Therapeutic effect of secretome from TNF-α stimulated mesenchymal stem cells in an experimental model of corneal limbal stem cell deficiency

AIM: To explore the secretome efficacy in tumor necrosis factor (TNF)-α stimulated mouse mesenchymal stem cells (MSCs) in a murine model of corneal limbal alkali injury. METHODS: Corneal limbal stem cell deficiency (LSCD) was created in the eyes of male C57 mice. Concentrated conditioned medium from TNF-α stimulated MSCs (MSC-CMT) was applied topically for 4wk, with basal medium and conditioned medium from MSCs as controls. Corneal opacification, corneal inflammatory response, and corneal neovascularization (NV) were evaluated. Corneal epithelial cell apoptosis, corneal conjunctivation, and inflammatory cell infiltration were assessed with TUNEL staining, CK3 and Muc-5AC immunostaining, and CD11b immunofluorescence staining, respectively. The effect of TSG-6 was further evaluated by knockdown with short hairpin RNA (shRNA). RESULTS: Compared to the controls, topical administration of MSC-CMT significantly ameliorated the clinical symptoms of alkali-induced LSCD, with restrained corneal NV, reduced corneal epithelial cell apoptosis, and inhibition of corneal conjunctivation. In addition, MSC-CMT treatment significantly reduced CD11b+ inflammatory cell infiltration, and inhibited the expression of pro-inflammatory cytokines (IL-1β, TNF-α and IL-6). Furthermore, the promotion of corneal epithelial reconstruction by MSC-CMT was largely abolished by TSG-6 knockdown. CONCLUSION: Our study provides evidence that MSC-CMT enhances the alleviation of corneal alkali injuries, partially through TSG-6-mediated anti-inflammatory protective mechanisms. MSC-CMT may serve as a potential strategy for treating corneal disorders.