Suchergebnisse

Background Human adult adipose-derived stem cells (hADSCs) have become the most promising cell source for regenerative medicine. However the prolonged ex vivo expansion periods required to obtain the necessary therapeutic dose promotes progressive senescence, with the concomitant reduction of their therapeutic potential. Aim and scope A better understanding of the determinants of hADSC senescence is needed to improve biosafety while preserving therapeutic efficiency. Here, we investigated the association between deregulation of the imprinted DLK1-DIO3 region and replicative senescence in hADSC cultures. Methods We compared hADSC cultures at short (P S ) and prolonged (P L ) passages, both in standard and low [O 2 ] (21 and 3%, respectively), in relation to replicative senescence. hADSCs were evaluated for expression alterations in the DLK1-DIO3 region on chromosome 14q32, and particularly in its main miRNA cluster. Results Comparison of hADSCs cultured at P L or P S surprisingly showed a quite significant fraction (69%) of upregulated miRNAs in P L cultures mapping to the imprinted 14q32 locus, the largest miRNA cluster described in the genome. In agreement, expression of the lncRNA MEG3 (Maternally Expressed 3; Meg3/Gtl2), cultured at 21 and 3% [O 2 ], was also significantly higher in P L than in P S passages. During hADSC replicative senescence the AcK16H4 activating mark was found to be significantly associated with the deregulation of the entire DLK1-DIO3 locus, with a secondary regulatory role for the methylation of DMR regions. Conclusion A direct relationship between DLK1-DIO3 deregulation and replicative senescence of hADSCs is reported, involving upregulation of a very significant fraction of its largest miRNA cluster (14q32.31), paralleled by the progressive overexpression of the lncRNA MEG3, which plays a central role in the regulation of Dlk1/Dio3 activation status in mice. ; This work was supported by grants to AB from the Spanish Ministry of Economy, Industry (SAF2015-70882-R; AEI/FEDER, UE), Comunidad Autónoma de Madrid (S2010/BMD-2420), Instituto Salud Carlos III (RETICS TerCel, RD12/0019/0018) and the European Commission (FP7-HEALTH- 2009/CARE-MI). AMS was supported by grants from the MINECO (SAF2010–17167) and Instituto Salud Carlos III (RETICS TerCel, RD12/0019/0013), and MFF and RGU by grants from the Plan Nacional de I+D+I 2013-2016/FEDER (PI15/ 00892), the Asturias Regional Government (GRUPIN14-052), the IUOPA (Obra Social Cajastur) and the Fundación Científica de la AECC. SGL held a predoctoral fellowship from the Spanish Programa de Formación del Profesorado Universitario

BACKGROUND: Age-associated changes in genomic DNA methylation have been primarily attributed to 5-methylcytosine (5mC). However, the recent discovery of 5-hydroxymethylcytosine (5hmC) suggests that this epigenetic mark might also play a role in the process. METHODS: Here, we analyzed the genome-wide profile of 5hmc in mesenchymal stem cells (MSCs) obtained from bone-marrow donors, aged 2-89 years. RESULTS: We identified 10,685 frequently hydroxymethylated CpG sites in MSCs that were, as in other cell types, significantly associated with low density CpG regions, introns, the histone posttranslational modification H3k4me1 and enhancers. Study of the age-associated changes to 5hmC identified 785 hyper- and 846 hypo-hydroxymethylated CpG sites in the MSCs obtained from older individuals. CONCLUSIONS: DNA hyper-hydroxymethylation in the advanced-age group was associated with loss of 5mC, which suggests that, at specific CpG sites, this epigenetic modification might play a role in DNA methylation changes during lifetime. Since bone-marrow MSCs have many clinical applications, and the fact that the epigenomic alterations in this cell type associated with aging identified in this study could have associated functional effects, the age of donors should be taken into account in clinical settings. ; This work has been financially supported by the Plan Nacional de I+D+I 2008–2011/2013–2016/FEDER (PI11/01728 to A.F.F.; PI12/01080 and PI15/00892 to M.F.F.; PI 12/0615 to J.A.R.; PI05/2217 and PI08/0029 to J.G‑C); the ISCIII‑Subdirección General de Evaluación y Fomento de la Investigación (Miguel Servet contract: CP11/00131 to A.F.F.); IUOPA (to G.F.B. and M.S); Fundacion Cientifica de la AECC (to R.G.U.); Fundación Ramón Areces (to M.F.F); and FICYT (to E.G.T., M.G.G and A.C.); the Madrid Regional Government (S‑BIO‑0204‑2006 and S2010/BMD‑2420 to J.G‑C) and the Asturias Regional Government (GRUPIN14‑052 to M.F.F.). The IUOPA is supported by the Obra Social Cajastur, Spain.

In differentiated cells, aging is associated with hypermethylation of DNA regions enriched in repressive histone post-translational modifications. However, the chromatin marks associated with changes in DNA methylation in adult stem cells during lifetime are still largely unknown. Here, DNA methylation profiling of mesenchymal stem cells (MSCs) obtained from individuals aged 2 to 92 yr identified 18,735 hypermethylated and 45,407 hypomethylated CpG sites associated with aging. As in differentiated cells, hypermethylated sequences were enriched in chromatin repressive marks. Most importantly, hypomethylated CpG sites were strongly enriched in the active chromatin mark H3K4me1 in stem and differentiated cells, suggesting this is a cell type-independent chromatin signature of DNA hypomethylation during aging. Analysis of scedasticity showed that interindividual variability of DNA methylation increased during aging in MSCs and differentiated cells, providing a new avenue for the identification of DNA methylation changes over time. DNA methylation profiling of genetically identical individuals showed that both the tendency of DNA methylation changes and scedasticity depended on nongenetic as well as genetic factors. Our results indicate that the dynamics of DNA methylation during aging depend on a complex mixture of factors that include the DNA sequence, cell type, and chromatin context involved and that, depending on the locus, the changes can be modulated by genetic and/or external factors. ; We thank Ronnie Lendrum for manuscript preparation and Tim Triche Jr. for his invaluable advice. This work has been financially supported by the Plan Nacional de I+D+I 2008-2011/2013-2016/FEDER (PI11/01728 to A.F.F., PI 12/0615 to J.A.R., PI10/0449 to P.M., and PI11/0119 to C.B.); the ISCIII-Subdirección General de Evaluación y Fomento de la Investigación (Miguel Servet contracts CP11/00131 to A.F.F. and CP07/0059 to C.B.); the Spanish Ministry of Health (PS09/02454 and PI12/01080 to M.F.F.); the Spanish National Research Council (CSIC; 200820I172 to M.F.F.); IUOPA (to C.F. and G.F.B.); Fundacion Cientifica de la AECC (to R.G.U. and P.M.); Fundación Ramón Areces (to M.F.F.); and FICYT (to E.G.T.). J.G.-C. receives funding from the Fondo de Investigaciones Sanitarias (FIS; PI05/2217 and PI08/0029) and the Madrid Regional Government (S-BIO-0204-2006 and S2010/BMD-2420). J.A.R. receives funding from the Fondo de Investigaciones Sanitarias (ISCIII-FIS PI 12/0615). P.M. is also supported by MINECO (SAF2013/43065), ERANET E-Rare (PI112/03112), and Fundación Sandra Ibarra. P.M. also acknowledges support from Obra Social "La Caixa/Fundacio Josep Carreras." The IUOPA is supported by the Obra Social Cajastur, Spain. ; Sí