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Local production of fibronectin by ectopic human retinal cells
P Hiscott1, H A Waller, I Grierson
1Department of Pathology, Institute of Ophthalmology, London, UK.
Abstract:
The distribution of fibronectin mRNA and fibronectin in adult human retina and epiretinal membranes was investigated by in situ hybridisation and immunohistochemical techniques. The cells in normal adult retina contained little or no fibronectin mRNA and the retina only showed fibronectin immunoreactivity in retinal vessels. The cells in detached neuroretina did not contain fibronectin message but the vitreoretinal interface of the detached retina exhibited variable fibronectin immunoreactivity. Retinal glia, retinal pigment epithelium and fibroblast-like cells in membranes at the vitreoretinal juncture (epiretinal membranes) showed variable labelling with the fibronectin mRNA probe and all the membranes immunostained for fibronectin. No difference could be detected between membrane cell types in the intensity of labelling with the mRNA probe or for fibronectin immunoreactivity. The results indicate that cells in situ in attached and detached adult human retina do not produce fibronectin. Although fibronectin at the vitreoretinal juncture in retinal detachment is probably partly derived from plasma fibronectin resulting from breakdown of the blood-retinal barrier, ectopic retinal cells produce fibronectin and contribute to the glycoprotein epiretinal membranes.
Insights
In adult human retinas, cells do not produce fibronectin. However, epiretinal membranes in retinal detachment show fibronectin production by ectopic retinal cells, contributing to membrane formation.
Area of Science:
- Ophthalmology
- Cell Biology
- Molecular Biology
Background:
- Fibronectin is a key glycoprotein in the extracellular matrix.
- Its role in retinal detachment and epiretinal membrane formation is not fully understood.
Purpose of the Study:
- To investigate the distribution and production of fibronectin mRNA and fibronectin protein in adult human retina and epiretinal membranes.
- To determine the cellular sources of fibronectin in these tissues.
Main Methods:
- In situ hybridization was used to detect fibronectin mRNA.
- Immunohistochemical techniques were employed to visualize fibronectin protein.
- Tissues examined included normal adult retina, detached neuroretina, and epiretinal membranes.
Main Results:
- Normal adult retinal cells showed minimal fibronectin mRNA; fibronectin was localized to retinal vessels.
- Detached neuroretina lacked fibronectin mRNA, but the vitreoretinal interface had fibronectin immunoreactivity.
- Epiretinal membranes contained fibronectin mRNA in retinal glia, retinal pigment epithelium, and fibroblast-like cells, and all membranes immunostained positive for fibronectin.
Conclusions:
- Cells within attached and detached adult human retinas do not produce fibronectin.
- Fibronectin at the vitreoretinal juncture in retinal detachment is partly from plasma, but ectopic retinal cells in epiretinal membranes actively produce fibronectin.
- Ectopic retinal cells contribute significantly to fibronectin accumulation in epiretinal membranes.