Immunologically untreated fresh xenograft implantation in a pig-to-goat model.
Immunologically untreated frozen-stored xenografts show controlled rejection and repair due to reduced cellularity in our previous study. To clarify the issue, we compared results obtained using fresh and frozen-stored xenografts. Porcine pulmonary valved conduits were prepared without immunologic treatment and implanted in the right ventricular outflow tract of goats under cardiopulmonary bypass immediately after harvest without frozen storage (the fresh group) or after frozen storage (-70 degrees C for 3 - 7 days) (the frozen group). Four goats were assigned to be raised for 3 (N = 1) or 6 (N = 3) months postoperatively in each group. One goat in the frozen group assigned for the 6-month observation expired at 2 months postoperatively because of thrombotic occlusion of the pulmonary valve. The other goats survived until the scheduled sacrifice. According to echocardiographic findings, one animal sacrificed at 3 months in the frozen group showed more than a moderate degree of pulmonary regurgitation, but all animals in the fresh group showed less than a mild degree. On gross examination, leaflets were slightly better preserved in the fresh group and aneurysmal dilatation of the pulmonary artery was observed at 3 months only in the frozen group. Microscopically, pulmonary arteries showed less severe degenerative changes in the fresh group. Moreover, in the fresh group, viable donor valve cells were still present until 3 months postoperatively (though it disappeared at 6 months postoperatively) and a linear endothelial lining of viable host cells was prominent on all leaflets, whereas this was not the case in the frozen group. In conclusion, fresh xenografts preserved cellular viability and showed fewer degenerative changes than frozen-stored xenografts. Thus, immunologically untreated fresh xenografts could provide a potential valve substitute with distinctive advantages in terms of self-healing potential as compared with frozen-stored xenografts.
Sung
Kiick
K
Department of Thoracic and Cardiovascular Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
Kim
Won Gon
WG
Seo
Jung Wook
JW
D000818:Animals; D015925:Cryopreservation; D004452:Echocardiography; D006041:Goats; D011183:Postoperative Complications; D011651:Pulmonary Artery / Q000473:pathology / Q000637:transplantation; D011664:Pulmonary Valve / Q000276:immunology* / Q000473:pathology / Q000637:transplantation*; D013552:Swine; D013997:Time Factors; D014183:Transplantation, Heterologous / Q000276:immunology* / Q000473:pathology