Effects of growth factors on cell migration and alkaline phosphatase release

Segmental defects in long bones pose a clinical challenge in orthopaedic surgery. These defects often require multiple surgeries to achieve the desired bridging and union. Bone morphogenetic protein 2 (BMP-2) has been used extensively to facilitate regeneration in these large defects. The two important roles that BMP-2 has to play in large defect regeneration are chemotaxis to bone cells to migrate and induction of bone matrix production. Experiments were designed to study the effect of BMP-2 on alkaline phosphatase (ALP) production in cells that have migrated through a porous membrane in a cell migration chamber under the influence of culture media supplemented with BMP-2. Two cell lines, UMR cells and MC3T3-E1 cells, were used. A modified Boyden chamber with 8 microm membrane filter was used. Cell migration under the influence of BMP-2 concentration of 1, 10, 100, and 1000 ng/ml was studied. In both cells, the highest chemotactic effect was observed at 10 ng/ml. The ALP activity in the migrated cell was then characterized. A pattern of increase in ALP activity with increased BMP-2 dose was observed in the migrated cells.