The Experimental Study On The Feasibility Of Intrathymic Inoculation With Mesenchymal Stem Cells In Inducing Tolerance To Cardiac Xenograft

Objective To study the living trace of bone mesenchymal stem cells (BMSCs) of guniea pig in the thymuses of rats, and further to explore the feasibility of intrathymic inoculation with MSCs in inducing immunotolerance of cardiac xenotransplantation,we proliferated BMSCs of cavia in the medium of DMEM and injected them intrathymuses(IT). To observe the phenomenon of immunotolerance in xenograft, we coppied the animal model of cardiac xenotransplantation of guinea pig-to-rat in abdomen followed with Ono K and Lindsey ES.Materials and methods BMSCs of cavia were expanded in medium to P3, and were labeled with superparamagetic iron-oxide(SPIO) or 4 , 6-diamidino-2- phenylindole (DAPI).The marked BMSCs were inoculated into thymuses gland of rats. The thymuses were sliced up and dyed with perls solution seven days later or observed directly under the fluorescenc microscope. Donor(guniea pig) and recipient (SD rat) were divided randomly into four groups. Group A (Control group): without pretreatment; Group B (IT group): the recipients received 1—5×105 BMSCs of cavia intrathyuses inoculating 7 days before transplantation; Group C (CVF plus IT inoculation with MSCs group): after IT inoculation 6 days, 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. Group D (CVF group): the recipients were injected with CVF 40u/kg in abdomen 24 hours before transplantation and CVF 60u/kg were injected in vein again just before transplantation.The grafted heart mean survival time (MST), the optical density(OD) of mixed cell reaction (MCR) and the pathology were observed.Results MSCs of cavia do meet with the micro-environment of thymuses in rats.