The cold chain delivery of organs for transplantation: from research laboratories and individual enthusiasts to pan- global networks in 50 years.

It is some 50 years since the first published reports appeared of ex vivo preservation of organs for transplantation. Over the intervening decades, organ preservation strategies have become one essential component of world-wide clinical transplant services. In the formative years, translational research in organ hypothermic preservation was grappling with the questions about whether static or dynamic storage was preferable, and the practical implications of those choices. Those studies were also informing the newly expanding clinical transplant services. During the middle years, both preservation modalities were practiced by individual group choices. By the 2000s, the shift in donor demographics demanded a re-evaluation of organ preservation strategies, and now a new era of research and development is promoting adoption of new technologies. In this review we outline many important academic studies which have contributed to this successful history, and give profile to the increasing innovative approaches which are being evaluated for the future. Doi.org/10.54680/fr24310110112.

The role of cryopreservation techniques in manufacturing, transport, and storage of Car-T therapy products.

Several clinical trials have proved the efficacy and safety of T-cells chimeric antigen receptor (CAR-T cells) in treatment of malignant lymphoma and the first products were registered in the European Union in 2018. The shelf-life of CAR-T cell products in the liquid state is short, so cryopreservation offers a significant benefit for logistics in manufacturing and patient management. Direct shipment of the cryopreserved CAR-T cell therapy products to the clinical department is feasible, nevertheless, intermediate storage in the hospital cryostorage facility gives significant advantage in planning of their administration to patients. Moreover, some manufacturers prefer transport of the starting material cryopreserved at the collection site. The cryopreservation protocol used for starting material by the authors is based on combining dimethyl sulphoxide (DMSO) with hydroxyethyl starch (HES) and slow controlled cooling in cryobags housed in metal cassettes. This achieves the mononuclear cell post-thaw viability of 98.8 ± 0.5 % and recovery of 72.8, ± 10.2 %. Transport of the starting material to the manufactures and return transport of the CAR-T therapy product is performed by authorized courier companies. Intermediate cryostorage of the final CAR-T cell therapy product is performed in a separate dry-storage liquid nitrogen container. On the day of infusion, the cryopreserved products are transported to the clinical department in a dry shipper. On the wards the product is removed from the cassette, inserted into a sterile plastic bag, thawed in a 37 degree C water bath followed by immediate intravenous administration. The authors discuss the adherence of the used technology to good manufacturing practice (GMP) principles and genetic safety assurance rules. Doi: 10.54680/fr23310110112.

Hypothermic organ perfusion in the 2020s: mixing the benefits of low temperatures and dynamic flow outside the body.

The cold chain supply of donor organs for transplantation has been an integral part of the delivery of transplant clinical services over the past five decades. Within the technologies used for this, hypothermic machine perfusion (HMP) was a concept, which was attractive to maintain organs under optimal conditions outside the body, and many early research studies on HMP were reported. However, it took the arrival of important new concepts to ensure that HMP was logistically feasible and valuable from an organ physiology perspective within the clinical pathways. This review provides details of the current status of HMP across the range of organs transplanted in the clinic, and discusses what new areas might benefit from applying HMP in coming years. In conclusion, HMP is now being used more frequently for clinical organ preservation in a variety of settings. As new therapies such as cell or gene therapy become more common, HMP will continue to play an important facilitator role for optimising organs in the donor pathway. doi.org/10.54680/fr22510110112.

Evolution of dynamic, biochemical, and morphological parameters in hypothermic machine perfusion of human livers: A proof-of-concept study.

INTRODUCTION: Hypothermic machine perfusion (HMP) is increasingly investigated as a means to assess liver quality, but data on viability markers is inconsistent and the effects of different perfusion routes and oxygenation on perfusion biomarkers are unclear. METHODS: This is a single-centre, randomised, multi-arm, parallel study using discarded human livers for evaluation of HMP using arterial, oxygen-supplemented venous and non-oxygen-supplemented venous perfusion. The study included 2 stages: in the first stage, 25 livers were randomised into static cold storage (n = 7), hepatic artery HMP (n = 10), and non-oxygen-supplemented portal vein HMP (n = 8). In the second stage, 20 livers were randomised into oxygen-supplemented and non-oxygen-supplemented portal vein HMP (n = 11 and 9, respectively). Changes in dynamic, biochemical, and morphologic parameters during 4-hour preservation were compared between perfusion groups, and between potentially transplantable and non-transplantable livers. RESULTS: During arterial perfusion, resistance was higher and flow was lower than venous perfusion (p = 0.001 and 0.01, respectively); this was associated with higher perfusate markers during arterial perfusion (p>0.05). Supplementary oxygen did not cause a significant alteration in the studied parameters. Morphology was similar between static and dynamic preservation groups. Perfusate markers were 2 fold higher in non-transplantable livers (p>0.05). CONCLUSIONS: Arterial only perfusion might not be adequate for graft perfusion. Hepatocellular injury markers are accessible and easy to perform and could offer insight into graft quality, but large randomised trials are needed to identify reliable quality assessment biomarkers.

Alginate Encapsulation to Enhance Biopreservation Scope and Success: A Multidisciplinary Review of Current Ideas and Applications in Cryopreservation and Non-Freezing Storage.

BACKGROUND: The development of encapsulation technologies has played an important role in improving cryopreservation outcomes for many cell and tissue types over the past 20 years. Alginate encapsulation cryopreservation (AECryo) has been incorporated into a range of applications in biotechnology, species conservation and clinical therapies, using cells from many different phyla, including higher plants, animal and human cells. This review describes the background to the origins of AECryo, the development of AECryo in higher plant tissues, broadening to current applications in algal conservation, the roles for AECryo in preserving phytodiversity, fungal species and in animal and human cells. OBJECTIVE: The main aims are to provide information resources on AECryo in different areas of biology and to stimulate new ideas for wider applications and future improvement. The translation of this useful biopreservation strategy into new opportunities for cell cryopreservation and storage at non-freezing temperatures are also discussed.

Advances in the slow freezing cryopreservation of microencapsulated cells.

Over the past few decades, the use of cell microencapsulation technology has been promoted for a wide range of applications as sustained drug delivery systems or as cells containing biosystems for regenerative medicine. However, difficulty in their preservation and storage has limited their availability to healthcare centers. Because the preservation in cryogenic temperatures poses many biological and biophysical challenges and that the technology has not been well understood, the slow cooling cryopreservation, which is the most used technique worldwide, has not given full measure of its full potential application yet. This review will discuss the different steps that should be understood and taken into account to preserve microencapsulated cells by slow freezing in a successful and simple manner. Moreover, it will review the slow freezing preservation of alginate-based microencapsulated cells and discuss some recommendations that the research community may pursue to optimize the preservation of microencapsulated cells, enabling the therapy translate from bench to the clinic.

The effect of thawing protocols on follicle conservation in human ovarian tissue cryopreservation.

BACKGROUND: Ovarian tissue cryopreservation has the potential to improve fertility preservation for a growing number of patients undergoing sterilising therapy, particularly where oocyte or embryo cryopreservation is not suitable. However, its success is limited by significant follicular apoptosis upon thawing, and there is wide variation in thawing protocols used with little evidence of efficacy. OBJECTIVE: To determine the best warming rates to maintain tissue viability. MATERIALS AND METHODS: Ovarian tissue biopsies from 11 patients were taken with informed consent and divided into four pieces, which were allocated to either fresh assessment or to one of several freeze-thaw protocols. Cryopreservation was undertaken using a Stirling cycle cryo-cooler and cryopreserved samples were exposed to different warming protocols. Tissue conservation was then assessed using a marker, neutral red, to identify viable follicles. RESULTS: The results showed greatest follicle conservation rates in fresh samples, followed by those thawed using a rapid thawing protocol (Protocol 1). Tissue thawed using an ultra fast protocol (Protocol 2) and slow warming (Protocol 3) resulted in greater follicle loss. CONCLUSION: These preliminary results indicate thawing conditions significantly affect follicle conservation in cryopreserved human ovarian tissue.

The effectiveness of chocolate milk as a post-climbing recovery aid.

AIM: Recovery is essential to effective performance in climbing competitions which often involve repeated bouts, and sport climbing where climbers may work a route over a number of days prior to a complete ascent. METHODS: This study employed a cross-over design to compare water with chocolate milk as recovery aids following an exhaustive bout of high intensity endurance climbing. Ten male climbers (age: 22±1 years; height: 178.5±7.9 cm; mass: 74.7±11.3 kg) climbed a Tredwall (Brewer Ledge M6) until volitional exhaustion. The participants consumed either water or chocolate milk 20 minutes after the climb and then again with their evening meal. The exercise protocol was repeated 24 hours after the original climb. The second condition was completed 7 days later. Workload indicators of heart rate, rate of perceived exertion (RPE), blood lactate and muscle soreness scores were recorded alongside climbing performance measures of duration and distance of the climb. A improved performance was found after the consumption of chocolate milk, with both a greater distance climbed (F(1,9)=11.704, P=0.008) and duration (F(1,9) =10.922, P=0.009), there were no differences in end of climb heart rate or RPE. RESULTS: Muscle soreness scores were lower three days after exercise following chocolate milk (t(8)=3.773, P=0.005). Chocolate milk as a recovery drink resulted in further sustained climbing, a decrease in muscle soreness, compared to water. It may be pertinent for climbers to consider its use as a recovery aid during repeated climbing bouts. Chocolate milk is a relatively unexplored recovery aid and warrants further attention.

Liquidus tracking: controlled rate vitrification for the cryopreservation of larger volumes and tissues.

BACKGROUND: Vitrification of cells or tissue at controlled cooling rates suitable for larger volumes, and with reduced cryoprotectant toxicity. OBJECTIVE: To set out the current understanding of the LiquidusTracking (LT) vitrification technique, and to discuss the challenges and benefits of translating the method into laboratory protocols more generally applicable to meet requirements of large volume and 3-D cryo-banking in the era of regenerative medicine. METHODS: By adding small amounts of cryoprotectants at each step and subsequently cooling the sample just above its freezing point before further increasing CPA concentration, cryoprotectant toxicity is minimized. RESULT: CPA toxicity can be reduced by lowering the temperature. Different manual approaches to LT were evaluated and further improved. CONCLUSIONS: Manual liquidus tracking is complicated and exhibits potential high variability. Nevertheless, this approach offers the possibility of testing several conditions simultaneously and could be used to pre-test conditions prior to automatic LT development.

Biopreservation of hepatocytes: current concepts on hypothermic preservation, cryopreservation, and vitrification.

Isolated liver cells (primarily isolated hepatocytes) have found important applications in science and medicine over the past 40 years in a wide range of areas, including physiological studies, investigations on liver metabolism, organ preservation and drug de-toxification, experimental and clinical transplantation. An integral component of many of these works is the need to store the isolated cells, either for short or long-term periods. This review covers the biopreservation of liver cells, with a focus on the history of liver cell biopreservation, the application of hypothermia for short-term storage, standard cryopreservation methods for isolated hepatocytes, the biopreservation of other types of liver cells, and recent developments such as vitrification of hepatocytes. By understanding the basis for the different approaches, it will be possible to select the best options for liver cell biopreservation in different applications, and identify ways to improve preservation protocols for the future.

Translating cryobiology principles into trans-disciplinary storage guidelines for biorepositories and biobanks: a concept paper.

Low temperatures are used routinely to preserve diverse biospecimens, genetic resources and non-viable or viable biosamples for medical and clinical research in hospital-based biobanks and non-medical biorepositories, such as genebanks and culture, scientific, museum, and environmental collections. However, the basic knowledge underpinning preservation can sometimes be overlooked by practitioners who are unfamiliar with fundamental cryobiological principles which are more usually described in research literature rather than in quality and risk management documents. Whilst procedures vary, low temperature storage is a common requirement and reaching consensus as to how best it is applied could facilitate the entire biopreservation sector. This may be achieved by encouraging an understanding of cryoprotection theory and emphasizing the criticality of thermal events (glass transitions, ice nucleation, thawing) for sample integrity, functionality and stability. The objective of this paper is to inspire diverse biopreservation sectors to communicate more clearly about low temperature storage and, raise awareness of the importance of cryobiology principles to field newcomers and biopreservation practitioners, by considering how the principles may be translated into evidence-based guidelines for biobank and biorepository operations.

Does hypothermic machine perfusion of human donor livers affect risks of sinusoidal endothelial injury and microbial infection? A feasibility study assessing flow parameters, sterility, and sinusoidal endothelial ultrastructure.

BACKGROUND: Hypothermic machine perfusion (HMP) is better than conventional cold storage in kidney transplantation. Large animal models suggest that HMP may be beneficial for the liver as well, but questions remain about perfusion mode (dual portal/arterial flow versus single flow) and hepatic vascular injury including endothelial dysfunction or potential microbial infectivity during HMP. METHODS: Sixteen human livers rejected for transplantation by all UK centers with appropriate consent for research were randomized into 4 groups (n = 4 each): group 1: ≥7 hours cold storage (CS) and 1 hour HMP through hepatic artery (HA) alone; group 2: ≥7 hours CS and 1 hour HMP through HA and portal vein (PV); group 3: ≥7 hours CS and 1 hour HMP through PV alone; and group 4: ≥8 hours CS. A pressure-controlled prototype based on Lifeport Kidney Transporter (Organ Recovery Systems) was used. Livers were perfused at 4-8°C under sterile conditions with Belzer MPS KPS-1. Perfusion parameters (pressure, flow, resistance, and temperature) were recorded every 15 minutes. Perfusate for microbial culture and sensitivity were taken before and after HMP. Electron microscopy of 3 liver biopsy samples taken before perfusion, were compared with 3 samples from adjacent areas after perfusion. RESULTS: Preset HA pressure of 30 mm Hg and PV pressure of 7 mm Hg were maintained throughout the perfusion. HA and PV flow ranged, respectively, from 11 to 107 mL/min (mean 59.5) and 39 to 199 mL/min (mean 96.2), with no differences between groups. The same was true for resistance: HA and PV resistance ranged, respectively from 0.17 to 1.99 mm Hg/mL/min (mean 0.71) and 0.07 to 0.17 mm Hg/mL/min (mean 0.08). Temperature was maintained at 4-8°C with the use of an external heat exchanger. No difference in sinusoidal endothelial ultrastructure was seen before and after machine perfusion or between any of the groups. Sterility was maintained throughout the HMP. CONCLUSIONS: HMP of human livers did not produce evidence of sinusoidal endothelial injury or breach of sterility. Single or dual perfusion modes did not affect vascular resistance or flow. The results suggest that further studies of HMP with human livers are warranted.

Cryopreservation of encapsulated liver spheroids using a cryogen-free cooler: high functional recovery using a multi-step cooling profile.

Acute liver failure has high mortality with unpredictable onset. A bioartificial liver, comprising alginate-encapsulated HepG2 spheroids, could temporarily replace liver function but must be cryopreservable. For clinical use, contamination risks from liquid coolants for cryopreservation and storage should be minimized. A cryogen-free cooler was compared to nitrogen vapour-controlled cryopreservation of alginate-encapsulated liver cell spheroids (AELS). AELS were cooled using a multi-step, slow-cooling profile in 12 percent v/v Me2SO Celsior and stored in liquid nitrogen; temperatures were recorded throughout, and the AELS were assayed at 24, 48 and 72 hours post-warming and results compared to unfrozen control values. Viability was assessed by fluorescent staining and quantified using image analysis; cell numbers were quantified using nuclear counts, and cell function using albumin synthesis. The cryogen-free cooler performed the cooling profile as desired, apart from one step requiring a rapid cool ramp. Viability, cell numbers and function were similarly decreased in both cryopreserved groups to about 90 percent, 70 percent and 65 percent of the controls respectively. This technology offers a clinic alternative to liquid nitrogen-coolant cryopreservation.

31-Phosphorus magnetic resonance spectroscopy for dynamic assessment of adenosine triphosphate levels in pancreas preserved by the two-layer method.

Cold preservation injury influences islet graft function. Reliable tools for real-time assessment of pancreas viability before islet isolation are lacking. Phosphorus magnetic resonance spectroscopy ((31)P-MRS) was used immediately after organ harvest to study rat pancreases at 4 °C to 6 °C in five randomized preservation groups: Marshall's solution, static two-layer method (TLM), continuous TLM with oxygen perfused at 0.5 L/min, and static TLM or continuous TLM both the latter following 30 minutes of warm ischemia (WI). (31)P spectra were analyzed for phosphomonoesters, inorganic phosphate (Pi) and α-, ß-and γ-nucleotide triphosphate. Intergroup rates of change of [γ-adenosine triphosphate (ATP)]/[Pi] and [ß-ATP]/[Pi] throughout preservation period were significantly different. For continuous TLM there was an increase relative to baseline (0.043 (SD0.033) h(-1) and 0.029 (0.029) h(-1), respectively) but a decrease for both static TLM (-0.023 (0.016) h(-1) and 0.015 (0.026), P < .001 and < .05, respectively) and Marshall's (-0.049 (0.025) h(-1) and -0.036 (0.019) h(-1), respectively, both P < .001) with respect to continuous TLM. Rate of decrease was similar for the Marshall's and static TLM groups. [γ-ATP]/[Pi] and [ß-ATP]/[Pi] increased with WI continuous TLM (0.008 [0.009] h(-1) and 0.007 [0.008] hr(-1), respectively) but decreased for WI static TLM (-0.018 (0.008) h(-1) and -0.014 (0.004) hr(-1), respectively, P < .001). (31)P-MRS is an effective tool for noninvasive assessment of pancreas bioenergetics. Continuous TLM preserves cellular bioenergetics and is superior to current non-perfluorocar bone based solutions for pancreas preservation.

Smoking and periodontal disease: discrimination of antibody responses to pathogenic and commensal oral bacteria.

Smoking is an independent risk factor for the initiation, extent and severity of periodontal disease. This study examined the ability of the host immune system to discriminate commensal oral bacteria from pathogens at mucosal surfaces, i.e. oral cavity. Serum immunoglobulin (Ig)G antibody reactive with three pathogenic and five commensal oral bacteria in 301 current smokers (age range 21-66 years) were examined by enzyme-linked immunosorbent assay. Clinical features of periodontal health were used as measures of periodontitis. Antibody to the pathogens and salivary cotinine levels were related positively to disease severity; however, the antibody levels were best described by the clinical disease unrelated to the amount of smoking. The data showed a greater immune response to pathogens than commensals that was related specifically to disease extent, and most noted in black males. Significant correlations in individual patient responses to the pathogens and commensals were lost with an increasing extent of periodontitis and serum antibody to the pathogens. Antibody to Porphyromonas gingivalis was particularly distinct with respect to the discriminatory nature of the immune responses in recognizing the pathogens. Antibody responses to selected pathogenic and commensal oral microorganisms differed among racial groups and genders. The antibody response to the pathogens was related to disease severity. The level of antibody to the pathogens, and in particular P. gingivalis, was correlated with disease severity in black and male subsets of patients. The amount of smoking did not appear to impact directly serum antibody levels to these oral bacteria.

Influence of zinc and zinc chelator on HT-29 colorectal cell line.

Trace elements are involved in many key pathways involving cell cycle control. The influence of zinc and zinc chelator (TPEN) on transcription levels of the main zinc transporters (ZnT1 and ZIP1) in the HT-29 colorectal cell line has not been reported. Proliferation of HT-29 cells was measured using the methylene blue assay after exposure to zinc (two concentrations), TPEN (two concentrations), or a combination of zinc and TPEN (simultaneously and sequentially) for 4 h, 8 h, and 24 h. The transcription levels of ZnT1, ZIP1, vascular endothelial growth factor (VEGF), and caspase-3 were determined using reverse transcriptase real-time polymerase chain reaction (RT-PCR) after exposure of cells to zinc and TPEN. The zinc content in the substrate (medium used for culture) was determined using atomic absorption spectrometry. TPEN decreased cellular proliferation causing complete cell death by 8 h. Zinc had a protective effect against short periods of exposure to TPEN. There was no correlation between the transcripts of main zinc transporters and the zinc content in the substrate. The zinc content in the substrate remained constant after varying periods of cell culture. TPEN decreased the transcript levels of caspase-3 and VEGF, which are surrogate markers for apoptosis and angiogenesis. Zinc chelation of HT-29 cells causes cell death. Zinc appears to be protective for short periods of exposure to TPEN but has no protective effect on prolonged exposure. HT-29 cells are not able to counteract the effect of intracellular chelation of zinc by altering zinc transport. Further research into the mechanisms of these findings is necessary and may lead to novel therapeutic options.

Clinical trial of a formal group fatigue program in multiple sclerosis.

Fatigue: Take Control is a novel program to teach fatigue management to people with multiple sclerosis (MS) following recommendations in the Fatigue and Multiple Sclerosis guideline. Fatigue: Take Control includes six 2-hour group sessions with DVD viewing, discussion and homework and accompanying participant and leader workbooks. While many people have participated in Fatigue: Take Control programs, its efficacy has not been determined. The objective of this study was to determine whether participation in Fatigue: Take Control reduces fatigue and increases self-efficacy in people with MS. Thirty participants were randomly assigned to a group who immediately participated in the program (FTC) or a wait-list group (WL). The primary outcome was the Modified Fatigue Impact Scale (MFIS) and secondary outcomes were the Multiple Sclerosis Self-Efficacy Scale (MSSE) and the Fatigue Severity Scale (FSS). The MFIS was administered on 10 occasions. Other measures were administered on four occasions. A mixed model tested the effects using all observations. Compared with the WL, the FTC group had significantly more improvement on the MFIS [F(1, 269) = 7.079, p = 0.008] and the MSSE [F(1, 111) = 5.636, p = 0.019]. No significant effect was found for the FSS. Across all visits, fatigue was significantly lower and self-efficacy was significantly higher for the FTC group compared with the WL group. This pilot study demonstrated significant effects in fatigue and self-efficacy among subjects taking the Fatigue: Take Control program, suggesting that this comprehensive program based on the Fatigue and Multiple Sclerosis guideline may be beneficial in MS.

Protective effects of a carbon monoxide-releasing molecule (CORM-3) during hepatic cold preservation.

UNLABELLED: There is increasing evidence that carbon monoxide (CO), a signaling molecule generated during the degradation of heme by heme oxygenase-1 (HO-1) in biological systems, has a variety of cytoprotective actions, including anti-hypoxic effects at low temperatures. However, during liver cold preservation, a direct effect needs to be established. Here, we designed a study to analyze the role of CO, delivered via a carbon monoxide-releasing molecule (CO-RM) in the maintenance of liver function, and integrity in rats during cold ischemia/reperfusion (CI/R) injury. We used an isolated normothermic perfused liver system (INPL) following a clinically relevant model of ex vivo 48 h cold ischemia stored in a modified University of Wisconsin (UW) solution, to determine the specific effects of CO in a rat model. CO was generated from 50 microM tricarbonylchloro ruthenium-glycinato (CORM-3), a water-soluble transition metal carbonyl that exerts pharmacological activities via the liberation of controlled amounts of CO in biological systems. The physiological effects of CORM-3 were confirmed by the parallel use of a specific inactive compound (iCORM-3), which does not liberate CO in the cellular environment. CORM-3 addition was found to prevent the injury caused by cold storage by improving significantly the perfusion flow during reperfusion (by almost 90%), and by decreasing the intrahepatic resistance (by 88%) when compared with livers cold preserved in UW alone. Also, CORM-3 supplementation preserved good metabolic capacity as indicated by hepatic oxygen consumption, glycogen content, and release of lactate dehydrogenase. Liver histology was also partially preserved by CORM-3 treatment. CONCLUSIONS: These findings suggest that CO-RM could be utilized as adjuvant therapeutics in UW solutions to limit the injury sustained by donor livers during cold storage prior to transplantation, as has been similarly proposed for the heart, and kidney.

Mitochondrial function after liver preservation in high or low ionic-strength solutions: a comparison between UW-based and sucrose-based solution.

In this study we evaluated mitochondrial function after liver cold storage and normothermic reperfusion. The preservation solutions were: modified University of Wisconsin (mod UW) and sucrose-based solution (SBS). After cold preservation liver was re-perfused for 1 hour in vitro with Krebs-Ringer buffer at 37 degree C. Samples of tissue were taken for ATP determination. Mitochondrial respiratory parameters, succinate oxidase complex activity, mitochondrial H+- ATPase and intramitochondrial potassium concentration were assayed. It was shown, that brief (1 hour) cold storage and subsequent normothermic reperfusion revealed no difference in liver ATP content between mod UW and SBS groups but resulted in a gradual decrease of 50 percent after 24-hour storage and reperfusion. Mitochondrial potassium ion concentration increased by 40 percent after 1-hour cold storage in the mod UW as compared to control (P value less than 0.05) and SBS. After brief cold storage ADP and uncoupler-stimulated respiration increased by 120 percent in SBS group, unlike mod UW, when succinate was used as substrate, and was more pronounced after 24 hour. Succinate oxidase complex activity did not change over either cold storage or warm reperfusion. Mitochondrial H+-ATPase activities in SBS and mod UW did not differ and both were inhibited after 24-hour cold storage. Our data demonstrate that low ionic strength preservation solution can substantially modulate mitochondrial energy turnover due to substrate oxidation increase. Many of the changes in mitochondrial function follow brief exposure to low temperatures.