Differential inflammatory responses of the native left and right ventricle associated with donor heart preservation

BACKGROUND

Dysfunction and inflammation of hearts subjected to cold ischemic preservation may differ between left and right ventricles, suggesting distinct strategies for amelioration.

METHODS AND RESULTS

Explanted murine hearts subjected to cold ischemia for 0, 4, or 8 h in preservation solution were assessed for function during 60 min of warm perfusion and then analyzed for cell death and inflammation by immunohistochemistry and western blotting and total RNA sequencing. Increased cold ischemic times led to greater left ventricle (LV) dysfunction compared to right ventricle (RV). The LV experienced greater cell death assessed by TUNEL+ cells and cleaved caspase-3 expression (n = 4). While IL-6 protein levels were upregulated in both LV and RV, IL-1β, TNFα, IL-10, and MyD88 were disproportionately increased in the LV. Inflammasome components (NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3), adaptor molecule apoptosis-associated speck-like protein containing a CARD (ASC), cleaved caspase-1) and products (cleaved IL-1β and gasdermin D) were also more upregulated in the LV. Pathway analysis of RNA sequencing showed increased signaling related to tumor necrosis factor, interferon, and innate immunity with ex-vivo ischemia, but no significant differences were found between the LV and RV. Human donor hearts showed comparable inflammatory responses to cold ischemia with greater LV increases of TNFα, IL-10, and inflammasomes (n = 3).

CONCLUSIONS

Mouse hearts subjected to cold ischemia showed time-dependent contractile dysfunction and increased cell death, inflammatory cytokine expression and inflammasome expression that are greater in the LV than RV. However, IL-6 protein elevations and altered transcriptional profiles were similar in both ventricles. Similar changes are observed in human hearts.

Do storage solutions protect endothelial function of arterialized vein graft in an experimental rat model?

BACKGROUND

This study aims to compare the effects of storage solutions commonly used in coronary artery bypass grafting on the vascular reactivity in vein graft interposed in arterial position in syngeneic rats.

METHODS

Twenty-seven male Lewis rats were sacrified to sample a vein graft implanted 6 weeks ago into abdominal aorta position. The vein grafts were inferior venae cavae initially pretreated with heparinized saline solution (HS) or autologous heparinized blood (AHB) or our referent solution, GALA. The endothelial functionality, the in situ Reactive Oxygen Species (ROS) levels and the histological characteristics were conducted from segments of arterialized vein graft.

RESULTS

At 6 weeks, graft thrombosis occurred respectively in 22% of AHB group, 62.5% in the HS group and 82.5% in the GALA group. In each group, significative intimal hyperplasia was observed. After 6 weeks, an endothelium-remodeling layer associated with an increase of wall thickness was observed in each group. Endothelium-dependent tone was reduced in the vein graft regardless of the group. No difference was observed concerning the ROS in vein graft between the different groups. In distal aortic sections, ROS levels were increased in HS and GALA groups.

CONCLUSIONS

Storage solutions used in this experimental model of vein graft implanted in arterial position cause graft injury and a complete disappearance of vascular reactivity. GALA solution did not reduce intimal risk hyperplasia when the vein graft was exposed to arterial flow in a rat model.

Warm HTK donor pretreatment reduces liver injury during static cold storage in experimental rat liver transplantation

BACKGROUND

Organ shortage has led to an increased number of transplantations from extended criteria donors. These organs are more vulnerable to ischemia-reperfusion injury. Thus, improvement of organ preservation is needed. HTK is a widely used preservation solution for static cold storage in liver transplantation. The present study was to investigate the beneficial effect of warm HTK donor pretreatment on liver preservation.

METHODS

Male inbred Wistar rats (weighing 230-260 g) served as donors and recipients (n=6/group). Donors of treatment groups received i.v. 0.01 mL/g body weight (BW) warm (21 degree centigrade) HTK systemically 15 minutes prior to cold perfusion. Control groups received 0.01 mL/g BW warm (21 degree centigrade) NaCl 0.9%. Following pretreatment, donors were flushed with 4 degree centigrade cold HTK, livers were explanted and stored in 4 degree centigrade HTK for six hours. Thereafter orthotopic liver transplantation was performed. Recipients were harvested four hours, two and five days after reperfusion and blood and liver tissue samples were obtained. Blood samples were analyzed for AST, ALT, lactate dehydrogenase and bilirubin. Liver histological analysis as well as tissue analysis for pro-MMP2, MMP2 and pro-MMP9 using zymography was conducted.

RESULTS

Treatment groups showed significantly lower ALT and lactate dehydrogenase levels as well as significantly lower activities of pro-MMP2, MMP2 and pro-MMP9. Histological analysis revealed only minor damage in all groups.

CONCLUSIONS

The new concept of warm HTK pretreatment significantly reduced ischemia-reperfusion injury. The reduced ischemia-reperfusion injury was due to MMP inhibition. Warm HTK donor pretreatment is easy to handle and could further improve HTK's potency in liver preservation.

Normothermic perfusion of donor lungs for preservation and assessment with the Organ Care System Lung before bilateral transplantation: a pilot study of 12 patients

BACKGROUND

Cold flush and static cold storage is the standard preservation technique for donor lungs before transplantations. Several research groups have assessed normothermic perfusion of donor lungs but all devices investigated were non-portable. We report first-in-man experience of the portable Organ Care System (OCS) Lung device for concomitant preservation, assessment, and transport of donor lungs.

METHODS

Between Feb 18, and July 1, 2011, 12 patients were transplanted at two academic lung transplantation centres in Hanover, Germany and Madrid, Spain. Lungs were perfused with low-potassium dextran solution, explanted, immediately connected to the OCS Lung, perfused with Steen's solution supplemented with two red-cell concentrates. We assessed donor and recipient characteristics and monitored extended criteria donor lung scores; primary graft dysfunction scores at 0, 24, 48, and 72 h; time on mechanical ventilation after surgery; length of stays in hospital and the intensive-care unit after surgery; blood gases; and survival of grafts and patients.

FINDINGS

Eight donors were female and four were male (mean age 44·5 years, range 14-72). Seven recipients were female and five were male (mean age 50·0 years, range 31-59). The preharvest donor ratio of partial pressure of oxyen (PaO(2)) to fractional concentration of oxygen in inspired air (F(I)O(2)) was 463·9 (SD 91·4). The final ratio of PaO(2) to F(I)O(2) measured with the OCS Lung was 471·58 (127·9). The difference between these ratios was not significant (p=0·72). All grafts and patients survived to 30 days; all recipients recovered and were discharged from hospital.

INTERPRETATION

Lungs can be safely preserved with the OCS Lung, resulting in complete organ use and successful transplantation in our series of high-risk recipients. In November, 2011, we began recruitment for a prospective, randomised, multicentre trial (INSPIRE) to compare preservation with OCS Lung with standard cold storage.

FUNDING

TransMedics and German Federal Ministry of Education and Research.

Techniques of flushing and reperfusion for liver transplantation

BACKGROUND

Various techniques of flushing and reperfusion have been advocated to improve outcomes after liver transplantation. There is considerable uncertainty as to which method is superior.

OBJECTIVES

To compare the benefits and harms of different methods of flushing and reperfusion during liver implantation in the transplant recipients.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded until March 2011.

SELECTION CRITERIA

We included all randomised clinical trials that were performed to compare different techniques of flushing and reperfusion during liver transplantation.

DATA COLLECTION AND ANALYSIS

Two authors independently identified the trials and extracted the data. We analysed the data with both the fixed-effect model and the random-effects model using RevMan analysis. For each outcome we calculated the hazard ratio (HR), risk ratio (RR), rate ratio, mean difference (MD), or standardised mean difference (SMD) with 95% confidence intervals (CI) based on available case analysis.

MAIN RESULTS

We included six trials involving 418 patients for this review. The sample size in the trials varied from 30 to 131 patients. Only one trial involving 131 patients was of low risk of bias for mortality. This trial was at high risk of bias for other outcomes. Four trials excluded patients who underwent liver transplantation for acute liver failure. All the trials included livers obtained from cadaveric donors. The remaining five trials were of high risk of bias for all outcomes. Liver transplantation was performed by the conventional method (caval replacement) in two trials and piggy-back method (caval preservation) in one trial. The method of liver transplantation was not available in the remaining three trials. The comparisons performed included an initial hepatic artery flush versus initial portal vein flush; blood venting via inferior vena cava in addition to venting of storage fluid versus no blood venting; initial hepatic artery reperfusion versus initial portal vein reperfusion; simultaneous hepatic artery and portal vein reperfusion versus initial portal vein reperfusion; and retrograde inferior vena cava reperfusion versus simultaneous hepatic artery and portal vein reperfusion. Only one or two trials could be included under each comparison. There was no significant difference in mortality, graft survival, or severe morbidity rates in any of the comparisons. Quality of life was not reported in any of the trials.

AUTHORS' CONCLUSIONS

There is currently no evidence to support or refute the use of any specific technique of flushing or reperfusion during liver transplantation. Due to the paucity of data, absence of evidence should not be confused with evidence of absence of any differences. Further well designed trials with low risk of systematic error and low risk of random errors are necessary.

Transplantation of the uterus in the sheep: oxidative stress and reperfusion injury after short-time cold storage

OBJECTIVE

To study the effects of cold ischemia and reperfusion after transplantation of the sheep uterus and to compare the preservation solution Perfadex (Vitrolife, Mölndal, Sweden) with Ringer's acetate.

DESIGN

Experimental animal study.

SETTING

University hospital.

ANIMAL(S)

Adult, female sheep.

INTERVENTION(S)

One uterine horn with the common uterine cavity and cervix of sexually mature ewes was auto-transplanted after 1 hour of cold ischemic storage in either Perfadex (n = 5) or Ringer's acetate (n = 5). During 3 hours of reperfusion, uterine venous blood was collected and analyzed for several parameters that were indicative of oxidative stress and reperfusion injury. A biopsy was taken for histological analysis at the end of the experiment.

MAIN OUTCOME MEASURE(S)

Lipid peroxidation and ascorbyl radicals in uterine venous blood during reperfusion. Light microscopy and quantification of neutrophils in tissue after 3 hours of reperfusion.

RESULT(S)

A decline in pH and a rise in lactate and pCO(2)-pO(2), as well as an elevation of antioxidant capacity, lipid peroxidation, and intensity of ascorbyl radical electron spin resonance signal, was found that was more prominent after storage in Ringer's acetate. The histological analysis revealed mild inflammation in both study groups.

CONCLUSION(S)

Short-time cold ischemic storage of the sheep uterus does not induce any severe reperfusion damage, but the use of the protective buffer Perfadex decreases oxidative stress and inflammation when compared with a more simple solution.

Flow and Pressure during Liver Preservation under ex situ and in situ Perfusion with University of Wisconsin Solution and Histidine-Tryptophan-Ketoglutarate Solution

Effective preservation of liver grafts is the first essential step for successful liver transplantation. Insufficient perfusion leads to ischemic-type biliary lesions after transplantation. Perfusion of the graft can be performed either in situ or ex situ, with gravity flow or pressure-controlled. Mainly University of Wisconsin (UW) and histidine-tryptophan-ketoglutarate (HTK) solutions are used widespread in clinical liver transplantation. Due to a persistent lack of data, we performed this systematic investigation of in situ and ex situ perfusion of liver grafts with HTK (low-viscous) and UW (high-viscous) solutions at different pressure steps on the perfusion solution (gravity flow, 50, 100, 150, and 200 mm Hg). End points were perfusion flow and pressure in the hepatic artery. A pig model was used with n = 8 pigs randomized to each (HTK and UW) group. In situ perfusion was ineffective for both solutions at any pressure on the perfusate bag. Ex situ perfusion showed significantly improved flow and pressure in the hepatic artery and, therefore, was highly effective. No major differences between HTK and UW solutions could be detected. Therefore, an additional ex situ perfusion of the hepatic artery should be mandatory in every liver procurement.

Development and testing of portable pump for the induction of profound hypothermia in a Swine model of lethal vascular injuries

Rapid induction of a profound hypothermic state (suspended animation) can maintain viability of key organs during repair of lethal injuries. Conventional cardiopulmonary bypass equipment (roller pump) used to induce and reverse hypothermia is expensive, bulky, requires standard electricity, and is not transportable. Development of a small, portable, battery operated, disposable, pump can logistically facilitate induction and maintenance of hypothermia. In this experiment, a portable prototype pump was tested and its performance was compared with the regular roller pump in a swine model of lethal vascular injuries.

METHODS

Uncontrolled hemorrhage was induced in 16 swine (80-120 lbs) by creating an iliac artery and vein injury (nonlethal). After 30 minutes of pulseless shock, the descending thoracic aorta was lacerated (lethal injury). Through a left thoracotomy approach, a catheter was placed in the aorta and cold organ preservation solution was infused to rapidly (2 degrees C/min) induce hypothermia (10 degrees C) for 60 minutes. The performance of the prototype pump was initially tested in a nonsurvival experiment (four animals). Then, 12 animals were cooled either with (n = 6/group) (1) conventional roller pump or (2) small prototype pump. The injuries were repaired during hypothermic arrest and the animals were re-warmed (0.5 degrees C/min). Whole blood was infused during resuscitation on cardiopulmonary bypass. Surviving animals were closely monitored for 3 weeks for postoperative complications, neurologic deficits, and organ dysfunction.

RESULTS

The flow rates and the time needed to induce and reverse profound hypothermia were no different between the prototype and the conventional roller pumps. Three-week survival rates were 83% in both groups. Only a transient increase in liver enzymes, and markers of cellular injury (creatine kinase, lactate dehydrogenase) was noted (no meaningful difference between groups), with no long-term organ dysfunction.

CONCLUSIONS

In this large animal model of lethal vascular injuries, a portable, battery operated, disposable, rotary pump performed as well as the conventional roller pump. The logistical advantages of this system make it an attractive choice for inducing hypothermia in emergency departments and austere settings, and for maintaining hypothermia during transport.

Analysis of the effect of partial vitrification on stress development in cryopreserved blood vessels

Thermal stress development in blood vessels, during processes associated with vitrification (vitreous means glassy in Latin), is studied. This paper addresses the limiting case where the specimen completely crystallizes, while the cryoprotectant medium (CPA) completely vitrifies. This case is expected to provide upper boundary estimates for stresses for the more common problem of a partially vitrified sample. The CPA is modeled as a linear viscoelastic medium, with viscosity increasing exponentially with decreasing temperature; given the assumption of complete crystallization, the blood vessel is modeled as linear elastic below the freezing temperature. Consistent with previous observations, the CPA is found to behave linear elastically below a set-temperature, at which point the viscosity rises sufficiently quickly with further cooling. This observation reduces computational efforts and allows for parametric studies based on suitably chosen wholly elastic models. Both 2D concentric cylinder models of the blood vessel in a straight configuration and a 3D model of the vessel curled in a vial of CPA are studied; 2D models are shown to bound the results of the more general 3D problem. It is found that stress in the CPA decreases with increase in CPA volume, at least under conditions where the temperature can be viewed as uniform. Planar cracks are predicted to form transverse to the vessel axis, and to propagate right up to the blood vessel wall. Should such cracks propagate into the vessel, even over only a few mum, the mechanical damage to the lumen, or to endothelial cells, may cause the blood vessel to completely loose its functionality at the end of the cryopreservation protocol.

Topical Vasodilators for Preventing Radial Artery Spasm during Harvesting for Coronary Revascularization: Comparison of 4 Agents

BACKGROUND

There is still controversy about which vasodilator solution is best for storing radial artery (RA) conduits prior to coronary artery bypass grafting. The aim of this pilot study was to investigate how 4 different topical vasodilators applied during RA harvesting affect blood flow with the vessel in situ.

MATERIALS AND METHODS

The subjects were 85 patients who underwent RA harvesting in preparation for coronary artery bypass grafting. Each case was assigned to 1 of 5 groups (17 RAs each) that were treated with different solutions: normal saline (control), nitroglycerin, diltiazem, papaverine, and adenosine. Standard clinical concentrations were used. The RA was partially harvested (pedicle attached proximally) and flow rates and hemodynamic parameters (mean arterial pressure, heart rate, central venous pressure) were recorded at 2 time points: (1) pretreatment and (2) after 5 minutes of immersion in 60 mL of treatment solution. Results were compared within and between groups, and post-treatment-to-pretreatment ratios were calculated for each variable.

RESULTS

There were no significant differences among the groups' mean pretreatment flow rates (P = .979) or mean posttreatment flow rates (P = .069). All except the diltiazem group showed a significant rise in mean flow rate from pretreatment to posttreatment. The mean posttreatment-to-pretreatment ratios for RA flow rate were 1.28 +/- 0.39 in the saline group, 1.85 +/- 0.72 in the nitroglycerin group, 1.31 +/- 0.48 in the diltiazem group, 1.37 +/- 0.64 in the papaverine group, and 1.23 +/- 0.42 in the adenosine group. Only the mean flow ratio in the nitroglycerin group was significantly higher than that in the saline group (P = .003). The mean flow ratios in the other vasodilator groups were not statistically different from the flow ratio in the saline group.

CONCLUSIONS

These preliminary results indicate that topical application of nitroglycerin solution effectively prevents perioperative spasm of the RA in patients undergoing coronary artery bypass surgery. The authors recommend this solution for preparation and storage of RA grafts. Randomized controlled trials with power analysis will give more definitive information.

Permeability of ovine primordial follicles to different cryoprotectants

OBJECTIVE

To determine the behavior of isolated primordial follicles that were exposed to different concentrations of dimethyl sulfoxide (DMSO), ethylene glycol (EG), propylene glycol (PROH), and glycerol (GLY).

DESIGN

Isolated primordial follicles were exposed to the cryoprotectant (CPA) solution and photographed to calculate their volume at different periods of exposure.

SETTING

Laboratorio Renzo Giuliani, University of Florence, Italy.

ANIMAL(S)

Lambs, 30-40 days old.

INTERVENTION(S)

Isolation of primordial follicles and subsequent exposure to CPA.

MAIN OUTCOME MEASURE(S)

Follicular volume.

RESULT(S)

At 2 minutes of CPA exposure, all follicles appeared to be shrunken. At approximately 5 minutes, shrinkage ceased, and follicles started to swell, absorbing the CPA and water to maintain osmotic equilibrium. When DMSO was tested, follicular dehydration in all concentrations did not exceed 17%; with PROH and EG, it reached 33% and 27%, respectively. The highest degree of dehydration (48%) was seen with GLY. In almost all tested concentrations, follicular shrinkage occurred up to 5 minutes.

CONCLUSION(S)

Volume changes in isolated primordial follicles can fluctuate according to the CPA used and its concentration.

Amplification of Herpes simplex type 1 and Human Herpes type 5 viral DNA from formalin-fixed Alzheimer brain tissue

It is known that nucleic acids from formalin-fixed tissues are not nearly as good templates for DNA amplification as those extracted from fresh tissues. However, specimens stored in most pathologic archives are initially fixed in formalin. The possibility of an infectious etiology of several diseases including Alzheimer's underscores the usefulness of archived tissue in assessing the association of infectious agents with specific pathology. In this report, we describe in detail a method resulting in robust amplification of HSV1 and Human Herpes type (HHV) 5 viral DNA targets using formalin-fixed Alzheimer brain frontal and temporal tissue as source of amplification template. Herpes simplex type 2 viral DNA was not detected in the limited samples examined in this study. Amplicons were verified by sequence analysis. Brain tissue stored in formalin longer than 1 year prior to post-formalin-fixation analysis gave rise to significantly shorter amplicons consistent with the observation that template DNA integrity decreases significantly with increasing time of storage in formalin. Thus, this report should be useful in PCR-based investigations assessing the regional presence of viral DNAs in formalin-fixed brain tissue.

New model of ventricular fibrillation

The purpose of this study was to develop a more efficient and stable model of ventricular fibrillation (VF) in the isolated rabbit heart, because there is not a satisfactory model with this animal. We also observed the effects of increasing extracellular calcium in the stability and reversibility of the arrhythmia. After suspending the hearts in a classical Langendorff preparation, VF was induced by burst stimulation (current = 2.0 mA, pulse duration = 3 milliseconds, frequency = 50 Hz, voltage = 10 V, duration of stimulation = 5 minutes). The hearts were then divided into 2 groups, A and B. The hearts in group B were perfused with a modified Krebs-Henseleit solution, which contained twice as much calcium as the solution used in the other group. The rate of success with this model was 100% for both groups. The hearts fibrillated up to 30 minutes in group A and more than 40 minutes in group B, longer then all studies ever published in rabbit hearts. Ventricular fibrillation reverted to sinus rhythm in 100% of the hearts of group A when treated with an antifibrillatory drug, whereas no reversion at all was observed in the hearts of group B. We conclude that high extracellular calcium makes the reversion to sinus rhythm more difficult in this model. Our high rate of success and the exceptionally stable and long-lasting VF turn our model very effective for the study of antiarrhythmic interventions in the isolated rabbit heart.

Survival rates of patients with malignant melanoma of the skin

This paper reports on cases of malignant melanoma of the skin diagnosed in Finland between 1963 and 1968. Sufficient data for estimating the survival was obtained in 691 cases. The ten-year relative survival rate for the entire series was 41% for males and 53% for females. This sex difference remained constant throughout the various divisions of the material. The ten-year relative survival rate of males with tumour in stage I was 52% and that of females 59%. The highest survival rate of stage I tumour in males was for the tumours of the lower extremities (77%) and in females for those in the head and neck (79%). The relative survival of patients with tumour of the trunk in stage I was lowest in both sexes (males 49%, females 45%). The ten-year relative survival rate of patients with a local recurrence was 33% in males and 27% in females. The relative ten-year survival rates of patients with superficial melanoma were 130% in males and 92% in females.

Apoptosis inhibition during preservation by fructose-1,6-diphosphate and theophylline in rat intestinal transplantation

OBJECTIVE

This study evaluated the effect of fructose-1,6-diphosphate (FDP), theophylline, or the addition of both together to the preservation solution (University of Wisconsin [UW]) on apoptosis during preservation and the effect of apoptosis minimization on the early reperfusion period after transplantation.

DESIGN

Prospective, randomized, and controlled animal study.

SETTING

Laboratory of a research institute.

SUBJECT

Male Wistar rats.

INTERVENTIONS

The jejunum was isolated and preserved for 6 hrs in UW solution. FDP and theophylline were added to the UW solution to evaluate their effects on apoptosis both alone and together. The role of adenosine with respect to FDP was examined by increasing endogenous adenosine. In addition, rats were subjected to intestinal transplantation for the evaluation of the effect of apoptosis on bacterial translocation, histology, and neutrophil infiltration after reperfusion.

MEASUREMENTS AND MAIN RESULTS

Caspase-3 activity, assayed both in vitro or by cleaved caspase-3 levels in Western blots or immunohistochemically, and the number of terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick-end labeling (TUNEL)-positive cells decreased with FDP and with theophylline addition to UW solution. Increase of endogenous adenosine reversed the antiapoptotic effect of FDP. FDP and theophylline together demonstrated a more pronounced antiapoptotic effect and prevented bacterial translocation after transplantation.

CONCLUSION

Supplementary FDP to UW solution decreased apoptosis through an adenosine-independent mechanism. Addition of theophylline to UW solution decreased both apoptosis and bacterial translocation. Concomitant theophylline and FDP addition to preservation solution is recommended to maintain low levels of apoptosis during intestinal hypothermic preservation and to decrease bacterial translocation.

Sustaining a Bioartificial Liver under Hypothermic Conditions

Bioartificial liver (BAL) devices employing xenogeneic hepatocytes are being developed as a temporary support of liver failure. For clinical applications, transporting such a device from the manufacturing site to the hospital is necessary. We investigated the effect of hypothermic treatment on the performance of the collagen-entrapment BAL device developed at the University of Minnesota. A number of chemical protectants were examined for their effectiveness in minimizing damage to hepatocytes. Preincubation with protectant (tauroursodeoxycholic acid, TUDCA) before hypothermic treatment improved posttreatment BAL performance. Oxygen consumption and albumin and urea synthesis all resumed at levels comparable to pretreatment levels. The method described will facilitate the application of BAL in the treatment of liver failure.

[Arterial back table pressure perfusion prevents ischemic biliary lesions after orthotopic liver transplantation]

INTRODUCTION

Ischemic biliary lesions are a threatening complication following orthotopic liver transplantation. Their exact pathophysiological mechanism is unknown so far, but insufficient perfusion of biliary arterial vessels might be responsible for the development of these lesions. This might be changed by improved perfusion techniques. We performed a controlled study of cases since February 2000.

MATERIALS AND METHODS

We used arterial back table pressure perfusion to achieve reliable perfusion of the capillary system of the biliary tract, which may be impaired by the high viscosity of University of Wisconsin solution. In this study, 190 orthotopic liver transplantations performed between September 1997 and July 2002 were investigated with regard to ischemic biliary lesions.

RESULTS

One hundred thirty-one grafts were preserved by in situ standard perfusion including portal perfusion,whereas additional arterial back table pressure perfusion was performed in 59 cases. Donor-related factors, recipient age, indications for transplantation, transplantation techniques, and ischemia times were comparable between groups. Twenty-one (16%) of the patients in the standard perfusion group and only one of the those receiving arterial back table pressure perfusion developed ischemic biliary lesions. This difference was highly significant (P=0.004). Maximal aspartate aminotransferase and alanine aminotransferase levels in the first 3 days were significantly lower in the arterial back table pressure perfusion group (P>0.05).

CONCLUSION

Arterial back table pressure perfusion is an easy and reliable method for preventing ischemic biliary lesions in orthotopic liver transplantation. It should, therefore, be the standard technique in liver procurement.

Oxygenated machine perfusion mitigates surface antigen expression and improves preservation of predamaged donor livers

The aim of the present study was to evaluate the potential benefit of machine preservation with the Belzer MPS or HTK solution, compared to standard cold storage, after procurement of marginal livers from non-heart beating donors in an experimental pilot study. Livers from male Wistar rats (250-300 g bw) were harvested after 60 min of cardiac arrest, flushed via the portal vein and cold stored submerged in HTK for 24 h at 4 degrees C while other organs were subjected to oxygenated machine perfusion with HTK or Belzer's MPS at 5 ml/min at 4 degrees C. Cold perfusion of livers with the non-colloidal HTK was not compromised by the lack of oncotic agents and there was no rise in vascular resistance during the 24 h of machine preservation with HTK or the colloidal Belzer MPS. Viability of the livers was assessed after the cold preservation period by warm reperfusion in vitro. Oxygenated machine perfusion was found to significantly increase viability of the livers vs simple cold storage with respect to portal vascular resistance upon reperfusion, enzyme release as well as functional recovery of oxygen utilization or bile production. Moreover, tissue antigen expression of ICAM-1 or histocompatibility antigen class II could be markedly reduced by oxygenated perfusion preservation as compared to cold storage. It is concluded that predamaged organs should preferably be preserved by oxygenated machine perfusion thus minimizing functional alterations and immunogenicity of the graft. In this setup HTK appeared equally effective as Belzer's MPS for machine preservation.

Surfactant function in lung transplantation after 24 hours of ischemia: advantage of retrograde flush perfusion for preservation

OBJECTIVE

Surfactant function was shown to be impaired in clinical and experimental lung transplantation. This study was designed to define the impact of retrograde flush perfusion on graft and surfactant function after an extended period of ischemia.

METHODS

Left lung transplantation was performed after 24 hours of graft ischemia in 12 pigs. In half of the grafts antegrade cold flush perfusion (Perfadex) was used for preservation. In the second group grafts were flushed in a retrograde fashion via the left atrium. Graft function was monitored for 7 hours after transplantation. Before transplantation (basal) and after 2 hours of reperfusion, bronchoalveolar lavage fluid was obtained. Minimal surface tension of bronchoalveolar lavage fluid was determined and the ratio of small and large surfactant aggregates was calculated. Lung water content was analyzed online in the reperfusion period.

RESULTS

Right-sided heart failure developed in 2 animals of group 1 (antegrade perfusion) within 2 and 4.5 hours of reperfusion, respectively. All other pigs survived the observation period. PO(2)/FIO(2) (P =.001) and dynamic lung compliance (P =.001) were superior in retrogradely flushed grafts. A comparable increase of minimal surface tension was found after reperfusion in both groups. Small/large surfactant aggregate ratio after reperfusion (P =.03), as well as extravascular lung water content, was higher in the antegrade perfusion group.

CONCLUSION

Retrograde flush perfusion for 24-hour lung preservation with low-potassium dextran (Perfadex) solution led to better initial graft function than the standard antegrade perfusion technique. A moderate impairment of surfactant function was found in both groups, which was more pronounced in the antegrade perfusion group.

Effects of hypothermic machine perfusion on rat liver function depending on the route of perfusion

BACKGROUND AND METHODS

The aim of this study was to evaluate the efficacy of hypothermic machine perfusion (HMP) to preserve rat livers according to the route of perfusion, i.e., via portal vein, hepatic veins (retrograde), or hepatic artery. Livers were preserved for 24 or 48 hr by simple cold storage (SCS) or by HMP. Preservation solution was supplemented with (HMP) or without (SCS) hydroxyethyl starch. After preservation, grafts were reperfused for 2 hr with an oxygenated Krebs-Henseleit bicarbonate buffer.

RESULTS

After 24 hr of preservation, total glutathione concentrations in HMP livers were similar (1287+/-37, 1418+/-118, and 1471+/-62 nmol/g in hepatic artery, portal vein, and hepatic vein HMP livers, respectively) and higher than in the SCS (833+/-118 nmol/g, P<0.05) group. These higher total glutathione values were due to higher reduced glutathione concentrations. ATP concentrations in the liver tissue were similar in HMP groups (0.75+/-0.4, 0.64+/-0.1, and 0.77+/-0.1 micromol/g in hepatic artery, portal vein, and hepatic vein HMP livers, respectively) and higher than in SCS (0.32+/-0.06 micromol/g, P<0.05). After 2 hr of normothermic reperfusion, bile production in the HMP portal and HMP retrograde groups were similar (391+/-29 ml and 372+/-25 ml) and higher than in the HMP artery or SCS groups (275+/-25 ml and 277+/-32 ml, respectively; P<0.05). Aspartate transaminase, alanine transaminase, lactate dehydrogenase, and purine nucleoside phosphorylase release into the perfusate of HMP portal and HMP retrograde perfused livers was similar and significantly lower compared to the HMP artery and SCS groups. At the end of reperfusion, no statistical differences were found for glutathione concentration and energetic reserves in the livers of each group. After 48 hr of preservation, livers from the HMP portal and HMP retrograde groups did significantly better than livers from the HMP artery or SCS groups.

CONCLUSIONS

This study confirms the superiority of HMP over SCS to preserve the liver graft. It shows that retrograde perfusion is similar to PV perfusion and that perfusion by HA is less beneficial.

Influence of long-term preservation with endobronchially administered perfluorodecalin on pulmonary graft function

BACKGROUND

Experimental studies demonstrated a suppression of oxygen-derived free radicals, reduced adhesion of activated neutrophils on the endothelium and an increase of de novo synthesis of surfactant during liquid ventilation with perflurocarbon. The purpose of this study was to assess the pulmonary graft function after preservation with endobronchially administered perfluorocarbon as an alternative to flush perfusion.

METHODS

Native bred pigs underwent orthotopic left lung transplantation. Donor lungs were flushed in situ with either a low-potassium dextran solution (LPD, n=6) or a perfluorochemical was administered endobronchially (PFC, n=6) and were then stored after removal for 18 hr at 4 degrees C. Pulmonary graft function was assessed after reperfusion for 5 hr by measuring pulmonary gas exchange and hemodynamics during isolated ventilation and perfusion. Tissue specimens were taken for analysis of morphology and wet/dry ratio. All values were compared to a sham-operated group (n=6).

RESULTS

Pulmonary gas exchange of the graft revealed reduced paO2 values and elevated paCO2 values in the PFC group throughout the observation period as compared with the LPD group and sham group. Endothelial alterations and fibrin exudate in the PFC group were significantly more pronounced. Lungs in the LPD group showed functional and morphological recovery close to sham group.

CONCLUSIONS

Long-term preservation with endobronchially administered perfuorocarbon is possible. Impaired pulmonary graft function and pronounced morphological alterations indicate an aggravation of the ischemic reperfusion injury after lung transplantation compared to LPD preserved lungs.

Retrograde flush perfusion with low-potassium solutions for improvement of experimental pulmonary preservation

BACKGROUND

Optimal preservation of post-ischemic organ function is a continuing challenge in clinical lung transplantation. Retrograde instillation of preservation solutions has the theoretic advantage of achieving homogeneous distribution in the lung because of perfusing both the pulmonary and the bronchial circulation. So far, we have seen no experimental studies that include stereologic analysis of intrapulmonary edema concerning the influence of retrograde preservation on post-ischemic lung function after preservation with Perfadex and Celsior.

METHODS

In an extracorporeal rat model, we perfused 8 lungs, each, using either antegrade or retrograde perfusion technique with Celsior (CE(ant)/CE(ret)) and Perfadex (PER(ant)/PER(ret)). Results were compared with low-potassium Euro-Collins. Post-ischemic lungs were reventilated and reperfused mechanically. We continuously monitored relative oxygenation capacity (ROC), pulmonary artery pressure, flush time, and wet/dry ratio. Furthermore, we used stereologic means to evaluate edema formation. Statistics comprised different analysis of variance models.

RESULTS

Relative oxygen capacity of CE(ant)-protected lungs was superior to that of PER(ant) preservation (p = 0.05). Use of PER(ret) resulted in significantly higher ROC as compared with PER(ant) (p < 0.001) and was comparable to results obtained with CE-preservation, which was not further improved with retrograde application.

CONCLUSIONS

Celsior provides better lung preservation than does Perfadex when administered antegradely. Retrograde application of Perfadex results in significant functional improvement as compared with antegrade perfusion, which reaches the standard of Celsior-protected organs. Additional in vivo experiments in combination with ultrastructural analysis are warranted to further evaluate retrograde delivery of preservation solutions, which could be used in clinical lung transplantation to further optimize current results.

The effect of short-term coronary perfusion using oxygenated diluted blood following cold storage for long-term heart preservation

BACKGROUND

The aim of this study was to compare the results obtained from the use of both University of Wisconsin (UW) solution and diluted blood in short-term coronary perfusion following 12-hour cold storage.

METHODS

Following coronary vascular washout of adult mongrel dogs with the UW solution, the heart was excised and immersed in a cold (4 degrees C) UW solution for 12 hours followed by 1-hour of coronary perfusion. Two different solutions were used for the coronary perfusion; a 4 degrees C oxygenated UW solution (Group U, n=7) and 15 degrees C oxygenated diluted blood (Group B, n=7). Myocardial high energy phosphate (HEP) levels, tissue water content (TWC), interstitial tissue space (ITS) rates and histological findings were evaluated at 0- and 12-hour cold storage and also following coronary perfusion. The preserved graft was then evaluated through orthotopic transplantation. The control group in this experiment consisted of seven hearts transplanted after 12-hour cold storage without coronary perfusion.

RESULTS

Myocardial HEP levels significantly decreased after 12-hour cold storage. The recovery rate of myocardial HEP levels after coronary perfusion was significantly (p<0.05) higher in Group B than in Group U. The increase of myocardial TWC during coronary perfusion was significantly (p<0.01) higher in Group B than in Group U. After 1-hour coronary perfusion, the subendocardial ITS rate was significantly (p<0.01) higher compared with the value at 0-hour cold storage in Group U, whereas it demonstrated no significant change in Group B. PAS stain revealed the glycogen content of the subendocardial tissues was higher in Group B than in Group U. The recovery rate of hemodynamic parameters 2 hours after heart transplantation was higher in Group U and significantly (p<0.05) higher in Group B than in the control.

CONCLUSIONS

Myocardial HEP levels recovered significantly after additional coronary perfusion. Though the UW solution prevented myocardial cellular edema, subendocardial perfusion was incomplete and the recovery rate of myocardial HEP levels was lower, suggesting that diluted blood may become the solution of choice as a perfusate.

Lowering reperfusion pressure reduces the injury after pulmonary ischemia

BACKGROUND

Controlled reperfusion with a modified solution limits pulmonary injury following ischemia. Our initial studies infused this modified reperfusate at a pressure of 40 to 50 mm Hg to insure distribution. However, perhaps a lower pressure, which is closer to the normal physiologic pressure in the lung, would improve results by decreasing sheer stress.

METHODS

Fifteen adult pigs underwent 2 hours of lung ischemia by clamping the left bronchus and pulmonary artery. Five (group 1) then underwent uncontrolled reperfusion by removing the vascular clamps and allowing unmodified blood to reperfuse the lung at a pulmonary artery pressure of 20 to 30 mm Hg. The other 10 pigs underwent controlled reperfusion by mixing blood from the femoral artery with a crystalloid solution, and infusing this modified reperfusate into the ischemic lung through the pulmonary artery for 10 minutes before removing the arterial clamp. In 5 (group 2), the modified solution was infused at a pressure of 40 to 50 mm Hg, and in 5 (group 3) 20 to 30 mm Hg. Lung function was assessed 60 minutes after reperfusion and expressed as percentage of control.

RESULTS

Compared to uncontrolled reperfusion (group 1), controlled reperfusion at a pressure of 40 to 50 mm Hg (group 2) significantly improved postreperfusion pulmonary compliance (77% versus 86%; p<0.001 versus group 1), and arterial/alveolar ratio (a/A) ratio (27% versus 52%; p<0.001 versus group 1); as well as decreased pulmonary vascular resistance (PVR) (198% versus 154%; p<0.001 versus group 1), lung water (84.3% versus 83.5%; p<0.001 versus group 1), and myeloperoxidase (0.35 versus 0.23 optical density/min/mg protein). Reducing the pressure of the modified reperfusate to 20 to 30 mm Hg further improved postreperfusion compliance (92%+/-1%; p<0.001 versus groups 1 and 2) and a/A ratio (76%+/-1%; p<0.001 versus groups 1 and 2); and lowered PVR (133%+/-2%; p<0.001 versus groups 1 and 2), lung water (82.7%+/-0.1%; p<0.001 versus groups 1 and 2), and myeloperoxidase (0.16%+/-0.01%; p<0.001 versus groups 1 and 2).

CONCLUSIONS

After 2 hours of pulmonary ischemia, a severe lung injury occurs following uncontrolled reperfusion, controlled reperfusion with a modified solution reduces this reperfusion injury, and lowering the pressure of the modified reperfusate to more physiologic levels (20 to 30 mm Hg) further reduces the reperfusion injury improving pulmonary function.

Influence of different routes of flush perfusion on the distribution of lung preservation solutions in parenchyma and airways

OBJECTIVE

The present study was performed to investigate the influence of different routes of perfusion on the distribution of the preservation solutions in the lung parenchyma and upper airways.

METHODS

Pigs were divided into four groups: control (n = 6), pulmonary artery (PA) (n = 6), simultaneous PA + bronchial artery (BA) (n = 8), and retrograde delivery (n = 6). After preparation and cannulation, cardioplegia solution and Euro-Collins solution (ECS) for lung preservation were given simultaneously. After removal of the heart, the double lung bloc was harvested. Following parameters were assessed: total and regional perfusion (dye-labeled microspheres), tissue water content, PA, aorta, left atrial and left ventricular pressures, cardiac output and lung temperature.

RESULTS

Our data show that flow of the ECS in lung parenchyma did not reach control values (9.4+/-1.0 ml/min per g lung wet weight) regardless of the route of delivery (PA 6.3+/-1.5, PA + BA 4.8+/-0.9, retrograde 2.7+/-0.9 ml/min per g lung wet weight). However, flow in the proximal and distal trachea were significantly increased by PA + BA delivery (0.970+/-0.4, respectively, 0.380+/-0.2 ml/min per g) in comparison with PA (0.023+/-0.007, respectively, 0.024+/-0.070 ml/min per g), retrograde (0.009+/-0.003, respectively, 0.021+/-0.006 ml/min per g) and control experiments (0.125+/-0.0018, respectively, 0.105+/-0.012 ml/g per min). Similarly the highest flow rates in the right main bronchus were achieved by PA + BA delivery (1.04+/-0.4 ml/min per g) in comparison with 0.11+/-0.03 in control, 0.033+/-0.008 in PA, and 0.019+/-0.005 ml/min per g in retrograde group. Flows in the left main bronchus were 0.09+/-0.02 ml/min per g in control, 0.045+/-0.012 ml/min per g in PA, and 0.027+/-0.006 ml/min per g in retrograde group. The flow rates were significantly (P = 0.001) increased by PA + BA delivery of the storage solution (0.97+/-0.3 ml/min per g).

CONCLUSIONS

Our data show that the distribution of ECS for lung preservation is significantly improved in airway tissues (trachea and bronchi) if a simultaneous PA + BA delivery is used.

Isolated vascular perfusion of human colon with adenocarcinoma

Based on the premise that optimal drug delivery might improve the efficacy of locoregional treatment for solid tumors, the authors set up an experimental model for isolation perfusion in surgical specimens from patients resected for carcinoma of the colon. Ten surgical specimens were cannulated, washed internally and externally with saline solution, promptly cooled to 4 degreesC, connected to a circuit, and perfused with Krebs-Henselait modified solution, concentrated red blood cells, albumin, desamethasone, glucose, and heparin for 60 minutes at a target temperature of 37 degreesC. Organ temperature, flow rate, perfusion pressure, and metabolic and functional parameters were checked at 5, 20, and 60 minutes of perfusion. A paraphysiologic perfusion procedure was achieved. Mean values (and ranges) were as follows: temperature 37 degreesC (35. 1-39.6 degreesC); flow rate 10.2 (5.6-17.9) ml/min/100 g; arterial pressure 96 (42-154) mmHg; arterial pH 7.3 (7.1-7.5); arterial PO2 183 (78-304) mmHg; arterial PCO2 36 (31-46) mmHg. No important signs of tissue damage were found at histology. Autonomous or stimulated peristalsis (or both) was present throughout the experiment. Mean O2 extraction was 7.9 ml/min/100 g (range 3.1-11.0). Mean glucose consumption was 229 mg/100 g (range 174-252). The model worked well and appears promising, particularly for future use in various pharmacokinetic and pharmacodynamic studies of antiblastic agents.

Preharvest nitroprusside flush improves posttransplantation lung function

BACKGROUND

Morbidity as a result of early allograft dysfunction remains a significant problem in clinical lung transplantation. We previously demonstrated that nitroprusside (NP), a potent nitric oxide donor, administered before storage and again during reperfusion, reduced lung reperfusion injury. The purpose of the present study was to determine whether these observations were storage effects, reperfusion effects, or both.

MATERIALS AND METHODS

Fifteen dogs underwent left lung allotransplant. Donor lungs were flushed with modified Euro-Collins solution and stored for 21 hours at 1 degree C. Immediately after transplantation, the contralateral right main pulmonary artery and bronchus were ligated to assess isolated allograft function. Hemodynamics and arterial blood gas analysis (FIO2 1.0) were assessed for 6 hours before sacrifice. Allograft myeloperoxidase (MPO) activity and wet to dry weight (W/D) ratio were assessed. Animals were divided into three groups for timing of NP administration. Group I (n = 5) animals received no NP. In group II (n = 5), donor lungs received NP (10 mg/L) in the flush solution only. In group III (n = 5), recipient animals received NP (0.2 mg/kg) just before reperfusion, as well as a continuous infusion (0.1 mg/kg/hr) during the assessment period.

RESULTS

Significant improvement in gas exchange was apparent in groups II and III compared with group I, but there was no significant difference between groups II and III. After 6-hour reperfusion, mean PaO2 values were 85.46 +/- 13.32 mm Hg in group I, 298.74 +/- 61.25 mm Hg in group II (p < 0.05), and 311.12 +/- 43.39 mm Hg in group III (p < 0.05). Systemic vascular resistance was significantly lower in group III than in group I (p < 0.05). MPO activities decreased in groups II (p < 0.05) and III (p < 0.05), indicating reduced neutrophil sequestration. W/D ratio was significantly lower in groups II and III.

CONCLUSION

Both methods of NP administration are effective, but NP administration in the recipient is accompanied by a decrease in systemic vascular resistance. From a clinical point of view, NP administration in the flush solution is a sufficiently effective and practical method to reduce lung allograft reperfusion injury.

Three-dimensional reconstruction of the liver venous system using the preservation solution as contrast agent

To investigate whether MRI without using artificial contrast agents can provide sufficient image contrast to visualize the venous tree in the cold stored liver graft, two pig liver grafts were scanned with a multislice turbo spin-echo sequence with long TE (200 msec). The quality of the data obtained at 1-T field strength was sufficient for three-dimensional reconstruction of the hepatic vascular system, potentially useful for liver splitting surgery.

Functional recovery of human mesenteric and coronary arteries after cryopreservation at -196 degrees C in a serum-free medium

PURPOSE

Long-term patency of cryopreserved vascular grafts is determined by maintained cellular and tissue viability, which implies preservation of various biochemical, smooth muscle, and endothelial functions. Therefore, it was investigated whether the presence of fetal calf serum (FCS) in the cryomedium improves the postthaw contractile and endothelial function of human arteries.

METHODS

Rings from human mesenteric (HMA) and left circumflex coronary arteries (HCA) obtained from organ donors were randomized into three groups and studied either unfrozen or after storage for 3 to 6 weeks at -196 degrees C while suspended in Krebs-Henseleit solution without or with 20% FCS as the vehicles and 1.8 mol/L dimethyl sulfoxide and 0.1 mol/L sucrose as cryoprotecting agents. The samples were slowly frozen to -70 degrees C and then stored in liquid nitrogen. Before use, the tissues were thawed within 3 minutes in a 40 degrees C water bath.

RESULTS

After thawing the sensitivity to various agonists and maximal responses to the endothelium-independent relaxing agent sodium nitroprusside were unchanged. However, after cryopreservation of HMA was performed without and with FCS, maximal contractile responses to noradrenaline were significantly reduced to 10.1 +/- 0.7 gm and 9.9 +/- 0.9 gm compared with 13.3 +/- 0.6 gm in unfrozen HMA (mean +/- SEM, n = 15). After cryopreservation of HCA was performed without and with FCS, maximal contractile responses to prostaglandin F2 alpha (6.9 +/- 0.4 gm in unfrozen HCA) were significantly reduced to 4.3 +/- 0.3 gm and 3.8 +/- 0.2 gm (mean +/- SEM, n = 6). In both types of arteries cryopreservation also attenuated significantly the endothelium-dependent relaxant responses to bradykinin during U46619 (10 nmol/L)-induced tone. In HMA the maximal bradykinin-induced relaxation (85% +/- 4%) was significantly diminished to 29% +/- 7% and 38% +/- 9% after cryopreservation without and with FCS (mean +/- SEM, n = 6). In HCA maximal bradykinin-induced relaxation (88% +/- 4%) was significantly diminished to 26% +/- 10% and 36% +/- 11% after cryopreservation without and with FCS (mean +/- SEM, n = 6). This result was reflected by a marked endothelial denudation in all groups of cryopreserved arteries. Neither functional nor morphologic preservation of the endothelial cell lining was significantly improved by FCS supplementation of the cryomedium.

CONCLUSIONS

Cryopreservation diminished contractile and endothelium-dependent relaxant responses of human arteries. The presence of FCS in the cryomedium did not modify these changes.

Influence of the perfusate temperature on lung preservation: is there an optimum?

The optimal temperature of the pulmonary flush perfusate is still a matter of controversy. At present, a temperature of 10 degrees C is favored. This study deals with the structural and functional impact of different perfusate temperatures on lung preservation. In an extracorporeal rat heart-lung model lungs were preserved with Perfadex solution of 4, 15 and 25 degrees C and submitted to 2 h ischemia. Heart-lung blocks harvested from male rats were perfused with Krebs-Henseleit solution and ventilated with room air. Lungs were perfused with deoxygenated perfusate via the working right ventricle while the coronary arteries were retrogradely perfused with oxygenated perfusate. Oxygenation capacity (dPO2), peak inspiratory pressure (PIP) and pulmonary vascular resistance were measured. After establishment of baseline functional parameters hearts were arrested with 10 ml St. Thomas cardioplegia and lungs were flushed with 20 ml Perfadex solution. The heart-lung block was then stored for 2 h at 10 degrees C. Reperfusion was performed thereafter under the same conditions. At the end of the trial the lung tissue water was measured by the wet/dry ratio. The perfusion time of the groups flushed with 15 or 25 degrees C perfusate was significantly lower than that of the 4 degrees C group. After 20 min reperfusion dPO2 of the groups flushed with 15 or 25 degrees C was superior to those submitted to a 4 degrees C flush perfusion. PIP was significantly lower in the 15 degrees C group than in the 4 and 25 degrees C groups. The wet/dry ratio revealed the smallest water content in the 15 degrees C group. We conclude that the post-ischemic lung function is dependent on the temperature of the flush perfusate. Among the tested temperatures, perfusion at 15 degrees C showed the best results. The optimum may therefore lie in this range.