title: Thrombospondin-2 Expression During Retinal Vascular Development and Neovascularization.
abstract: OBJECTIVE
  To determine thrombospondin-2 (TSP2) expression and its impact on postnatal retinal vascular development and retinal neovascularization.
  
  
  METHODS
  The TSP2-deficient (TSP2(-/-)) mice and a line of TSP2 reporter mice were used to assess the expression of TSP2 during postnatal retinal vascular development and neovascularization. The postnatal retinal vascularization was evaluated using immunostaining of wholemount retinas prepared at different postnatal days by collagen IV staining and/or TSP2 promoter driven green fluorescent protein (GFP) expression. The organization of astrocytes was evaluated by glial fibrillary acidic protein (GFAP) staining. Retinal vascular densities were determined using trypsin digestion preparation of wholemount retinas at 3- and 6-weeks of age. Retinal neovascularization was assessed during the oxygen-induced ischemic retinopathy (OIR). Choroidal neovascularization (CNV) was assessed using laser-induced CNV.
  
  
  RESULTS
  Using the TSP2-GFP reporter mice, we observed significant expression of TSP2 mRNA in retinas of postnatal day 5 (P5) mice, which increased by P7 and remained high up to P42. Similar results were observed in retinal wholemount preparations, and western blotting for GFP with the highest level of GFP was observed at P21. In contrast to high level of mRNA at P42, the GFP fluorescence or protein level was dramatically downregulated. The primary retinal vasculature developed at a faster rate in TSP2(-/-) mice compared with TSP2(+/+) mice up to P5. However, the developing retinal vasculature in TSP2(+/+) mice caught up with that of TSP2(-/-) mice after P7. No significant differences in retinal vascular density were observed at 3- or 6-weeks of age. TSP2(-/-) mice also exhibited a similar sensitivity to the hyperoxia-mediated vessel obliteration and similar level of neovascularization during OIR as TSP2(+/+) mice. Lack of TSP2 expression minimally affected laser-induced CNV compared with TSP2(+/+) mice.
  
  
  CONCLUSIONS
  Lack of TSP2 expression was associated with enhanced retinal vascularization during early postnatal days but not at late postnatal times, and minimally affected retinal and CNV. However, the utility of TSP2 as a potential therapeutic target for inhibition of ocular neovascularization awaits further investigation.
authors.affiliation: 1 Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health , Madison, Wisconsin.|2 Department of Ophthalmology, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University , Shanghai, China .
authors.forename: Ping
authors.initials: P
authors.lastname: Fei
authors.affiliation: 1 Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health , Madison, Wisconsin.
authors.forename: Tammy L
authors.initials: TL
authors.lastname: Palenski
authors.affiliation: 1 Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health , Madison, Wisconsin.
authors.forename: Shoujian
authors.initials: S
authors.lastname: Wang
authors.affiliation: 1 Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health , Madison, Wisconsin.
authors.forename: Zafer
authors.initials: Z
authors.lastname: Gurel
authors.affiliation: 3 Department of Physiology, Michigan State University College of Veterinary Medicine , East Lansing, Michigan.
authors.forename: Kurt D
authors.initials: KD
authors.lastname: Hankenson
authors.affiliation: 4 Department of Pediatrics, University of Wisconsin School of Medicine and Public Health , Madison, Wisconsin.|5 McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health , Madison, Wisconsin.
authors.forename: Christine M
authors.initials: CM
authors.lastname: Sorenson
authors.affiliation: 1 Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health , Madison, Wisconsin.|5 McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health , Madison, Wisconsin.|6 Department of Biomedical Engineering, University of Wisconsin School of Medicine and Public Health , Madison, Wisconsin.
authors.forename: Nader
authors.initials: N
authors.lastname: Sheibani
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D020256:Choroidal Neovascularization / Q000150:complications; D004195:Disease Models, Animal; D005260:Female; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018919:Neovascularization, Physiologic; D010100:Oxygen / Q000378:metabolism; D015861:Retinal Neovascularization / Q000378:metabolism*; D012171:Retinal Vessels / Q000378:metabolism* / Q000473:pathology; D012178:Retinopathy of Prematurity / Q000378:metabolism* / Q000473:pathology; D019699:Thrombospondins / Q000096:biosynthesis* / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D000099262:Thrombospondin 2
chemical_list: D049452:Green Fluorescent Proteins; D010100:Oxygen; D019699:Thrombospondins; D042461:Vascular Endothelial Growth Factor A; D000099262:Thrombospondin 2