Advantages and challenges in processing and quality control of decellularized heart valves.

More than 1000 donated aortic and pulmonary valves from predominantly European tissue banks were centrally decellularized and delivered to hospitals in Europe and Japan. Here, we report on the processing and quality controls before, during and after the decellularization of these allografts. Our experiences show that all tissue establishments, which provide native cardiovascular allografts for decellularization, meet comparably high-quality standards, regardless of their national origin. A total of 84% of all received allografts could be released as cell-free allografts. By far the most frequent reasons for rejection were non-release of the donor by the tissue establishment or severe contaminations of the native tissue donation. Only in 2% of all cases the specification for freedom from cells was not fulfilled, indicating that decellularization of human heart valves is a safe process with a very low discard ratio. In clinical use, cell-free cardiovascular allografts have been shown to be advantageous over conventional heart valve replacements, at least in young adults. These results open the discussion on the future gold standard and funding of this innovative therapeutic option for heart valve replacement.