Methylome Analysis of Human Bone Marrow MSCs Reveals Extensive Age- and Culture-Induced Changes at Distal Regulatory Elements

Summary Human bone marrow stromal cells, or mesenchymal stem cells (BM-MSCs), need expansion prior to use as cell-based therapies in immunological and tissue repair applications. Aging and expansion of BM-MSCs induce epigenetic changes that can impact therapeutic outcomes. By applying sequencing-based methods, we reveal that the breadth of DNA methylation dynamics associated with aging and expansion is greater than previously reported. Methylation changes are enriched at known distal transcription factor binding sites such as enhancer elements, instead of CpG-rich regions, and are associated with changes in gene expression. From this, we constructed hypo- and hypermethylation-specific regulatory networks, including a sub-network of BM-MSC master regulators and their predicted target genes, and identified putatively disrupted signaling pathways. Our genome-wide analyses provide a broader overview of age- and expansion-induced DNA methylation changes and a better understanding of the extent to which these changes alter gene expression and functionality of human BM-MSCs.
Graphical Abstract
Highlights • Global DNA methylome analysis for human bone marrow mesenchymal stromal cells • Young versus aged adult donors compared at early and late passages • Differential methylation is enriched at distal transcription factor binding sites • These TFBSs are frequently found within BM-MSC enhancers indicated by H3K4me1
Bone marrow MSCs are of great therapeutic interest. Hawkins and colleagues show that sequencing-based approaches to study differential DNA methylation induced by donor age or cell passage reveal more extensive changes than previous array-based studies. These changes are enriched at known transcription factor binding sites within BM-MSC enhancer elements and can be associated with changes in gene expression.