title: Roles of tissue plasminogen activator and its inhibitor in proliferative diabetic retinopathy.
abstract: OBJECTIVE
  To investigate the role of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI) in proliferative diabetic retinopathy (PDR) and to discuss the correlations among t-PA, PAI and vascular endothelial growth factor (VEGF) expressions.
  
  
  METHODS
  A total of 36 vitreous samples were collected from 36 patients with PDR (PDR group), and 17 vitreous samples from 17 patients with idiopathic macular hole were used as control. The concentrations of t-PA, PAI and VEGF in samples were determined by ELISA method. The correlations among t-PA, PAI and VEGF expressions were discussed.
  
  
  RESULTS
  The concentrations of t-PA, PAI and VEGF in the PDR group were significantly higher than those in the control group (P<0.001). The t-PA and PAI expressions were highly correlated with the VEGF expression (P<0.001).
  
  
  CONCLUSIONS
  In addition to VEGF, a variety of bioactive substances, such as t-PA and PAI, are involved in the pathogenesis involved in the angiogenesis of PDR. VEGF can activate t-PA expression, resulting in collagen tissue degradation and angiogenesis. VEGF may also activate the mechanism for endogenous anti-neovascularization.
authors.affiliation: Department of Ophthalmology, General Hospital of Ningxia Medical University, Yinchuan 750004, Ningxia Hui Autonomous Region, China.
authors.forename: Shu-Ling
authors.initials: SL
authors.lastname: Wu
authors.affiliation: Department of Ophthalmology, General Hospital of Ningxia Medical University, Yinchuan 750004, Ningxia Hui Autonomous Region, China.
authors.forename: Dong-Mei
authors.initials: DM
authors.lastname: Zhan
authors.affiliation: Department of Ophthalmology, General Hospital of Ningxia Medical University, Yinchuan 750004, Ningxia Hui Autonomous Region, China.
authors.forename: Shu-Hong
authors.initials: SH
authors.lastname: Xi
authors.affiliation: Department of Ophthalmology, General Hospital of Ningxia Medical University, Yinchuan 750004, Ningxia Hui Autonomous Region, China.
authors.forename: Xiang-Lian
authors.initials: XL
authors.lastname: He
keywords: angiogenesis; plasminogen activator inhibitor; proliferative diabetic retinopathy; tissue plasminogen activator; vascular endothelial growth factor