Immunomodulatory effects of bone marrow mesenchymal stem cells derived from homologous recipients in rats after heart transplantation

Objective　To observe the immunomodulatory effects of homologous bone marrow mesenchymal stem cells (MSCs) obtained from the bone marrow in rats after heart transplantation. Methods　Twenty adult male Lewis rats were used as donors for the heart transplantation, whereas twenty adult male Wistar rats served as recipients. The recipients with cervical heart transplantation were randomly divided into two groups (10 each). Approximately 3ml 0.9% NaCl solution was injected through the tail vein 24h after heart transplantation in the control group (group A). About 2×106 MSCs (suspended in 3ml 0.9% NaCl solution) were injected through the tail vein 24h after heart transplantation in the MSCs treatment group (group B). Four recipient rats from each group were randomly chosen one week after transplantation for determining proportion of CD4+ T, CD8+ T, CD4+CD25high T, and CD4+CD25highfoxp3+ T cells in the lymphocytes in the venous blood and grafts. Subsequently, the CD4+/CD8+ ratio was calculated. The survival time of the grafts were observed in the remaining six rats in each group. Results　(1)The survival time of the transplanted hearts was 7.2±1.3d in group A, and 14.8±2.9d in group B, showing a significant difference between the two groups (P 0.05). The ratios of CD4+CD25high T cells/total lymphocytes and CD4+CD25highFoxp3+ T cells/ total lymphocytes in the allografts were evidently higher in group B (2.74%±0.28%, 2.54%±0.31%) than in group A (0.61%±0.06%, 0.53%±0.06%), showing a significant statistical difference (P < 0.01). Conclusion　Intravenous infusion with MSCs from the bone marrow of the recipients can induce immune tolerance and prolong the survival time of transplanted heart in rats.