title: Effect of dexamethasone on cultured human tenocytes and its reversibility by platelet-derived growth factor.
abstract: BACKGROUND
  Many cases of tendon rupture after glucocorticoid injections have been reported in the literature. Despite previous studies on the histological and biomechanical changes in tendons after glucocorticoid injections, the role of glucocorticoid in causing tendon rupture still remains controversial. The objective of this study was to determine whether glucocorticoid has deleterious effects on the cellular metabolism and collagen production of cultured human tenocytes and the reversibility of these effects by platelet-derived growth factor-BB (PDGFBB).
  
  
  METHODS
  Primary cultures of human tenocytes obtained from explants of healthy patellar tendon, harvested during anterior cruciate ligament reconstructions, were performed. The effects on cell viability, cell proliferation, and induction of apoptosis were measured by [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay, 5-bromo-deoxyuridine incorporation, and DNA fragmentation assay, respectively. The effect on collagen synthesis was measured by (3) H-proline incorporation assay.
  
  
  RESULTS
  The number of viable cells was decreased, in a dose-dependent manner, by the administration of 10 (-9) to 10 (-4) -M dexamethasone. This dose range also suppressed cell proliferation. No apoptotic effect was detected. Treatment with 10 (-6) -M dexamethasone significantly reduced the amount of collagen synthesis. Co-incubation with 10 ng/mL of PDGFBB significantly reversed the effects caused by 10 (-6) -M dexamethasone.
  
  
  CONCLUSIONS
  Dexamethasone significantly decreased cell viability, suppressed cell proliferation, and reduced collagen synthesis in cultured human tenocytes. The effects were reversed by the simultaneous administration of PDGFBB.
authors.affiliation: Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Shatin. mwnwong@cuhk.edu.hk
authors.forename: Margaret Wan Nar
authors.initials: MW
authors.lastname: Wong
authors.forename: Yvonne Yin Nei
authors.initials: YY
authors.lastname: Tang
authors.forename: Simon Kwong Man
authors.initials: SK
authors.lastname: Lee
authors.forename: Bruma Sai Chuen
authors.initials: BS
authors.lastname: Fu
authors.forename: Barbara Pui
authors.initials: BP
authors.lastname: Chan
authors.forename: Cavor Kai Ming
authors.initials: CK
authors.lastname: Chan
mesh_terms: D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D000925:Anticoagulants / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D000077214:Becaplermin; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D066298:In Vitro Techniques; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D020574:Proto-Oncogene Proteins c-sis; D013710:Tendons / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D013997:Time Factors
chemical_list: D000893:Anti-Inflammatory Agents; D000925:Anticoagulants; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D000077214:Becaplermin; D003907:Dexamethasone; D003094:Collagen