Temporal Evaluation of Decellularised Porcine Pulmonary Root Performance and Regeneration in a Juvenile Sheep Model
Helen E. Berry1, Tayyebeh Vafaee2, Fiona Walker2, Amisha Desai3, Louise M. Jennings3, João G. Roderjan4, Claudinei Collatusso5, Francisco D. da Costa6, John Fisher3, Eileen Ingham2.
1Institute of Medical and Biological Engineering, School of Biomedical Sciences, University of Leeds; and Tissue Regenix Group Plc, Leeds, United Kingdom, 2Institute of Medical and Biological Engineering, School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom, 3Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, United Kingdom, 4Pontificia Universidade Catolica do Parana (PUCPR), Curitiba, Brazil, 5Santa Casa Misericordia Curitiba, Curitiba, Brazil, 6Pontificia Universidade Catolica do Parana (PUCPR) and Santa Casa Misericordia Curitiba, Curitiba, Brazil.
OBJECTIVE: To investigate the functional performance and regeneration potential of decellularised porcine pulmonary valve roots implanted in right ventricular outflow tract of juvenile sheep for 1, 3, 6 and 12-months.
METHODS: Cryopreserved decellularised porcine pulmonary roots (DecellCP porcine) were implanted into the right ventricular outflow tract in juvenile sheep for 1, 3, 6 and 12 months (n=4 for each time point). Cryopreserved cellular ovine pulmonary roots (CellCP ovine; n = 4) were implanted for 12 months only, for comparative morphology purposes. Valve function and morphological characteristics were evaluated at each time point by echocardiography, gross observation, histology, and calcium quantification.
RESULTS: Two of the DecellCP porcine roots explanted at 6 months had endocarditis and were excluded from evaluation. All other DecellCP porcine and CellCP ovine roots had low gradients, no substantial valve insufficiency, and blood flow velocities within normal range. The remaining explanted DecellCP porcine roots were in excellent macroscopic condition with no overt calcification, thrombi, aneurysms or vegetations. Explanted CellCP ovine roots exhibited weaknesses in the pulmonary artery wall with one rupture and one aneurysm detected, but no other gross abnormalities. Leaflets remained thin, soft and pliable in both groups.
Cell infiltration into DecellCP porcine roots was progressive over the time course of the study, with a gradient of migrated cells emanating from the adventitia, and full thickness penetration of the DecellCP porcine wall by 12 months. Normal histioarchitecture was retained and CellCP ovine roots remained cellular. Calcification was predominantly localised at the suture sites of all DecellCP porcine and CellCP ovine roots. Calcium levels in DecellCP porcine root distal wall, proximal wall and leaflets at 12 months were minimal (401 ± 57.7 µg.g-1, 389 ± 151 µg.g-1 and 278 ± 133 µg.g-1, respectively) but significantly (P < 0.05) greater than those of explanted CellCP ovine roots (210 ± 74.5 µg.g-1, 228 ± 45.1 µg.g-1 and 179 ± 99 µg.g-1, respectively). Overall there was no evidence of overt calcification in either group at 12 months.
CONCLUSIONS: Functional performance of DecellCP porcine roots over a 12 month period was excellent, with progressive recellularisation evident and no overt calcification.
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