title: Ab-externo AAV-mediated gene delivery to the suprachoroidal space using a 250 micron flexible microcatheter.
abstract: BACKGROUND
  The current method of delivering gene replacement to the posterior segment of the eye involves a three-port pars plana vitrectomy followed by injection of the agent through a 37-gauge cannula, which is potentially wrought with retinal complications. In this paper we investigate the safety and efficacy of delivering adeno-associated viral (AAV) vector to the suprachoroidal space using an ab externo approach that utilizes an illuminated microcatheter.
  
  
  METHODS
  6 New Zealand White rabbits and 2 Dutch Belted rabbits were used to evaluate the ab externo delivery method. sc-AAV5-smCBA-hGFP vector was delivered into the suprachoroidal space using an illuminated iTrackTM 250A microcatheter. Six weeks after surgery, the rabbits were sacrificed and their eyes evaluated for AAV transfection using immunofluorescent antibody staining of GFP.
  
  
  RESULTS
  Immunostaining of sectioned and whole-mounted eyes demonstrated robust transfection in all treated eyes, with no fluorescence in untreated control eyes. Transfection occurred diffusely and involved both the choroid and the retina. No apparent adverse effects caused by either the viral vector or the procedure itself could be seen either clinically or histologically.
  
  
  CONCLUSIONS
  The ab externo method of delivery using a microcatheter was successful in safely and effectively delivering a gene therapy agent to the suprachoroidal space. This method presents a less invasive alternative to the current method of virally vectored gene delivery.
authors.affiliation: Ophthalmology, University of Florida, Gainesville, Florida, United States of America.
authors.forename: Marc C
authors.initials: MC
authors.lastname: Peden
authors.forename: Jeff
authors.initials: J
authors.lastname: Min
authors.forename: Craig
authors.initials: C
authors.lastname: Meyers
authors.forename: Zachary
authors.initials: Z
authors.lastname: Lukowski
authors.forename: Qiuhong
authors.initials: Q
authors.lastname: Li
authors.forename: Sanford L
authors.initials: SL
authors.lastname: Boye
authors.forename: Monica
authors.initials: M
authors.lastname: Levine
authors.forename: William W
authors.initials: WW
authors.lastname: Hauswirth
authors.forename: Ramakrishna
authors.initials: R
authors.lastname: Ratnakaram
authors.forename: William
authors.initials: W
authors.lastname: Dawson
authors.forename: Wesley C
authors.initials: WC
authors.lastname: Smith
authors.forename: Mark B
authors.initials: MB
authors.lastname: Sherwood
mesh_terms: D000818:Animals; D057785:Catheters / Q000009:adverse effects; D002829:Choroid / Q000378:metabolism; D000229:Dependovirus / Q000235:genetics*; D018014:Gene Transfer Techniques / Q000009:adverse effects / Q000295:instrumentation*; D005822:Genetic Vectors / Q000235:genetics; D008856:Microscopy, Fluorescence; D055616:Microtechnology / Q000295:instrumentation*; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism; D011817:Rabbits