Biomechanical Properties of Decellularized Porcine Pulmonary Valve Conduits *Gernot Seebacher, †Christian Grasl, †Martin Stoiber, ‡Erwin Rieder, *Marie-Theres Kasimir, §Daniela Dunkler, *Paul Simon, *Günter Weigel, and †¶Heinrich Schima *Department of Cardiothoracic Surgery, Medical University of Vienna; †Institute of Biomedical Engineering and Physics, Medical University of Vienna; ‡Department of General Surgery, Medical University of Vienna; §Core Unit for Medical Statistics and Informatics, Medical University of Vienna; and ¶Ludwig Boltzmann Cluster for Cardiovascular Research, Medical University of Vienna, Vienna, Austria Abstract: Tissue-engineered heart valves constructed from a xenogeneic or allogeneic decellularized matrix might over- come the disadvantages of current heart valve substitutes. One major necessity besides effective decellularization is to preserve the biomechanical properties of the valve. Native and decellularized porcine pulmonary heart valve conduits (PPVCs) (with [n = 10] or without [n = 10] cryopreserva- tion) were compared to cryopreserved human pulmonary valve conduits (n = 7). Samples of the conduit were mea- sured for wall thickness and underwent tensile tests. Elongation measurement was performed with a video extensometer. Decellularized PPVC showed a higher failure force both in longitudinal (+73%; P < 0.01) and transverse (+66%; P < 0.001) direction compared to human homografts. Failure force of the tissue after cryopreserva- tion was still higher in the porcine group (longitudinal: +106%, P < 0.01; transverse: +58%, P < 0.001). In com- parison to human homografts, both decellularized and decellularized cryopreserved porcine conduits showed a higher extensibility in longitudinal (decellularized: +61%, P < 0.001; decellularized + cryopreserved: +51%, P < 0.01) and transverse (decellularized: +126%, P < 0.001; decel- lularized + cryopreserved: +118%, P < 0.001) direction. Again, cryopreservation did not influence the biomechani- cal properties of the decellularized porcine matrix. Key Words: Tissue engineering—Heart valve—Biomechanical testing. The limited durability of conventionally used bio- logical heart valve substitutes, and the consecutive high risk of thromboembolic events and bleeding after implantation of mechanical valve prostheses, are still major problems in cardiovascular surgery that remain unsolved (1,2). Due to limited durability and the lack of growth potential of current artificial heart valves especially in young patients who would benefit from a new durable biological heart valve, tissue engineering as a multidisciplinary approach could help to develop alternative devices. But the durable, nonimmunogenic, and nonthrombogenic heart valve prosthesis with the ability to grow is still not available (3–5).The decellularization approach of xenogeneic heart valves might be one option besides the use of biodegradable polymer as scaffolds for tissue engineering purposes. For clinical implementa- tion, not only a thorough decellularization and even- tual reseeding are needed, but also biomechanical stability has to be preserved. In former studies, we could demonstrate the decel- lularization of heart valve material and the successful seeding with human cells (6). The present study was carried out to describe the effects of decellularization, freezing, and thawing on the biomechanical properties of porcine heart valve tissue, and for the first time these data were compared to the stability of conventionally used homograft heart valve tissue. doi:10.1111/j.1525-1594.2007.00452.x Received September 2006; revised February 2007. Address correspondence and reprint requests to Dr. Günter Weigel, Department of Surgery, Division of Cardiothoracic Surgery, Surgical Research Laboratories, Medical University of Vienna, Vienna, Austria. E-mail: guenter.weigel@meduniwien. ac.at Artificial Organs 32(1):28–35, Blackwell Publishing, Inc. © 2007, Copyright the Authors Journal compilation © 2007, International Center for Artificial Organs and Transplantation and Blackwell Publishing 28