Project description:To determine miRNA expression changes during in vitro senescence of mesenchymal stem cells (MSC) we have analyzed differential expression of the corresponding early passage (P2) and senescent passage (PX). Keywords: miRNA, senescence, mesenchymal stromal cells, mesenchymal stem cells, MSC
Project description:<p><strong>BACKGROUND:</strong> Periodontal ligament mesenchymal stem cells (PDLSCs) are a promising cell resource for cell-based regenerative medicine in dentistry. PDLSCs inevitably acquire a senescent phenotype after prolonged in vitro expansion, and the key regulators of cells during replicative senescence remain unclear.</p><p><strong>METHODS:</strong> We cultured periodontal ligament stem cells to passages 4, 10 and 20 (P4, P10, P20). The senescent phenotypes, proliferation and migration ability of PDLSCs (P4, P10, P20) were detected, and non-targeted metabonomic sequencing was performed. We treated PDLSCs with AICAR and detected the expression of FOXO1, FOXO3a, FOXO6 and AMPK phosphorylation (p-AMPK) levels of replicating senescent PDLSCs to explore the correlation between the metabolic changes and the AMPK pathway.</p><p><strong>RESULTS:</strong> Immunofluorescence staining of γ-H2AX, β-galactosidase staining, cell scratch test and qPCR were performed to confirm the occurrence of replicative senescence in PDLSCs during passaging. Three groups of cells at passage 4 (P4), passage 10 (P10) and passage 20 (P20) were collected for non-targeted metabolomics analysis. Metabonomic sequencing showed that the metabolism of replicative senescence in PDLSCs varied significantly. In particular, the content of fatty acid metabolites decreased with senescence, including capric acid, stearic acid, myristic acid and dodecanoic acid. KEGG pathway analysis showed that the AMPK signaling pathway was closely related to AMP levels. The AMP:ATP ratio increased in senescent PDLSCs; however, the levels of p-AMPK and the profile of FOXO1 and FOXO3a, which are downstream of the AMPK signaling pathway, decreased with senescence. We treated PDLSCs with AICAR, an activator of the AMPK pathway, and the phosphorylated AMPK level at P20 PDLSCs was partially restored. </p><p><strong>CONCLUSION:</strong> In summary, our study suggests that the metabolic process of PDLSCs is active in the early stage of senescence, prefers to consume fatty acids, and is attenuated in the later stages of senescence. AMP accumulates in replicative senescent PDLSCs; however, the sensitivity of AMPK phosphorylation sites is impaired, causing senescent PDLSCs to fail to respond to changes in energy metabolism. Our findings provide a new basis for the clinical application of periodontal ligament stem cells.</p>
Project description:Understanding how cells respond to the mechanics of their environment, and what affect senescence may have on this response, is important to gain a better understanding of mechanobiology, both in health and ageing-associated pathology. This experiment assessed the mRNA levels in early and late passage donor-matched human mesenchymal stem cells (MSCs) cultured for four days on soft (2 kPa) or stiff (25 kPa) collagen-I coated polyacrylamide (PA) gels. A minimum of three donors were analysed under each condition. Protein coding RNAs were sequenced with Illumina HiSeq technology. In a parallel experiment, protein was quantified by mass spectrometry proteomics.
Project description:Pathogenic mutations in lamin A/C (LMNA) lead to nuclear structural abnormalities, mesenchymal tissue damage, and laminopathies, which have numerous tissue-specific and progeria phenotypes. However, how LMNA mutations lead to accelerated mesenchymal-derived cell senescence remains unclear. Here, we established a replicative senescence model in vitro using induced pluripotent stem cell-derived mesenchymal stem cells (iMSCs) from patients with homozygous LMNA p.R527C mutation (LMNA R527C iMSCs). R527C iMSCs exhibited marked cell senescence and stemness potential attenuation, accompanied by immunophenotypic changes when expanded to passage 13 in vitro. Proteome analysis revealed that DNA replication, nuclear structure, and chromatin-related gene sets were the most significant changes in R527C iMSCs during replicative senescence, and pathways such as cell cycle, DNA replication, cell adhesion, and inflammation might play important roles in senescence.
Project description:In the present study we analyzed the effect of cellular senescence on the transcriptome of human mesenchymal stem cells (hMSC; alternatively named mesenchymal stromal cells) from bone marrow. Human MSC were isolated from femoral heads of non-osteoporotic donors after total hip arthroplasty. Cells were isolated from human bone marrow according to the previously described protocol (Noth et al., 2002, J Orthop Res, 20/5, 1060-1069) under agreement of the local Ethics Committee of the University of Würzburg. Bone marrow was obtained of femoral heads after total hip arthroplasty due to osteoarthritis and/or hip dysplasia. MSC were replated after reaching 70-90% confluence until they entered state of cellular senescence. RNA samples of control cells were taken from passage 1 or passage 2.
Project description:Human mesenchymal stem cells (hMSCs) promote endogenous tissue regeneration and have become a promising candidate for cell therapy. However, in vitro culture expansion of hMSCs induces a rapid decline of stem cell properties through replicative senescence. Here we characterize metabolic profiles of hMSCs during expansion. We show that alterations of cellular nicotinamide adenine dinucleotide (NAD+ /NADH) redox balance and activity of the Sirtuin (Sirt) family enzymes regulate cellular senescence of hMSCs. Treatment with NAD+ precursor nicotinamide increases the intracellular NAD+ level and re-balances the NAD+ /NADH ratio, with enhanced Sirt-1 activity in hMSCs at high passage, partially restores mitochondrial fitness and rejuvenates senescent hMSCs. By contrast, human fibroblasts exhibit limited senescence as their cellular NAD+ /NADH balance is comparatively stable during expansion. These results indicate a potential metabolic and redox connection to replicative senescence in adult stem cells and identify NAD+ as a metabolic regulator that distinguishes stem cells from mature cells. This study also suggests potential strategies to maintain cellular homeostasis of hMSCs in clinical applications.
Project description:Cells in culture undergo replicative senescence and unequivocally stop proliferation after a limited number of cell divisions. In this study, we have expanded mesenchymal stem cells (MSC) from human adipose tissue and analyzed genetic and epigenetic sequels. The subpopulation of highly proliferative cells and the in vitro differentiation potential decayed already within early passages. Relevant chromosomal aberrations were not detected by karyotyping and SNP-microarrays. Comparison of early and late passage of five samples of mesenchymal stem cells from human adipose tissue.
Project description:Global gene expressions of human bone-derived 11Lin-CD45-CD271+SSEA-4+ mesenchymal stem/stromal cells from young and elderly patients were analyzed. Results provide an insight into the molecular mechanisms of aging and cellular senescence.