Mechanism of action of washout solutions for kidney preservation

Organ Preservation into the 2020s: The Era of Dynamic Intervention

Organ preservation has been of major importance ever since transplantation developed into a global clinical activity. The relatively simple procedures were developed on a basic comprehension of low-temperature biology as related to organs outside the body. In the past decade, there has been a significant increase in knowledge of the sequelae of effects in preserved organs, and how dynamic intervention by perfusion can be used to mitigate injury and improve the quality of the donated organs. The present review focuses on (1) new information about the cell and molecular events impacting on ischemia/reperfusion injury during organ preservation, (2) strategies which use varied compositions and additives in organ preservation solutions to deal with these, (3) clear definitions of the developing protocols for dynamic organ perfusion preservation, (4) information on how the choice of perfusion solutions can impact on desired attributes of dynamic organ perfusion, and (5) summary and future horizons.

An integrated theory of the no-reflow phenomenon and the beneficial effect of vascular washout on no-reflow

OBJECTIVES

No-reflow is failure of perfusion in free tissue transfer despite adequate arterial inflow. The objectives of this study were to construct a theory of interactive mechanisms of the no-reflow phenomenon and to determine whether preischemic vascular washout could increase flap ischemia tolerance.

STUDY DESIGN

The evidence for the role of various mechanisms in the development of no-reflow is reviewed, and an integrated network proposed. A rat-groin free flap model is used to test preischemic vascular washout with normal saline, heparinized normal saline, lactated Ringer's solution, Tis-U-Sol, and Viaspan.

METHODS

The mean ischemia tolerance of this flap without any therapeutic intervention was first determined, using 22 animals. An additional 50 animals were used to compare with the control group the ischemia tolerance of flaps washed out with the above fluids before their ischemic period.

RESULTS

The critical ischemia time 50 (time after which half of the flaps are expected to survive and half, die) of the untreated flap is 23.4 hours in this model (P<.05). Flaps washed out with normal saline or lactated Ringer's solution have significantly worse ischemia tolerance (P<.0001). Flaps washed out with Tis-U-Sol or Viaspan behave similarly to the control group (P>.57). Flaps receiving preischemic washout with heparinized normal saline (4,000 units/L) had a significantly better outcome than the control group (P<.027).

CONCLUSIONS

Preischemic washout with normal saline, lactated Ringer's solution, or heparinized Tis-U-Sol is detrimental for flap survival after ischemia, Tis-U-Sol- and Viaspan-treated flaps do have ischemia tolerance similar to the control group, and flaps washed out with heparinized normal saline have a survival advantage in this model.

Organ preservation

Organ preservation is the supply line for organ transplantation. Currently, the liver, pancreas, and kidney can be successfully preserved for up to two days by flushing the organs with the University of Wisconsin (UW) organ preservation solution and storing them at hypothermia (0-5 degree C). The UW solution is effective because it uses a number of cell impermeant agents (lactobionic acid, raffinose, hydroxyethyl starch) that prevent the cells from swelling during cold ischemic storage. Additionally, the UW solution contains glutathione and adenosine, agents that may stimulate recovery of normal metabolism upon reperfusion by augmenting the antioxidant capacity of the organs (glutathione) or by stimulating high-energy phosphate generation (adenosine) upon reperfusion. Although this method of organ preservation is effective, some organs (5-15% of livers and 20-30% of kidneys) do not function well upon transplant. Injury may be preservation related but may also result from donor and recipient factors that render the organs more susceptible to preservation damage. Results with continuous perfusion of kidneys in the clinics show a reduction in preservation/reperfusion damage. This may be a more appropriate preservation method than cold storage. In this chapter we discuss the development and use of the UW solution and present clinical results. Although intraabdominal organs are well preserved at present, intrathoracic organs (lungs and heart) are less well preserved, and better methods for preservation of these organs are needed for increased use of lung and heart transplantation.

Pancreatic islet purification using bovine serum albumin: the importance of density gradient temperature and osmolality

Euro-Ficoll and bovine serum albumin (BSA) are two of the most commonly used density gradient media for the purification of pancreatic islets. Euro-Ficoll is based upon Euro-Collins, a cold storage medium, and must, therefore, be used at 4 degrees C. The ionic composition of BSA, however, is likely to contribute to hypothermic cellular swelling, and this may influence the efficiency of islet purification using this medium at 4 degrees C. Experience in this laboratory also suggested that batch-to-batch variation in islet purity using BSA was related to differences in BSA osmolality. The aim of this study was to assess the effect of gradient medium temperature and osmolality on the purification of human and porcine islets using BSA. Pancreata were collagenase-digested, and islets were purified on continuous linear density gradients of BSA. The distribution of insulin and amylase in each gradient was assayed, and used to calculate the median density of islets and exocrine tissue, and the efficiency of islet purification (% amylase contamination at a fixed insulin yield), using: 1) gradient osmolalities of 300, 400, and 500 mOsm/kg H2O (seven porcine pancreata), and 2) gradients at 4 degrees C and at 22 degrees C (eight human and seven porcine pancreata). Increase in density gradient osmolality produced increases in porcine exocrine tissue density which exceeded changes in islet density, resulting in improved islet purity, maximal at a BSA osmolality of 400 mOsm/kg H2O. For human pancreata there was no significant change in pancreatic tissue densities nor islet purity with temperature.(ABSTRACT TRUNCATED AT 400 WORDS)

Safe pulmonary preservation for 12 hours with low-potassium-dextran solution

The function of porcine left lung allografts was studied after perfusion with (150 mL/kg) and storage for 12 hours in a 4 degrees to 6 degrees C low-potassium-dextran solution (Perfadex; Kabi Pharmacia AB, Uppsala, Sweden). After a left lung transplantation, an artificial lung in the form of venoarterial extracorporeal membrane oxygenation was established. The artificial lung has a "biological" heparin-coated surface (Carmeda AB, Stockholm, Sweden), and there is no need for systemic anticoagulation. Immediately thereafter, pneumonectomy of the normal right lung was done. All the animals were weaned from the artificial lung within 1 hour after the pneumonectomy. Six animals were followed up for 24 hours. They were in good condition throughout the 24-hour observation period with arterial oxygen tensions around 200 mm Hg (inspired oxygen fraction = 0.4) and arterial carbon dioxide tensions around 40 mm Hg. This study demonstrates a reliable method for continuous evaluation of the function of a transplanted lung immediately after transplantation and over the ensuing postoperative period. Safe 12-hour lung preservation can be obtained with the low-potassium-dextran solution Perfadex.

Prolongation of secondary critical ischemia time of experimental skin flaps using UW solution as a normothermic perfusate

A myriad of investigations have been published on the pharmacologic manipulation of flaps to enhance tolerance to ischemia. We recently reported a threefold increase in ischemic tolerance of the rat abdominal skin flap pedicle after 6 hours of primary ischemia and 12 hours of reperfusion. Flaps underwent normothermic perfusion washout with lactated Ringer's or U.W. solution, a newly developed organ preservation medium. Perfusion washouts were performed at one of three different points in the protocol: (1) onset of primary ischemia; (2) onset of secondary ischemia; or (3) 2 hours after onset of secondary ischemia. The last group was used to simulate the clinical situation in which flaps are discovered and salvage procedures instituted at a delayed time interval. This is the longest normothermic ischemic interval reported. We undertook the present study to determine the utility of the U.W solution in prolonging the tolerance of the flap to a second ischemic insult after a period of reperfusion. Seventy-five unilateral rat abdominal skin flaps were raised. Secondary ischemia was produced by placing a microvascular clamp across the inferior epigastric pedicle. Flap survival was assessed at 1 week postoperatively. While none of the nonperfused flaps survived 8 hours of secondary ischemia, at least 50% of the U.W. perfused flaps survived an average of 14 hours of secondary ischemia. Lactated Ringer's perfusion washout only modestly increased the ischemic tolerance. Perfusion washout in the secondary ischemic phase improved the ischemic tolerance to a significantly greater degree than in the primary ischemic interval.

The use of continuous density gradients for the assessment of islet and exocrine tissue densities and islet purification

The purification of large numbers of human pancreatic islets remains one of the limiting factors in islet transplantation. This paper describes and validates a method for accurately and reproducibly determining the density of islets and exocrine tissue in pancreatic digest on the basis of their isopycnic distribution on linear continuous density gradients. The use of this data to analyse and compare the purity of a standard 60% islet yield is described. The results obtained using such gradients will enable factors responsible for the variation in yield between pancreases to be determined and optimized, improving the results and reliability of islet purification.

The functional effects of suppression of hypothermia-induced cell swelling in liver preservation by cold storage

It is known that cellular edema and functional impairment develop during anaerobic cold storage of organs. The extent of both is related to the storage time and the composition of the preservation solution used. We studied hypothermia-induced cell swelling and its effect on liver function after cold storage preservation with either Eurocollins (EC), a number of modified EC solutions in which glucose was replaced by various concentrations of raffinose, or UW solution. After 24 h storage, tissue swelling as determined by total tissue water (TTW) in rat liver tissue slices was most pronounced in slices incubated in Eurocollins, whereas the TTW was only moderately increased in slices stored in modified Eurocollins containing 90 to 120 mM raffinose. In contrast, slices incubated in UW solution had a TTW equal to normal rat liver tissue. Furthermore, intact rabbit livers preserved with Eurocollins had an increase in the whole organ weight, while there was no weight change after preservation with the modified solution containing 120 mM raffinose (M120). In contrast, a pronounced weight loss was observed after preservation with UW solution. After cold storage, the livers were reperfused for 2 h at 38 degrees C in an isolated perfusion circuit (IPL) with an acellular perfusate. Bile flow was significantly greater in livers preserved in M120 than in those preserved with the conventional Eurocollins. However, the bile flow in the livers stored in M120 was inferior to that in the livers preserved with UW solution, which in turn was equal to that in control livers. The release of alanine-aspartate-aminotransferase into the perfusate was higher in livers preserved with Eurocollins, with or without modification, than in the livers preserved with UW solution.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of hypoxic cell-free perfusion and ischemia on cell morphology in the proximal tubular S2-segment of the rat kidney

In the present study, in-situ perfused rat kidneys were used as a model to demonstrate the different morphological changes induced by various periods of warm ischemia or of warm hypoxic cell-free perfusion. Light and electron microscopic evaluation revealed no changes in the S2 proximal tubular cells after short exposure times of up to 4 min, whereas longer periods resulted in changes ranging from slight alterations (at 10 min) to severe damage (at 60 min). Warm hypoxic cell-free perfusion induced obvious alterations in the proximal tubular cells somewhat sooner than warm ischemia. The microscopical findings were consistent with the statistics of a detailed morphometrical analysis performed on the mitochondrial diameter. The results were further substantiated by counting intramitochondrial electron-dense condensations ('flocculent densities') as indicators of irreversible cell alteration.

Hypothermic preservation of rabbit kidneys for 48 hours using low ionic strength solutions

Microwaves offer the prospect of rapid and uniform heating of frozen organs. This is significant in the context of cryopreservation, and particularly of vitrification, because microwave heating may help to avoid crystallization or recrystallization of ice during warming, minimize any effects of high cell density, and reduce thermal-mechanical stresses. Previous work has established a rationale for reducing the ionic strength of solutions used to prepare tissues for microwave heating, since this permits the use of lower frequencies, which makes heating more uniform, without increasing the risk of thermal runaway (T. P. Marsland, S. Evans, and D. E. Pegg, Cryobiology 24, 311-323, 1987). In this paper we report a study of two possible low ionic strength perfusates, in rabbit kidneys, using 48 hr of hypothermic storage and autotransplantation as the test system. This model was chosen because there is a great deal of basic information about it. Both a single-pass "flush" preservation solution and a solution designed for continuous perfusion gave excellent results. The continuous perfusion system, which would be the more suitable for introducing cryoprotectants, gave five of five surviving animals with peak serum creatinine levels of 353-555 mumol/liter normal histology in three cases, and only very minor damage in the other two. There would therefore seem to be no obstacle to the use of perfusates having a low ionic strength in renal cryopreservations studies.

Hypothermic preservation of hepatocytes. II. Importance of Ca2 and amino acids

The importance of the components of a tissue culture media, Leibovitz-15 (L-15), for maintaining viability of hypothermically preserved hepatocytes was analyzed. Hepatocytes isolated from rat livers were incubated at 5 degrees C in an oxygenated environment with continuous shaking (to simulate organ perfusion preservation). L-15 + 5 g% polyethylene glycol (PEG) or variants of this solution were used as the preservation media. After 48 hr of storage, hepatocyte viability was assessed by measuring the release of LDH into the incubation medium and cell volumes were determined. Following 90 min of normothermic incubation (to simulate organ reperfusion), mitochondrial function was measured. Hepatocytes stored in the complete L-15 solution were about 90% viable at the end of 48 hr of storage, while cells stored in a solution containing only the principle electrolytes (PE) lost viability (70% viable). Only the addition of a combination of divalent cations (Ca/Mg) and amino acids was sufficient to maintain viability equivalent to that obtained in the complete L-15 mixture. Hepatocytes suspended in L-15 maintained normal cell volumes (3.85 microliters/mg protein), while cells in the PE solution were swollen with cell volumes of 4.66 microliters/mg protein. Only the addition of Ca/Mg to the PE solution was effective at suppressing cell swelling similar to the complete L-15 media. Both basal and uncoupler-stimulated respiration were depressed in cells stored in the PE solution (15 and 28 nmol O2/min/mg protein) as compared to cells in L-15 (21 and 41 nmol O2/min/mg protein).(ABSTRACT TRUNCATED AT 250 WORDS)

Viability assays in organ preservation

Assays to determine the viability of preserved organs ideally must meet two important requirements: (i) in the clinical environment, they should allow the surgeon to determine if an organ will be viable when it is transplanted (this needs to be done in a noninvasive, nondestructive manner, and currently no such assay exists), and (ii) in the research environment, they should aid in the development of improved methods of organ preservation. Currently, however, the only reliable means of assessing viability is actual transplantation. Many conventional biochemical and physiological techniques have been used to describe the mechanism of preservation-induced injury and to help improve preservation. This paper reviews some techniques that have been used to aid in the development of organ preservation.

Extracellular calcium protects cultured rat hepatocytes from injury caused by hypothermic preservation

Effects of various preservation solutions were compared in an experimental hypothermic preservation model using cultured rat hepatocytes. Hepatocytes prepared by the collagenase perfusion method were cultured for 48 hr, then the medium in each culture dish was exchanged for various preservation solutions, and the dishes were hypothermically (0-2 degrees C) stored in a refrigerator for 12-72 hr. After the preservation period, the hepatocytes were cultured again at 37 degrees C for 2 hr. Hepatocytes' viability after 18-hr preservation and reculture was greater when they were preserved in "intracellular" rather than "extracellular" solutions. Even with Euro-Collins solution (intracellular solution), hepatocyte viability decreased to approximately 20% after 24-hr preservation, and an increase in the cellular lipid peroxide content was observed. However, when this solution contained a submillimolar concentration of calcium, lipid peroxidation was significantly suppressed and hepatocyte viability was dramatically improved. Vitamin E was almost equally effective and a marked synergistic effect was observed with calcium. Calcium was found to be capable of maintaining the cellular glutathione level during cold storage, which seems to suppress lipid peroxidation and consequently improve hepatocyte survival.

Extended preservation of the liver for clinical transplantation

A new solution (UW solution) was used for flushing and storage of 17 livers before transplantation. In 9 cases the preservation times exceeded 10 hours (mean 12.7, range 11-20) but all left hospital with good liver function.

Assessment of clinical renal preservation by phosphorus-31 magnetic resonance spectroscopy

To evaluate the role of magnetic resonance spectroscopy (MRS) and to develop surface coils for assessing cadaveric renal viability during hypothermic storage, we used the monophosphate/inorganic phosphate ratio (MP/Pi) to monitor phosphorous metabolites in intact kidneys during various renal preservation maneuvers. Eighteen canine kidneys and 16 cadaveric kidneys were studied as follows: Group 1 (N = 4) in situ kidneys were monitored by implanted MRS coils; Group 1 (N = 4) ex vivo kidneys were immediately attached to vascular cannulas and monitored by MRS surface coils during normothermic perfusion; Group 3 (N = 4) kidneys were removed, cold-flushed and, after 24 hours of 4C storage, monitored by MRS surface coils before and during four hours of reperfusion via vascular cannulas; Group 4 (N = 6) kidneys were removed, cold-flushed and monitored by surface coils during cold storage up to 72 hours. In addition, 16 cadaveric kidneys were studied while in sterile cold-storage containers. Postoperative renal function was followed in recipient patients. The MP/Pi ratios in Group 1 kidneys correlated with the ability to regenerate adenosine triphosphate (ATP). Groups 2 and 3 showed similar regeneration of ATP and MP/Pi after postischemic reperfusion, and the signal-to-noise ratios of the surface coils were better than those in the implanted coils in Group 1. Surface-coil monitoring in Group 4 kidneys showed predictable decay rates of MP/Pi during one to 72 hours of cold storage; in contrast, simultaneous cortical medullary microcirculation studies with 99mTc-macroaggregated albumin were inconclusive. Human cadaveric kidneys with high MP levels were associated with excellent renal function after transplantation, while those with low MP (less than or equal to 0.50) were associated with nonviability. We conclude that MRS is a practical and safe diagnostic modality for clinical transplantation.

Assessment of renal preservation by phosphorus-31 magnetic resonance spectroscopy: in vivo normothermic blood perfusion

To evaluate the usefulness of the monophosphate/inorganic phosphate ratio (MP/Pi) in assessing renal viability in a renal transplantation setting, we monitored intracellular phosphorous metabolites of 33 canine kidneys by phosphorus-31 magnetic resonance spectroscopy (MRS) after various amounts of ischemia. Renal viability (adequate perfusion and function) was directly assessed by the presence of intraoperative urine production in each kidney. Twelve normal, well-perfused kidneys (Group 1) exhibited high control MP/Pi ratios, with a mean of 0.87 +/- 0.12. Six in situ kidneys (Group 2), subjected to 45 minutes' warm ischemia followed by reperfusion, had a mean MP/Pi ratio of 0.50 +/- 0.12 after warm ischemia, which increased by a mean of 0.50 +/- 0.11 (to 1.0 +/- 0.07) after two to four hours of reperfusion. Fifteen kidneys (Group 3) were removed, cold-flushed and transplanted after 24 hours of hypothermic storage. In eight (Group 3A), reperfusion was excellent; in seven (Group 3B), reperfusion was inadequate secondary to hypotension in two, hemorrhage in two, and renal vein thrombosis in three. Group 3A kidneys had a mean MP/Pi ratio after cold-storage ischemia of 0.54 +/- 0.08. After successful transplantation and two to four hours of reperfusion, this increased by a mean of 0.23 +/- 0.12 to 0.77 +/- 0.15. Group 3B kidneys all showed a continuous decline of MP/Pi, with a mean loss of 0.26 +/- 0.09 from baseline values (mean 0.56 +/- 0.08) to nonviable levels of 0.28 +/- 0.12 within four hours of transplantation. We conclude that MP/Pi ratios enable assessment of renal viability and ischemic damage and can predict the efficacy of renal preservation maneuvers in the dog kidney. These preliminary data support the theory that MRS can be applied to the noninvasive assessment of viability in ex vivo, cold-stored cadaveric human kidneys awaiting renal transplantation.

Development of a cold storage solution for pancreas preservation

Canine pancreas tissue slices were incubated at 5 degrees C for 24 hr in solutions containing different saccharides (raffinose, sucrose, mannitol, or glucose). At the end of incubation tissue water (TW expressed as kg H2O/kg dry wt) was determined as a measure of tissue edema. Tissue edema was greatest in slices stored in Eurocollins (EC) solution (TW = 4.96 +/- 0.14) which contains glucose for osmotic pressure. The degree of edema was decreased by saccharides in proportion to their molecular mass: mannitol (MW = 180, TW = 3.84 +/- 0.08), sucrose (MW = 348, TW = 3.54 +/- 0.08), and raffinose (MW = 594, TW = 3.30 +/- 0.07). Tissue edema was also greatest in slices incubated in solutions containing the smallest molecular mass anions: Cl- (TW = 4.02 +/- 0.16), gluconate (TW = 3.69 +/- 0.10), and lactobionate (TW = 3.28 +/- 0.13). Cold storage of the intact pancreas in EC solution for 24 hr did not induce as much edema as in slices (TW = 2.88 +/- 0.10). However, on isolated reperfusion at normothermia (37 degrees C) the pancreas became edematous (TW = 3.33 +/- 0.12). Storage of the pancreas in a lactobionate-raffinose solution did not induce edema after 90 min of normothermic reperfusion. The suppression of tissue edema in the pancreas may be essential to obtaining long-term preservation (24-72 hr) of this organ which is currently limited to about 6-8 hr in EC solution. The newly developed lactobionate-raffinose solution appears to control tissue edema in both tissue slices and the intact-flushed out organ.

Factors influencing survival of mammalian cells exposed to hypothermia. II. Effects of various hypertonic media

Survival of Chinese hamster lung (V79) cells, exposed as a function of time to hypothermia in tissue culture, in isosmotic and various hypertonic media was measured using a colony assay. The mechanism of hypothermic cell killing is different above and below 7 degrees C in this cell line. Addition of NaCl or mannitol to increase the tonicity to 400 mOsm greatly decreased the survival at 10 degrees C while addition of KCl had no significant effect. When these experiments were repeated at 5 degrees C, addition of either NaCl, KCl, or mannitol was detrimental to long-term cell survival. Furthermore, addition of mannitol to the medium did not improve survival when cells were stored at 7 degrees C. Addition of KCl at 5 or 10 degrees C or NaCl at 5 degrees C only affected the cells' ability to accumulate sublethal damage, while addition of mannitol at 5 or 10 degrees C affected both of the above and the cold sensitivity of the cells. Addition of NaCl at 10 degrees C only affected the latter. These experiments suggest that prevention of cell swelling by these conditions, while possibly necessary during clinical hypothermic organ storage, is detrimental to single cell survival at these temperatures.

Evaluation of a flushing solution designed to protect kidneys from in situ ischemia

An in situ flushing solution was evaluated with regard to the following: (1) its ability to protect the kidney during 60, 90, and 120 minutes of normothermic ischemia; (2) the effects of using an intracellular versus extracellular electrolyte composition in the flushing solution; and (3) the ability of the flushing solution to complement in situ hypothermia as a protective measure during long-term ischemia. Rat kidneys were briefly flushed in situ with an isotonic phosphate buffered solution (pH 7.2) containing 50 milliosmole of sucrose. The left renal pedicle was then immediately clamped to render the kidney ischemic and to hold the flushing solution in the kidney. Following removal of the pedicle clamp, a contralateral nephrectomy of the right kidney was performed and daily serum creatinine levels determined to evaluate postischemic renal function. The results indicate the following: (1) the flushing procedure is very effective in preventing postischemic acute renal failure following 60 minutes of normothermic ischemia, but is considerably less effective for ischemic times of 90 minutes or more; (2) an intracellular electrolyte composition in the flushing solution does not improve the protective effects of this solution; and (3) the flushing procedure can significantly improve on the protection otherwise provided by in situ hypothermia.

Small bowel transplantation in the rat: the adverse effect of increased pressure during the flushing procedure of the graft

The influence of the pressure during the flushing procedure on the results of the subsequent transplantation was investigated in a model of heterotopic functional small bowel transplantation in the outbred Wistar rat. In this model insufficient small bowel preservation will result in a lethal shock, soon after revascularization. If the size of the small bowel graft was reduced to a 15-cm segment of the proximal jejunum, improper preservation did not lead to lethal shock, but to histological changes of the graft. The influence of high flushing pressure (80 cm), medium flushing pressure (50 cm), low flushing pressure (35 cm), and no flushing procedure at all, was investigated in different groups of rats. Flushing was performed by gravity using chilled Ringer's lactate solution (4 degrees C), buffered with NaHCO3 at a pH of 7.4. The results were evaluated histologically as well as clinically. Results indicated flushing of the graft to be superior to a nonflushing procedure. A flushing pressure of 80 cm and even 50 cm proved to be harmful to the jejunal graft. Flushing pressure of 35 cm resulted in successful segmental (jejunal) and subtotal (minus 5- to 7-cm distal ileum) small bowel transplantation. However, survival of a total small bowel graft could not be achieved with the optimal flushing procedure indicating that the functional integrity of a small bowel graft also depends on conditions other than the method of short-term preservation.

The value of magnesium in flush solutions for human cadaveric kidney preservation

A cooperative clinical trial was conducted among 5 transplant centers in the western United States to determine the value of magnesium sulfate in intracellular electrolyte flush solutions for hypothermic, human kidney storage. Kidneys from alternate donors were flushed with either magnesium-free Euro-Collins' solution or magnesium-containing Collins' 2 solution. Donor and recipient ages, and mean preservation times were not significantly different between the 2 groups. There was a significantly lower dialysis requirement during the first week in the magnesium-containing Collins 2 group (33 per cent) versus the Euro-Collins group (54 per cent). Function rates and serum creatinine nadirs at 1 month were not significantly different. The beneficial effect of magnesium sulfate was more evident when preservation times exceeded 24 hours.

Experimental observations on the mode of action of "intracellular" flush solution

Experiments were conducted using rabbit kidneys stored on ice for 48 hr to elucidate the mode of action of "intracellular" flush solutions. Measurements were made of renal function on a shunt and they were correlated with blood flow and the efficiency of the mechanical expulsion of red cells. By comparison with unflushed, ice-stored kidneys, near complete mechanical expulsion of blood by 30 to 60 min of continuous perfusion with hypertonic Ringer's albumin resulted in significantly higher blood flow with little gain in function. Similarly, increasing the content of nonelectrolyte in Ringer's albumin improved blood flow but not function. A simple flush with a low ionic strength sodium solution (LIE), containing impermeant anions and glucose was superior to that with Ringer's albumin. A high-potassium version of the low ionic strength solution (LIC) was in turn significantly better than LIE for kidney preservation by simple flushing and ice storage. These results were interpreted to mean that whereas mechanical flushing is a relatively minor component of the action of flush solutions, the major benefit results from a reduced sodium and elevated potassium content in the presence of impermeant anions. The primary importance of prevention of cell swelling by the inclusion of nonelectrolytes in "extracellular" flush solutions, is questioned.

Factors influencing survival and growth of mammalian cells exposed to hypothermia. I. Effects of temperature and membrane lipid perturbers

The Arrhenius plot of the rate of V79 Chinese hamster cell inactivation due to hypothermia has a "break" around 7-10 degrees C with optimum storage temperature for unprotected cells being about 10 degrees C. Addition of the membrane lipid perturber, butylated hydroxytoluene, improves survival of cells when compared to controls at temperatures below this break but not above. Arrhenius plots of growth rates of the cells show breaks at 30 and 40 degrees C. Measurements of membrane fluidity by electron spin resonance or membrane polarization anisotropy by fluorescence spectrophotometry techniques as a function of temperature in these cells also reveal "breaks" centered around 8 and 30 degrees C. Hence, the changes in the rate of cell inactivation and growth as a function of temperature may be related to membrane lipid phase changes.

Efficiency and limitation of Euro-Collins solution in kidney preservation

The efficiency of Euro-Collins solution against cellular swelling and the reason for its 50-hr upper tolerance limit in kidney preservation prior to human transplantation is investigated. Dog kidneys were removed, flushed with saline, Euro-Collins, or a modified sucrose Euro-Collins solution, and stored at 4 degrees C in the same fluid for 96 hr. Total and intracellular water contents and intracellular sodium and potassium contents were calculated at various times according to a methodology taking into account the weight of the dry matter of the solution and the value of extracellular space determined from the inulin distribution space. Main results show that, in the Euro-Collins group, the intracellular water is unchanged up to 48 hr but is suddenly increased between 48- and 72-hr preservation, after which it remains unchanged. This marked cellular edema does not occur in the sucrose group. Euro-Collins solution is thus able to protect kidneys from cellular swelling and ionic changes during a 48-hr preservation period which corresponds to the upper tolerance limit admitted in clinical transplantation. The limiting factor of the swelling inhibition is the penetration of glucose into the cell and can be related to a first step in membrane injury. Some cellular components are, however, probably lost after 72-hr preservation, which suggests a second step in the membrane deterioration.

The effects of storage media and perfusion on osteoblast and osteocyte survival in free composite bone grafts

Twenty-two adult mongrel dogs were used to investigate the effects of storage alone and storage and perfusion in 3 different storage media on the survival of osteocytes and osteoblasts in free bone grafts revascularized by microvascular anastomoses. Evaluation of the grafts at 2 weeks demonstrated that storage in chilled (+ 5 degrees C) physiologic saline or Collins-Terasaki solution resulted in greater survival of osteocytes and osteoblasts than did storage in chilled BGJb solution or in room temperature air. No beneficial effect could be detected from perfusing the bone grafts with their storage media. On the contrary, deleterious effects were noted at the sites of the anastomoses, with thromboses of vessels secondary to endothelial damage.

In situ hypothermic renal perfusion. Evaluation of three intracellular solutions

Description of a simple technique for in situ hypothermic renal perfusion is presented. Three intracellular solutions simulating perfusates were tried on three groups of mongrel dogs with a fourth group that served as control. Right nephrectomy was performed on all dogs. The left kidney was perfused for two and one-half hours at a temperature of 15 degrees to 17 degrees C. Follow-up evaluation by estimation of five enzymes, glutamic oxaloacetic transaminase, alkaline phosphatase, lactic dehydrogenase, sorbitol dehydrogenase, and phospholexose isomerase in serum, urine, and renal tissue was conducted. Renal function was evaluated by the level of serum creatinine and its twenty-four-hour urinary excretion. Minimal biochemical changes comparable to the control group were observed in the group perfused by Chapman solution.

A simplified kidney preservation system: the use of hyperosmolar perfusates for continuous perfusion preservation of canine kidneys

Since the quality of renal preservation following simple ice storage is improved by the use of hyperosmolar washout solutions, hyperosmolar perfusates were evaluated for continuous perfusion preservation. Canine kidneys were preserved for 48 hours by continuous perfusion at 5 degrees C, using hyperosmolar cryoprecipitated plasma and 5% albumin perfusates of osmolalities 397 to 430 mOsm/kg H2O. Hyperosmolar plasma gave significantly better preservation than isosmolar plasma, but the results were only marginally superior to those already obtainable with isosmolar albumin solution. No further improvement in preservation by albumin perfusion was obtained with the hyperosmolar formulations. Because isosmolar albumin solution is easier to prepare than hyperosmolar cryoprecipitated plasma and gives comparable results, it remains our perfusate of choice for continuous perfusion preservation.

Description and interpretation of structural changes in canine kidneys after preservation with a hyperosmolar solution and reperfusion

The effects of hypothermic preservation of canine kidneys for 24 hours by the use of the Sacks solution, and additional autogenous reperfusion were studied by means of submicroscopic morphological methods. While preservation with the Sacks solution was to ensure normal organization of the lipoprotein structures of the basement and cell membranes, in case of additional reperfusion, even of short duration, a substantial or complete loss of anisotropy of the cytomembranes was demonstrable. The present report is the first to be published in the literature on polarization microscopic studies concerned with the effects of kidney preservation and of reperfusion.