[The physiological response of osteoblasts to pulsatile fluid flow shear stress in vitro]

This is an experimental study in the realm of physiology inquiring about the effect of pulsatile fluid flow shear stress on the proliferation, differentiation and functions of osteoblasts;the objective is to validate the important effect of fluid flow shear stress on the mechanics adaptability of bone tissue. The osteoblasts derived from Wistar rat's calvaria were exposed to fluid shear stress 5, 10, 20 and 30 mN/cm2 for 3, 6, 9, 12, 24, 36h respectively in the flow chamber. The ability of proliferation, alkaline phosphatase (ALP) activity and extracellular calcium secretion of osteoblasts were assessed. The results showed that fluid flow shear stress at 5, and 10 mN/cm2 increased the proliferation, but at 20 and 30 N/cm2, the shear stress inhibited the proliferation. The shear stress at 5, 10, 20 mN/cm2 increased the ALP activity and extracellular calcium secretion of osteoblasts, and advanced the time of the peak value of ALP activity during the experiment period, but the shear stress at 30 mN/cm2 decreased ALP activity. So osteoblasts responded rapidly to shear stress; the proliferation, differentiation and mineralization of cells were regulated in the presence of some shear stress; and such regulation exhibited a pattern of dependence on the mN/cm2 level of shear stress.