Remodeling retinal neovascularization by ALK1 gene transfection in vitro.
OBJECTIVE
To explore a novel strategy for balancing retinal neovascularization by assessing the role activin-like kinase receptor 1 (ALK1) plays in neovascularization in vascular endothelial growth factor (VEGF)-stimulated human retinal capillary endothelial cells (HRCECs).


METHODS
HRCECs were transfected with an ALK1 gene-encoding plasmid or a pSIREN-ALK1 RNAi vector and stimulated with VEGF. The mRNA and protein expression levels of ALK1, occludin, ANG2, and ALK5 were evaluated by real-time PCR and/or Western blot analysis. Microscopy techniques and flow cytometry were used to assess the effects of enhanced levels of ALK1 on migration and proliferation and the formation of tubelike structures of HRCECs.


RESULTS
The level of ALK1 in ALK1-transfected cells was significantly increased compared with that in control cells. ALK1-transfected cells exhibited increased expression of occludin and decreased expression of ANG2 and ALK5, compared with expression in the control cells. HRCECs transfected with pSIREN-ALK1 RNAi exhibited decreased expression of ALK1 and occludin and increased expression of ANG2 and ALK5 compared with the control cells. Transfection with ALK1 affected the migration and proliferation of VEGF-stimulated HRCECs. ALK1 also inhibited the formation of endothelial tubelike structures, but did allow the formation of entire vessel structures.


CONCLUSIONS
Overexpression of ALK1 promoted remodeling of newly formed blood vessels and prevented further angiogenesis. These findings provide insight into the control of retinal neovascularization and demonstrate a novel strategy for maintaining a stable phase of vessel formation, allowing for effective retinal neovascularization without the common adverse effects seen in patients with diabetic retinopathy, age-related macular degeneration, and retinal vein occlusion.
Li
Bin
B
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Peoples Republic of China. scotopsin@yahoo.com.cn
Yin
Wei
W
Hong
Xun
X
Shi
Yu
Y
Wang
Hong-Sheng
HS
Lin
Shao-Fen
SF
Tang
Shi-Bo
SB
D030301:Activin Receptors, Type II / Q000235:genetics* / Q000378:metabolism; D000328:Adult; D042702:Angiopoietin-2 / Q000235:genetics; D015153:Blotting, Western; D002196:Capillaries; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D005434:Flow Cytometry; D005822:Genetic Vectors; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics; D062793:Occludin; D010957:Plasmids; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics; D015861:Retinal Neovascularization / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control; D012171:Retinal Vessels / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology
D042702:Angiopoietin-2; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; D042461:Vascular Endothelial Growth Factor A; D017346:Protein Serine-Threonine Kinases; C425364:ACVRL1 protein, human; D030301:Activin Receptors, Type II; D000077293:Receptor, Transforming Growth Factor-beta Type I; C000625841:TGFBR1 protein, human