title: Effect of calcium on the proliferation kinetics of synovium-derived mesenchymal stromal cells.
abstract: OBJECTIVE
  Synovium-derived mesenchymal stromal cells (S-MSCs) have potential utility in clinical joint repair applications. However, their scarcity in tissues means S-MSCs cannot be isolated in large quantities and need to be expanded in culture. Because synovial tissues in vivo are exposed to higher calcium (Ca(2+)) levels than typically found in culture media, this study examined the impact of Ca(2+) supplementation on the rate of S-MSC proliferation in culture.
  
  
  METHODS
  S-MSCs were serially cultured with or without Ca(2+) supplementation. The effect of inhibiting Ca(2+) uptake was assessed using Ca(2+) channel blockers. After extended exposure to elevated Ca(2+) concentrations, S-MSCs were characterized by evaluating surface marker profiles, performing reverse transcriptase quantitative polymerase chain reaction and carrying out tri-lineage differentiation assays.
  
  
  RESULTS
  Elevated Ca(2+) concentrations resulted in enhanced S-MSC proliferation. Peak growth occurred at 5.0 mmol/L Ca(2+), with an average fold increase of 4.52 ± 0.65 per passage over 8 passages compared with 2.03 ± 0.46 in un-supplemented medium. Proliferation was inhibited by Ca(2+) channel blockers. Ca(2+)-supplemented cells showed enhanced capacity toward osteogenesis (17.82 ± 4.21 μg Ca(2+) deposited/sample vs. 12.70 ± 2.11 μg Ca(2+) deposited/sample) and adipogenesis (0.47 ± 0.04 mg oil red O/sample vs. 0.352 ± 0.005 mg oil red O/sample) and retained their capacity to undergo chondrogenesis (1.37 ± 0.07 μg glycosaminoglycan/pellet vs. 1.33 ± 0.17 μg glycosaminoglycan/pellet). S-MSCs cultured in elevated Ca(2+) expressed enhanced messenger RNA levels for SOX-9 and peroxisome proliferator activated receptor gamma and depressed levels for collagen I.
  
  
  CONCLUSIONS
  S-MSC sensitivity to Ca(2+) has not been reported previously. These findings indicate that S-MSC population expansion rates may be up-regulated by Ca(2+) supplementation without compromising defining cell characteristics. This study exemplifies the need to consider medium composition when culturing stem cells.
authors.affiliation: Pharmaceutical Production Research Facility, Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Helen
authors.initials: H
authors.lastname: Dry
authors.forename: Kristen
authors.initials: K
authors.lastname: Jorgenson
authors.forename: Wataru
authors.initials: W
authors.lastname: Ando
authors.forename: David A
authors.initials: DA
authors.lastname: Hart
authors.forename: Cyril B
authors.initials: CB
authors.lastname: Frank
authors.forename: Arindom
authors.initials: A
authors.lastname: Sen
mesh_terms: D050156:Adipogenesis / Q000187:drug effects; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D018929:Cell Culture Techniques; D049109:Cell Proliferation / Q000187:drug effects*; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects; D020219:Chondrogenesis / Q000187:drug effects; D006801:Humans; D007596:Joints / Q000166:cytology / Q000473:pathology; D007700:Kinetics; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects; D010012:Osteogenesis / Q000187:drug effects; D013583:Synovial Membrane / Q000166:cytology*
chemical_list: D002118:Calcium