Date Published:2014 Sep 16
Purpose: To investigate whether systemically-injected syngeneic mesenchymal stem cells (MSCs) can home to the inflamed transplanted cornea, suppress induction of alloimmunity, and promote allograft survival. Methods: MSCs were generated from bone marrow of wild-type BALB/c or GFP+ C57BL/6 mice, and 1x106 cells were intravenously injected to allografted recipients 3 hours after surgery. MSCs homing to the cornea were examined at day 3 post-transplantation by immunohistochemistry. CD11c+MHC II+ cells were detected in the cornea and lymph nodes (LNs) 14 days post-transplantation using flow cytometry. Cytokine expression of bone marrow-derived dendritic cells (BMDCs) was determined using real-time PCR. ELISPOT assay was used to assess indirect and direct host T cell allosensitization, and graft survival was evaluated by slit-lamp biomicroscopy weekly up to 8 weeks. Results: Intravenously injected GFP+ MSCs were found in abundance in the transplanted cornea, conjunctiva, and lymph nodes, but not in the ungrafted (contralateral) tissue. The frequencies of mature CD11c+MHC II+ APCs were substantially decreased in the corneas and draining LNs of MSC-injected allograft recipients compared to control recipients. Maturation and function of in vitro cultured BMDCs was decreased when cocultured with MSCs. Draining LNs of MSC-injected allograft recipients showed significantly lower frequencies of IFNγ-secreting Th1 cells compared to the control group. Allograft survival rate was significantly higher in MSC-injected recipients compared to non-MSC injected recipients. Conclusions: Our data demonstrate that systemically-administered MSCs specifically home to transplanted corneas and promote allograft survival by inhibiting APC maturation and induction of alloreactive T cells.