Introduction: di-2-ethylhexyl phthalate (DEHP) is a plasticizer, used in preparation of polyvinyl chloride products from food-container to medical-devices. Bone marrow mesenchymal stem cells (BMSCs) as osteoblast-precursors are exposed to DEHP which hinders its differentiation. Since gallic acid (GA) improves osteogenic differentiation of BMSCs, in this study it was used to prevent toxic effect of DEHP. Methods: BMSCs were extracted from Wistar rats and treated with 100 µM of DEHP and 0.25 µm GA individually and in combination for 20 days. Further analysis includes matrix production, total protein content, alkaline-phosphatase activity, MDA level, total antioxidant capacity, CAT and SOD activity and osteogenic related gene expression were carried out. Results: Significant decrease in bone matrix production was observed in DEHP treated cell whereas GA prevented the hindering effect of this chemical. In addition, significant increase of BMP2, RUNX2 and ALP genes expression was detected which was imprinted in ALP activity elevation. DEHP induced oxidative stress which was ameliorated by GA through reduction of MDA production and improvement in activity of CAT and SOD. Conclusion: GA was able to compensate the toxic effect of DEHP, and improved osteogenic differentiation of BMSCs through BMP/RUNX2 pathway.
