In Vitro Generation of Atrioventricular Heart Valve Neoscaffolds *†Alexander Weymann, *‡Tamás Radovits, *Bastian Schmack, *Shiliang Li, *Sevil Korkmaz, *‡Pál Soós, §Roland Istók, *‡Gabor Veres, *Nicole Chaimow, *Matthias Karck, and *Gábor Szabó *Heart and Marfan Center, Department of Cardiac Surgery, University of Heidelberg, Heidelberg, Germany; †Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton & Harefield NHS Foundation Trust, Harefield, Middlesex, UK; and ‡Heart Center and §Second Department of Pathology, Semmelweis University, Budapest, Hungary Abstract: Tissue engineering of cardiovascular structures represents a novel approach to improve clinical strategies in heart valve disease treatment. The aim of this study was to engineer decellularized atrioventricular heart valve neoscaffolds with an intact ultrastructure and to reseed them with umbilical cord-derived endothelial cells under physiological conditions in a bioreactor environment. Mitral (n = 38) and tricuspid (n = 36) valves were harvested from 40 hearts of German Landrace swine from a selected abattoir. Decellularization of atrioventricular heart valves was achieved by a detergent-based cell extraction protocol. Evaluation of the decellularization method was conducted with light microscopy and quantitative analysis of collagen and elastin content. The presence of residual DNA within the decellularized atrioventricular heart valves was determined with spectrophotometric quantification. The described decellularization regime produced full removal of native cells while maintaining the mechanical stability and the quantitative composition of the atrioventricular heart valve neoscaffolds. The surface of the xenogeneic matrix could be successfully reseeded with in vitro- expanded human umbilical cord-derived endothelial cells under physiological flow conditions. After com- plete decellularization with the detergent-based protocol described here, physiological reseeding of the xenogeneic neoscaffolds resulted in the formation of a confluent layer of human umbilical cord-derived endothelial cells. These results warrant further research toward the generation of atrioventricular heart valve neoscaffolds on the basis of decellularized xenogeneic tissue. Key Words: Tissue engineering—Decellularization—Atrioventricular heart valves—Bioreactor. Heart valve defects are among the most common and deleterious of all cardiac diseases and remain a major cause of morbidity and mortality. Current treatment methods involve the implantation of mechanical or biological replacement heart valves, which can give 15–20 years of adequate function in adults (1). Drawbacks of mechanical valves include requirement for lifelong anticoagulation therapy with the possibility of anticoagulant-related hemorrhage, valve-related infection risk and thromboembolism induced by rough valve wear, nonphysiological transvalvular blood flow with excessive pressure gradients (1), and reduced perfor- mance in children who require several reoperations to achieve appropriate valve diameters (2). Biologi- cal valves and cryopreserved human allografts possess superior hemodynamic performance and do not require anticoagulation therapy. However, these tissue valves have a limited durability (3) and suffer from leaflet destruction and calcification in the long term because of their immunogenic potential (4,5). Thus, a great need still exists for better replacement options. Promising alternatives to modern replacement heart valves have been developed with the help of doi:10.1111/aor.12321 Received February 2014; revised March 2014. Address correspondence and reprint requests to Dr. Alexander Weymann, Head, Whole Heart Tissue Engineering and Advanced Cell Technologies Workgroup, Heart and Marfan Center, Experi- mental Laboratory of Cardiac Surgery, Department of Cardiac Surgery, University of Heidelberg, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany. E-mail: weymann.alexander @googlemail.com Copyright © 2014 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc. Artificial Organs 2014, ••(••):••–••