Time-lapse imaging of vitreoretinal angiogenesis originating from both quiescent and mature vessels in a novel ex vivo system.
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.
Murakami
Tomoaki
T
Department of Ophthalmology and Visual Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Suzuma
Kiyoshi
K
Takagi
Hitoshi
H
Kita
Mihori
M
Ohashi
Hirokazu
H
Watanabe
Daisuke
D
Ojima
Tomonari
T
Kurimoto
Masafumi
M
Kimura
Tetsushi
T
Sakamoto
Atsushi
A
Unoki
Noriharu
N
Yoshimura
Nagahisa
N
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*
D036341:Intercellular Signaling Peptides and Proteins; D049452:Green Fluorescent Proteins; D042787:Receptor, TIE-2