Bioengineering approaches to organ preservation ex vivo

The advent of successful solid organ transplantation is undoubtedly among the most significant medical achievements of the 20th century. Despite advances in the field of transplantation since its inception over 50 years ago, our approach to donor organ preservation outside of the body remains unchanged. Recently, attempts have been made to replace static cold storage with more sophisticated ex vivo machine perfusion. Rather than cooling the organ on ice to slow metabolic processes, machine perfusion aims to support normal metabolic function in a near-physiologic environment and to provide a platform on which the organ can be evaluated, preserved, and recovered. Ex vivo machine perfusion devices have demonstrated early success with respect to transplant outcomes in heart, lung, and liver, with perfusion times limited to several hours. The continued development of more advanced perfusion systems is likely to extend the duration of ex vivo organ support to days or even weeks, and enable recovery of initially unsuitable donor organs. In this review, we discuss recent clinical and pre-clinical studies, state-of-the-art organ preservation technologies, existing limitations, and a perspective on future developments. Over the past several decades, ex vivo perfusion has emerged as a promising technology for the assessment, preservation, and recovery of donor organs. Many exciting pre-clinical findings have now been translated to clinical use, and successful transplantation following ex vivo perfusion has been achieved for heart, lung, and liver. While machine perfusion provides distinct advantages over traditional cold preservation, many challenges remain, including that of long-term (multi-day) ex vivo support. Here, we provide an overview of the current status of ex vivo machine perfusion in the pre-clinical and clinical setting and share our perspective on the future direction of the field