title: From cytogenomic to epigenomic profiles: monitoring the biologic behavior of in vitro cultured human bone marrow mesenchymal stem cells.
abstract: BACKGROUND
  Bone marrow mesenchymal stem cells (BM-MSCs) are multipotent cells that can differentiate into different cell lineages and have emerged as a promising tool for cell-targeted therapies and tissue engineering. Their use in a therapeutic context requires large-scale in vitro expansion, increasing the probability of genetic and epigenetic instabilities. Some evidence shows that an organized program of replicative senescence is triggered in human BM-MSCs (hBM-MSCs) on prolonged in vitro expansion that includes alterations in phenotype, differentiation potential, telomere length, proliferation rates, global gene-expression patterns, and DNA methylation profiles.
  
  
  METHODS
  In this study, we monitored the chromosomal status, the biologic behavior, and the senescence state of hBM-MSCs derived from eight healthy donors at different passages during in vitro propagation. For a more complete picture, the telomere length was also monitored in five of eight donors, whereas the genomic profile was evaluated in three of eight donors by array-comparative genomic hybridization (array-CGH). Finally, an epigenomic profile was delineated and compared between early and late passages, by pooling DNA of hBM-MSCs from four donors.
  
  
  RESULTS
  Our data indicate that long-term culture severely affects the characteristics of hBM-MSCs. All the observed changes (that is, enlarged morphology, decreased number of cell divisions, random loss of genomic regions, telomere shortening) might be regulated by epigenetic modifications. Gene Ontology analysis revealed that specific biologic processes of hBM-MSCs are affected by variations in DNA methylation from early to late passages.
  
  
  CONCLUSIONS
  Because we revealed a significant decrease in DNA methylation levels in hBM-MSCs during long-term culture, it is very important to unravel how these modifications can influence the biologic features of hBM-MSCs to keep track of this organized program and also to clarify the conflicting observations on hBM-MSC malignant transformation in the literature.
authors.forename: Serena
authors.initials: S
authors.lastname: Redaelli
authors.forename: Angela
authors.initials: A
authors.lastname: Bentivegna
authors.forename: Dana
authors.initials: D
authors.lastname: Foudah
authors.forename: Mariarosaria
authors.initials: M
authors.lastname: Miloso
authors.forename: Juliana
authors.initials: J
authors.lastname: Redondo
authors.forename: Gabriele
authors.initials: G
authors.lastname: Riva
authors.forename: Simona
authors.initials: S
authors.lastname: Baronchelli
authors.forename: Leda
authors.initials: L
authors.lastname: Dalprà
authors.forename: Giovanni
authors.initials: G
authors.lastname: Tredici
mesh_terms: D000328:Adult; D001854:Bone Marrow Cells / Q000166:cytology*; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D016922:Cellular Senescence; D002875:Chromosomes / Q000235:genetics; D055028:Comparative Genomic Hybridization; D056915:DNA Copy Number Variations; D019175:DNA Methylation; D057890:Epigenomics; D005260:Female; D006801:Humans; D016130:Immunophenotyping; D007621:Karyotyping; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D008875:Middle Aged; D016615:Telomere / Q000737:chemistry