title: Novel therapy to reverse the cellular effects of bisphosphonates on primary human oral fibroblasts.
abstract: OBJECTIVE
  Osteonecrosis of the jaws (ONJ) is a clinical condition that is characterized by a nonhealing breach in the oral mucosa resulting in exposure of bone and has been increasingly reported in patients receiving bisphosphonate (BP) therapy. Although the pathogenesis and natural history of ONJ remain ill-defined, it appears that the oral soft tissues play a critical role in the development of this condition. We examined the effects of the nitrogen-containing BPs pamidronate and zoledronate on primary human gingival fibroblasts.
  
  
  METHODS
  Primary gingival fibroblasts were exposed to clinically relevant doses of pamidronate and zoledronate. Cellular proliferation was measured with an MTS/PMS reagent-based kit (Promega, Madison, WI), scratch wound assays were performed to measure cellular migration, and apoptosis was measured by use of terminal deoxynucleotidyl transferase-mediated dUTP-FITC end labeling and caspase assays. The BP-exposed cells were treated with 10-ng/mL recombinant human platelet-derived growth factor BB (rhPDGF-BB) and 50-μmol/L geranylgeraniol (GGOH).
  
  
  RESULTS
  Gingival fibroblasts are significantly more sensitive to inhibition of proliferation by zoledronate compared with pamidronate. Exposure of these cells to pamidronate but not zoledronate resulted in an increase in cellular apoptosis. Furthermore, exposure of gingival fibroblasts to pamidronate or zoledronate resulted in a decrease in cellular migration. We show that these defects are due to a loss of cell-substratum adhesion and a reduction of F-actin bundles. Finally, we show that the addition of rhPDGF-BB and GGOH in vitro is able to partially rescue the cell proliferation, migration, and adhesion defects.
  
  
  CONCLUSIONS
  The cytotoxic effects of BPs on oral fibroblasts and their significant reversal by the addition of GGOH and rhPDGF-BB provide both the potential mechanism and treatment options for ONJ.
authors.affiliation: College of Dental Medicine, Columbia University, New York, NY 10032, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Cozin
authors.forename: Bradley M
authors.initials: BM
authors.lastname: Pinker
authors.forename: Kimberley
authors.initials: K
authors.lastname: Solemani
authors.forename: Jeremy M
authors.initials: JM
authors.lastname: Zuniga
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Dadaian
authors.forename: Serge
authors.initials: S
authors.lastname: Cremers
authors.forename: Regina
authors.initials: R
authors.lastname: Landesberg
authors.forename: Srikala
authors.initials: S
authors.lastname: Raghavan
mesh_terms: D000199:Actins / Q000378:metabolism; D017209:Apoptosis; D000077214:Becaplermin; D050071:Bone Density Conservation Agents / Q000009:adverse effects*; D053148:Caspase 3 / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects; D018929:Cell Culture Techniques; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004164:Diphosphonates / Q000009:adverse effects*; D004224:Diterpenes / Q000494:pharmacology*; D005347:Fibroblasts / Q000187:drug effects; D005881:Gingiva / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D007093:Imidazoles / Q000009:adverse effects; D020287:In Situ Nick-End Labeling; D000077268:Pamidronate; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D020574:Proto-Oncogene Proteins c-sis; D011994:Recombinant Proteins / Q000494:pharmacology; D014945:Wound Healing / Q000187:drug effects*; D000077211:Zoledronic Acid
chemical_list: D000199:Actins; D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D004224:Diterpenes; D007093:Imidazoles; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D011994:Recombinant Proteins; D000077214:Becaplermin; D000077211:Zoledronic Acid; C017338:geranylgeraniol; D053148:Caspase 3; D000077268:Pamidronate