The second paper of this week\'s Lancet series on stem cells, reports on a possible solution to the organ donor crisis by using a new technique, whereby a patient\'s own stem cells are inserted into an artificial scaffold where they turn into a fully functional organ. This novel approach to regenerate and transplant organs does not require the need for human donors, and would therefore alleviate rejection problems and the need for immunosuppressive drugs. Leading author, Paolo Macchiarini from the Karolinska Institutet in Stockholm, Sweden, declares: ? \"Such an approach has already been used successfully for the repair and reconstruction of several complex tissues such as the trachea, esophagus, and skeletal muscle in animal models and human beings, and guided by appropriate scientific and ethical oversight, could serve as a platform for the engineering of whole organs and other tissues, and might become a viable and practical future therapeutic approach to meet demand after organ failure.\" Due to an aging population, the crisis for whole-organ donor supplies continues to grow. Just in the U.S., each year, chronic lung disease claims the life of around 120,000 people, whilst 112,000 die from kidney failure and 425,000 from coronary heart disease, and even for those fortunate enough to receive a donor organ, the battle for survival continues, having to take expensive and potentially dangerous immunosuppressive therapy for the rest of their lives. Macchiarini, and his team discuss using a new regenerative technique that is based on using naturally occurring extra cellular matrix as a biological scaffold. Their paper describes the main scientific and ethical hurdles that need to be overcome before this approach can be utilized and the review progress of reconstructed individual organs. Before the novel approach can be widely applied for clinical use, researchers have to tackle challenges, such as identifying the best possible cell sources for various organs, the optimum scaffold material, and which patients would be suitable. The authors state: \"For clinical trials, due consideration needs to be given to who to recruit: suitable patients should be able to provide competent consent, have some amount of social support, have few co morbidities, and be willing to face loss of privacy.\" In addition to the scientific challenges, the new technology also raises several ethical issues that need to be overcome. The authors warn to be cautious, saying: \"The pressure to advance this technique, driven by demand, the race for prestige, and the potential for huge profits, mandates an early commitment be made to establish the safety of various strategies...particularly when there are so many potential patients and doctors who are desperate for any remedy that offers hope.\" They call for policies addressing these issues, such as transparency with regard to the involved techniques, cell sources, informed consent, financial costs to patients, strategies for dealing with experimental failure, and assisting patients after initial treatment. They conclude saying: \"Perhaps the strongest ethical duty the bioengineering community faces is the identification of criteria that constitute sufficient evidence of the evolution of an intervention from research to therapy...Establishment of adequate safety and functional success will need input from investigators and key professional societies and organizations.\" Dusko Ilic from King\'s College London and Julia Polak from the Imperial College in London write in a linked comment: \"Although several questions are unresolved, the promise of an off-the-shelf scaffold that can be repopulated with autologous stem cells expanded in vitro seems much closer than one could have hoped for even a few years ago.\"