The preferred method of organ preservation is simple cold storage (CS), which involves flushing the organ with the preservative and storing at 0ºC to 4ºC prior to
transplantation.

Lindbergh pump : a perfusion apparatus by means of which an organ removed from the body may be kept alive indefinitely.

• Collins solution (1970s) : potassium, magnesium, phosphate, sulfate and glucose
• Euro-Collins^® (EC) solution : as above but without magnesium to prevent precipitation as magnesium phosphate; it became the standard for CS of the kidneys^ref. A phosphate-buffered saccharide solution and the high concentration of glucose suppressed hypothermic-induced cell swelling, which made these solutions suitable for 24 to 30-hour preservation of kidneys. For the liver and pancreas, the safe preservation time was less (4-8 hours). Distribution of EC ceased in the US in 2002 but continues to be used in Europe.
• a hypertonic solution was developed by Marshall (1970s) that contained citrate as an agent to suppress hypothermic-induced cell swelling^ref. This solution was also successful in kidney preservation for approximately 30 hours and in liver preservation for up to approximately 8 hours. The short period of safe preservation for the kidney (24 to 30 hours) was not a large detriment to sharing
• ET-Kyoto (ET-K) solution^ref contains trehalose, gluconate, and hydroxyethyl starch
• modified ET-Kyoto solution^ref by adding N-acetylcysteine, nitroglycerin, and dibutyryl adenosine 3', 5'-cyclic phosphate
• Belzer University of Wisconsin (UW) solution (ViaSpan^®; source : DuPont Pharmaceuticals Co. => NPBI International BV, The Netherlands) (late 1980s^ref) was shown to be equally effective for relatively long-term preservation of all 3 organs with safe preservation in dogs for 48 to 72 hours^{ref1, ref2}. This solution became the clinical standard throughout the world with excellent results. In a prospective, randomised trial of 695 cadaveric renal transplants comparing kidneys preserved in UW and EC, the incidence of delayed graft function was significantly less in transplant recipients receiving UW-preserved kidneys than those receiving EC-preserved kidneys (23% versus 33%, respectively; P=0.003)^ref. Another study conducted at the University of Pittsburgh demonstrated UW to safely increase preservation time for livers to more than 15 hours (maximum of 37 hours) compared with EC^ref.
• pentafraction of hydroxyethyl starch (HES) : 50 g/l
• lactobionic acid (as lactone) : 35.83 g/l
• potassium phosphate monobasic : 3.4 g/l
• magnesium sulfate heptahydrate : 1.23 g/l
• raffinose pentahydrate : 17.83 g/l
• adenosine : 1.34 g/l
• allopurinol : 0.136 g/l
• total glutathione : 0.922 g/l
• potassium hydroxide : 5.61 g/l
• sodium hydroxide/hydrochloride acid : adjust to pH 7.4
• water for injection : q.s.
It is clear to light yellow, sterile, non-pyrogenic solution for hypothermic flushing and storage of organs. The solution has an approximate calculated osmolarity of 320 mOsm, a sodium concentration of 29 mEq/l, a potassium concentration of 125 mEq/l, and a pH of about 7.4 at room temperature. Before reperfusion is established in the recipient, , the donor organ must be flushed free of the cold storage solution using a physiological solution to prevent occurrence in the recipient of potentially serious cardiovascular complications such as hyperkaliemic cardiac arrest or bradyarrhythmia. Because of the high concentration of potassium in the solution, precautions must be taken during organ retrieval to prevent cardiac arrest. VioSpan contains variable amounts of visible and subvisible particles (primarily 5-100 mm in size) which have been identified as stearate and palmitate fatty acids salts. Stearates and palmitates are used in manufacturing the bags in which ViaSpan is distributed (see filtration instructions). ViaSpan includes components (allopurinol and pentafraction) which individually have caused hypersensitivity reactions in patients. Additionally, the additives recommended for use in ViaSpan (penicillin, insulin, and dexamethasone) have individually been associated with hypersensitivity reactions in patients. Physicians should consult individual drug labeling and be alert to treat possible reactions.
• Celsior Cold Flush, Storage and Transport Solution (SangStat Medical Corporation) is a modified UW solution^ref that takes advantage of the primary agent in UW that makes it a superior preservation solution – lactobionic acid^{ref1, ref2}. Therefore, it is not surprising that Celsior should provide similar preservation efficacy to UW solution. However, Celsior has not been tested for long-term (48 to 72 hour) preservation in renal, pancreas or liver transplant models. Celsior is suggested to be superior to UW because it has a lower concentration of potassium (replaced with sodium) and a decrease in viscosity due to the elimination of hydroxyethyl starch. There is no definitive evidence that either lowering the potassium concentration or omitting the colloid affects preservation efficacy. Furthermore, in a study examining cell death in 69 rat livers preserved with UW, HTK and Celsior after 24-hour storage, bile secretion was best preserved in UW^ref. Leakage of hepatocellular enzymes (i.e. serum gultamicoxaloacetic transaminase (SGOT) and lactate dehydrogenase (LDH)) was lower in UW than HTK at all time points and lower than Celsior after 16 hours. In this study, rat livers were best preserved in UW for long-term storage (16 to 24 hour) and the data suggest that even for short-term cold storage of liver grafts (eight hour), HTK is less effective than UW.
• histidine-tryptophan-ketoglutarate (HTK) solution (Custodiol^®; source : Odyssey Pharmaceuticals, Inc.)^{ref1, ref2}. HTK solution, originally developed as a

cardioplegia solution, is being touted as a solution of equal efficacy to UW solution^{ref1, ref2, ref3}. Some centres are now comparing the solutions clinically. The claimed advantages of HTK solution to ViaSpan include lower cost per litre, lower viscosity resulting in easier diffusion into the organ, faster cooling rates and low potassium so that HTK can be allowed direct release into the patients circulation. These claims are unsupported as important in organ preservation. The role of viscosity and the rate of cooling in preservation efficacy are not clear. Release of a high concentration of potassium from residual preservative in a large organ such as the liver can lead to cardiac arrhythmias. This is not a problem with smaller organs like the kidney because of the smaller vascular and extracellular space. Thus, the organ is flushed with a solution containing a low concentration of potassium prior to transplantation (i.e. lactated ringers). Instead of this pre-transplant, vascular flush being perceived as an extra task, this step may be highly beneficial to the organ since it  washes out the potentially harmful cellular metabolites that can accumulate during the period of cold ischaemia. Some of these are powerful vasoconstrictors (chemokines and cytokines) and can exacerbate reperfusion injury in the organ. Furthermore, various intracellular, catabolic enzymes are released from cells during cold storage and removal of these enzymes with a pre-transplant vascular flush should be performed regardless of the potassium content. The best method for comparing various solutions exists in a laboratory or clinical trial where the only variable is the composition of the preservation solution. This is difficult in clinical studies because
it is not possible to control for the many variables including donor characteristics (i.e. age, preexisting health condition, intensive-care unit (ICU) care and cause of death), skill of the organ procurement team and surgical staff, method of preservation solution application or health of the recipient. Furthermore, in clinical organ transplantation, there is an immunological factor that can have a dramatic effect on both short and long-term organ function. Therefore, the best method to compare solutions occurs in an experimental setting where most transplant variables can be controlled. For kidney studies, performing auto-transplants can eliminate the immunological complications. In a study conducted in the University of Wisconsin laboratory, UW was compared to phosphate-buffered sucrose (PBS) and HTK in 3-day preservation of dog kidneys. In those dogs receiving UW-preserved kidneys there was 100% survival (6 dogs) and a rapid return of kidney function to normal after 3 day preservation, with PBS survival was only 17% (1 in 6) and HTK survival was 83% (5 in 6). In all cases, there was delayed graft function with serum creatinines elevated to an average of 8mg/dL on day 3 and it remained high out to 10 days (4 mg/dL versus 2 mg/dL for UW). A comparative study with dog livers also showed that HTK was not efficacious. No dogs survived after liver transplantation with a 48-hour preservation time with HTK. All dogs receiving a liver preserved with UW for 48 hours survived. Three studies further support the superiority of UW in comparison to HTK when the cold ischaemic time (CIT) exceeds 24 hours^{ref1, ref2, ref3}. In a retrospective analysis of 323 cadaveric kidney transplantation, there was no significant difference in delayed graft function in those kidneys preserved for less than 24 hours.12 However, when CIT exceeded 24 hours, the delayed graft function rates for UW-preserved kidneys were 23.9% versus 50% with HTK-preserved kidneys (P=0.006). Furthermore, graft survival at one year was 91% in those patients receiving UW-preserved kidneys compared with 77.4% for HTK (P=0.059). In a small study of 12 non-heart-beating canine kidneys, after two weeks four of the 6 UW preserved kidney recipients survived and only one of 6 in the HTK group survived^ref. This study also examined total adenine nucleotide (TAN) levels, showing that higher TAN levels indicate better preservation of energy metabolism, enhanced protection against the deleterious effects of warm ischaemia and more cellular viability. In this study, one hour after reperfusion, TAN levels were significantly higher in the UW group (P <.05). There was no recovery of TAN levels observed within one hour of reperfusion in the HTK group. The results of this study demonstrate that UW solution is superior to HTK for cold storage preservation of ischaemically damaged kidneys. Lastly, another study tested the viability of endothelial cells stored in UW, HTK and EC^ref. Endothelial cells are the first targets of deterioration during cold ischaemia. Endothelial damage has been shown to cause liver failure. In this trial, the UWpreserved cells maintained 99% cell viability after 24 and 48 hours of cold storage and 86.7% cell viability after 72 hours. However, preservation with HTK and EC allowed cell survival for only 24 hours with no viable cells seen after 48 hours. Experimentally, no other preservation solution has been shown to consistently preserve kidneys and livers for as long as UW. The solution is safe for long-term preservation of livers, kidneys and pancreas and is ideally suited as a universal intraaortic flush and CS solution^{ref1, ref2, ref3, ref4, ref5, ref6, ref7, ref8, ref9}. Preservation times in the clinical setting are usually shorter than the maximum allowed by UW due to the differences in the initial quality of the organs. In the laboratory, the organs are ideal; they come from healthy donors and are transplanted into healthy recipients. These conditions do not exist clinically, so safe preservation times are considered to be less than 24 hours. Since short preservation times are typical in the clinical setting, many preservation solutions may yield similar results. For instance, in comparing UW to HTK and Celsior clinically, equivalency is claimed because preservation times are short. If the goal is shortened preservation time, then EC, Marshall’s solution and PBS may also be suitable. Only UW has been shown to give effective, safe, long-term kidney and liver preservation. Some clinical studies have questioned the efficacy of HTK solution for use in the ideally harvested and non-ideally harvested kidney^{ref1, ref2}. The extra margin of safety given by long-term organ preservation with UW should provide surgeons with a degree of assurance that if organs could not be transplanted within a short preservation time, the longer times would be well tolerated in most cases. Furthermore, the quality of organs preserved with UW continues to be excellent. Lastly, HTK purports greater cost savings than UW. The average wholesale price (AWP) for UW solution is US$282 per litre and the AWP for HTK is US$211 per litre. However, since HTK is less viscous than UW solution, HTK requires more volume than UW in order to completely flush the extracellular space and maintain equilibration of the preservation solution throughout the organ, thereby minimising any savings. In a study of 60 human liver transplants comparing preservation with UW and HTK, the preservation costs were equivalent due to the increased volume requirements for HTK^ref. Also, in a randomised study of 711 kidney donors, the recommended volume for the in situ flush-out was 5,000ml to 6,000ml for HTK, 4,000ml for EC and 1,000ml to 2,000ml for UW^ref. In addition, the product labelling for HTK indicates that as a general rule, 8-12 litres of HTK at 2ºC to 4ºC should be perfused (about 300ml per kg of body weight) versus the product labelling for UW, which indicates using 4-6 litres for the same procedure. The question of which solution to use is a controversial question for some transplant centres. For short-term preservation and with a highly skilled team for organ procurement and surgery many solutions will give similar results. However, UW continues to be the state-of-the-art preservation solution, continues to be widely used in the USA and produces outstanding results^ref.
• advantages :
• unique composition and mechanism of action :
• low in sodium and potassium
• induces cell membrane deactivation with sodium, not potassium
• buffered with histidine, not phosphates
• low viscosity
• no need to flush donor kidney before transplantation
• no reported side effects
• for added convenience :
• ready to use : no additives, premixing, or filtering
• 1-liter and 5-liter packaging, with 1-year shelf-life
• composition : 1,000 mL Custodiol^® contain :
• 0.8766 g = 15 mmol sodium chloride
• 0.6710 g = 9.0 mmol potassium chloride
• 0.1842 g = 1.0 mmol potassium hydrogen 2-ketoglutarate
• 0.8132 g = 4 mmol magnesium chloride ^. 6 H₂O
• 3.7733 g = 18 mmol histidine ^. HCl ^. H₂O
• 27.9289 g = 180 mmol histidine
• 0.4085 g = 2.0 mmol tryptophan
• 5.4561 g = 30.0 mmol mannitol
• 0.0022 g = 0.015 mmol calcium chloride ^. 2 H₂O
• physical properties :
• pH = 7.02 - 7.20 at 25°C (pH 7.4-7.45 at 4°C)
• osmolality : 310 mosmol/kg
• indications for use : Custodiol^® HTK solution is indicated for perfusion and flushing of donor kidneys prior to removal from the donor or immediately after removal from the donor. The solution is left in the organ vasculature during hypothermic storage and transportation (not for continuous perfusion) to the recipient
• overdoses : in the case of entry of the HTK solution into the general circulation, the resultant change in the concentration of sodium and calcium are very slight. After checking sodium and calcium levels in the extracorporeal circulation both of these electrolytes should be replaced if necessary
• instructions for use : required equipment :
• infusion apparatus with a Y piece for bottle or bag
• infusion cannula tube 2.5 to 3 mm
• tube clamp
• infusion stand with a height setting of up to 200 cm with tape measure
• cooling equipment (5° to 8°C) for use in cardiac surgery
• infusion tube with an internal diameter of 6 mm
• transport container with sterile pouch for transport of the cooled organ from donor to recipient
• tolerance to ischemia by the kidney : the kidney may be stored with ice cold Custodiol^® solution at about 2 to 4°C with a period of (cold) ischemia of up to 48 hours. Warm ischemia time, that is to say the average time period required for the completion of anastomosis of the vessels, is usually 30 minutes. Taking this time as a basis, the organ recovers completely with optimal immediate function within 24 hours.
• introduction of renal perfusion : following successful laparotomy, the kidney is prepared by ligature of the capsular vessels. The perfusion catheter for selective kidney perfusion is fixed in the renal artery using a tourniquet. Perfusion is performed under hydrostatic pressure (maximum of 120 mmHg). Within the first minute of perfusion, the renal vein is incised and clamped off adjacent to the vena cava. The escaping perfusate is removed from the abdominal cavity. After approximately 10 minutes of perfusion, the kidney is resected before transplantation. Should the center decide to use the so-called aorto-single flush technique, the total amount of the preservation solution needed is perfused only via the aortal line. Once again, a pressurized infusion is not necessary. A Y-perfusion system is recommended in addition to perfusion tubing of the largest possible caliber and perfusion cannulae with an internal bore of at least Charrière 15 (5 mm)
• transport of a donor organ : the transport of a donor organ to the recipient utilizes a sterile pouch accomodating the size of the kidney in an ince cold Custodiol^® solution. The organ must be completely covered by the solution. The pouch is sealed with adhesive tape and is placed into a second container which is also filled with Custodiol solution in order to prevent a breakdown of insulation and cooling by trapped air. The double bagged organ is placed into a sterile plastic container and is closed with a secure lid. The plastic bag is then placed into a transport container packed with ice for transport. Information about the donor, copies of the laboratory results and blood samples from the donor are also included. The transport of the donor organ in Custodiol solution must be accomplished as quickly as possible
• clinical experience : a major multi-center prospective randomized trial has been carried out in Europe comparing 3 perfusion and preservation solutions for use in kidney transplants^ref. The 3 solutions were Custodiol^® HTK solution, the Belzer UW solution, and the Euro-Collins (EC) solution. 47 centers partecipated and followed a strict protocol. Over a thousand kidneys were included in the study. In the HTK-UW study, there were 342 donors and 611 transplants (the UW group had 168 donor and 297 transplants, the HTK group had 174 donors and 314 transplants). In the HTK-EC study, there were 317 donors and 569 translants (the EC group had 155 donors and 277 transplants, the HTK group had 162 donors and 292 transplants). This study compared kidney survival in the HTK group with the UW group, and also with the EC solution, and showed that for k idney transplants, the HTK solution performs as well overall as the UW solution, and significantly better than EC solution for initial nonfunction. The average cold ischemia time in the HTK-UW study was 25.8 hours in the HTK group and 25.5 hours in the UW group. In the HTK-EC group, the average cold ischemia time was 24.1 hours in the HTK group and 24.2 hours in the EC group. The overall kidney survival rates from the 47-center study for HTK versus UW, and HTK versus EC at 4 time points were :

	HTK	UW	HTK	EC
1 month	91%	91%	85%	86%
12 months	83%	82%	80%	74%
24 months	77%	74%	76%	71%
36 months	74%	68%	70%	67%

Delayed graft function that required 2 or more dialysis sessions during the first week was 20% (107/544) in the pooled HTK groups, 25% (66/266) for the UW group, and 32% (85/268) for the EC group. Initial nonfunction (INF) occurred in 33% of the kidneys in both HTK and UW groups, and in the other sudy, INF occurred in 29% of the HTK group and 43% of the EC group
• no adverse events
• how supplied : bottles of 1000 mL, bag of 5000 mL. Store at 8°C-15°C (46°F - 59°F) and protect from light.

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