Introduction & Objective: According to some study, wnt signaling pathway is among those molecular pathways that involve in cellular proliferation and bone differentiation. On the other hand, investigations have indicated that 6-bromoindirubin-3´-oxim (BIO) is able to activate this pathway. In the present study, effect of BIO on in vitro proliferation and bone differentiation of mesenchymal stem cell (MSC) was considered.

Materials & Methods: In this experimental study, rat marrow-derived MSCs was used. Initially, a range of BIO concentration was examined in terms of their effect on MSC viability using MTT assay. The concentrations with no toxic effect on cell viability including 0.01, 0.1, 1 and 1.5 µM were then selected and added into either MSC proliferation or bone differentiation culture medium. To determine the BIO effect on MSC proliferation, population doubling number (PDN) was calculated and to quantify the BIO effect on MSC bone differentiation, expression level of the bone specific genes and the amount of culture mineralization was measured. In these experiments, culture without BIO was considered as control.

Results: PDN results indicated that the cell population at cultures with 0.1 and 1 µM BIO was doubled in number significantly more than the other cultures (P<0.05). Differentiation experiment indicated the negative effect of BIO on MSC bone differentiation. At all BIO-treated cultures, the expression level of osteocalcin and alkaline phosphatase genes as well as the amount of culture mineralization appeared to be significantly lower than those in control cultures (P<0.05).

Conclusion: It seems that BIO enhances MSC proliferation in culture while inhibits the in vitro bone differentiation.