Objective: This study is an attempt to examine the anti apoptotic effects of BIO on ratMSC culture.Materials and Methods: Rat marrow primary cell culture was established and exposuregroups were defined; cultures with 0.01, 0.1, 1 μM BIO. Cells cultured without BIOtreatment were used as controls. During culture expantion, the average doubling time,as an index of the rate of cell growth, were determined and compared. To examinewhether or not BIO is able to protect MSCs against apoptosis, the passaged-3 cellsfrom each group were induced to undergo apoptosis with the addition of TNF-α (Tumornecrotic factor-α). Three days after, the cultures were quantified in terms of the percentagesof apoptotic cells using either the Tunnel or Annexin V staining method.Results: Marrow cells cultivated with 0.1 and 1 μM BIO appeared to expand at a significantlymore rapid rate than the 0.01 μM BIO and the control cultures (p<0.05). Tunnelstaining indicated that in 1 μM BIO-treated groups, there were lower percentagesof apoptotic nuclei than in groups with other concentrations of BIO (p<0.05). The BIOprotective effect appeared to be dose-dependent in that the cultures with high BIO contentpossessed less apoptotic nuclei. The results obtained by Annexin staining were inagreement with the results of Tunnel staining. The Annexin method additionally takesinto account the early apoptotic cells which are not detectable by the Tunnel method.Conclusion: Taken together, it seems that cultivation with BIO could both increase thegrowth rate of marrow cells and protect MSCs against induced apoptosis