Effect of osteocytes subjected to fluid flow on osteoblasts

Osteocytes act as mechanosensors in bone and can send mechanical signals directly to osteoblasts through gap junctions. However, under physiological conditions the number of gap junctions is limited because of the quantity variance of the two kinds of cells. In this study, the possibility of indirect interaction between these two cells was investigated. A new flow champer was designed in which osteocytes and osteoblasts were cocultured in two champers separately. Osteocytes were exposed to fluid flow and then the ALP activity, osteocalcin and osteopotin of osteoblasts were determined. The results showed that either ALP activity or production of osteocalcin and osteopotin in osteoblasts which were cocultured with sheared osteocytes increased. This indicated that osteocytes could regulate osteoblasts indirectly through some soluble factors.