title: Adult-derived human liver progenitor cells in long-term culture maintain appropriate gatekeeper mechanisms against transformation.
abstract: The use of human liver progenitor cells in the development of clinical cell therapy depends on their constant availability and unaltered properties during culture. The present study investigates the effects of long-term in vitro culture on the specific characteristics of these cells  and on their genetic stability. Adult-derived human liver progenitor cells (ADHLPCs) were isolated from 12 donors and cultured until senescence and cell death. Cells were analyzed at different time points for their phenotype stability and differentiation potential. In addition, growth characteristics,  chromosomal karyotype, telomere maintenance mechanisms, and activity of cell cycle-related genes were studied. Finally, their in vivo tumorigenicity was investigated in a xenograft assay. The long-term culture of ADHLPCs revealed a variable proliferation capacity. Cells maintained their original  phenotype and acquired hepatocyte-like metabolic functions after differentiation. Eight of the 12 cell populations grew fast (doubling time of 6.3 days) during a limited time period (mean, 116.2 days), and mainly presented normal cytogenetic features. The four other cell cultures presented  an early decline in growth potential (doubling time of 28.6 days) and premature senescence. Chromosomal alterations were detected in three of four cultures at passage 6. Cytogenetic anomalies were not correlated with tumorigenic potential in vitro or in vivo, and expression of cell cycle-related  genes was appropriately upregulated, inducing senescence. Although chromosomal anomalies may occur in long-term cell cultures, neither transformation nor alteration of their characteristics was noted during in vitro expansion. All ADHLPCs reached senescence and growth arrest. Presenescent  ADHLPCs might therefore be considered as a suitable source for liver-based cell therapy.
authors.affiliation: Université Catholique de Louvain, Institut de Recherche Clinique et Expérimentale, Laboratory of Pediatric Hepatology and Cell Therapy, Brussels, Belgium.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Scheers
authors.forename: Cedric
authors.initials: C
authors.lastname: Maerckx
authors.forename: Dung Ngoc
authors.initials: DN
authors.lastname: Khuu
authors.forename: Sabrina
authors.initials: S
authors.lastname: Marcelle
authors.forename: Anabelle
authors.initials: A
authors.lastname: Decottignies
authors.forename: Mustapha
authors.initials: M
authors.lastname: Najimi
authors.forename: Etienne
authors.initials: E
authors.lastname: Sokal
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002454:Cell Differentiation / Q000502:physiology; D048708:Cell Growth Processes / Q000502:physiology; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000502:physiology; D002648:Child; D003584:Cytological Techniques / Q000379:methods; D005260:Female; D006801:Humans; D008099:Liver / Q000166:cytology* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D013234:Stem Cells / Q000166:cytology*; D055815:Young Adult