title: QLT091001, a 9-cis-retinal analog, is well-tolerated by retinas of mice with impaired visual cycles.
abstract: OBJECTIVE
  Investigate whether retinas of mice with impaired retinal cycles exposed to light or kept in the dark tolerate prolonged high-dose administration of QLT091001, which contains as an active ingredient, the 9-cis-retinal precursor, 9-cis-retinyl acetate.
  
  
  METHODS
  Four- to six-week-old Lrat(-/-) and Rpe65(-/-) mice (n = 126) as well as crossbred Gnat1(-/-) mice lacking rod phototransduction (n = 110) were gavaged weekly for 6 months with 50 mg/kg QLT091001, either after being kept in the dark or after light bleaching for 30 min/wk followed by maintenance in a 12-hour light ≤ 10 lux)/12-hour dark cycle. Retinal health was monitored by spectral-domain optical coherent tomography (SD-OCT) and scanning laser ophthalmoscopy (SLO) every other month and histological, biochemical, and visual functional analyses were performed at the end of the experiment. Two-photon microscopy (TPM) was used to observe retinoid-containing retinosome structures in the RPE.
  
  
  RESULTS
  Retinal thickness and morphology examined by SD-OCT were well maintained in all strains treated with QLT091001. No significant increases of fundus autofluorescence were detected by SLO imaging of any strain. Accumulation of all-trans-retinyl esters varied with genetic background, types of administered compounds and lighting conditions but retinal health was not compromised. TPM imaging clearly revealed maintenance of retinosomes in the RPE of all mouse strains tested.
  
  
  CONCLUSIONS
  Retinas of Lrat(-/-), Rpe65(-/-), and crossbred Gnat1(-/-) mice tolerated prolonged high-dose QLT091001 treatment well.
authors.affiliation: Department of Ophthalmology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA.
authors.forename: Tadao
authors.initials: T
authors.lastname: Maeda
authors.forename: Zhiqian
authors.initials: Z
authors.lastname: Dong
authors.forename: Hui
authors.initials: H
authors.lastname: Jin
authors.forename: Osamu
authors.initials: O
authors.lastname: Sawada
authors.forename: Songqi
authors.initials: S
authors.lastname: Gao
authors.forename: Deepank
authors.initials: D
authors.lastname: Utkhede
authors.forename: Wendy
authors.initials: W
authors.lastname: Monk
authors.forename: Grazyna
authors.initials: G
authors.lastname: Palczewska
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Palczewski
mesh_terms: D000818:Animals; D003623:Dark Adaptation / Q000187:drug effects*; D004195:Disease Models, Animal; D004224:Diterpenes; D004596:Electroretinography; D005260:Female; D007536:Isomerism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010857:Pigment Epithelium of Eye / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D017949:Retinal Cone Photoreceptor Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D012172:Retinaldehyde / Q000494:pharmacology*; D041623:Tomography, Optical Coherence; D014786:Vision Disorders / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology
chemical_list: D004224:Diterpenes; C031390:9-cis-retinal; D012172:Retinaldehyde