Development of a combined cardiac and aortic transplant model to investigate the development of transplant arteriosclerosis in the mouse

Background: The degree of transplant arteriosclerosis in murine cardiac allografts is difficult to assess. Aortic allografts represent an alternative model for evaluating the impact of novel transplant strategies on transplant arteriosclerosis in which the vascular changes can be quantified easily. However, it remains controversial as to whether vascular lesions seen in this model are equivalent to those that develop in solid-organ transplants. The aim of this study was to develop a model of combined cardiac and aortic transplantation to allow more precise quantification of transplant arteriosclerosis and to establish a correlation between the lesions that develop in the 2 types of graft. Methods: CBA (H2(k)) recipients received a C57BL/10 (H2^b) cervical cardiac allograft on Day 0 and a C57BL/10 (H2^b) abdominal aortic allograft on Day 1. Recipients were treated with anti-CD154 mAb (MR1) on Days 0, 2, and 4. We performed histology and morphometric measurements for both grafts 30 days after transplantation. Results: We observed significant intimal proliferation in both the cervical cardiac and abdominal aortic allografts from recipients treated with anti-CD154 mAb (heart, 64% ± 9%; aorta, 67% ± 8%; n = 5). Abdominal aortic grafts transplanted alone into anti-CD154-treated recipients developed a degree of transplant arteriosclerosis equivalent to that seen in the aortic grafts of the combined group (aorta alone, 68% ± 9%, vs aorta + heart, 67% ± 8%; n = 5). Conclusions: This combined cardiac and aortic transplant model permitted quantitative assessment of transplant arteriosclerosis while monitoring graft survival by cardiac palpation. Furthermore, development of transplant arteriosclerosis was equivalent in abdominal aortic allografts either in the presence or absence of an additional solid-organ transplant.