Inhibitory effects of polysaccharide extract from Spirulina platensis on corneal neovascularization.
OBJECTIVE
To assess the effects of polysaccharide extract from Spirulina platensis (PSP) on corneal neovascularization (CNV) in vivo and in vitro.


METHODS
PSP was extracted from dry powder of Spirulina platensis. Its anti-angiogenic activity was evaluated in the mouse corneal alkali burn model after topical administration of PSP four times daily for up to seven days. Corneal samples were processed for histochemical, immunohistochemical, and gene expression analyses. The effects of PSP on proliferation, migration, tube formation, and serine threonine kinase (AKT) and extracellular regulated kinase1/2 (ERK1/2) signaling levels in vascular endothelial cells were determined using 3-(4,5)-dimethylthiahiazo (-z-y1)-3, 5-di-phenytetrazoliumromide (MTT) and carboxyfluorescein succinimidyl ester (CFSE) labeling assays, wound healing assay, Matrigel tube formation assay, and western blot.


RESULTS
Topical application of PSP significantly inhibited CNV caused by alkali burn. Corneas treated with PSP showed reduced levels of platelet endothelial cell adhesion molecule (CD31) and stromal cell-derived factor 1 (SDF1) proteins, reduced levels of vascular endothelial growth factor (VEGF), matrix metalloproteinase-2 (MMP2), matrix metalloproteinase-9 (MMP9), SDF1, and tumor necrosis factor-alpha (TNF-alpha) mRNAs, and an increased level of pigment epithelium-derived factor (PEDF) mRNA. These are parameters that have all been related to CNV and/or inflammation. In human vascular endothelial cells, PSP significantly inhibited proliferation, migration, and tube formation in a dose-dependent manner. Furthermore, PSP also decreased the levels of activated AKT and ERK 1/2.


CONCLUSIONS
These data suggest that polysaccharide extract from Spirulina platensis is a potent inhibitor of CNV and that it may be of benefit in the therapy of corneal diseases involving neovascularization and inflammation.
State Key Laboratory Cultivation Base, Shandong Provincial Key Lab of Ophthalmology, Shandong Eye Institute, Qingdao, China.
Lingling
L
Yang
Yao
Y
Wang
Qingjun
Q
Zhou
Peng
P
Chen
Yiqiang
Y
Wang
Ye
Y
Wang
Ting
T
Liu
Lixin
L
Xie
D000818:Animals; D002056:Burns; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D054377:Chemokine CXCL12 / Q000378:metabolism; D003315:Cornea / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D016510:Corneal Neovascularization / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007249:Inflammation / Q000235:genetics; D051379:Mice; D010766:Phosphorylation / Q000187:drug effects; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D011135:Polysaccharides, Bacterial / Q000302:isolation & purification* / Q000494:pharmacology / Q000627:therapeutic use*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D053545:Spirulina / Q000737:chemistry*
D054377:Chemokine CXCL12; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D011135:Polysaccharides, Bacterial; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases