Survival of pig-to-rhesus corneal xenografts prolonged by prior donor bone marrow transplantation

The aim of the present study was to explore the survival of pig-rhesus corneal xenografts following donor bone marrow transplantation (BMT). Wuzhishan pigs were used as donors and rhesus monkeys as recipients for corneal xenotransplantation. Twelve rhesus monkeys were divided into two groups. Group 1 received intravenous injection of cyclophosphamide (CP) followed by pig bone marrow cell transplantation, while group 2 was used as a control and only received intravenous CP injection. All xenografts were evaluated using a slit-lamp microscope. The immunological status of the recipients following transplantation, including the formation of chimerism, mixed lymphocyte reaction (MLR) and immunoglobulin and complement in the serum, was analyzed. Two rhesus monkeys in each group were sacrificed for corneal histopathology examination. The mean survival time was 36.0 +/- 4.7 days in group 1 and 17.7 +/- 3.2 days in group 2. The mean chimerism percentage in group 1 at week 1 was 5.20 +/- 1.02%, but decreased with time and was <1% after week 3. MLR demonstrated that immune reactivity to donor spleen cells in group 1 was decreased following surgery. Immunoglobulin and complement levels in the serum revealed a decreasing trend. Histopathological examination demonstrated that the corneal xenografts in group 1 had minimal inflammatory cell infiltration and no eosinophil infiltration. Survival of corneal xenografts may be prolonged by prior BMT, suggesting that immune reactivity to donors is suppressed, and is highly dependent on chimerism formation.