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In Vitro and In Vivo Models to Study Corneal Endothelial-mesenchymal Transition
Published on: August 20, 2016
MMP-type endopeptidase activity in the cornea. Its evolution during organ culture storage at the Eye Bank. Effect of
N Isnard1, P Sabatier, A M Robert
1Laboratoire de Recherche Ophtalmologique, Hôpital Hôtel Dieu, Université Paris 5, France.
Abstract:
About 46% of total corneas obtained from donors in the French Eye Bank cannot be grafted for several reasons as loss of endothelium or other. Corneal cells express proteolytic enzymes, essentially matrix metallo-proteinase MMP-2 and MMP-9. In presence of hyaluronan and some other GAG-s their activity increases as could be shown on keratocyte cultures. Hyaluronan concentration increases during in vitro preservation and can represent a serious hazard for corneal conservation. The control of MMP-release and activation might well be one of the factors involved in graft deterioration. We could show however that only a slight fraction (< or =12%) of total, relatively high endopeptidase activity of the cornea is released in the media during storing. It appears therefore that most of the proteolytic activity determined in corneal extracts remains confined to the stroma and might not represent an important risk for preservation, at least for the endothelium.
Insights
Corneal preservation is challenged by enzymes like matrix metalloproteinases (MMPs). While hyaluronan increases MMP activity, most proteolytic activity remains within the corneal stroma, posing minimal risk to the endothelium during storage.
Area of Science:
- Ophthalmology
- Biochemistry
- Tissue Engineering
Background:
- Corneal transplantation is crucial for vision restoration.
- A significant percentage of donor corneas are unsuitable for grafting due to various factors.
- Corneal cells produce proteolytic enzymes, including matrix metalloproteinases (MMPs), which can degrade tissue.
Purpose of the Study:
- To investigate the role of MMPs and their activation by glycosaminoglycans (GAGs) like hyaluronan in corneal tissue preservation.
- To assess the risk of proteolytic activity to corneal endothelium during in vitro storage.
Main Methods:
- Analysis of proteolytic enzyme activity in corneal tissue and storage media.
- Keratocyte cultures were used to study the effect of hyaluronan on MMP activity.
- Quantification of enzyme release during in vitro preservation.
Main Results:
- Hyaluronan and other GAGs can increase the activity of MMP-2 and MMP-9 in corneal cells.
- Hyaluronan concentration increases during in vitro corneal storage, potentially harming tissue.
- Only a small fraction (<12%) of the total endopeptidase activity is released into the storage media.
Conclusions:
- While hyaluronan can enhance MMP activity, the majority of proteolytic enzymes remain localized within the corneal stroma.
- This compartmentalization suggests that stromal proteolytic activity may not pose a significant threat to the corneal endothelium during preservation.
- Further research into controlling MMP release and activation could improve corneal graft viability.
