Vitrification and Nanowarming: Redefining the Limits of Allograft Preservation for Partial Heart Transplants

Over 48,000 organ transplants were performed in 2024, but thousands of organs were discarded due to exceeding cold ischemic times (CIT), which can be as short as 4 hours for hearts. Therefore, current cold storage methods lead to significant loss of transplantation opportunities. Vitrification, a cryopreservation technique that prevents ice formation by rapidly cooling tissues into a glass-like state, offers a promising solution for long-term organ banking. Nanowarming, which uses iron oxide nanoparticles to rewarm tissues uniformly and rapidly, addresses limitations of traditional rewarming methods that can cause cell damage. Clinically, vitrification is already used for embryo storage in IVF and for preserving ovarian tissue in cancer patients. Preclinical studies are now optimizing vitrification and nanowarming for organs and tissues such as kidneys, pancreatic islets, and knee menisci. These efforts focus on improving cryoprotectant (CPA) formulations, refining warming strategies, and standardizing protocols. A promising future application includes banking heart valves for partial heart transplantation (PHT) by providing growing, living valve grafts for children with congenital heart valve defects. Together, vitrification and nanowarming represent a transformative advance in organ preservation, with the potential to reduce discard rates, expand donor pools, and improve transplantation outcomes.