Age-Related Methylation Of Genomic Dna In Human Adipose-Derived Stem Cells

Objective: Human adipose-derived stem cells (ADSCs) are multipotent stromal cells, andthe cellular functionsof ADSCs are regulated by genomic DNA methylation. The objective of this study was to research the relationship between age and ADSC genomic DNA methylation. Materials and methods: We examined the age-related gene expression and methylation of ADSCs from young (< 25 years) and elderly (> 55 years) patients. Real-time quantitative PCR was used to analyze OCT-4, NANOG and SOX-2 expression levels. Bisulfite sequencing was performed to determine the density of DNA methylation on target gene promoters. Results: After ADSCs from elderly patients (oldADSCs) were treated with the DNA-demethylating drug 5-aza-2'-deoxycytidine (5-Aza-dC), the OCT-4 and NANOG expression levels were significantly lower in oldADSCs than those in ADSCs from young patients (youngADSCs) (P=0.011 and P=0.030, respectively). Conversely, SOX-2 expression was significantly increased in oldADSCs (P=0.029). OCT-4 and NANOG promoter methylation was extremely dense in oldADSCs, but these promoters were hypomethylated in youngADSCs (P=0.031 and P=0.048, respectively). Moreover, significant associationswere found between methylation and the expression of OCT-4 and NANOG (R=-0.693, P=0.026 and R=-0.839, P=0.002, respectively). However, significant differencesin SOX-2 methylation were not observed between the two groups (P=0.179). Conclusion: ADSCs treated with 5-Aza-dC exhibited significant increases inOCT-4, NANOG, and SOX-2 expression. Our results suggest that DNA methylation plays an important role in ADSC aging and that DNA methylation density increases with patient age. More importantly, demethylation drugs may restore OCT-4 and NANOG expression inoldADSCs and could have implications regarding the potential for autologous stem cell therapies in elderly patients.