The Effect Of Intrathymic Inoculation To Cardiac Xenograft Rejection With Mesenchymal Stem Cells

Objective This study was designed to investigate the effect of intrathymic inoculation with MSCs on the recipient immunoloregulation and on the discordant rodent Cardiac Xenograft Rejection in the model of guinea pig to rat xenotransplantation. The mechanisms of rejection in xenotransplantation will be explored in the model.Materials and methods BMSCs of guinea pig were expanded in medium to the third generation, then inoculated into thymuses gland of rats. After inoculation, we observe the quantity change of rat CD4+CD25+ T regulatory cells at different time.Donor(guniea pig) and recipient (SD rat) were divided randomly into four groups. Group A (Control group): The heart from guinea pig was transplanted into the abdomen of SD rat.; Group B (IT group): 14 days before transplantation, the recipients were inoculated with 1×105 BMSCs of guniea pig; Group C (CVF group): the recipients were injected with chinese cobra venom factor(CVF) 40u/kg in abdomen and 24 hours later CVF 60u/kg were injected in vein again just before transplantation, but without intrathymic inoculation; Group D (CVF plus IT inoculation with MSCs group): the recipients which inoculated with BMSCs of guniea pig 14 days ago were injected with CVF before transplantation as Group C. The grafted heart mean survival time (MST), the optical density(OD) of mixed cell reaction (MCR), the expression of GATA-3, CCR3 and the pathology were observed.Results (1)The quantity of Rat blood CD4+CD25+ T regulatory cells increased obviously as early as 1 wk and the levels reached the top after injection and the levels returned to normal at 3 wk. (2)MST: Group A: 23±8min, Group B: 23.8±9.31min, Group C: 333.8±48.33min, Group D: 450.2±50.03min. The MST of Group B> Group A, but P >0.05. Group C and group D were prolonged significantly longer than group A and group B(P<0.05). The MST of Group D > Group C, and P<0.05. (3)The results of MCR: Group IT: 382.2±12.03; Group Control: 589±15.56. The optical density (OD) of group IT was much lower than group Control,P<0.05. (4)The expression of GATA-3 of rat spleen: Group A:80.89±1.50, Group B: 81.73±1.98, Group C: 153.78±8.40,Group D: 115.60±3.11. The expression of GATA-3 of Group C was increased significantly than Group D, P<0.05. (5)The expression of CCR3 of rat spleen: The expression of CCR3 of Group C was increased significantly higher than Group D .Conclusions The IT rat can generate CD4+CD25+ T regulatory cells which can regulate the recipient T cells. Intrathymic inoculation with MSCs of guinea pig can prolong the survival time of xenograft by using Chinese Cobra Venom Factor (CVF) and can inhibit the expression of Th2 .