title: Immunotargeted photodynamic therapy for cholesteatoma: in vitro results with anti-EGFR-coated indocyanine green nanocapsules.
abstract: OBJECTIVE
  The objective was to test the hypothesis that immunotargeted photodynamic therapy (IT-PDT) using anti-epithelial growth factor receptor (EGFR)-coated indocyanine green (ICG) nanocapsules would selectively kill cholesteatoma-derived keratinocytes while sparing middle ear-derived mucosa cells in vitro.
  
  
  BACKGROUND
  Rates of residual cholesteatoma caused by incomplete microsurgical removal are unacceptably high; thus, development of an adjuvant therapy to safely destroy undetected residual cholesteatoma cells would be desirable. IT-PDT is a possible means to achieve this end.
  
  
  METHODS
  ICG nanocapsules coated with anti-EGFR were synthesized and applied to cholesteatoma-derived keratinocytes and middle ear mucosa cells in vitro. Selective binding to keratinocytes was evaluated by fluorescence microscopy. Activation of ICG was undertaken by applying near-infrared light (810 nm) at an applied energy dose of 1,080 J/cm. Cell death was evaluated 2 hours after treatment with trypan blue staining.
  
  
  RESULTS
  Selective and robust nanocapsule binding to keratinocytes, but not mucosa cells, was confirmed by preapplication and postapplication fluorescence measurements. A keratinocyte cell death rate of 70.12% ± 2.50% was achieved, whereas negligible mucosa cell death was observed. Negligible cell death was also observed for both cell types with application of the nanocapsules alone or with application of near-infrared light alone.
  
  
  CONCLUSIONS
  Anti-EGFR ICG nanocapsules applied topically and activated as part of an IT-PDT scheme results in a high rate of cholesteatoma-derived keratinocyte cell death while negligibly affecting middle ear mucosal cells in vitro. These preliminary findings suggest that this is a feasible concept and that further investigation is warranted.
authors.affiliation: *Section of Otolaryngology-Head and Neck Surgery, University of Chicago Medicine and Biological Sciences, Chicago, Illinois; and †Departments of Surgery and ‡Otolaryngology-Head and Neck Surgery, and §Phillips Classic Laser and Nanomedicine Laboratory, University of Arkansas for Medical Sciences, Little Rock, Arkansas, U.S.A.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Gluth
authors.forename: Yihong C
authors.initials: YC
authors.lastname: Kaufmann
authors.forename: John L
authors.initials: JL
authors.lastname: Dornhoffer
authors.forename: Scott
authors.initials: S
authors.lastname: Ferguson
mesh_terms: D000906:Antibodies / Q000008:administration & dosage*; D018424:Cholesteatoma, Middle Ear / Q000188:drug therapy*; D066246:ErbB Receptors / Q000276:immunology*; D006801:Humans; D066298:In Vitro Techniques; D007208:Indocyanine Green / Q000008:administration & dosage*; D015603:Keratinocytes / Q000187:drug effects; D053769:Nanocapsules; D010778:Photochemotherapy / Q000379:methods*
chemical_list: D000906:Antibodies; D053769:Nanocapsules; C512478:EGFR protein, human; D066246:ErbB Receptors; D007208:Indocyanine Green