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Background and Aim: Bone sialoprotein (BSP) is a specific marker of osteoblastic differentiation. In this research, the effect of Zoledronic Acid on BSP expression and methylation status during osteoblastic differentiation of mesenchymal stem cells (MSCs) was evaluated.

Materials and Methods: In this experimental study, MSCs were isolated from human bone marrow. For osteogenic differentiation, hMSCs were pulse treated with zoledronic acid, and were incubated in osteogenic differentiation medium for 3 weeks. The DNA and RNA were extracted after the first, second and third weeks of culture and also from undifferentiated MSCs. After Sodium bisulfate (SBS) treatment, gene specific methylation analysis for BSP was carried out using Methylation Specific PCR technique.

Results: BSP expression was observed in osteoblastic differentiated cells whereas it was not seen in MSCs. MSP showed that BSP was unmethylated during osteoblastic differentiation.

Conclusion: BSP was expressed from the first week of differentiation. This confirms that zoledronic acid accelerates osteoblastic differentiation. Unmethylation status of BSP indicates that zoledronic acid does not have any effect on BSP methylation status. Other genetic or epigenetic mechanisms may control BSP expression during osteoblastic differentiation induction by zoledronic acid.

Background and Aim: Obesity is now considered as one of the main risk factors of certain known diseases such as cardio-vascular diseases, non- insulin-dependent diabetes, and common cancers. Moreover, the increase of white fat tissue is known as a main factor in the obesity process, in terms of physiology and pathology. Therefore, the understanding of adipocytes differentiation processes is crucial.

Materials and Methods: In this study, mesenchymal stem cells (MSCs) were isolated from human bone marrow by ficol-gradient, and then, their surface markers were confirmed by flow cytometry. Osteoblastic and adipocytes differentiation were done by dexamethasone protocol and confirmed by staining. Then qualitative and quantitative expressions of PPARgamma (PPAR-γ) gene as an important transcription factor in the differentiation of fat were studied by RT-PCR and REAL TIME PCR before and after differentiation into adipocytes. For statistical analysis, paired t-test was performed, using pfaffl and graph pad software.

Results: PPAR-gamma gene expression showed a significant increase after differentiation of human bone marrow mesenchymal stem cells into adipocytes (p<0/05).

Conclusion: According to the results, the PPAR-γ gene acts as one of the important factors in the differentiation of MSCs into adipocytes. In brief, the inhibition of this gene's expression to prevent obesity is suggested as an idea for treatment in the future.

Background and Aim: Different regulation processes have an effect on osteoblastic differentiation of mesenchymal stem cells (MSCs), and among them Wnt signaling pathway is particularly desirable. In Wnt signaling pathway, Adenomatous Polyposis Coli (APC) bind to β-catenin and induce its degradation, thereby acting as a negative regulator of canonical Wnt pathway. In this study, gene expression and DNA methylation of APC gene during osteoblastic differentiation were determined.

Materials and Methods: In this experimental study, after the isolation of MSCs, the induction of osteoblastic differentiation was done. To confirm osteoblastic differentiation, alizarin red staining together with the expression of Alkaline Phosphatase (ALP) and osteocalcin as specific osteoblastic markers was performed. APC gene methylation status by MSP (Methylation Specific PCR) and gene expression status of APC gene using Real-Time PCR technique during different times were evaluated.

Results: The results of alizarin red staining and the expression of ALP and osteocalcin confirmed osteoblastic differentiation. In addition, the results showed a significant decrease in the expression of APC gene on the 7^th day of osteoblastic differentiation (P<0.05). Also, the results revealed hypermethylation status of APC gene promoter during osteoblastic differentiation.

Conclusion: It seems that the decreased expression APC gene will play an important role in Wnt signaling pathway regulation in different stages during osteoblastic differentiation of bone marrow-derived MSC. Also, according to the results, APC gene promoter methylation will play an important role in controlling gene expression.