Abstract
Cells in culture undergo replicative senescence. In this study, we analyzed functional, genetic and epigenetic sequels of long-term culture in human mesenchymal stem cells (MSC). Already within early passages the fibroblastoid colony-forming unit (CFU-f) frequency and the differentiation potential of MSC declined significantly. Relevant chromosomal aberrations were not detected by karyotyping and SNP-microarrays. Subsequently, we have compared DNA-methylation profiles with the Infinium HumanMethylation27 Bead Array and the profiles differed markedly in MSC derived from adipose tissue and bone marrow. Notably, all MSC revealed highly consistent senescence-associated modifications at specific CpG sites. These DNA-methylation changes correlated with histone marks of previously published data sets, such as trimethylation of H3K9, H3K27 and EZH2 targets. Taken together, culture expansion of MSC has profound functional implications - these are hardly reflected by genomic instability but they are associated with highly reproducible DNA-methylation changes which correlate with repressive histone marks. Therefore replicative senescence seems to be epigenetically controlled.
Highlights
Fifty years ago, Leonhard Hayflick discovered that the number of cell divisions is limited for cells in culture [1] - after about 40 to 60 divisions the proliferation rate decays until the cells enter a senescent state
Mesenchymal stem cells from adipose tissue were expanded in culture medium with human platelet lysate (HPL) until they entered replicative senescence
Human mesenchymal stem cells (MSC) are relatively stable towards chromosomal aberrations whereas long-term culture induces highly reproducible epigenetic modifications at specific sites in the genome
Summary
Leonhard Hayflick discovered that the number of cell divisions is limited for cells in culture [1] - after about 40 to 60 divisions the proliferation rate decays until the cells enter a senescent state. This phenomenon applies to all somatic cells in culture which are not immortalized. It has been suggested that replicative senescence is induced by oxidative stress, UV light or γirradiation [5,6] This has led to the perception, that long-term culture leads to the accumulation of chromosomal aberrations resulting in cellular www.impactaging.com
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
