Integrative Epigenetic And Single-Cell Rna-Seq Profiling Of Human Hematopoietic Stem Cells Reveals Epigenetic Reprogramming Of Enhancer And Regulatory Elements During Normal Aging

Aging is associated with impaired hematopoietic stem cell (HSC) function, increased risk of myeloid malignancies and the acquisition of clonal hematopoiesis of indeterminate potential (CHIP). Little is known about how epigenetic regulation contributes to these age-related changes in human HSC biology. Here we report a comprehensive epigenetic and transcriptomic profiling study of human HSC aging. The HSC enriched (HSCe; Lin- CD34+ CD38-) population was purified from young (18-30 yo) and aged (65-75 yo) healthy donors and used for ChIP-Seq of H3K4me1, H3K27ac, H3K4me3, H3K27me3, DNA methylation, and bulk and single-cell (sc) RNA-seq. 5-hydroxymethylcytosine (hmC) was also profiled in the Lin- CD34+ CD38+ fraction (n=4-7 per modification, per age group). Targeted exon sequencing of 128 genes revealed only 1 out of 24 donors with any mutation (DNMT3A mutation with variant allele frequency of 0.12); thus, we concluded that any observed epigenetic or transcriptional changes with age could not be due to CHIP.