title: Differential analysis of genome-wide methylation and gene expression in mesenchymal stem cells of patients with fractures and osteoarthritis.
abstract: Insufficient activity of the bone-forming osteoblasts leads to low bone mass and predisposes to fragility fractures. The functional capacity of human mesenchymal stem cells (hMSCs), the precursors of osteoblasts, may be compromised in elderly individuals, in relation with the epigenetic changes associated with aging. However, the role of hMSCs in the pathogenesis of osteoporosis is still unclear. Therefore, we aimed to characterize the genome-wide methylation and gene expression signatures and the differentiation capacity of hMSCs from patients with hip fractures. We obtained hMSCs from the femoral heads of women undergoing hip replacement due to hip fractures and controls with hip osteoarthritis. DNA methylation was explored with the Infinium 450K bead array. Transcriptome analysis was done by RNA sequencing. The genomic analyses revealed that most differentially methylated loci were situated in genomic regions with enhancer activity, distant from gene bodies and promoters. These regions were associated with differentially expressed genes enriched in pathways related to hMSC growth and osteoblast differentiation. hMSCs from patients with fractures showed enhanced proliferation and upregulation of the osteogenic drivers RUNX2/OSX. Also, they showed some signs of accelerated methylation aging. When cultured in osteogenic medium, hMSCs from patients with fractures showed an impaired differentiation capacity, with reduced alkaline phosphatase activity and poor accumulation of a mineralized matrix. Our results point to 2 areas of potential interest for discovering new therapeutic targets for low bone mass disorders and bone regeneration: the mechanisms stimulating MSCs proliferation after fracture and those impairing their terminal differentiation.
authors.affiliation: a Department of Medicine and Psychiatry , University of Cantabria, and Service of Internal Medicine, Hospital U.M. Valdecilla-IDIVAL , Santander , Spain.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Del Real
authors.affiliation: a Department of Medicine and Psychiatry , University of Cantabria, and Service of Internal Medicine, Hospital U.M. Valdecilla-IDIVAL , Santander , Spain.
authors.forename: Flor M
authors.initials: FM
authors.lastname: Pérez-Campo
authors.affiliation: b Cancer Epigenetics Laboratory , Institute of Oncology of Asturias (IUOPA), HUCA, University of Oviedo , Oviedo , Spain.
authors.forename: Agustín F
authors.initials: AF
authors.lastname: Fernández
authors.affiliation: a Department of Medicine and Psychiatry , University of Cantabria, and Service of Internal Medicine, Hospital U.M. Valdecilla-IDIVAL , Santander , Spain.
authors.forename: Carolina
authors.initials: C
authors.lastname: Sañudo
authors.affiliation: a Department of Medicine and Psychiatry , University of Cantabria, and Service of Internal Medicine, Hospital U.M. Valdecilla-IDIVAL , Santander , Spain.
authors.forename: Carmen G
authors.initials: CG
authors.lastname: Ibarbia
authors.affiliation: c Service of Traumatology and Orthopedic Surgery , Hospital U.M. Valdecilla, University of Cantabria , Santander , Spain.
authors.forename: María I
authors.initials: MI
authors.lastname: Pérez-Núñez
authors.affiliation: d Mathematical Modelling , Statistics and Bio-informatics, Faculty Bioscience Engineering, University Ghent , Gent , Belgium.
authors.forename: Wim Van
authors.initials: WV
authors.lastname: Criekinge
authors.affiliation: e NXT-Dx , Gent , Belgium.
authors.forename: Maarten
authors.initials: M
authors.lastname: Braspenning
authors.affiliation: c Service of Traumatology and Orthopedic Surgery , Hospital U.M. Valdecilla, University of Cantabria , Santander , Spain.
authors.forename: María A
authors.initials: MA
authors.lastname: Alonso
authors.affiliation: b Cancer Epigenetics Laboratory , Institute of Oncology of Asturias (IUOPA), HUCA, University of Oviedo , Oviedo , Spain.
authors.forename: Mario F
authors.initials: MF
authors.lastname: Fraga
authors.affiliation: a Department of Medicine and Psychiatry , University of Cantabria, and Service of Internal Medicine, Hospital U.M. Valdecilla-IDIVAL , Santander , Spain.
authors.forename: Jose A
authors.initials: JA
authors.lastname: Riancho
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D049109:Cell Proliferation; D002478:Cells, Cultured; D019175:DNA Methylation; D005260:Female; D055106:Genome-Wide Association Study; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000378:metabolism* / Q000502:physiology; D008875:Middle Aged; D058866:Osteoporotic Fractures / Q000235:genetics* / Q000378:metabolism; D059467:Transcriptome
keywords: Epigenetics; osteoarthritis; osteoporosis; stem cells; transcription factors