Histologic examination of heart allograft biopsies for control and experimental animals. Hematoxylineosin staining (magnification ×40) shows no or mild myocardial inflammation and no myocyte necrosis at the time of sacrifice for control animals C1 (International Society for Heart and Lung Transplantation [ISHLT] Grade 0R), C2 (ISHLT Grade 0R), and C5 (ISHLT Grade 1R), respectively (A–C). In contrast, experimental animals P1, P2, and P3 exhibited diffuse myocardial inflammation and necrosis (ISHLT Grade 3R) on postoperative day (POD) 125, POD 133, and POD 91, respectively (D–F).