Abstract
Purpose:
Mesenchymal stem cells (MSC) are the stromal cells of bone marrow, but they can also be found in other tissues including the cornea. Our goal was to isolate and cultivate human corneal stroma MSC-like cells (CSMSCs) and study their role in immunity and wound healing.
Methods:
Corneal buttons were harvested from cadavers (according to the Guidelines of the Helsinki Declaration). The isolated stromal cells were cultured ex vivo in human serum containing medium. The expression of well-known MSC, hematopoietic, endothelial markers as well as high-end glycosylation products were measured by fluorescent microscopy and FACS in comparison to bone marrow derived MSCs. To investigate the stemness of CSMSCs, gene array analysis and standardized in vitro differentiation assays were performed. The immunosuppressive function of these cells was studied by mitogen activated lymphocyte reaction in a co-culture with CSMSCs. Proliferation was measured by BrDU incorporation assay. To describe the immunophenotype of the CSMSCs, the cells were activated by TLR ligands and pro-inflammatory cytokines and the secreted cytokines measured by ELISA. ECIS based wound healing assay was performed to test the regenerative potential of these cells.
Results:
The cells isolated from human corneal stroma grew as monolayers in vitro and could be maintained in culture for more than 10 passages (n=6). According to the definition of the ISCT, the most important MSC markers (CD73, CD90 and CD105) were highly expressed on the surface of CSMSCs with absence of endothelial (CD31, VEGFR2) or hematopoietic cell markers (CD34, CD45, CD69, CD133). The CSMSCs were able to differentiate into fat, bone and cartilage tissues showing the potency of the CSMSCs. These cells could close wounds within 24 hrs in vitro. They could suppress the proliferation of mitogen activated peripheral blood lymphocytes and secrete suppressive cytokines upon pro-inflammatory activation, therefore, strengthening their unique immunosuppressive phenotype in inflammation.
Conclusions:
We demonstrate a method for isolating and cultivating MSC-like cells from human corneal stroma. The ex vivo data suggest that these cells may have a role in wound healing and immunological processes in the eye that can possibly be used in future treatments of ocular diseases and corneal stroma injuries.
Keywords: 721 stem cells •
555 immunomodulation/immunoregulation •
765 wound healing