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Abstract Banking cryopreserved organs could transform transplantation into a planned procedure that more equitably reaches patients regardless of geographical and time constraints. Previous organ cryopreservation attempts have failed primarily due to ice formation, but a promising alternative is vitrification, or the rapid cooling of organs to a stable, ice-free, glass-like state. However, rewarming of vitrified organs can similarly fail due to ice crystallization if rewarming is too slow or cracking from thermal stress if rewarming is not uniform. Here we use “nanowarming,” which employs alternating magnetic fields to heat nanoparticles within the organ vasculature, to achieve both rapid and uniform warming, after which the nanoparticles are removed by perfusion. We show that vitrified kidneys can be cryogenically stored (up to 100 days) and successfully recovered by nanowarming to allow transplantation and restore life-sustaining full renal function in nephrectomized recipients in a male rat model. Scaling this technology may one day enable organ banking for improved transplantation.

Organ transplantation remains the only treatment option for patients with end-stage organ failure. The last decade has seen a flurry of activity in improving organ preservation technologies, which promise to increase utilization in a dramatic fashion. They also bring the promise of extending the preservation duration significantly, which opens the doors to sharing organs across local and international boundaries and transforms the field. In this work, we review the recent literature on machine perfusion of livers across various protocols in development and clinical use, in the context of extending the preservation duration. We then review the next generation of technologies that have the potential to further extend the limits and open the door to banking organs, including supercooling, partial freezing, and nanowarming, and outline the opportunities arising in the field for researchers in the short and long term.

Vitrification could enable long-term organ preservation, but only after loading high-concentration, potentially toxic cryoprotective agents (CPAs) by perfusion. In this paper, we combine a two-compartment Krogh cylinder model with a toxicity cost function to theoretically optimize the loading of CPA (VMP) in rat kidneys as a model system. First, based on kidney perfusion experiments, we systematically derived the parameters for a CPA transport loading model, including the following: Vb = 86.0% (ra = 3.86 μm), Lp = 1.5 × 10–14 m3/(N·s), ω = 7.0 × 10–13 mol/(N·s), σ = 0.10. Next, we measured the toxicity cost function model parameters as α = 3.12 and β = 9.39 × 10–6. Combining these models, we developed an improved kidney-loading protocol predicted to achieve vitrification while minimizing toxicity. The optimized protocol resulted in shorter exposure (25 min or 18.5% less) than the gold standard kidney-loading protocol for VMP, which had been developed based on decades of empirical practice. After testing both protocols on rat kidneys, we found comparable physical and biological outcomes. While we did not dramatically reduce toxicity, we did reduce the time. As our approach is now validated, it can be used on other organs lacking defined toxicity data to reduce CPA exposure time and provide a rapid path toward developing CPA perfusion protocols for other organs and CPAs. [ABSTRACT FROM AUTHOR]

Banking cryopreserved organs could transform transplantation into a planned procedure that more equitably reaches patients regardless of geographical and time constraints. Previous organ cryopreservation attempts have failed primarily due to ice formation, but a promising alternative is vitrification, or the rapid cooling of organs to a stable, ice-free, glass-like state. However, rewarming of vitrified organs can similarly fail due to ice crystallization if rewarming is too slow or cracking from thermal stress if rewarming is not uniform. Here we use "nanowarming," which employs alternating magnetic fields to heat nanoparticles within the organ vasculature, to achieve both rapid and uniform warming, after which the nanoparticles are removed by perfusion. We show that vitrified kidneys can be cryogenically stored (up to 100 days) and successfully recovered by nanowarming to allow transplantation and restore life-sustaining full renal function in nephrectomized recipients in a male rat model. Scaling this technology may one day enable organ banking for improved transplantation. The possibility of banking cryopreserved organs could make transplantation medicine much more accessible. Here, the authors show that vitrification and nanowarming—cooling organs to an ice-free state followed by rapid rewarming using nanoparticles and magnetic fields—enables organ cryopreservation, long-term banking, and recovery of full function in a rat kidney transplant model. [ABSTRACT FROM AUTHOR]

B Correction: Annals of Biomedical Engineering b https://doi.org/10.1007/s10439-022-03064-2 The authors would like to add a final sentence to the Acknowledgments section: "We appreciate the contributions of Dr. Hattie Ring with microCT imaging." Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. [Extracted from the article]

Liver cryopreservation has the potential to enable indefinite organ banking. This study investigated vitrification—the ice-free cryopreservation of livers in a glass-like state—as a promising alternative to conventional cryopreservation, which uniformly fails due to damage from ice formation or cracking. Our unique "nanowarming" technology, which involves perfusing biospecimens with cryoprotective agents (CPAs) and silica-coated iron oxide nanoparticles (sIONPs) and then, after vitrification, exciting the nanoparticles via radiofrequency waves, enables rewarming of vitrified specimens fast enough to avoid ice formation and uniformly enough to prevent cracking from thermal stresses, thereby addressing the two main failures of conventional cryopreservation. This study demonstrates the ability to load rat livers with both CPA and sIONPs by vascular perfusion, cool them rapidly to an ice-free vitrified state, and rapidly and homogenously rewarm them. While there was some elevation of liver enzymes (Alanine Aminotransferase) and impaired indocyanine green (ICG) excretion, the nanowarmed livers were viable, maintained normal tissue architecture, had preserved vascular endothelium, and demonstrated hepatocyte and organ-level function, including production of bile and hepatocyte uptake of ICG during normothermic reperfusion. These findings suggest that cryopreservation of whole livers via vitrification and nanowarming has the potential to achieve organ banking for transplant and other biomedical applications. [ABSTRACT FROM AUTHOR]

Cryosurgery is a minimally invasive approach to the treatment of focal prostate cancer (PCa). A major complication is the cryoinjury to the cavernous nerve in the neurovascular bundle (NVB). This nerve cryoinjury halts conduction of action potentials (APs) and can eventually result in erectile dysfunction and therefore diminished quality of life for the patient. Here, we propose the application of cryoprotective agents (CPA) to the regions of the nerves in the NVB, prior to prostate cryosurgery, to minimize non-recoverable loss of AP conduction. We modeled a cryosurgical procedure based on data taken during a clinical case and applied ex-vivo porcine phrenic nerves and rat sciatic nerve with temperature profile of NVB. The APs were measured before and after the CPA exposures and during 3 h of recovery. Comparisons of AP amplitude recovery with various CPA compositions reveal that certain CPAs (e.g., 5% DMSO + 7.5% Trehalose and 5% M22 for porcine and rat nerves, respectively) showed little or no toxicity and effective cryoprotection from freezing (on average 48% and 30% of recovered AP, respectively). In summary, we demonstrate that neural conduction can be preserved after exposure to freezing conditions if CPAs are properly selected and deployed onto the nerve. [ABSTRACT FROM AUTHOR]