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.