title: Efficacy and Safety of Human Retinal Progenitor Cells.
abstract: OBJECTIVE
  We assessed the long-term efficacy and safety of human retinal progenitor cells (hRPC) using established rodent models.
  
  
  METHODS
  Efficacy of hRPC was tested initially in Royal College of Surgeons (RCS) dystrophic rats immunosuppressed with cyclosporine/dexamethasone. Due to adverse effects of dexamethasone, this drug was omitted from a subsequent dose-ranging study, where different hRPC doses were tested for their ability to preserve visual function (measured by optokinetic head tracking) and retinal structure in RCS rats at 3 to 6 months after grafting. Safety of hRPC was assessed by subretinal transplantation into wild type (WT) rats and NIH-III nude mice, with analysis at 3 to 6 and 9 months after grafting, respectively.
  
  
  RESULTS
  The optimal dose of hRPC for preserving visual function/retinal structure in dystrophic rats was 50,000 to 100,000 cells. Human retinal progenitor cells integrated/survived in dystrophic and WT rat retina up to 6 months after grafting and expressed nestin, vimentin, GFAP, andβIII tubulin. Vision and retinal structure remained normal in WT rats injected with hRPC and there was no evidence of tumors. A comparison between dexamethasone-treated and untreated dystrophic rats at 3 months after grafting revealed an unexpected reduction in the baseline visual acuity of dexamethasone-treated animals.
  
  
  CONCLUSIONS
  Human retinal progenitor cells appear safe and efficacious in the preclinical models used here.
  
  
  CONCLUSIONS
  Human retinal progenitor cells could be deployed during early stages of retinal degeneration or in regions of intact retina, without adverse effects on visual function. The ability of dexamethasone to reduce baseline visual acuity in RCS dystrophic rats has important implications for the interpretation of preclinical and clinical cell transplant studies.
authors.affiliation: Department of Ocular Biology and Therapeutics, UCL-Institute of Ophthalmology, London, UK.
authors.forename: Ma'ayan
authors.initials: M
authors.lastname: Semo
authors.affiliation: Department of Ocular Biology and Therapeutics, UCL-Institute of Ophthalmology, London, UK.
authors.forename: Nasrin
authors.initials: N
authors.lastname: Haamedi
authors.affiliation: ReNeuron, Guildford, UK.
authors.forename: Lara
authors.initials: L
authors.lastname: Stevanato
authors.affiliation: Department of Ocular Biology and Therapeutics, UCL-Institute of Ophthalmology, London, UK.
authors.forename: David
authors.initials: D
authors.lastname: Carter
authors.affiliation: ReNeuron, Guildford, UK.
authors.forename: Gary
authors.initials: G
authors.lastname: Brooke
authors.affiliation: Massachusetts Eye and Ear, Schepens Eye Research Institute, Boston, MA, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Young
authors.affiliation: Department of Ocular Biology and Therapeutics, UCL-Institute of Ophthalmology, London, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Coffey
authors.affiliation: ReNeuron, Guildford, UK.
authors.forename: John
authors.initials: J
authors.lastname: Sinden
authors.affiliation: ReNeuron, Guildford, UK.
authors.forename: Sara
authors.initials: S
authors.lastname: Patel
authors.affiliation: Department of Ocular Biology and Therapeutics, UCL-Institute of Ophthalmology, London, UK.
authors.forename: Anthony
authors.initials: A
authors.lastname: Vugler
keywords: dexamethasone; nestin; retinal degeneration; retinal progenitor cells, human