Mesenchymal stem cell derived exosomes-based immunological signature in a rat model of corneal allograft rejection therapy

Abstract

Background: Mesenchymal stem cells (MSCs) are promising candidates for immunomodulatory therapy that are currently being tested in corneal allograft rejection. In this study, we tested the effects of Mesenchymal stem cells derived exosomes in the corneal allograft rejection model. Methods: Mesenchymal stem cells derived exosomes (MSC-exo) were collected and characterized. Wistar-Lewis rat corneal allograft rejection models were established. PKH26 labeled exosomes were used for track experiment. Models were randomly separated into four groups and treated with graded doses of exosomes or same volumn of PBS. Corneal grafts were assessed for rejection degree using slit-lamp biomicroscopy. Grafts were examined histologically using hematoxylin-eosin (H-E) staining and immunohistochemically using antibodies against CD4, CD8 and CD25. A comprehensive graft mRNA gene expression array analysis was conducted and checked by real-time polymerase chain reaction (PCR). Results: The nanovesicles obtained were expressing exosome specific protein markers CD9, CD63, CD81. The labeled exosomes could be detected in both cornea and anterior chamber two hours after injection.The 10 µg exosomes subconjunctival injection can effectively prolong graft survival time (MST 16.3 ± 2.5 days). 10 µg exosomes-treated group can inhibit the infiltration of CD4+ and CD25+ T cells. IFN-γ and CXCL11 levels were significantly decreased in grafts obtained from postoperative exosomes-treated rats when compared with controls. Conclusions: MSC-exo can cross biological barrier and play better role directly towards target tissue. MSC-exo can effectively prolong grafts survival time. Th1 signaling pathway was significantly inhibited in the exosomes treated group.