title: Zoledronic acid suppresses mineralization through direct cytotoxicity and osteoblast differentiation inhibition.
abstract: BACKGROUND
  Zoledronic acid (ZA) is prescribed to treat various metabolic bone diseases. Despite its efficacy in preventing bone loss, ZA has been linked to osteonecrosis of the jaw in several reports. However, a mechanism underlying this occurrence is still unclear.
  
  
  OBJECTIVE
  This study was to investigate causative roles of ZA on osseous cellular activities of pre-osteoblastic cell line MC3T3-E1 (MC3T3) and mesenchymal stem cell (MSC).
  
  
  METHODS
  Morphological analysis, RT-PCR, annexin V/PI staining, together with mineralization, cell viability, and alkaline phosphatase (ALP) activity assays were performed.
  
  
  RESULTS
  Zoledronic acid treatment decreased bone nodule formation at all concentrations tested (0.01-100 μM). Cell morphologies of both cell types were altered from their normal appearances after the addition of ZA (≥ 5 μM), and cell viability was significantly inhibited at concentrations ≥ 0.1 μM for MC3T3 and at concentrations ≥ 10 μM for MSC. ZA (100 μM) induced apoptosis in MC3T3 and MSC. Furthermore, ALP activity from both cells was strongly reduced when exposed to ZA (≥ 1 μM for MC3T3 and ≥ 5 μM for MSC). ZA also down-regulated Runx 2 and Col I mRNA expressions.
  
  
  CONCLUSIONS
  With this in vitro study, ZA mediated defective bone mineralization by directly disrupting osteoblast/osteoprogenitor cellular activities at several levels, that is, cell proliferation, osteoblast differentiation, and osteoblast function of both pre-osteoblastic cells and MSC.
authors.affiliation: Thammasat University, Pathumthani, Thailand. p_somying@hotmail.com
authors.forename: Somying
authors.initials: S
authors.lastname: Patntirapong
authors.forename: Weerachai
authors.initials: W
authors.lastname: Singhatanadgit
authors.forename: Chatvadee
authors.initials: C
authors.lastname: Chanruangvanit
authors.forename: Kwankamol
authors.initials: K
authors.lastname: Lavanrattanakul
authors.forename: Yodhathai
authors.initials: Y
authors.lastname: Satravaha
mesh_terms: D016475:3T3 Cells; D000469:Alkaline Phosphatase / Q000032:analysis / Q000037:antagonists & inhibitors; D000818:Animals; D017304:Annexin A5; D017209:Apoptosis / Q000187:drug effects; D050071:Bone Density Conservation Agents / Q000008:administration & dosage / Q000633:toxicity*; D002113:Calcification, Physiologic / Q000187:drug effects*; D002448:Cell Adhesion / Q000187:drug effects; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D024042:Collagen Type I / Q000187:drug effects; D004396:Coloring Agents; D050659:Core Binding Factor Alpha 1 Subunit / Q000187:drug effects; D004164:Diphosphonates / Q000008:administration & dosage / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D007093:Imidazoles / Q000008:administration & dosage / Q000633:toxicity*; D059630:Mesenchymal Stem Cells / Q000187:drug effects*; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects*; D010012:Osteogenesis / Q000187:drug effects; D011419:Propidium; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000077211:Zoledronic Acid
chemical_list: D017304:Annexin A5; D050071:Bone Density Conservation Agents; D024042:Collagen Type I; D004396:Coloring Agents; D050659:Core Binding Factor Alpha 1 Subunit; D004164:Diphosphonates; D007093:Imidazoles; C493716:Runx2 protein, mouse; D011419:Propidium; D000077211:Zoledronic Acid; D000469:Alkaline Phosphatase