Increased vitreous shedding of microparticles in proliferative diabetic retinopathy stimulates endothelial proliferation.
OBJECTIVE
Diabetic retinopathy is associated with progressive retinal capillary activation and proliferation, leading to vision impairment and blindness. Microparticles are submicron membrane vesicles with biological activities, released following cell activation or apoptosis. We tested the hypothesis that proangiogenic microparticles accumulate in vitreous fluid in diabetic retinopathy.


METHODS
Levels and cellular origin of vitreous and plasma microparticles from control (n = 26) and diabetic (n = 104) patients were analyzed by flow cytometry, and their proangiogenic activity was assessed by in vitro thymidine incorporation and neovessel formation in subcutaneous Matrigel plugs in mice.


RESULTS
Microparticles of endothelial, platelet, photoreceptor, and microglial origin were identified in vitreous samples. Levels of photoreceptor and microglial microparticles were undetectable in plasmas but were comparable in diabetic and control vitreous samples. Vitreous platelet and endothelial microparticles levels were increased in diabetic patients and decreased following panretinal laser photocoagulation or intravitreal antivascular endothelial growth factor injection in proliferative diabetic retinopathy (PDR). The ratio of vitreous to plasma microparticle levels was calculated to estimate local formation versus potential plasma leakage. In PDR, the endothelial microparticles ratio--but not that for platelet--was greater than 1.0, indicating local formation of endothelial microparticles from retinal vessels and permeation of platelet microparticles from plasma. Isolated vitreous microparticles stimulated by 1.6-fold endothelial proliferation and increased new vessel formation in mice.


CONCLUSIONS
The present study demonstrates that vitreous fluid contains shed membrane microparticles of endothelial, platelet, and retinal origin. Vitreous microparticles levels are increased in patients with diabetic retinopathy, where they could contribute to disease progression.
Chahed
Sadri
S
Paris-Cardiovascular Research Centre, Inserm U970, Paris, France.
Leroyer
Aurélie S
AS
Benzerroug
Mounir
M
Gaucher
David
D
Georgescu
Adriana
A
Picaud
Serge
S
Silvestre
Jean-Sébastien
JS
Gaudric
Alain
A
Tedgui
Alain
A
Massin
Pascale
P
Boulanger
Chantal M
CM
D000368:Aged; D000818:Animals; D001792:Blood Platelets / Q000473:pathology; D002455:Cell Division / Q000502:physiology; D003094:Collagen; D003930:Diabetic Retinopathy / Q000473:pathology* / Q000601:surgery / Q000628:therapy; D018450:Disease Progression; D004338:Drug Combinations; D042783:Endothelial Cells / Q000473:pathology*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007797:Laminin; D008028:Light Coagulation; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000473:pathology; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000473:pathology; D010316:Particle Size; D020419:Photoreceptor Cells, Vertebrate / Q000473:pathology; D011509:Proteoglycans; D012171:Retinal Vessels / Q000473:pathology*; D014821:Vitrectomy; D014822:Vitreous Body / Q000473:pathology* / Q000601:surgery
D004338:Drug Combinations; D007797:Laminin; D011509:Proteoglycans; C059485:matrigel; D003094:Collagen