Purpose:
The role of corneal stromal cells (CSC) in ocular surface healing has long been debated. Their conventional activated role has been indicated as scar tissue formation, while a potential role in tissue regeneration was, until now not reported. Our aim was to investigate the stem cell properties of these cells and determine any potential role in ocular surface regeneration.
Methods:
CSC were cultured up to passage 3 (P0-3) from donor rims and assessed against criteria set by the international society of cellular therapy (ISCT) for multipotent mesenchymal stromal cells (MSC) which are:1. Adherence to plastic,2. Defined cell surface markers (CSM) expression,3. Differentiation into adipocytes osteocytes and chondroblasts.These were compared against fetal liver MSC as control cells. CSC were sorted into three separate populations based on their unique CSM expression profiles and were assessed against ISCT criteria. Each of these sub-groups of cells was also analysed for their potential to differentiate into corneal epithelial cells (CEC) followed by validation with flow cytometry and qPCR
Results:
CSC fulfilled the ISCT criteria for MSC comparable to fetal liver MSC, also they expressed novel tissue specific markers. Three distinct sub populations expressing unique CSM profile isolated from CSC demonstrated significant differences in their CSM expression and their tri-lineage potential. More importantly, CSC demonstrated the capacity to differentiate into corneal epithelial and progenitor lineages. The differentiation capacity and resulting corneal epithelial phenotype was found to be population specific, with one population showing a superior progenitor and self renew capacity.
Conclusions:
This is first study to show mesenchymal-epithelial transition (MET) in Ophthalmology. This is also the first study to fully validate CSC are MSC of cornea. CSC have potential of being pre-limbal stem cell and if the correct population under suitable culturing environment is stimulated, they can be used as a source for generating CEC for various ocular surface diseases.
Keywords: cornea: stroma and keratocytes • EMT (epithelial mesenchymal transition) • gene/expression