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Updated: Aug 30, 2026
MicroRNA Expression Profiles of Human iPS Cells, Retinal Pigment Epithelium Derived From iPS, and Fetal Retinal Pigment Epithelium
Published on: June 24, 2014
uPA, tPA and PAI-1 mRNA expression in periretinal membranes
1Department of Virology, Haartman Institute, University of Helsinki, Helsinki, Finland. vappu.siren@helsinki.fi
Purpose:
Formation of periretinal membranes occurs in proliferative vitreoretinopathy (PVR) and proliferative diabetic retinopathy (PDR) and includes cell migration, proliferation, extracellular matrix formation and tissue contraction, processes in which plasminogen activation (PA) system is involved.
Methods:
Twenty PVR, PDR or pucker membranes were examined to identify the cells with cell specific markers and to detect the expression of urokinase (uPA), tissue-type plasminogen activator (tPA) or plasminogen activator inhibitor-1 (PAI-1) by in situ hybridization and by immunohistochemistry.
Results:
In PVR, uPA, tPA and PAI-1 were expressed by retinal pigment epithelial (RPE) cells, macrophages or retinal glial cells. In PDR, PA components were also expressed by endothelial cells. Semiquantitative analysis in in situ hybridization and immunohistochemistry results demonstrated no notable differences in uPA, tPA or PAI-1 expression between PDR and PVR membranes.
Conclusions:
We conclude that local proteolytic activation is involved in extracellular matrix production both in diabetic and non-diabetic membranes.
Insights
The plasminogen activation system is involved in forming membranes in proliferative vitreoretinopathy (PVR) and proliferative diabetic retinopathy (PDR). Key components like uPA, tPA, and PAI-1 are expressed by various retinal cells in both conditions.
Area of Science:
- Ophthalmology
- Cell Biology
- Molecular Biology
Background:
- Periretinal membrane formation is a hallmark of proliferative vitreoretinopathy (PVR) and proliferative diabetic retinopathy (PDR).
- These processes involve complex cellular events including migration, proliferation, extracellular matrix deposition, and contraction.
- The plasminogen activation (PA) system plays a crucial role in regulating extracellular matrix remodeling.
Purpose of the Study:
- To investigate the involvement of the plasminogen activation system in the pathogenesis of PVR and PDR.
- To identify the specific cells expressing components of the PA system within these membranes.
- To compare the expression patterns of PA components between PVR and PDR membranes.
Main Methods:
- Examination of twenty PVR, PDR, or pucker membranes.
- Utilized cell-specific markers to identify cell types.
- Employed in situ hybridization and immunohistochemistry to detect urokinase (uPA), tissue-type plasminogen activator (tPA), and plasminogen activator inhibitor-1 (PAI-1) expression.
Main Results:
- In PVR membranes, uPA, tPA, and PAI-1 were expressed by retinal pigment epithelial (RPE) cells, macrophages, and retinal glial cells.
- In PDR membranes, PA components were also found in endothelial cells.
- Semiquantitative analysis revealed no significant differences in the expression levels of uPA, tPA, or PAI-1 between PDR and PVR membranes.
Conclusions:
- Local proteolytic activation via the PA system is implicated in extracellular matrix production in both diabetic and non-diabetic retinal membranes.
- These findings highlight the shared molecular mechanisms in the development of proliferative retinopathies.
