At six months, the recipient had stable graft function, a serum creatinine of 142 µmol/L and an estimated glomerular filtration rate of approximately 55 mL/min/1.73 m². The authors describe the case as evidence of operational feasibility, while emphasizing that it cannot establish superiority over static cold storage or a causal benefit from machine perfusion. The transplant followed a journey from Ho Chi Minh City to Hue involving road transfers and a single direct scheduled commercial flight lasting approximately 1.5 hours.

The kidney was connected to a LifePort Kidney Transporter for hypothermic machine perfusion, or HMP, under a pressure setting of 30 mmHg. The system used 1,000 mL of KPS-1 preservation solution. Battery power allowed the device to operate during the flight without an external electrical connection, and recipient-center personnel carried the machine in the business-class cabin under their direct supervision.

Those escorts had been trained to operate the device and reviewed its readings and alarms during transport. They also carried sterile supplies and additional ice. Total cold ischemia time, defined as the interval from the start of cold flushing until the kidney was removed from HMP, was 10 hours 50 minutes.

This comprised 1 hour 35 minutes of pre-HMP static cold storage, including approximately 30 minutes of back-table preparation, and 9 hours 15 minutes of elapsed machine-perfusion time. The elapsed figure included an intentional interruption: approximately 3.5 to four hours after HMP began, the team paused perfusion for about 20 to 30 minutes to replenish ice. During that pause, device-recorded flow, pressure and displayed resistance fell to zero, while the bubble-trap temperature rose transiently to approximately 15°C. Perfusion then resumed.

Active perfusion lasted approximately 8 hours 45–55 minutes after excluding the pause, and no post-HMP static cold storage was used. The machine’s perfusion measurements improved over the journey. At HMP initiation, renal vascular resistance was 1.68 mmHg/mL/min and perfusate flow was 16 mL/min.

At one hour, the corresponding values were 1.55 mmHg/mL/min and 18 mL/min. By arrival in Hue, resistance had decreased to 0.44 mmHg/mL/min and flow had increased to 52 mL/min. The investigators regarded this trend as an objective record of perfusion during transportation, but cautioned that flow and resistance have limited predictive accuracy when considered alone and are not definitive evidence of graft viability.

Decisions to transplant a kidney therefore require assessment of donor characteristics, organ function, ischemic exposure, graft appearance and recipient factors alongside device readings. All three renal arterial openings were contained in an intact aortic patch, allowing the patch to be secured within a single cannula so that all three arteries could be perfused. The recorded flow and resistance consequently reflected aggregate perfusion through the cannulation system rather than the distribution of preservation solution among the individual arteries.

Temperature control was the principal operational limitation. Although ice-compartment readings during active HMP generally ranged from approximately 1.5 to 7°C, bubble-trap readings were predominantly 9 to 10°C and exceeded the protocol target of 2 to 8°C for substantial periods. Renal parenchymal temperature was not measured, and the case included no comparator, so the clinical effect of the sensor excursions could not be determined.

The report suggests that programs using portable HMP need predefined responsibilities for device checks, ice replenishment, temperature thresholds, transport delays and handover at the receiving center. The donor had several features associated with increased risk of early graft dysfunction. He was 61 years old and met the conventional expanded-criteria donor definition by age alone, while also having hypertension, type 2 diabetes mellitus and ischemic heart disease.

He was anti-HCV antibody positive, although donor HCV RNA was unavailable. Serum creatinine transiently increased to 229 µmol/L before decreasing to 82 µmol/L before procurement. Detailed donor hemodynamic data, vasopressor requirements, terminal urine output and intensive-care duration were also unavailable, and no preimplantation biopsy was performed.

The donor had been declared brain dead after severe polytrauma, with a Glasgow Coma Scale score of 3. The contralateral kidney was transplanted elsewhere, but information about its preservation and the recipient’s outcome was unavailable, leaving the present report focused on one kidney and one interregional transport pathway. The recipient had received hemodialysis for two years after a kidney implanted 11 years earlier failed.

The prior graft’s failure was clinically attributed to chronic rejection, although no confirmatory biopsy report was available, and the failed kidney remained in situ. Against the new donor, the recipient had two of six HLA mismatches: none at HLA-A, one at HLA-B and one at HLA-DR. Qualitative screening for anti-HLA class I and class II antibodies was negative, no preformed donor-specific antibodies were detected by a Luminex single-antigen bead assay, and an urgent flow-cytometric lymphocyte crossmatch was negative. A numerical cPRA value and HLA typing data for the first donor were unavailable, limiting retrospective assessment of immunological risk and repeated HLA mismatches.

Basiliximab rather than lymphocyte-depleting induction was selected, while initial maintenance treatment comprised tacrolimus, mycophenolate mofetil and prednisolone. Implantation was technically demanding because the kidney had three renal arteries, each of which was separately anastomosed to the external iliac artery. The second warm ischemia time—the interval from removal of the graft from cold preservation to reperfusion—was 55 minutes, reflecting the vascular complexity and technical considerations associated with retransplantation.

After blood flow was restored, the graft showed uniform cortical coloration, satisfactory turgor and immediate urine production. Urine output reached 4,600 mL during the first 24 hours and remained between 3,000 and 4,000 mL per day thereafter. Serum creatinine was 1,227 µmol/L before transplantation, 1,064.9 µmol/L on postoperative day 1 and 872.1 µmol/L on day 2, producing a day-1-to-day-2 reduction ratio of 18.1%.

It subsequently fell to 664 µmol/L on day 5, 301 µmol/L on day 9 and 154 µmol/L on day 21. Because the recipient did not require dialysis during the first postoperative week, the conventional dialysis-based definition of delayed graft function was not met, although the authors characterized the creatinine trajectory as slow graft function rather than immediate functional recovery. The patient was discharged on postoperative day 28 with stable graft function.

Doppler ultrasonography on postoperative day 10 showed an intrarenal resistive index of 0.66 and a peak systolic velocity of 35 cm/s; at the renal artery origin and anastomotic region, the corresponding values were 0.62 and 70 cm/s. The recipient was also positive for HCV RNA before treatment and began a planned 12-week course of sofosbuvir and velpatasvir during the peri-transplant period. After completing antiviral therapy, tacrolimus was replaced with cyclosporine A because of tremor and sleep disturbance attributed to tacrolimus.

The antiviral course was completed before cyclosporine was introduced, so the drugs were not coadministered. At six months, the graft remained functional, with a serum creatinine of 142 µmol/L and an estimated glomerular filtration rate of approximately 55 mL/min/1.73 m² calculated using the 2021 CKD-EPI creatinine equation. Urinalysis was protein-negative at the available visits around three and six months.

Surveillance was clinical and serological: repeat Luminex single-antigen bead testing remained negative for donor-specific anti-HLA antibodies, and no acute rejection requiring treatment occurred. HCV RNA was undetectable after antiviral treatment, and subsequent cyclosporine trough concentrations were 93–117 ng/mL. The report nevertheless has important limitations, including its single-patient design, absence of a static-cold-storage comparator, lack of preimplantation biopsy data and relatively short follow-up.

It demonstrates that portable HMP can be integrated into a complex interregional sharing pathway, but prospective evidence is still needed to determine comparative clinical outcomes, transport-related complications and cost-effectiveness.

Subject of Research: Single-patient case report of portable hypothermic machine perfusion during interregional deceased-donor kidney transport in Vietnam

Article Title: Case Report: Portable hypothermic machine perfusion for interregional deceased-donor kidney sharing in Vietnam

Article References: Pham, H. N., Nguyen, X. T., Tran, K. N., Nguyen, D. D., Nguyen, A. V. Q., Bui, K. C. L., & Pham, H. N. (2026). Case Report: Portable hypothermic machine perfusion for interregional deceased-donor kidney sharing in Vietnam. Frontiers in Transplantation, 5, Article 1982759. https://doi.org/10.3389/frtra.2026.1982759

Image Credits: AI Generated

DOI: 10.3389/frtra.2026.1982759

Keywords: portable machine perfusion, kidney transplantation, deceased donor, organ preservation, interregional transport, expanded-criteria donor, Vietnam, slow graft function, delayed graft function, hypothermic perfusion, Case, Report

The review, led by Marissa C. Kuo and W. Christian Crannell of Vanderbilt University Medical Center with colleagues across Vanderbilt’s surgical, nephrology, biomedical engineering, and cardiac surgery departments, synthesized preclinical and clinical evidence on 10 degrees Celsius static storage in heart, lung, liver, and kidney transplantation. Guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analysis scoping review guidelines, the team searched PubMed, Embase, Web of Science, and Scopus on May 22, 2025, returning 1,182 articles. After duplicate removal and independent screening by two reviewers, 45 studies met inclusion criteria, supplemented by 8 studies retrieved from reference lists and 15 additional references covering perfusion strategies, mitochondrial biomarkers, and controlled rewarming. The result is the most complete picture to date of a preservation approach that is quietly reshaping transplant practice.

The strongest evidence comes from lung transplantation. In animal models, storage at 10 degrees Celsius compared with conventional ice has been associated with improved oxygen uptake, lower airway pressures, greater lung compliance, less edema, better arterial oxygenation, and lower pulmonary vascular resistance after transplantation. Biochemical markers of inflammation, including interleukin-8 and interleukin-1 beta, were lower after reperfusion in organs kept at the warmer temperature. Metabolomic studies add mechanistic depth: in a porcine model, lungs stored at 10 degrees Celsius showed upregulation of protective metabolites such as glutathione and ascorbate, downregulation of substrates that induce mitochondrial depolarization, and elevated mitochondrial respiration supported primarily by complexes I and II. Lipid byproducts dominated the metabolite profile, suggesting that beta-oxidation may serve as an alternative energy substrate that keeps graft metabolism gently active, an organ-protective state the authors liken to hibernation.

Clinical experience in lungs has moved rapidly from proof of concept to multicenter trials. A 2021 pilot study of five bilateral lung transplants using 10 degrees Celsius storage reported zero cases of grade 3 primary graft dysfunction, no need for postoperative extracorporeal membrane oxygenation, and 100 percent 30-day survival. A retrospective matched cohort study found that preservation times extending up to 24 hours at 10 degrees Celsius produced no differences in mechanical ventilation time, intensive care or hospital stay, primary graft dysfunction rates, or survival compared with ice storage. A single-institution prospective study and the largest trial to date, a multicenter non-randomized prospective study of 70 donor lungs stored at 10 degrees Celsius overnight and transplanted the next morning, both found outcomes equivalent to conventional storage, with the multicenter trial reporting primary graft dysfunction rates of 5.7 percent versus 9.3 percent in controls. An international randomized non-inferiority trial has recently completed enrollment and may settle the question definitively.

The clinical implications extend beyond graft function into the logistics of transplantation itself. Because organs stored at 10 degrees Celsius tolerate longer cold ischemic times, surgical teams can schedule transplants during daytime hours rather than performing emergency operations in the middle of the night. Case reports describe hearts transported more than 10 hours without machine perfusion, from Anchorage, Alaska to Nashville, Tennessee, and sequential transplantation of two lungs from a single donor into two different recipients at different institutions. For a field in which more than 23,000 waitlisted patients died awaiting a kidney transplant in the United States between 2020 and 2024, and nearly 31,000 died waiting for any organ, every hour of safe preservation time translates into more organs reaching more patients.

Heart transplantation data, though earlier in its development, are similarly encouraging. A propensity-matched cohort study using a reusable 10 degrees Celsius cooler for organ transport found lower lactate changes and slightly higher cardiac index at 24 and 72 hours postoperatively compared with ice storage, though primary graft dysfunction rates did not differ and donor characteristics were not perfectly balanced. A more recent study of hearts procured after thoracoabdominal normothermic regional perfusion found that 10 degrees Celsius storage was associated with reduced risk of primary graft dysfunction, lower postoperative vasoactive inotropic scores, decreased use of renal replacement therapy, shorter intensive care stays, and reduced six-month mortality. Animal work dating back decades supports the temperature window: canine and rat studies found mitochondrial structural changes were less severe below 14 degrees Celsius, and that high-energy phosphate content was severely depleted only when storage temperatures exceeded 10 degrees Celsius.

The biochemical rationale centers on the mitochondria. At deep hypothermic temperatures near 4 degrees Celsius, the oxygen-binding equilibrium of myoglobin strongly favors the oxygenated form, but cytosolic oxygen diffusion slows dramatically and mitochondrial respiration becomes markedly attenuated. In this near-static state, the mitochondrial proton-motive force collapses, forcing ATP synthase to run in reverse and hydrolyze ATP, while electron flow reverses through succinate dehydrogenase, causing succinate to accumulate, a metabolic hallmark of ischemia. Upon reperfusion, rapid oxidation of that succinate generates a burst of superoxide radicals that can trigger mitochondrial permeability transition pore opening, cytochrome c release, and apoptotic signaling. Released mitochondrial DNA then circulates as a damage-associated molecular pattern, activating innate immune pathways that contribute to graft inflammation and rejection. Moderate cooling to around 10 degrees Celsius, by contrast, appears to preserve slow, reversible electron transport, maintain mitochondrial ultrastructure, and keep myoglobin-mitochondrial oxygen coupling intact.

Evidence in liver and kidney transplantation remains thinner and more mixed. In a comprehensive porcine model of donation after circulatory death, 10 hours of 10 degrees Celsius static storage followed by normothermic perfusion produced superior hemodynamic profiles, more bile with higher pH and bicarbonate, and metabolomic evidence of less citric acid cycle dysfunction and mitochondrial oxidative damage than ice storage, but no human liver studies have yet been published. Older kidney studies yielded conflicting results, with some suggesting slightly higher temperatures may better preserve adenine nucleotide levels, and species differences in mitochondrial temperature responses complicate extrapolation to humans. A 2024 rat cell study found the highest viability at 10 degrees Celsius, and a single human deceased donor kidney transplant after 10 degrees Celsius storage achieved immediate graft function, the first patient in a larger prospective trial now underway.

The review also situates 10 degrees Celsius storage within the broader landscape of preservation technology, including oxygenated hypothermic perfusion and controlled rewarming. Randomized trials of hypothermic oxygenated perfusion in liver transplantation have shown fewer non-anastomotic biliary strictures and less early allograft dysfunction, while a kidney trial of extended criteria donors showed no benefit, possibly because organs were stored on ice before perfusion began. Controlled oxygenated rewarming studies suggest that a gentler temperature gradient at reperfusion protects mitochondrial coupling, a benefit that 10 degrees Celsius storage could amplify by starting closer to physiological temperature. Notably, no study has directly compared static 10 degrees Celsius storage with machine perfusion, and the authors suggest that a simple, inexpensive cooler could in some cases obviate the need for costly perfusion devices.

The authors are careful about the limits of the evidence. Definitive conclusions, they write, await well-designed randomized clinical trials capable of providing the highest quality evidence, and the data are far stronger for heart and lung storage than for liver and kidney. Yet the convergence of mechanistic plausibility, decades of animal data, and increasingly positive clinical experience has given the field reason to reconsider a fundamental assumption: that colder is always better. If ongoing randomized trials confirm the early signals, the humble bag of ice that has defined organ preservation since the advent of transplantation may give way to a precisely controlled 10 degrees Celsius, a change that costs little, requires no complex machinery, and could extend the reach of every donated organ.

Subject of Research: Static organ storage at 10 degrees Celsius as an alternative to conventional ice preservation in deceased donor heart, lung, liver, and kidney transplantation

Article Title: 10° Celsius Static Storage in Deceased Donor Organ Transplantation: A Narrative Review

Article References: Kuo, M. C., Breeding, E., Kiyimba, F., Gohar, E. Y., Walden, R. L., Bacchetta, M., & Crannell, W. C. (2026). 10° Celsius Static Storage in Deceased Donor Organ Transplantation: A Narrative Review. Current Transplantation Reports, 13(1), Article 31. https://doi.org/10.1007/s40472-026-00528-5

Image Credits: AI Generated

DOI: 10.1007/s40472-026-00528-5

Keywords: organ transplantation, organ preservation, 10 degrees Celsius storage, static cold storage, mitochondria, ischemia-reperfusion injury, lung transplantation, heart transplantation, cold ischemia time, machine perfusion, deceased donor, primary graft dysfunction