title: Time-lapse imaging of vitreoretinal angiogenesis originating from both quiescent and mature vessels in a novel ex vivo system.
abstract: OBJECTIVE
  Diabetic retinopathy (DR) is an angiogenic disease that leads to severe visual loss. However, adequate animal models of vitreoretinal neovascularization in proliferative diabetic retinopathy (PDR) have not yet been described. The purpose of this study was to develop a novel ex vivo system for assessing vitreoretinal angiogenic processes that originate from both quiescent and mature vessels that could be observed with time-sequential imaging.
  
  
  METHODS
  The retinas of 7- to 8-week-old mice were cultured for 4 days, with or without several growth factors with novel procedures, and immunohistochemistry was performed. The retinas from Tie2-GFP mice were cultured with vascular endothelial growth factor (VEGF), and time-sequential imaging of vitreoretinal angiogenesis was acquired.
  
  
  RESULTS
  Vascular sprouts were induced by both VEGF and placenta growth factor, but not by insulin-like growth factor-1, basic fibroblast growth factor or angiopoietin-2. In explants with or without VEGF, perivascular mural cells were dissociated from endothelial cells, which is an important step during angiogenesis and in the progression of DR. Furthermore, use of time-lapse observations of retinal neovascularization events visualized that the first step in vascular sprout emergence from quiescent vessels was a single cell extension. The leading edges of a sprouting endothelial cell extended and retracted in a sequential manner. From newly formed vessels, additional vascular sprouts then emerged and new vessels fused to each other, resulting in vascular branching.
  
  
  CONCLUSIONS
  Time-lapse imaging of this system visualized the dynamic process in vitreoretinal neovascularization from quiescent and mature vessels.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Murakami
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Suzuma
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Takagi
authors.forename: Mihori
authors.initials: M
authors.lastname: Kita
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Ohashi
authors.forename: Daisuke
authors.initials: D
authors.lastname: Watanabe
authors.forename: Tomonari
authors.initials: T
authors.lastname: Ojima
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kurimoto
authors.forename: Tetsushi
authors.initials: T
authors.lastname: Kimura
authors.forename: Atsushi
authors.initials: A
authors.lastname: Sakamoto
authors.forename: Noriharu
authors.initials: N
authors.lastname: Unoki
authors.forename: Nagahisa
authors.initials: N
authors.lastname: Yoshimura
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005451:Fluorescein Angiography; D049452:Green Fluorescent Proteins / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D018715:Microscopy, Video; D009924:Organ Culture Techniques; D042787:Receptor, TIE-2 / Q000378:metabolism; D015861:Retinal Neovascularization / Q000175:diagnosis*; D012171:Retinal Vessels / Q000187:drug effects; D013997:Time Factors; D014822:Vitreous Body / Q000098:blood supply*
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D049452:Green Fluorescent Proteins; D042787:Receptor, TIE-2