Time for treating bone fracture using rhBMP-2: a randomised placebo controlled mouse fracture trial.
The purpose of this investigation was to evaluate the chemotactic potential of a partially purified protein extract from bone matrix when tested against osteosarcoma cells with osteoblast characteristics. The chemotactic response of ROS 17/2 cells to a lyophilized bovine bone extract purified to "Urist step eight" was evaluated in Boyden blind well chambers. A checkerboard design was employed to test cell migration against positive, negative, and no concentration gradients, thereby controlling the effects of chemokinesis and/or random migration on results. The results demonstrate that the partially purified protein extract from bovine bone matrix is chemotactic since more cells migrated to positive gradients than to negative gradients (P less than .01). The chemotactic effect was confirmed by an increase in cell migration toward positive gradients of the bone extract compared to cell migration in the presence of no gradient (P less than .01). When no gradient was present, the cells exhibited an increased response in the presence of equal concentrations of the bone extract (P less than .01) indicating a chemokinetic effect. The proteinaceous nature of the chemoattractant was confirmed by its susceptibility to trypsin digestion and heat exposure.