免疫排斥反应是角膜移植手术失败的最主要原因。间充质干细胞（mesenchymal stem cells，MSCs）具有抑制多种免疫细胞增殖的功能，它在其它组织器官移植排斥方面作用的研究已经开展，系统应用MSCs治疗角膜移植排斥反应研究尚未见报道。本研究采用大鼠异体角膜移植排斥模型，观察MSCs对角膜移植排斥反应临床进程的影响，并通过T细胞增殖实验来检测实验中各组大鼠免疫应答水平，检测IL-2、IL-4、IL-10、IFN-γ和IL-17的因子分泌水平以及CD4+CD25+Foxp3+调节性T细胞的变化，观察MSCs在进行异体角膜移植的大鼠体内能否发挥免疫调节作用，并初步阐明其作用机制和角膜移植免疫排斥机制，并将MSCs与环孢霉素A联合应用，观察二者的相互作用并为临床治疗角膜移植排斥反应提供新的思路以及可供选择的治疗方法。

Although corneal allografts enjoy a remarkable degree of immune privilege, immune rejection remains the leading cause of keratoplasty failure. Mesenchymal stem cells (MSCs) have been proved to have immunosuppressive properties and have been successfully used as cellular therapy in organ transplantation. Herein we investigated the immunomodulatory effects of MSCs in a rat corneal allograft rejection model. Recipient corneas were examined following transplant, and rejection was defined according to Larkin. T cell proliferation tests by BrdU to measure the direct suppressive effect. Using ELISA kit to measure the concentrations of cytokine productions related to T helper cells, such as IL-2, IL-4, IL-10, IFN-γ and IL-17. The ratio and expression of CD4+CD25+Foxp3+Tregs, which closely related to Anterior Chamber-Associated Immune Deviation (ACAID), are determined and analyzed by flow cytometry and PCR, respectively. .In the present study, we investigated the effect of MSCs on corneal allograft rejection across the full MHC barrier and the therapeutic efficacy of MSCs. We also studied the effects of MSCs on T cell proliferation, on the Th1/Th2 cytokine profiles of T cells, and on the Treg population. We observed that MSCs could inhibit corneal allograft rejection and prolong corneal allograft survival in a rat model. This effect might be due to an inhibition of the pro-inflammatory Th1 response and to upregulation of Tregs. These data support the potential use of MSCs as a treatment for corneal allograft rejection.?Considered the mild but promising results, we will further combined MSCs with different dosage of CsA . Although systemic immunosuppressants like CsA can prolong grafts survival time, therapeutic dosages are limited by the potentially life-threaten complications associated with immune suppression system and by drug toxicity. Thus, less toxic and more efficient methods of immunomodulation are needed to reduce corneal allograft rejection. The combined effect of MSCs and CsA varied according to CsA dose. Based on the former results, we will further investigate the combination effect of MSCs and Cyclosporin A (CsA) to investigated the potential therapeutic approach for clinical use.