Functional recovery of vitrified and nanowarmed human-scale pig kidneys

Organ transplantation faces significant limitations due to the brief preservation window for donor organs, leading to organ discard and increased waitlist mortality. Cryogenic organ banking has the potential to extend preservation from hours to months or even years, but challenges arise as organ size increases, particularly with ice formation, thermal stress, and cryoprotectant toxicity.

While vitrification and nanowarming have enabled long-term preservation and transplantation of smaller rodent kidneys, their application to human-scale organs has not been demonstrated. In this study, researchers show that vitrification and electromagnetic nanowarming can enable long-term cryogenic storage and functional recovery of human-scale porcine kidneys.

These kidneys, 100 times larger than previously successfully nanowarmed, were successfully recovered after storage at -150°C for up to one year using a new cryoprotectant formulation and a multithermic perfusion strategy. The cooling rates achieved in large kidneys during vitrification were made possible by controlled cooling with annealing and staged volumetric nanowarming, which limited thermal stress and enabled rapid rewarming without cracking.

Rewarmed kidneys exhibited vascular, metabolic, and excretory function during normothermic perfusion, with minimal histological injury. These kidneys also reperfused homogeneously and produced urine immediately after transplantation. Functional recovery approached static cold storage outcomes for several measures and was comparable to kidneys treated with cryoprotectant alone, indicating minimal additional functional injury from the vitrification, cryogenic storage, and nanowarming processes.

These findings address major scale and storage-duration barriers to organ cryopreservation and pave the way for organ banking on timescales far beyond conventional preservation methods.