Biocompatibility and Histopathologic Changes of the Acellular Xenogenic Pulmonary Valved Conduit Grafted in the Right Ventricular Outflow Tract

Huh, Jae Hak; Kim, Won Gon; Kim, Yong Jin; Park, Hyun Jeong

Abstract

BACKGROUND: The xenogenic or allogenic valves after in vitro repopulation with autologous cells or in vivo repopulation after acellularization treatment to remove the antigenicity could be used as an alternative to synthetic polymer scaffold. In the present study, we evaluated the process of repopulation by recipient cell to the acellularized xenograft treated with NaCl-SDS solution and grafted in the right ventricular outflow tract. MATERIAL AND METHOD: Porcine pulmonary valved conduits were treated with NaCl-SDS solution to make the grafts acellularized and implanted in the right ventricular outflow tract of the goats under cardiopulmonary bypass. After evaluating the functions of pulmonary valves by echocardiography, goats were sacrificed at 1 week, 1 month, 3 months, 6 months, and 12 months after implantation, respectively. After retrieving the implanted valved conduits, histopathologic examination with Hematoxylin-Eosin, Masson's trichrome staining and immunohistochemical staining was performed. RESULT: Among the six goats, which had been implanted with acellularized pulmonary valved conduits, five survived the expected time period. Echocardiographic examinations for pulmonary valves revealed good function except mild regurgitation and stenosis. Microscopic analysis of the leaflets showed progressive cellular in-growth, composed of fibroblasts, myofibroblasts, and endothelial cells, into the acellularized leaflets over time. Severe inflammatory response was detected in early phase, though it gradually decreased afterwards. The extracellular matrices were regenerated by repopulated cells on the recellularized portion of the acellularized leaflet.
CONCLUSION
The acellularized xenogenic pulmonary valved conuits were repopulated with fibroblasts, myofibroblasts, and endothelial cells of the recipient and extracellullar matrices were regenerated by repopulated cells 12 months after the implantation. The functional integrity of pulmonary valves was well preserved. This study showed that the acellularized porcine xenogenic valved conduits could be used as an ideal valve prosthesis with long term durability.