Normothermic recirculation reduces primary graft dysfunction of kidneys obtained from non-heart-beating donors

Development of a preclinical model of donation after circulatory determination of death for translational application

Background

Extracorporeal membranous oxygenation is proposed for abdominal organ procurement from donation after circulatory determination of death (DCD). In France, the national Agency of Biomedicine supervises the procurement of kidneys from DCD, specifying the durations of tolerated warm and cold ischemia. However, no study has determined the optimal conditions of this technique. The aim of this work was to develop a preclinical model of DCD using abdominal normothermic oxygenated recirculation (ANOR). In short, our objectives are to characterize the mechanisms involved during ANOR and its impact on abdominal organs.

Methods

We used Large White pigs weighing between 45 and 55 kg. After 30 minutes of potassium-induced cardiac arrest, the descending thoracic aorta was clamped and ANOR set up between the inferior vena cava and the abdominal aorta for 4 hours. Hemodynamic, respiratory and biochemical parameters were collected. Blood gasometry and biochemistry analysis were performed during the ANOR procedure.

Results

Six ANOR procedures were performed. The surgical procedure is described and intraoperative parameters and biological data are presented. Pump flow rates were between 2.5 and 3 l/min. Hemodynamic, respiratory, and biochemical objectives were achieved under reproducible conditions. Interestingly, animals remained hemodynamically stable following the targeted protocol. Arterial pH was controlled, and natremia and renal function remained stable 4 hours after the procedure was started. Decreased hemoglobin and serum proteins levels, concomitant with increased lactate dehydrogenase activity, were observed as a consequence of the surgery. The serum potassium level was increased, owing to the extracorporeal circulation circuit.

Conclusions

Our ANOR model is the closest to clinical conditions reported in the literature and will allow the study of the systemic and abdominal organ impact of this technique. The translational relevance of the pig will permit the determination of new biomarkers and protocols to improve DCD donor management.

Donation after circulatory death: current practices, ongoing challenges, and potential improvements

Organ donation after circulatory death (DCD) has been endorsed by the World Health Organization and is practiced worldwide. This overview examines current DCD practices, identifies problems and challenges, and suggests clinical strategies for possible improvement. Although there is uniform agreement on DCD donor candidacy (ventilator-dependent individuals with nonrecoverable or irreversible neurologic injury not meeting brain death criteria), there are variations in all aspects of DCD practice. Utilization of DCD organs is limited by hypoxia, hypotension, reduced--then absent--organ perfusion, and ischemia/reperfusion syndrome. Nevertheless, DCD kidneys exhibit comparable function and survival to donors with brain death kidneys, although they have higher rates of primary graft nonfunction, delayed graft function, discard, and retrieval associated injury. Concern over ischemic organ injury underscores the reluctance to recover extrarenal DCD organs since lack of medical therapy to support inadequate allograft function limits their acceptability. Nevertheless, limited results with DCD pancreas, liver, and lung allografts (but not heart) are now approaching that of donors with brain death organs. Pretransplant machine perfusion of DCD kidneys (vs. static storage) may reduce delayed graft function but has no effect on long-term organ function and survival. Normothermic regional perfusion used during DCD abdominal organ retrieval may reduce ischemic organ injury and increase the number of usable organs, although critical confirmative studies have yet to be done. Minor increases in usable DCD kidneys could accrue from increased use of pediatric DCD kidneys and from selective use of DCD/ECD kidneys, whereas a modest increase could result through utilization of donors declared dead beyond 1 hr from withdrawal of life support therapy. A significant increase in transplantable kidneys could be achieved by extension of the concept of living kidney donation in relation to imminent death of potential DCD donors. Progress in research to identify, prevent, and repair DCD-associated organ retrieval injury should improve utilization of DCD organs. Recent results using ex situ pretransplant organ perfusion of DCD organs has been encouraging in this regard.

Regional perfusion by extracorporeal membrane oxygenation of abdominal organs from donors after circulatory death: a systematic review

Organs from donors after circulatory death (DCDs) are particularly susceptible to the effects of warm ischemia injury. Regional perfusion (RP) by extracorporeal membrane oxygenation (ECMO) is increasingly being advocated as a useful remedy to the effects of ischemia/reperfusion injury, and it has been reported to enable the transplantation of organs from donors previously deemed unsuitable. The MEDLINE, Embase, and Cochrane databases were searched, and articles published between 1997 and 2013 were obtained. A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Two hundred ten articles were identified, and 11 were eligible for inclusion. Four hundred eighty-two kidneys and 79 livers were transplanted from regional perfusion-supported donor after circulatory death (RP-DCD) sources. One-year graft survival was lower with uncontrolled RP-DCD liver transplantation, whereas 1-year patient survival was similar. Primary nonfunction and ischemic cholangiopathy were significantly more frequent with RP-DCDs versus donors after brain death (DBDs), but there was no difference in postoperative mortality between the 2 groups. The 1-year patient and graft survival rates for RP-DCD kidney transplantation were better than the rates with standard DCDs and were comparable to, if not better than, the rates with DBDs. At experienced centers, delayed graft function (DGF) for kidney transplantation from RP-DCDs was much less frequent in comparison with all other donor types. In conclusion, RP aids the recovery of DCD organs from ischemic injury and enables transplantation with acceptable survival. RP may help to increase the donor pool, but its benefits must still be balanced with the recognition of significantly higher rates of complications in liver transplantation. In kidney transplantation, significant reductions in DGF can be obtained with RP, and there are potentially important implications for long-term outcomes. Significant ethicolegal issues exist, and they are preventing a worldwide consensus on optimum RP protocols and an accurate appreciation of outcomes.

Challenges in machine perfusion preservation for liver grafts from donation after circulatory death

Donation after circulatory death (DCD) is a promising solution to the critical shortage of donor graft tissue. Maintaining organ viability after donation until transplantation is essential for optimal graft function and survival. To date, static cold storage is the most widely used form of preservation in clinical practice. However, ischemic damage present in DCD grafts jeopardizes organ viability during cold storage, and whether static cold storage is the most effective method to prevent deterioration of organ quality in the increasing numbers of organs from DCD is unknown. Here we describe the historical background of DCD liver grafts and a new preservation method for experimental and clinical transplantation. To prevent ischemia-reperfusion injury in DCD liver grafts, a hypothermic machine perfusion (HMP) technique has recently been developed and may be superior to static cold preservation. We present evidence supporting the need for improving liver perfusion performance and discuss how doing so will benefit liver transplantation recipients.

Non-invasive magnetic resonance imaging in rats for prediction of the fate of grafted kidneys from cardiac death donors

The main objective of this study was to assess cardiac death (CD) kidney grafts before transplantation to determine whether blood oxygen level-dependent (BOLD) and diffusion MRI techniques can predict damage to these grafts after transplantation. We assessed CD kidney tissue by BOLD and diffusion MRI. We also examined pathological and gene expression changes in CD kidney grafts before and after transplantation. Although there was significantly more red cell congestion (RCC) in the inner stripe of the outer medulla (IS) in both 1 h after cardiac death (CD1h) and CD2h kidneys destined for grafts before transplantation compared with CD0h (p<0.05), CD2h, but not CD1h, kidney grafts had significantly different RCC in the IS 2 days after transplantation (p<0.05). Consistent with these pathological findings, tissue plasminogen activator (tPA) gene expression was increased only in the cortex and medulla of CD2h kidney grafts after transplantation. BOLD MRI successfully and non-invasively imaged and quantified RCC in the IS in both CD1h and CD2h kidney grafts (p<0.05). Diffusion MRI also non-invasively assessed increased the apparent diffusion coefficient in the IS and decreased it in the outer stripe (OS) of CD2h grafts, in concordance with interstitial edema in the IS and tubule cellular edema in the OS. These two types of edema in the outer medulla could explain the prolonged RCC in the IS only of CD2h kidney grafts, creating part of a vicious cycle inhibiting red cells coming out of capillary vessels in the IS. Perfusion with University of Wisconsin solution before MRI measurements did not diminish the difference in tissue damage between CD1h and CD2h kidney grafts. BOLD and diffusion MRI, which are readily available non-invasive tools for evaluating CD kidney grafts tissue damage, can predict prolonged organ damage, and therefore the outcome, of transplanted CD kidney grafts.

Innovations in organ donation

The growing disparity between organ availability for transplantation and the number of patients in need has challenged the donation and transplantation community of practice to develop innovative processes, ideas, and techniques to bridge the gaps. Advances in the sharing of best practices in the donation community have contributed greatly over the last 8 years. Broader sharing of updated guidelines for declaration of brain death in conjunction with improvements in deceased donor management have increased opportunities for organ donation. New techniques for organ preservation and organ resuscitation have allowed for better utilization of the potential donor pool. This review will highlight processes, ideas, and techniques in organ donation.

The conditioning effect of ex vivo normothermic perfusion in an experimental kidney model

BACKGROUND

A short period of isolated normothermic perfusion (NP) can be used to improve the condition of the kidney after periods of warm and cold ischemic injury. However, the mechanisms underlying this beneficial effect have not been determined.

MATERIALS AND METHODS

Porcine kidneys were retrieved after 10 min of warm ischemic injury and stored by either static cold storage (CS) for 24 h (control) or CS for 23 h followed by 1 h of NP at 38°C with leukocyte-depleted autologous blood (NP). After preservation, kidneys in both groups underwent 3 h of ex vivo reperfusion to assess the injury (n = 6).

RESULTS

NP kidneys had significantly lower levels of intrarenal resistance (NP 2.28 ± 1.1 versus control 3.86 ± 1.2 mm Hg/mL/h; P = 0.040), maintained their acid base homeostasis (P = 0.080), and had higher levels of oxygen consumption (NP 42.6 ± 19.5 versus control 20.8 ± 5.7 mL/min/g; P = 0.026) and reduced tubular injury (P = 0.008) compared with kidneys in the control group during reperfusion. There were no significant differences in the levels of inflammatory cytokines (interleukin [IL]-1β, IL-8, or tumor necrosis factor-α; P > 0.05) or in renal function (creatinine clearance NP 2.6 ± 1.3 versus control 3.0 ± 1.5 mL/min/100 g; P = 0.070). However, levels of IL-6 were significantly raised in the NP group after reperfusion (P = 0.016). Levels of heat shock protein 70 were upregulated after 1 h of NP and expression increased during reperfusion to a significantly higher level than in the control group (P = 0.045).

CONCLUSION

Kidneys undergoing a short period of NP had improved metabolic function and less tubular injury compared with static cold-stored kidneys. The increased expression of heat shock protein 70 and IL-6 suggests that NP may upregulate mechanisms that condition the kidney.

Impact of a new refrigerator on the preservation of hepatic grafts

AIM

  Current medical transplantation methods focus on solutions for major problems such as the shortage of donors. To overcome these issues, expanding organ preservation time has become a major concern. A new refrigerating chamber has been recently developed, which can cool the inside of a material to the required temperature by frequently sensing the temperature of both inside and surface of the materials. The purpose of this study is to evaluate the usefulness of a new refrigerating system in hepatic preservation.

METHODS

  The liver grafts were harvested from rats and divided into two groups. Group A consisted of grafts preserved in chilled University of Wisconsin solution (UW) solution (on ice) for 24, 72 and 168 h. Group B consisted of grafts preserved in the UW solution in a new refrigerator at 4°C.

RESULTS

  In group B, aspartate aminotransferase released into effluent after cold storage for 72 h showed a marked decrease compared to group A (P < 0.05). The levels of ammonia and lactate decreased significantly in group B (P < 0.05). In group B, the levels of adenosine triphosphate were significantly preserved after cold storage for 24 h and 72 h compared to group A (P < 0.05). Immunohistochemistry showed positive cells for heme oxygenase-1 were significantly increased in group B after cold storage.

CONCLUSION

  This new refrigerator can improve preservation injury of hepatic grafts and may provide an innovative technique for liver transplantation.

Kidney graft outcome and quality (after transplantation) from uncontrolled deceased donors after cardiac arrest

The use of uncontrolled deceased donors after cardiac arrest (uDDCA) has been developed in France to compensate for organ shortage. The quality of these kidneys remains unclear. We analyzed kidney graft function and histology from 27 uDDCA and compared them with kidneys from 30 extended criteria donors (ECD) and from 24 simultaneous pancreas kidney (SPK) donors as a control group of optimal deceased donors. Kidneys from ECD and SPK donors were preserved by static cold storage while kidneys from uDDCA were preserved by pulsatile perfusion. The uDDCA graft function at 3 years posttransplantation (estimated with MDRD and measured with inulin clearance) did not differ from that of the ECD group (eGFR 44.1 vs. 37.4 mL/min/1.73 m(2) , p = 0.13; mGFR 44.6 vs. 36.1 mL/min/1.73 m(2) , p = 0.07 in the uDDCA and ECD groups, respectively). The histological assessment of 3-month and 1-year protocol biopsies did not show differences for interstitial lesions between the uDDCA and ECD grafts (IF score at M3 was 30 vs. 28% and at M12 36 vs. 33%, p = NS). In conclusion, the results at 3 years with carefully selected and machine-perfused uDDCA kidneys have been comparable to ECD kidneys and encourage continuation of this program and development of similar programs.

Organ transplantation: historical perspective and current practice

Over the course of the last century, organ transplantation has overcome major technical limitations to become the success it is today. The breakthroughs include developing techniques for vascular anastomoses, managing the immune response (initially by avoiding it with the use of identical twins and subsequently controlling it with chemical immunosuppressants), and devising preservation solutions that enable prolonged periods of ex vivo storage while preserving function. One challenge that has remained from the outset is to overcome the shortage of suitable donor organs. The results of organ transplantation continue to improve, both as a consequence of the above innovations and the improvements in peri- and postoperative management. This review describes some of the achievements and challenges of organ transplantation.

Kidney transplantation from a donor following cardiac death supported with extracorporeal membrane oxygenation

To expand the donor pool, organ donation after cardiac death (DCD) has emerged. However, kidneys from DCD donors have a period of long warm ischemia between cardiac arrest and the harvesting of the organs. Recently, we used extracorporeal membrane oxygenation (ECMO) to minimize ischemic injury during 'no touch' periods in a Maastricht category II DCD donor and performed two successful kidney transplantations. The kidneys were procured from a 49-yr-old male donor. The warm ischemia time was 31 min, and the time of maintained circulation using ECMO was 7 hr 55 min. The cold ischemia time was 9 hr 15 min. The kidneys were transplanted into two recipients and functioned immediately after reperfusion. The grafts showed excellent function at one and three months post-transplantation; serum creatinine (SCr) levels were 1.0 mg/dL and 0.8 mg/dL and the estimated glomerular filtration rates (eGFR) were 63 mL/min/1.73 m(2) and 78 mL/min/1.73 m(2) in the first recipient, and SCr levels were 1.1 mg/dL and 1.0 mg/dL and eGFR were 56 mL/min/1.73 m(2) and 64 mL/min/1.73 m(2) in the second recipient. In conclusion, it is suggested that kidney transplantation from a category II DCD donor assisted by ECMO is a reasonable modality for expanding donor pool.

Organ procurement: Spanish transplant procurement management

Transplantation is an accepted therapeutic option to save or improve the quality of life when organ failure occurs or tissue replacements are needed. However, the lack of organs is the major limitation. The deceased organ procurement organization and professionals provide the solution to this international problem. In this review, we identify the elements involved in the organ procurement management process to analyze the possibility of implementation of deceased organ procurement for a transplantation program. While the donation rates are subject to several negative factors including religious, economic, cultural, and legal issues, the existence of well-trained professionals may considerably increase them. Professional training in organ donation along with the establishment of a solid organizational system has been identified as the crucial factor in developing efficient organ donation and transplantation programs.

The effect of normothermic recirculation before cold preservation on post-transplant injury of ischemically damaged donor kidneys

Kidneys recovered from donation after cardiac death (DCD) are increasingly used to enlarge the deceased donor pool. Such renal grafts, especially those derived from uncontrolled DCD, have inevitably sustained profound warm ischemic injury, which compromises post-transplant function. Normothermic recirculation (NR) of the deceased donor's body before organ cooling could be an interesting approach to mitigate the detrimental effect of warm ischemia. To date, however, there is no evidence coming from preclinical studies to support the principle of NR in kidney transplantation. In this study, we subjected 48 Lewis rat kidneys to 15 or 30 min of warm ischemia, and subsequently 0, 1, or 2 h of NR. After 24 h cold storage, kidneys were transplanted into a recipient animal and 24 h later we measured the percentage of cortical necrosis, and determined gene expression of heme oxigenase-1, heat shock protein-70, transforming growth factor-β, kidney injury molecule-1, interleukin-6, hypoxia inducible factor-1α, monocyte chemoattractant protein-1, and α-smooth muscle actin in kidney tissue. We found that NR had no significant influence on any of these markers. Therefore, we conclude that this animal study by no means supports the presumed beneficial effect of NR on kidneys that have been severely damaged by warm ischemia.

Derivation of the uncontrolled donation after circulatory determination of death protocol for New York city

Evidence from Europe suggests establishing out-of-hospital, uncontrolled donation after circulatory determination of death (UDCDD) protocols has potential to substantially increase organ availability. The study objective was to derive an out-of-hospital UDCDD protocol that would be acceptable to New York City (NYC) residents. Participatory action research and the SEED-SCALE process for social change guided protocol development in NYC from July 2007 to September 2010. A coalition of government officials, subject experts and communities necessary to achieve support was formed. Authorized NY State and NYC government officials and their legal representatives collaboratively investigated how the program could be implemented under current law and regulations. Community stakeholders (secular and religious organizations) were engaged in town hall style meetings. Ethnographic data (meeting minutes, field notes, quantitative surveys) were collected and posted in a collaborative internet environment. Data were analyzed using an iterative coding scheme to discern themes, theoretical constructs and a summary narrative to guide protocol development. A clinically appropriate, ethically sound UDCDD protocol for out-of-hospital settings has been derived. This program is likely to be accepted by NYC residents since the protocol was derived through partnership with government officials, subject experts and community participants.

Normothermic kidney preservation

PURPOSE OF REVIEW

Kidneys from marginal or donation after cardiac death (DCD) donors are particularly susceptible to injury during hypothermic preservation and may benefit from alternative methods of preservation. Normothermic preservation can be adapted to improve the quality of kidneys for transplantation by a variety of techniques.

RECENT FINDINGS

Extracorporeal membrane support to maintain circulation before cooling and organ retrieval has been used to improve the condition of DCD donor kidneys, with lower rates of delayed graft function (DGF) compared with standard retrieval conditions. Experimentally, normothermic perfusion has been used in conjunction with hypothermic techniques as a resuscitation technique to improve graft outcome. An ex-vivo porcine kidney model showed that energy levels could be replenished to improve tissue perfusion during reperfusion. This technique was translated into a porcine transplant model demonstrating that it was a feasible and safe method of preservation.

SUMMARY

Normothermic preservation techniques have the potential to be adapted into an improved method of retaining tissue viability compared with hypothermic techniques. Furthermore, they may be used as a device to enhance and assess the condition of the kidney which would be particularly beneficial for kidneys from DCD donors.

Preservation techniques for donors after cardiac death kidneys

PURPOSE OF REVIEW

The purpose of the present review is to describe the techniques currently used to preserve kidneys from donors after cardiac death.

RECENT FINDINGS

Automated chest compression devices may be used to improve organ perfusion between cardiac death and preservation measures. Normothermic extracorporeal membrane oxygenation reduces warm ischemic injury and has the ability to improve organ viability in donors after cardiac death.

SUMMARY

Kidneys from donors after cardiac death expand the donor pool but are inevitably subjected to a period of warm ischemia. Reduction of warm ischemic injury to the organs improves transplant outcome. To reduce this injury in organs from donors after cardiac death, different preservation techniques are used. Automated chest compression devices improve organ perfusion between cardiac death and the start of organ preservation. In-situ preservation with double-balloon triple-lumen catheter is an easy technique to preserve organs in uncontrolled donors and is used in many centers to cool and flush the organs. In controlled donors, organs can also be flushed after laparotomy and direct cannulation of the aorta. Extracorporeal membrane oxygenation reduces warm ischemic injury and the use of normothermic perfusion seems promising. Optimal preservation is essential to improve the viability of kidneys from donors after cardiac death, to fully utilize this large donor pool.

Lessons learned from a single center's experience with 134 donation after cardiac death donor kidney transplants

BACKGROUND

Reports of kidney transplantation from donation after cardiac death (DCD) donors describe high rates of delayed graft function (DGF).

STUDY DESIGN

From April 1, 2003 to October 17, 2010, we performed 134 kidney transplants from DCD donors including 120 (90%) from standard-criteria donors (SCDs) and 14 (10%) from expanded-criteria donors (ECDs). Nineteen kidneys were recovered from donors managed with extracorporeal interval support for organ retrieval (EISOR) after cardiac arrest to minimize ischemic injury.

RESULTS

Comparison of donor and recipient characteristics found no differences for cases managed with or without EISOR. Overall actuarial patient survival rates were 93%, 91%, and 89% at 1, 3, and 5 years, respectively, with a mean follow-up of 31 months. Overall actuarial kidney graft survival rates were 89%, 76%, and 76% at 1, 3, and 5 years, respectively. Actuarial graft survival rates of DCD ECD kidneys were 58% and 48% at 1 and 3 years, compared with 90% and 79% at 1 and 3 years for non-ECD grafts (p = 0.013). DGF occurred in 73 patients (54%) overall and was reduced from 55% to 21% (p = 0.016) with the use of EISOR in locally recovered kidneys. The mean resistance value on machine perfusion and the mean estimated glomerular filtration rate 1 month after transplantation were both improved (p < 0.05) in kidneys from donors managed with EISOR. Mean initial hospital stay was reduced from 8.0 to 5.0 days in patients receiving kidneys recovered with EISOR (p = 0.04).

CONCLUSIONS

EISOR is associated with a lower rate of DGF, lower graft resistance on machine perfusion, and shorter initial hospitalization. Kidneys from DCD SCDs have excellent medium-term outcomes and represent an important means of expanding the donor pool. Kidneys from DCD ECDs have inferior outcomes.

In-vivo normothermic recirculation: an update

PURPOSE OF REVIEW

The use of nonheart-beating donors (NHBD), as a source for liver grafts, is the only way to objectively increase the activity in liver transplantation. Through the use of more strict criteria, 1-year graft survival has increased from 50% in initial series to 84-100%. With respect to type II NHBD (failure of cardiopulmonary resuscitation) we believe that the use of normothermic recirculation provides the possibility to obtain good quality grafts for transplantation. Our recent experience shows a 66% and 73% graft and patient survival respectively.

RECENT FINDINGS

However, the incidence of biliary tract complications (ischemic type), as well as the relative low number of grafts procured that are finally transplanted, makes this methodology difficult to develop. The use of a 'normothermic machine perfusion' (once the liver is procured), added to the already described method, may actually increase the efficacy and safety of the whole procedure. Recent experience by our group as well as others have shown that the liver so perfused is able to recover from the warm ischemic lesion and at the same time the procedure allows the possibility to evaluate the quality of the potential graft.

SUMMARY

NHBD are the only source that may objectively increased the number of liver transplant. The use of normothermic recirculation has proved to be effective and well tolerated. The addition of the 'normothermic machine perfusion' to the whole procedure may significantly increase the number of transplants.

Extracorporeal support: improves donor renal graft function after cardiac death

Donors after cardiac death (DCD) could increase the organ pool. Data supports good long-term renal graft survival. However, DCDs are <10% of deceased donors in the United States, due to delayed graft function, and primary nonfunction. These complications are minimized by extracorporeal support after cardiac death (ECS-DCD). This study assesses immediate and acute renal function from different donor types. DCDs kidneys were recovered by conventional rapid recovery or by ECS, and transplanted into nephrectomized healthy swine. Warm ischemia of 10 and 30 min were evaluated. Swine living donors were controls (LVD). ECS-DCDs were treated with 90 min of perfusion until organ recovery. After procurement, kidneys were cold storage 4-6 h. Renal vascular resistance (RVR), urine output (UO), urine protein concentration (UrPr) and creatinine clearance (CrCl), were collected during 4 h posttransplantation. All grafts functioned with adequate renal blood flow for 4 h. RVR at 4 h posttransplant returned to baseline only in the LVD group (0.36 mmHg/mL/min +/- 0.03). RVR was higher in all DCDs (0.66 mmHg/mL/min +/- 0.13), without differences between them. UO was >50 mL/h in all DCDs, except in DCD-30 (6.8 mL/h +/- 1.7). DCD-30 had lower CrCl (0.9 mL/min +/- 0.2) and higher UrPr >200 mg/dL, compared to other DCDs >10 mL/min and <160 mg/dL, respectively. Normothermic ECS can resuscitate kidneys to transplantable status after 30 min of cardiac arrest/WI.

Machine perfusion or cold storage in organ transplantation: indication, mechanisms, and future perspectives

Most organs are currently preserved by cold storage (CS) prior to transplantation. However, as more so called marginal donor organs are utilized, machine perfusion has regained clinical interest. Recent studies have demonstrated advantages of pulsatile perfusion over CS preservation for kidney transplantation. However, it remains unclear whether there is a significant benefit of one preservation method over the other in general, or, whether the utilization of particular preservation approaches needs to be linked to organ characteristics. Proposed protective mechanisms of pulsatile perfusion remain largely obscure. It can be speculated that pulsatile perfusion may not only provide nutrition and facilitate the elimination of toxins but also trigger protective mechanisms leading to the amelioration of innate immune responses. Those aspects may be of particular relevance when utilizing grafts with suboptimal quality which may have an increased vulnerability to ischemia/reperfusion injury and compromised repair mechanisms. This review aims to enunciate the principles of organ perfusion and preservation as they relate to indication, aspects of organ protection and to highlight future developments.

[Organ preservation]

Maintaining organ viability from extraction to transplantation is crucial to ensure the function and survival of the graft. In recent years, maintaining organ viability has become more challenging because the shortage of donors has led to broader criteria for donor acceptability and consequently to organs with greater compromise. Organ damage occurs primarily as a result of ischemia-reperfusion injury, which is associated to additional damage from the preservation process. To minimize this damage, different techniques of organ preservation are used with the aim of optimizing organ function once perfusion is restored. Static cold storage is the most commonly used method of preservation because it is extremely simple, nearly universally available, and easy to transport. However, static cold storage may be unable to prevent the deterioration of the quality of organs from donors included under the broader criteria. In this article, we describe current preservation techniques; we place special emphasis on continuous machine perfusion.

Lung physiology during ECS resuscitation of DCD donors followed by in situ assessment of lung function

Extracorporeal cardiopulmonary support (ECS) of donors after cardiac death (DCD) has been shown to improve abdominal organs for transplantation. This study assesses whether pulmonary congestion occurs during ECS with the heart arrested and describes an in vivo method to assess if lungs are suitable for transplantation from DCD donors after ECS resuscitation. Cardiac arrest was induced in 30 kg pigs, followed by 10 min of warm ischemia. Cannulae were placed into the right atrium (RA) and iliac artery, and veno-arterial ECS was initiated for 90 min with lungs inflated, group 1 (n = 5) or deflated, group 2 (n = 3). Left atrial pressures were measured as a marker for pulmonary congestion. After 90 min of ECS, lung function was evaluated. Cannulae were placed into the pulmonary artery (PA) and left ventricle (LV). A second pump was included, and ECS was converted to a bi-ventricular (bi-VAD) system. The RVAD drained from the RA and pumped into the PA, and the LVAD drained the LV and pumped into the iliac. This brought the lungs back into circulation for a 1-hr assessment period. The oxygenator was turned off, and ventilation was restarted. Flows, blood gases, PA and left atrial pressures, and compliance were recorded. In both the groups, LA pressure was <15 mm Hg during ECS. During the lung assessment period, PA flows were 1.4-2.2 L/min. PO2 was >300 mm Hg, with normal PCO2. Extracorporeal cardiopulmonary support resuscitation of DCD donors is feasible and allows for assessment of function before procurement. Extracorporeal cardiopulmonary support does not cause pulmonary congestion, and the lungs retain adequate function for transplantation. Compliance correlated with lung function.

Peritoneal cooling may provide improved protection for uncontrolled donors after cardiac death: an exploratory porcine study

Uncontrolled donation after cardiac death (DCD) renal transplantation relies on rapid establishment of organ preservation interventions. We have developed a model of the uncontrolled DCD, comparing current in situ perfusion (ISP) techniques with additional peritoneal cooling (PC). Ten pigs were killed and subjected to a 2 h ischemia period. The ISP group modeled current DCD protocols. The PC group (PC) modeled current protocols plus PC. Two animals were used as controls and subjected to 2 h of warm ischemia. Core renal temperature and microdialysis markers of ischemia were measured. Preservation interventions began at 30 min, with rapid laparotomy and kidney recovery performed at 2 h, prior to machine perfusion viability testing. The final mean renal temperature achieved in the ISP group was 26.3 degrees C versus 16.9 degrees C in the PC group (p = 0.0001). A significant cryopreservation benefit was suggested by lower peak microdialysate lactate and glycerol levels (ISP vs. PC, p = 0.0003 and 0.0008), and the superiority of the PC group viability criteria (p = 0.0147). This pilot study has demonstrated significant temperature, ischemia protection and viability assessment benefits with the use of supplementary PC. The data suggests a need for further research to determine the potential for reductions in the rates of ischemia-related clinical phenomena for uncontrolled DCDs.

The approach to delayed resuscitation in paediatric cardiac arrest: A survey of paediatric intensivists in Canada

AIM

To determine how long a period of having had no cardiopulmonary-resuscitation (CPR) (delay time) is considered to result in subsequent futile efforts at resuscitation.

METHODS

In 2007 a survey was mailed to all 77 paediatric intensivists in Canada. Three scenarios of witnessed cardiac arrest were presented: out-of-hospital, in-hospital, and in-hospital with extracorporeal-CPR (E-CPR). Each scenario asked what delay time would make attempts at resuscitation futile for survival to hospital discharge, and for survival to hospital discharge in a better than vegetative state. Comparisons of median [inter-quartile range] used Wilcoxon-signed-rank or Friedman tests with Bonferroni corrections.

RESULTS

The response rate was 49/77 (64%). The delay time was significantly different between rhythms within all scenarios (p<.001); and was significantly shorter for survival than for better than vegetative survival (p<.006) except when E-CPR was to be used. The delay time was not significantly different between the in-hospital and out-of-hospital scenario with the same rhythms (p>.01). The delay time was significantly shorter in scenarios with asystole versus pulseless electrical activity with (p=.010) or without (p<.001) an arterial line with absent pulsation. In out-of-hospital arrest, the delay time for survival varied from 15 [10-20]min for asystole to 20 [15-20]min for pulseless electrical activity. In in-hospital scenarios, the delay time for survival varied from 10 [10-20]min for asystole, to 15 [10-20]min for most other rhythms.

CONCLUSION

A delay time of 15 [10-20] (range 5-30)min was considered futile for survival. This has implications for pronouncing death in donation after cardiac death.

Organ preservation in pancreas and islet transplantation

PURPOSE OF REVIEW

Organ preservation aims at reducing ischemia-reperfusion injury and maintains or even improves its function, and, therefore, increases transplant safety and efficiency. With the chronic lack of organs for transplantation, marginal donors are more and more frequently used in Western countries. New challenges, therefore, have to be met in organ preservation.

RECENT FINDINGS

We summarize the effects of cold preservation on various organ grafts, with particular emphasis on the pancreas. We review the different preservation solutions currently available in the clinic, and we present the current knowledge and clinical experience in pancreas and islet transplantation.

SUMMARY

Overall, in whole pancreas and islet transplantation, current cold preservation solutions (University of Wisconsin solution, Celsior, histidine-tryptophan-ketoglutarate) seem to be equivalent, with only few studies showing better results with University of Wisconsin solution. Regarding preservation with the two-layer method, conflicting results have been reported, and proper prospective controlled studies have yet to be performed to gather evidence on its impact on islet yield and function. Some recent developments and future strategies in general organ preservation not yet applied to pancreas preservation are reviewed at the end of the article.

Experimental renal preservation by normothermic resuscitation perfusion with autologous blood

BACKGROUND

Normothermic perfusion (NP) has the potential to improve metabolic support and maintain the viability of ischaemically damaged organs. This study investigated the effects of NP compared with current methods of organ preservation in a model of controlled non-heart-beating donor (NHBD) kidneys.

METHODS

Porcine kidneys (n = 6 in each group) were subjected to 10 min warm ischaemia and then preserved as follows: 2 h cold storage (CS) in ice (CS2 group), 18 h CS (CS18 group), 18 h cold machine perfusion (CP group) or 16 h CS + 2 h NP (NP group). Renal haemodynamics and function were measured during 3 h reperfusion with autologous blood using an isolated organ perfusion system.

RESULTS

Increasing CS from 2 to 18 h reduced renal blood flow (mean(s.d.) area under the curve (AUC) 444(57) versus 325(70) ml per 100 g; P = 0.004), but this was restored by NP (563(119) ml per 100 g; P = 0.035 versus CS18). Renal function was also better in CS2, CP and NP groups than in the CS18 group (mean(s.d.) serum creatinine fall 92(6), 79(9) and 64(17) versus 44(13) per cent respectively; P = 0.001). The AUC for serum creatinine was significantly lower with CS for 2 h than for 18 h (mean(s.d.) 1102(2600) versus 2156(401) micromol/l.h; P = 0.001), although values in CP and NP groups were not significantly different from those in the CS2 group (1354(300) and 1756(280) micromol/l.h respectively). Two hours of NP increased the adenosine 3'-triphosphate : adenosine 3'-diphosphate ratio to a significantly higher level than the preperfusion values in all other groups (P = 0.046).

CONCLUSION

NP with oxygenated blood was able to restore depleted ATP levels and reverse some of the deleterious effects of CS.

In situ preservation of kidneys from donors after cardiac death: results and complications

OBJECTIVES

To describe the results and complications of in situ preservation (ISP) of kidneys from donors after cardiac death (DCD).

BACKGROUND

DCD donors are increasingly being used to expand the pool of donor kidneys. ISP reduces warm ischemic injury which is associated with DCD donation.

METHODS

Insertion of a double-balloon triple-lumen catheter allows selective perfusion of the abdominal aorta to preserve the kidneys in situ. From January 2001 until August 2005, 133 ISP procedures were initiated in our procurement area.

RESULTS

Fifty-six (42%) ISP procedures led to transplantation; in the remaining 77 cases (58%), the donation procedure was abandoned or both kidneys were discarded because of ISP complications (n = 31), poor graft quality (n = 23), no consent for donation (n = 13), medical contraindications (n = 8), or unknown cause (n = 2). Increasing donor age (odds ratio (OR) 1.06 per year, P < 0.001) and uncontrolled DCD donation (OR 5.4, P < 0.001) were independently correlated with ISP complications. After transplantation, prolonged double-balloon triple-lumen catheter insertion time was an independent predictor of graft failure (OR 2.0, P = 0.05). Selected controlled DCD donors were managed by rapid laparotomy and direct aortic cannulation; graft survival of these kidneys was superior to kidneys from controlled DCD donors managed by ISP.

CONCLUSIONS

A minority of initiated ISP procedures led to transplantation, resulting in a high workload compared with donation after brain death. The association between increasing catheter insertion time and inferior graft outcome emphasizes the need for fast and effective surgery. Therefore, rapid laparotomy with direct aortic cannulation is preferred over ISP in controlled DCD donation. Despite these limitations, we have expanded our donor pool 3- to 4-fold by procuring DCD kidneys that were preserved in situ.

Perspectives in organ preservation

Maintaining organ viability after donation until transplantation is critically important for optimal graft function and survival. To date, static cold storage is the most widely used form of preservation in every day clinical practice. Although simple and effective, it is questionable whether this method is able to prevent deterioration of organ quality in the present era with increasing numbers of organs retrieved from older, more marginal, and even non-heart-beating donors. This review describes principles involved in effective preservation and focuses on some basic components and methods of abdominal organ preservation in clinical and experimental transplantation. Concepts and developments to reduce ischemia related injury are discussed, including hypothermic machine perfusion. Despite the fact that hypothermic machine perfusion might be superior to static cold storage preservation, organs are still exposed to hypothermia induced damage. Therefore, recently some groups have pointed at the beneficial effects of normothermic machine perfusion as a new perspective in organ preservation and transplantation.

Antioxidant Patterns (Superoxide Dismutase, Glutathione Reductase, and Glutathione Peroxidase) in Kidneys From Non–Heart-Beating-Donors: Experimental Study

INTRODUCTION

The evolution of renal antioxidant concentrations in the different phases of a non-heart-beating donor (NHBD) transplant after prolonged warm ischemia (40 and 90 minutes) and the effect of normothermic extracorporeal recirculation (37 degrees C) for 30 minutes were evaluated on antioxidant tissue concentrations in the kidney.

METHODS

Forty pairs of pigs, were divided into groups of 10 as follows: group 0, control donor with beating heart; group 1, 40 minutes of warm ischemia without recirculation by cardiopulmonary bypass pump (groups 2 and 3); group 2, 40 minutes of warm ischemia and recirculation for 30 minutes at 37 degrees C; and group 3, 90 minutes of warm ischemia and recirculation for 30 minutes at 37 degrees C. The concentrations of superoxide dismutase (SOD), glutathione peroxidase, and glutathione reductase were determined at the tissue level by biopsy at baseline the end of warm ischemia, the end of recirculation, at the end of cold ischemia, and 1 hour after reperfusion.

RESULTS

SOD was consumed at the end of the cold ischemia phase (P < .009) and increased during reperfusion (P < .02). Glutathione reductase was consumed during the cold ischemia phase (P < .04). In kidneys submitted to 40 minutes of warm ischemia, SOD was consumed during the cold ischemia phase (P < .04) and increased with reperfusion (P < .03). In kidneys undergoing 90 minutes of hot ischemia, SOD was consumed during cold ischemia (P < .04) and glutathione reductase during extracorporeal recirculation (P < .01).

CONCLUSIONS

Recirculation increased the tissue level of SOD at the end of the cold ischemia period.

Renal Transplantation From Non–Heart-Beating Donors: A Single-Center 10-Year Experience

BACKGROUND

Reluctance to accept non-heart-beating donors (NHBD) as a source of kidneys, is due to medical, ethical, and logistical reasons. Evidence suggest that the short-term graft survival is similar to that of kidneys obtained from heart-beating donors (HBD). However, few studies, with long-term follow-up are available. We conducted a single-center study of kidneys obtained from NHBD, in a 14-year period.

METHODS

We studied 100 patients transplanted with kidneys between 1989 and 2004, using NHBD, supported by heart compression and mechanical ventilation (n = 24), intravascular in situ cooling (n = 59), or cardiorespiratory resuscitation plus manual abdominal counterpulsation without cooling (n = 17), the last technique being used from 1998. The median follow-up was 51 +/- 51 months (range, 1 to 170). The outcomes of these procedures were compared to those of 1025 transplantations of kidneys from HBD performed during the same period.

RESULTS

The characteristics of the recipients did not differ significantly between the two groups. Kidneys from NHBD showed a significantly higher rate of delayed graft function (DGF; 84% vs 26%; (P < .001), furthermore, the primary nonfunction (PNF) incidence was significantly higher with NHBD vs HBD (16% vs 10%; P < .001). The incidence of acute rejection episodes (ARE) within 3 months and at 1 year did not differ between the groups of donors; however, more NHBD kidneys were lost from ARE. The short-term (3-month and 1 year) and long-term (5 and 10 years) renal function, determined by the serum creatinine levels, and patient and graft survival were not different for kidneys obtained from NHBD.

CONCLUSIONS

The incidences of PNF and DGF were significantly higher with NHBD, which produced poorer renal function at the time of hospital discharge. One-, 5-, and 10-year graft survivals and renal function did not differ between NHBD and HBD grafts. In our series, PNF was the main barrier to the use of NHBD.

The use of a supercooling refrigerator improves the preservation of organ grafts

Current medical transplantation confronts major problems such as the shortage of donors and geographical restrictions that inhibit efficient utilization of finite donor organs within their storage lives. To overcome these issues, expanding organ preservation time has become a major concern. We investigated whether a strategy which best preserves organ grafts can be achieved by the use of a newly developed refrigerating chamber, which is capable of establishing a supercooled and unfrozen state stably by generating an electrostatic field in its inside. When adult rat organs such as heart, liver, and kidneys were stored in the supercooled conditions, the levels of major biochemical markers leaked from the preserved organs were significantly lower than in the ordinary hypothermic storage. No apparent tissue damages were observed histologically after the supercooled preservation. Our results suggest that the use of this supercooling refrigerator improves organ preservation and may provide an innovative technique for human organ transplantation.

Extracorporeal support for organ donation after cardiac death effectively expands the donor pool

BACKGROUND

We sought to evaluate the effect on short-term outcomes of normothermic, extracorporeal perfusion (ECMO) for donation of abdominal organs for transplantation after cardiac death (DCD). Study parameters included increase in number of donors and organs, types of organs procured, and viability of kidneys transplanted.

METHODS

We retrospectively reviewed medical record data for all patients enrolled in our ECMO-supported DCD donor protocol between 10/1/2000 to 2/01/2004. We also reviewed the records for all patients undergoing organ donation after brain-death (DBD) during the study period at our institution. Recipient data were obtained and analyzed for all kidneys procured from both groups.

RESULTS

Twenty patients were enrolled in our DCD protocol and underwent attempted organ donation. Fifteen patients completed the protocol; 3 maintained cardiac function throughout the prescribed 60 minutes after withdrawal of life support, and two patients' organs were deemed unsuitable for transplantation. Fourteen (70%) of the DCD donor patients originated on the trauma service and six (30%) were from other clinical services. The DCD program increased the potential donor pool by 33% (61 versus 81 patients) and the number of kidneys transplanted by 24% (100 versus 124). A total of 24 kidney, 5 liver, and 1 pancreas transplants were performed with these organs. Two of 24 (8.3%) DCD kidneys had delayed graft function. There were no perioperative rejection episodes or deaths.

CONCLUSION

The implementation of a DCD protocol using extracorporeal perfusion increased the potential organ donor pool at our institution by 33%. This was accomplished without short term adverse effect on organ function compared with kidneys transplanted from DBD donors.

Liver transplantation from non-heart-beating donors: current status and future prospects

Liver transplantation is the treatment of choice for many patients with acute and chronic liver failure, but its application is limited by a shortage of donor organs. Donor organ shortage is the principal cause of increasing waiting lists, and a number of patients die while awaiting transplantation. Non-heart-beating donor (NHBD) livers are a potential means of expanding the donor pool. This is not a new concept. Prior to the recognition of brainstem death, organs were retrieved from deceased donors only after cardiac arrest. Given the preservation techniques available at that time, this restricted the use of extrarenal organs for transplantation. In conclusion, after establishment of brain death criteria, deceased donor organs were almost exclusively from heart-beating donors (HBDs). To increase organ availability, there is now a resurgence of interest in NHBD liver transplantation. This review explores the basis for this and considers some of the published results.

Preservation of porcine non-heart-beating donor livers by sequential cold storage and warm perfusion

BACKGROUND

Normothermic perfusion has been shown to resuscitate and maintain viability of non-heart-beating donor (NHBD) livers that have undergone significant warm ischemic injury. However, the logistics of clinical organ retrieval are complex, and a period of cold storage before warm preservation would simplify the process. We have investigated the effects of short duration of cold preservation before normothermic preservation on the function of porcine NHBD livers.

METHODS

Porcine livers were subjected to 60 minutes of warm ischemia and then assigned to the following groups: group W (n=5), normothermic preservation for 24 hours; and group C (n=4), cold preservation in University of Wisconsin solution for 4 hours followed by normothermic preservation for 20 hours (total preservation time 24 hours). Outcome parameters that were measured included bile production, serum transaminases and hyaluronic acid levels (cellular damage), and base deficit and glucose use (metabolic function).

RESULTS

Group W livers had superior bile production, metabolic activity (base deficit and greater glucose use), and less evidence of hepatocellular damage (alanine aminotransferase, aspartate aminotransferase), and sinusoidal endothelial cell dysfunction (hyaluronic acid). Group C livers showed greater necrosis and destruction of architecture on histology.

CONCLUSION

Normothermic perfusion failed to resuscitate porcine livers after 60 minutes of warm ischemia and 4 hours of cold preservation. Even a short period of cold ischemia is significantly deleterious to the function of ischemically damaged (NHBD) livers.