Ethics of bioengineering organs and tissues.

Tissue-engineered medical products are now entering the clinical testing phase of development. Therefore, an open discussion is warranted regarding ethical issues that may arise as these novel 'combination' products move forward, such as when to conduct clinical trials, how to regulate such trials, when and how to responsibly introduce these strategies into clinical practice and how to maintain a positive public perception of the tissue-engineering field as a whole. These issues are discussed, and recommendations are provided for conducting first-in-human clinical studies.

Future of liver transplantation: non-human primates for patient-specific organs from induced pluripotent stem cells.

Strategies to fill the huge gap in supply versus demand of human organs include bioartificial organs, growing humanized organs in animals, cell therapy, and implantable bioengineered constructs. Reproducing the complex relations between different cell types, generation of adequate vasculature, and immunological complications are road blocks in generation of bioengineered organs, while immunological complications limit the use of humanized organs produced in animals. Recent developments in induced pluripotent stem cell (iPSC) biology offer a possibility of generating human, patient-specific organs in non-human primates (NHP) using patient-derived iPSC and NHP-derived iPSC lacking the critical developmental genes for the organ of interest complementing a NHP tetraploid embryo. The organ derived in this way will have the same human leukocyte antigen (HLA) profile as the patient. This approach can be curative in genetic disorders as this offers the possibility of gene manipulation and correction of the patient's genome at the iPSC stage before tetraploid complementation. The process of generation of patient-specific organs such as the liver in this way has the great advantage of making use of the natural signaling cascades in the natural milieu probably resulting in organs of great quality for transplantation. However, the inexorable scientific developments in this direction involve several social issues and hence we need to educate and prepare society in advance to accept the revolutionary consequences, good, bad and ugly.