Regenerative urology clinical trials: an ethical assessment of road blocks and solutions.

Tissue engineering--part of regenerative medicine--is a promising technology that could potentially offer elegant solutions to urogenital defects, but so far, it has fallen short of its potential. Within experimental studies for bladder and urethra reconstructions, two clinical applications have been described, but extension of these techniques to the broader urological patient population has not happened so far. In this article, we aim to identify the ethical road blocks in the clinical evaluation of tissue-engineered products under the European Medicines Agency and Food and Drug Administration regulations for pediatric urological conditions and, ultimately, to recommend strategies to overcome them. The use of human tissue-engineered products (HTEPs) to treat children with congenital urogenital defects poses challenges in the clinical testing phase, connected to three features of the application of this treatment in this patient group: (1) those associated with the product, namely, the multifaceted complexity of the HTEP; (2) those connected to the procedure, namely, the lack of a randomized controlled trial (RCT)-tested gold standard to compare the new treatment to and difficulties surrounding standardization of the treatment protocol; and (3) the patient's young age and associated problems concerning possible long-term effects and the informed consent process. Due to these problems, a conventional RCT is not the methodology of choice to evaluate this treatment in this patient group. The unpredictability of HTEPs necessitates stringent and long-term surveillance and registry to ensure the safety of patients treated with these products.