]
- Acknowledgements : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up
- Author information : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up [1]
- Author information : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up [2]
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- About this article : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up
- Table 1 Listing of the single components of the flow chamber together with manufacturers’ data : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up
- Table 2 Listing of the culture media and additives together with manufacturers’ data : Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up
- Fig. 1. Three-dimensional illustration (a–e) and photography (f) of the experimental setup with the components marked numerical. a1 Lower petri dish (s’ bottom serving as the lower plate); 2 Rotating glass panel [60 mm diameter (cell bearing)]; 3 Titanium axis. b4 Liquid medium (red). c5 Reversed upper petri dish. d6 Gearwheel with set screw. e7 Closing; 8 Electronic motor device and adjusting ring with additional set screw : Cellular fluid shear stress on implant
- Fig. 2. Side view of a computerized simulation, showing the flow chambers’ lower compartment and the flow profile in between the two plates; shearing gap and bottom plate are shown on the left side; rotation speed = 200 rpm; colour code bar (left edge) showing shear force values [Pa] [1 Pa = 10 dyn/cm2]; flow direction presented by arrows : Cellular fluid shear stress on implant
- Fig. 3. Diagram for visualisation of the calculation of shear stress rates taking into account the centrifugal force and the glass plates’ dimensions. For example, at a distance of 25 mm from the centre of the upper plate, the shear forces’ value is 8.33 dyn/cm2, together with an additional centrifugal force that has a value of 0.55 dyn/cm2 : Cellular fluid shear stress on implant
- Fig. 4. Randomly orientated osteoblasts without influence of rotation (phallacidin fluorescence staining). On the left side with 200× and on the right side with 400× magnification. The white X on the coloured circle marks the location upon the plate where the osteoblasts were located. The red X marks the centre of the plate : Cellular fluid shear stress on implant
- Fig. 5. Osteoblasts with an orientation tendency after 24 h of rotation (phallacidin fluorescence staining). On the left side with 200× and on the right side with 400× magnification. The yellow arrows show the orientation of the cells. The red arched arrow within the coloured circle shows the direction of rotation. The dashed white line oriented to the right stands for the resulting centrifugal force. The dashed white line pointing upwards shows the direction of the resulting flow resistance. The solid white arrow stands for the vectorial sum of the abovementioned forces : Cellular fluid shear stress on implant