Introduction: It is important to observe histopathologic findings for the diagnosis and treatment of rejection in cardiac xenotransplantation. However, there is still a limited literature describing the histopathologic findings in cardiac xenotransplantation.
Methods: We performed 13 porcine cardiac xenotransplantation to cynomolgus monkeys. Autopsy of transplanted porcine heart was carried out. Tissue samples were analyzed using H&E, histochemical staining for PAS, Elastic fiber, Masson-Trichrome, and immunohistochemical staining for CD3, CD4, CD8, CD20, CD56, CD68, C4d.
Results: 4 died or were euthanized within hours. 9 survived for 9, 13, 15, 18, 21, 22, 46, 60 and 216 days. Two of the short-term survived transplants at 0 day showed intravascular macrophages and strong C4d staining. Myocardial infarction and intravascular fibrin thrombi were present at 9, 22, 46 and 60 days. Mild C4d endothelial staining was present at 22, 46 days. Long-term survived transplant at 216 days showed confluent myocardial infarction with interstitial hemorrhage and fibrosis. Severe arteriosclerosis with intimal thickening and medial sclerosis were present. In our case, there were no findings of acute cellular rejection such as lymphocytic infiltrates with myocyte damage.
Conclusion: In our study, no clear histopathological findings could be diagnosed as acute cellular rejection. It is necessary to develop diagnostic pathology criteria or grading schemes to properly treat rejection and evaluate prognosis.