title: Distinct mesenchymal progenitor cell subsets in the adult human synovium.
abstract: OBJECTIVE
  To analyse the heterogeneity at the single-cell level of human mesenchymal progenitor cells from SM.
  
  
  METHODS
  Cell populations were enzymatically released from the knee joint synovium of adult human individuals. Single cell-derived clonal populations were obtained by limiting dilution and serially passaged to determine growth rates. Phenotypic analysis was carried out by flow cytometry. Replicative senescence was assessed by the senescence-associated beta-galactosidase staining. Telomere lengths were determined semiquantitatively by Southern blotting. Telomerase activity was measured using a real-time quantitative telomerase repeat amplification procedure. Culture-expanded clonal populations were subjected to in vitro differentiation assays to investigate their mesenchymal multipotency.
  
  
  RESULTS
  The 50 clones analysed displayed wide variations in the proliferation rates, even within the same donor sample. The time taken to reach 20 population doublings ranged from 44 to 130 days. The phenotype of the clones tested was compatible with that of mesenchymal stem cells. Mean telomere lengths ranged from 5.2 to 10.9 kb with positive linear trend with telomerase activity, but no correlation with proliferative rates or cell senescence. All clones tested were capable of chondrogenic and osteogenic differentiation, though with large variability in potency. In contrast, only 30% of the clones were adipogenic.
  
  
  CONCLUSIONS
  We report for the first time the co-existence, within the synovium, of progenitor cell subsets with distinct mesenchymal differentiation potency. Our findings further emphasize the need for strategies to purify cell populations with the clinically desired tissue formation potentials.
authors: Division of Applied Medicine, University of Aberdeen, Aberdeen, UK.
authors: Alexandra
authors: A
authors: Karystinou
authors: Francesco
authors: F
authors: Dell'Accio
authors: Tobias B A
authors: TB
authors: Kurth
authors: Henning
authors: H
authors: Wackerhage
authors: Ilyas M
authors: IM
authors: Khan
authors: Charles W
authors: CW
authors: Archer
authors: Elena A
authors: EA
authors: Jones
authors: Thimios A
authors: TA
authors: Mitsiadis
authors: Cosimo
authors: C
authors: De Bari
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002455:Cell Division / Q000502:physiology; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000502:physiology; D020219:Chondrogenesis / Q000502:physiology; D005260:Female; D006801:Humans; D016130:Immunophenotyping; D007719:Knee Joint / Q000166:cytology; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D008875:Middle Aged; D010012:Osteogenesis / Q000502:physiology; D013583:Synovial Membrane / Q000166:cytology*; D019098:Telomerase / Q000378:metabolism; D016615:Telomere / Q000648:ultrastructure
chemical_list: D019098:Telomerase