title: Storage media enhance osteoclastogenic potential of human periodontal ligament cells via RANKL-independent signaling.
abstract: BACKGROUND
  Hank's balanced salt solution (HBSS) and milk have gained wide acceptance as storage media for avulsed tooth. However, the effect of the media and storage time on the periodontal ligament (PDL) cells involvement in the development of root resorption is still unclear. The purpose of this study was to evaluate whether precultured PDL cells in HBSS, milk, or modified Eagle's medium alpha (α-MEM) would affect osteoclastogenesis.
  
  
  METHODS
  PDL cells were precultured in HBSS, milk, or α-MEM for 1 h or 6 h before being co-cultured with RAW 264.7 cells for an additional 3 days for mRNA analysis and 11 days for osteoclastogenesis assay.
  
  
  RESULTS
  Cyclooxygenase-2 (COX-2) mRNA was detected immediately in PDL cells precultured in the three storage media. The expression was up-regulated markedly in all co-cultures when compared with RAW cells alone. As a result of the co-culture, interleukin-1β (IL-1β) expression was detectable in both PDL and RAW cells. TRAP+ multinucleated, osteoclast-like cells developed in all co-cultures; the number of TRAP+ cells was highest (P < 0.05) in the co-cultures that PDL cells precultured in milk for 6 h. The mRNA level of receptor activator of nuclear factor-kappa B ligand (RANKL) was not detected in PDL cells. Osteoprotegerin (OPG) mRNA expression reduced with increased preculture time, but the difference was not significant (P > 0.05).
  
  
  CONCLUSIONS
  PDL cells kept in the three storage media led to TRAP+ multinucleated, osteoclast-like cells formation via RANKL-independent signaling. The ability to induce osteoclastogenesis may be considered as one of the factors to evaluate the ability of storage medium to maintain PDL viability after tooth avulsion.
authors.affiliation: Endodontics, Comprehensive Dental Care, The University of Hong Kong, Hong Kong, China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Zhan
authors.forename: Chengfei
authors.initials: C
authors.lastname: Zhang
authors.forename: Waruna L
authors.initials: WL
authors.lastname: Dissanayaka
authors.forename: Gary S P
authors.initials: GS
authors.lastname: Cheung
authors.forename: Lijian
authors.initials: L
authors.lastname: Jin
authors.forename: Yangqi
authors.initials: Y
authors.lastname: Yang
authors.forename: Fuhua
authors.initials: F
authors.lastname: Yan
authors.forename: Edith H Y
authors.initials: EH
authors.lastname: Tong
mesh_terms: D000135:Acid Phosphatase / Q000032:analysis; D000818:Animals; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D018920:Coculture Techniques; D003470:Culture Media; D051546:Cyclooxygenase 2 / Q000032:analysis; D006801:Humans; D053583:Interleukin-1beta / Q000032:analysis; D007527:Isoenzymes / Q000032:analysis; D007552:Isotonic Solutions / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects; D051379:Mice; D008892:Milk / Q000502:physiology; D019188:Organ Preservation Solutions / Q000494:pharmacology*; D009930:Organic Chemicals / Q000494:pharmacology; D010010:Osteoclasts / Q000187:drug effects*; D053244:Osteoprotegerin / Q000032:analysis; D010513:Periodontal Ligament / Q000166:cytology* / Q000187:drug effects; D053245:RANK Ligand / Q000187:drug effects*; D015398:Signal Transduction / Q000187:drug effects; D000071681:Tartrate-Resistant Acid Phosphatase; D014021:Tissue Preservation / Q000379:methods
chemical_list: D003470:Culture Media; C072670:Hanks Balanced Salt Solution; D053583:Interleukin-1beta; D007527:Isoenzymes; D007552:Isotonic Solutions; D019188:Organ Preservation Solutions; D009930:Organic Chemicals; D053244:Osteoprotegerin; D053245:RANK Ligand; C506030:TNFRSF11B protein, human; C505688:TNFSF11 protein, human; C420642:alpha minimal essential medium; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D000135:Acid Phosphatase; C000605511:Acp5 protein, mouse; D000071681:Tartrate-Resistant Acid Phosphatase