title: The effects of retinoic acid on ciliary function of regenerated sinus mucosa.
abstract: BACKGROUND
  Retinoic acid (RA) has been shown to enhance ciliary ultrastructure in regenerated sinus mucosa compared with controls. However, the functional status of the regenerated cilia has not been studied. Our objective was to evaluate the ciliary beat frequency (CBF) of regenerated sinus mucosa treated with topical RA in a rabbit model.
  
  
  METHODS
  Twelve rabbits underwent bilateral surgical stripping of the maxillary sinuses, followed by treatment with RA gel in the right side and an inert gel control in the left side. The rabbits were then killed at either 2 or 4 weeks, and CBF analysis of the regenerated mucosa was performed. Three unoperated rabbits were used to establish normative CBF data.
  
  
  RESULTS
  Functional cilia were recovered from 11/12 RA-treated sinuses and 12/12 gel control sinuses. At 2 weeks postoperatively, the RA-treated sinuses showed an average CBF of 19.78 Hz, which was statistically comparable with the normal unoperated controls (p < 0.26). The inert gel-treated mucosa showed a CBF of 29.24 Hz, which was significantly elevated compared with normals (p < 0.05). At 4 weeks, ciliary activity persisted, but both RA-treated sinuses and gel controls showed elevated CBF compared with normals (p < 0.03).
  
  
  CONCLUSIONS
  Topical RA placed in a demucosalized maxillary sinus yields functional cilia. RA appears to have a normalizing effect on CBF early in the mucosal wound healing process compared with control. This effect appears to be mitigated in later stages of wound healing. RA may be beneficial in enhancing morphological and functional aspects of regenerating cilia.
authors.affiliation: Division of Rhinology, Department of Otolaryngology, Stanford University, Stanford, California, USA.
authors.forename: Vanessa R
authors.initials: VR
authors.lastname: Erickson
authors.forename: Marcelo
authors.initials: M
authors.lastname: Antunes
authors.forename: Bei
authors.initials: B
authors.lastname: Chen
authors.forename: Noam A
authors.initials: NA
authors.lastname: Cohen
authors.forename: Peter H
authors.initials: PH
authors.lastname: Hwang
mesh_terms: D000818:Animals; D002923:Cilia / Q000187:drug effects / Q000502:physiology; D004195:Disease Models, Animal; D005500:Follow-Up Studies; D007641:Keratolytic Agents / Q000494:pharmacology*; D008443:Maxillary Sinus / Q000187:drug effects / Q000473:pathology* / Q000601:surgery; D010254:Paranasal Sinus Diseases / Q000473:pathology / Q000601:surgery; D011817:Rabbits; D012038:Regeneration / Q000187:drug effects*; D020545:Respiratory Mucosa / Q000187:drug effects / Q000502:physiology*; D014212:Tretinoin / Q000494:pharmacology*; D014945:Wound Healing / Q000187:drug effects*
chemical_list: D007641:Keratolytic Agents; D014212:Tretinoin