title: Round window membrane permeability to transforming growth factor-alpha: an in vitro study.
abstract: OBJECTIVE
  Recent studies have identified the capacity of transforming growth factor-alpha (TGF-alpha) to stimulate mammalian labyrinthine hair cell regeneration after acute ototoxic damage. Augmenting hair cell regeneration with such growth factors may have a role in potentiation of recovery of cochlear function after hair cell injury. Transtympanic application of aqueous solutions to the round window membrane (RWM) has proved successful as a drug delivery route. The purpose of this study was to test the permeability of the mammalian RWM to TGF-alpha in an inexpensive and reliable in vitro model.
  
  
  METHODS
  Guinea pig RWM niches were harvested and transferred to a 2-chamber apparatus, and TGF-alpha was applied to the middle-ear side of the chamber. ELISAs of TGF-alpha were measured at intervals during a 96-hour period.
  
  
  RESULTS
  Aliquots taken during a 96-hour interval demonstrated passage of TGF-alpha in concentrations sufficient to stimulate hair cell regrowth.
  
  
  CONCLUSIONS
  The apparatus allows study of RWM permeability to other substances and provides a basic model for study of RWM physiology. TGF-alpha is able to pass through a mammalian RWM.
authors.affiliation: Department of Otorhinolaryngology, Mayo Clinic and Mayo Foundation, Rochester, MN 55905, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Witte
authors.forename: J L
authors.initials: JL
authors.lastname: Kasperbauer
mesh_terms: D000818:Animals; D002463:Cell Membrane Permeability / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D012405:Round Window, Ear / Q000502:physiology*; D016211:Transforming Growth Factor alpha / Q000378:metabolism*
chemical_list: D016211:Transforming Growth Factor alpha