Acute Rejection Pattern of an Outbred Strain Combination on Mouse-to-Rat Heterotopic Heart Xenotransplantation

Abstract

Objectives. This study aimed to investigate the acute rejection patterns of outbred mice and rats on a xenotransplantation model.

Materials and Methods. Thirty male Balb/c mice weighing from 30 to 40 g were used as donors, and 30 male outbred Sprague-Dawley rats weighing from 150 to 200 g were used as recipients for heterotopic heart xenotransplantation models. Animals were allocated into 5 groups according to their killed days, and each group had 6 animals. Animals in group 1 were followed for 1 day and then killed; animals in groups 2, 3, 4, and 5 were followed up 2, 3, 4, and 5 days after transplantation, respectively. Operative findings, the appearance and heartbeat strength of the grafts, and histopathologic examinations of the grafts were evaluated to determine acute rejection.

Results. There were no mortalities during the study period, and the animal survival rate was 100%. Heartbeat strengths were strong (4.5 +/- 0.5) and graft appearances were normal in group 1 animals. The heartbeat scores of the xenografts dramatically declined thereafter. Histopathologically, there were inflammation patterns in all xenografts. The infiltration of neutrophils and the formation of platelet and fibrin thrombi were seen in the first postoperative day and gradually increased daily.

Conclusions. This study concluded that outbred Balb/c mouse to Sprague-Dawley rat combination has reliable acute xenograft rejection patterns microscopically and macroscopically in the heterotopic heart xenotransplantation model.