Specific Age-Associated DNA Methylation Changes in Human Dermal Fibroblasts

Abstract

Epigenetic modifications of cytosine residues in the DNA play a critical role for cellular differentiation and potentially also for aging. In mesenchymal stromal cells (MSC) from human bone marrow we have previously demonstrated age-associated methylation changes at specific CpG-sites of developmental genes. In continuation of this work, we have now isolated human dermal fibroblasts from young (<23 years) and elderly donors (>60 years) for comparison of their DNA methylation profiles using the Infinium HumanMethylation27 assay. In contrast to MSC, fibroblasts could not be induced towards adipogenic, osteogenic and chondrogenic lineage and this is reflected by highly significant differences between the two cell types: 766 CpG sites were hyper-methylated and 752 CpG sites were hypo-methylated in fibroblasts in comparison to MSC. Strikingly, global DNA methylation profiles of fibroblasts from the same dermal region clustered closely together indicating that fibroblasts maintain positional memory even after in vitro culture. 75 CpG sites were more than 15% differentially methylated in fibroblasts upon aging. Very high hyper-methylation was observed in the aged group within the INK4A/ARF/INK4b locus and this was validated by pyrosequencing. Age-associated DNA methylation changes were related in fibroblasts and MSC but they were often regulated in opposite directions between the two cell types. In contrast, long-term culture associated changes were very consistent in fibroblasts and MSC. Epigenetic modifications at specific CpG sites support the notion that aging represents a coordinated developmental mechanism that seems to be regulated in a cell type specific manner.

Surface topography enhances differentiation of mesenchymal stem cells towards osteogenic and adipogenic lineages

“…Adipogenic and osteogenic differentiation of MSCs was induced as described before [44]. After 2 weeks samples were fixed and stained with DAPI and the fluorescent dye BODIPY (4,4-difluoro-1,3,5,7,8-pentamethyl-4-bora-3a, 4a-diaza-s-indacene; Life Technologies, Darmstadt, Germany).…”

Bone Marrow Mesenchymal Stem Cells Are an Attractive Donor Cell Type for Production of Cloned Pigs As Well As Genetically Modified Cloned Pigs by Somatic Cell Nuclear Transfer

“…Genome-wide DNA methylation analysis showed that human bone marrow MSCs and skin fibroblasts have different DNA methylation profiles on global promoter regions; CpG sites within the promoter of genes involved in regulation of development are hypomethylated in MSCs, in comparison to fibroblasts (Koch et al, 2011). This suggests that a lower methylation level of development-related genes is needed to maintain the multipotent capacity of MSCs.…”

Pluripotent stem cells escape from senescence-associated DNA methylation changes

“…It may influence gene expression by direct interference with transcription factors or with methyl-CpG-binding proteins that modify histones, and thereby inactivate promoter regions. Our group has previously demonstrated that long-term culture of mesenchymal stromal cells (MSC) and fibroblasts coincides with differential methylation at specific CpG sites Koch et al 2011;Schellenberg et al 2011). These senescence-associated (SA) modifications are highly reproducible and continuously acquired in the course of culture expansion-they can even be used as biomarkers to account for the number of passages or the time of in vitro culture .…”