Evaluation of Changes in Global DNA Methylation during Osteoblastic Differentiation of Mesenchymal Stem Cells: A Laboratory Study

Control processes in osteoblastic differentiation of mesenchymal stem cells are not yet fully understood. Epigenetic mechanisms, especially the methylation of CpG Islands in the promoter of genes, are considered as one of the most important control mechanisms in stem cell differentiation. In the process of differentiation, it is debated whether only the methylation of specific genes changes or the methylation of global DNA. Therefore, in the present study, the state of global DNA methylation was evaluated during osteoblastic differentiation of mesenchymal stem cells by differentiation medium and also in treatment by zoledronic acid.

In this laboratory study, after isolation and proliferation of mesenchymal stem cells, induction of osteoblastic differentiation was done using differentiating medium and zoledronic acid. DNA extraction was performed at differentiation weeks 1, 2, and 3 as well as from undifferentiated mesenchymal stem cells. Global DNA methylation status was assessed by antibodies against 5-methyl cytosine. Repeated measurement design test was used to analyze the data.

Global DNA methylation status of the genome did not change during osteoblastic differentiation of mesenchymal stem cells (p=0.093). Also, treatment with zoledronic acid had no effect on global DNA methylation (p=0.057).

Osteoblastic differentiation of mesenchymal stem cells by differentiation medium and also in treatment with zoledronic acid is not associated with altered global methylation of the genome. Therefore, the differentiation process of mesenchymal stem cells to osteoblasts is a unique pathway, and possibly other genetic and epigenetic mechanisms play a role in controlling it.