title: Human sinonasal explant system for testing cytotoxicity of intranasal agents.
abstract: BACKGROUND
  Intranasal agents play a critical role in the management of sinonasal disorders. There are ongoing efforts to develop new intranasal medications to combat sinonasal disease. Some intranasal agents, however, can have cytotoxic effects on human sinonasal tissue. In order to facilitate safe drug discovery, we developed a simple and reliable in vitro screening assay using human sinonasal explants to measure the cytotoxic profiles of intranasal agents.
  
  
  METHODS
  We obtained sinonasal tissues from several regions of the nasal cavity from 12 patients undergoing endoscopic sinonasal surgery. These tissues were cultured on polytetrafluoroethylene membrane in serum-free growth medium. We determined the biochemical properties of these explants by measuring extracellular lactate dehydrogenase (LDH) levels and performing histological analyses over a period of 1 to 2 weeks. We then examined the cytotoxic profiles of 13 intranasal agents by measuring extracellular LDH levels using the human sinonasal explant system.
  
  
  RESULTS
  Sinonasal explants exhibited a rapid reduction in extracellular LDH levels indicating stabilization in the culture environment within 2 days. Histological analysis showed maintenance of good cellular architecture for up to 2 weeks. The explants displayed intact epithelium and expressed βIII-tubulin and Ki-67. Of the 13 tested intranasal agents, 1% zinc sulfate (ZnSO(4) ), 5% ZnSO(4) , and Zicam application were cytotoxic.
  
  
  CONCLUSIONS
  Based on the unique biochemical properties of the human nasal explant culture system, we developed a simple and reliable in vitro screening assay to determine the cytotoxic profiles of various intranasal agents by examining extracellular LDH levels and histopathology.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle, WA 98195, USA. dstorm@u.washington.edu
authors.forename: Jae H
authors.initials: JH
authors.lastname: Lim
authors.forename: Greg E
authors.initials: GE
authors.lastname: Davis
authors.forename: Tessa C
authors.initials: TC
authors.lastname: Rue
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Storm
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D002478:Cells, Cultured; D055808:Drug Discovery / Q000379:methods*; D064420:Drug-Related Side Effects and Adverse Reactions; D057075:Enzyme Assays / Q000379:methods; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D009296:Nasal Cavity / Q000201:enzymology*; D010254:Paranasal Sinus Diseases / Q000188:drug therapy; D019141:Respiratory System Agents / Q000633:toxicity*; D018675:Toxicity Tests / Q000379:methods
chemical_list: D015415:Biomarkers; D019141:Respiratory System Agents; D007770:L-Lactate Dehydrogenase