Liver transplantation in children using non-heart-beating donors (NHBD)

British Transplantation Society guidelines on abdominal organ transplantation from deceased donors after circulatory death

The British Transplantation Society (BTS) 'Guideline on transplantation from deceased donors after circulatory death' has recently been updated and this manuscript summarises the relevant recommendations in abdominal organ transplantation from Donation after Circulatory Death (DCD) donors, encompassing the chapters on liver, kidney, pancreas and islet cell transplantation.

Preclinical Study of DCD and Normothermic Perfusion for Visceral Transplantation

Considering recent clinical and experimental evidence, expectations for using DCD-derived intestines have increased considerably. However, more knowledge about DCD procedure and long-term results after intestinal transplantation (ITx) is needed. We aimed to describe in detail a DCD procedure for ITx using normothermic regional perfusion (NRP) in a preclinical model. Small bowel was obtained from pigs donors after 1 h of NRP and transplanted to the recipients. Graft Intestinal samples were obtained during the procedure and after transplantation. Ischemia-reperfusion injury (Park-Chiu score), graft rejection and transplanted intestines absorptive function were evaluated. Seven of 8 DCD procedures with NRP and ITx were successful (87.5%), with a good graft reperfusion and an excellent recovery of the recipient. The architecture of grafts was well conserved during NRP. After an initial damage of Park-chiu score of 4, all grafts recovered from ischemia-reperfusion, with no or very subtle alterations 2 days after ITx. Most recipients (71.5%) did not show signs of rejection. Only two cases demonstrated histologic signs of mild rejection 7 days after ITx. Interestingly intestinal grafts showed good absorptive capacity. The study's results support the viability of intestinal grafts from DCD using NRP, contributing more evidence for the use of DCD for ITx.

Use of DCD organs: Expanding the donor pool to increase pediatric transplantation

The number of children being listed for transplant continues to be greater than the number of available organs. In fact, over the past decade, rates of liver and kidney transplants in pediatric transplantation are essentially unchanged (Am J Transplant. 2020;20:193 and Am J Transplant. 2020;20:20). The use of DCD donors offers a potential solution to organ scarcity; however, the use of DCD organs in pediatric transplantation remains a rare event. Pediatric transplants done using carefully chosen DCD donor organs have shown to have outcomes similar to those seen with the use of donation after brain death (DBD) donors. Herein, we review the literature to examine the utilization of DCD livers and kidneys, outcomes of these allografts, and assess if DCD organs are a viable method to increase organ availability in pediatric transplantation.

Experimental Assessment of Intestinal Damage in Controlled Donation After Circulatory Death for Visceral Transplantation

There is an urgent need to address the shortage of potential multivisceral grafts in order to reduce the average time in waiting list. Since donation after circulatory death (DCD) has been successfully employed for other solid organs, a thorough evaluation of the use of intestinal grafts from DCD is warranted. Here, we have generated a model of Maastricht III DCD in rodents, focusing on the viability of intestinal and multivisceral grafts at five (DCD5) and twenty (DCD20) minutes of cardiac arrest compared to living and brain death donors. DCD groups exhibited time-dependent damage. DCD20 generated substantial intestinal mucosal injury and decreased number of Goblet cells whereas grafts from DCD5 closely resemble those of brain death and living donors groups in terms intestinal morphology, expression of tight junction proteins and number of Paneth and Globet cells. Upon transplantation, intestines from DCD5 showed increased ischemia/reperfusion damage compared to living donor grafts, however mucosal integrity was recovered 48 h after transplantation. No differences in terms of graft rejection, gene expression and absorptive function between DCD5 and living donor were observed at 7 post-transplant days. Collectively, our results highlight DCD as a possible strategy to increase multivisceral donation and transplantation procedures.

Donation after Circulatory Death Liver Transplantation in Paediatric Recipients

Waiting list mortality together, with limited availability of organs, are one of the major challenges in liver transplantation (LT). Especially in the paediatric population, another limiting factor is the scarcity of transplantable liver grafts due to additional concerns regarding graft size matching. In adults, donation after circulatory death (DCD) liver grafts have been used to expand the donor pool with satisfactory results. Although several studies suggest that DCD livers could also be used in paediatric recipients with good outcomes, their utilisation in children is still limited to a small number of reports. Novel organ perfusion strategies could be used to improve organ quality and help to increase the number of DCD grafts utilised for children. With the current manuscript, we present the available literature of LT using DCD grafts in paediatric recipients, discussing current challenges with the use of these livers in children and how machine perfusion technologies could be of impact in the future.

Should We Be Utilizing More Liver Grafts From Pediatric Donation After Circulatory Death Donors? A National Analysis of the SRTR from 2002 to 2017

BACKGROUND

Rates of withdrawal of life-sustaining treatment are higher among critically ill pediatric patients compared to adults. Therefore, livers from pediatric donation after circulatory death (pDCD) could improve graft organ shortage and waiting time for listed patients. As knowledge on the utilization of pDCD is limited, this study used US national registry data (2002-2017) to estimate the prognostic impact of pDCD in both adult and pediatric liver transplant (LT).

METHODS

In adult LT, the short-term (1-year) and long-term (overall) graft survival (GS) between pDCD and adult donation after circulatory death (aDCD) grafts was compared. In pediatric LT, the short- and long-term prognostic outcomes of pDCD were compared with other type of grafts (brain dead, split, and living donor).

RESULTS

Of 80 843 LTs in the study, 8967 (11.1%) were from pediatric donors. Among these, only 443 were pDCD, which were utilized mainly in adult recipients (91.9%). In adult recipients, short- and long-term GS did not differ significantly between pDCD and aDCD grafts (hazard ratio = 0.82 in short term and 0.73 in long term, both P > 0.05, respectively). Even "very young" (≤12 y) pDCD grafts had similar GS to aDCD grafts, although the rate of graft loss from vascular complications was higher in the former (14.0% versus 3.6%, P < 0.01). In pediatric recipients, pDCD grafts showed similar GS with other graft types whereas waiting time for DCD livers was significantly shorter (36.5 d versus 53.0 d, P < 0.01).

CONCLUSIONS

Given the comparable survival seen to aDCDs, this data show that there is still much scope to improve the utilization of pDCD liver grafts.

First report of successful transplantation of a pediatric donor liver graft after hypothermic machine perfusion

One of the main limiting factors in pediatric liver transplantation is donor availability. For adults, DCD liver grafts are increasingly used to expand the donor pool. To improve outcome after DCD liver transplantation, ex situ machine perfusion is used as an alternative organ preservation strategy, with the supplemental value of providing oxygen to the graft during preservation. We here report the first successful transplantation of a pediatric DCD liver graft after hypothermic oxygenated machine perfusion. The full-size liver graft was derived from a 13-year-old, female DCD donor and was end-ischemic pretreated with dual hypothermic oxygenated machine perfusion. Arterial and portal pressures were set at 18 and 4 mm Hg, slightly lower than protocolized settings for adult livers. During 2 hours of machine perfusion, portal and arterial flows increased from 100 to 210 mL/min and 30 to 63 mL/min, respectively. The pretreated liver graft was implanted in a 16-year-old girl with progressive familial intrahepatic cholestasis type 2. Postoperative AST, ALT, and prothrombin time normalized within a week. The recipient quickly recovered and was discharged from the hospital after 18 days. One year after transplantation, she is in excellent condition with a completely normal liver function and histology. This case is the first report of successful transplantation of a pediatric DCD liver graft after hypothermic oxygenated machine perfusion and illustrates the potential role of ex situ machine perfusion in expanding the donor pool and improving outcome after pediatric liver transplantation.

Donation after Circulatory Death in Paediatric Liver Transplantation: Current Status and Future Perspectives in the Machine Perfusion Era

Efforts have been made by the transplant community to expand the deceased donor pool in paediatric liver transplantation (LT). The growing experience on donation after circulatory death (DCD) for adult LT has encouraged its use also in children, albeit in selective cases, opening new perspectives for paediatric patients. Even though there has recently been a slight increase in the number of DCD livers transplanted in children, with satisfactory graft and patient outcomes, the use of DCD grafts in paediatric recipients is still controversial due to morbid outcomes associated with DCD grafts. In this context, recent advances in the optimization of donor support by extracorporeal membrane oxygenation and in the graft preservation by liver machine perfusion could find application in order to expand the donor pool in paediatric LT. In the present study we review the current literature on DCD liver grafts transplanted in children and on the use of extracorporeal donor support and liver perfusion machines in paediatrics, with the aim of defining the current status and future perspectives of paediatric LT.

Long-term results after transplantation of pediatric liver grafts from donation after circulatory death donors

Background

Liver grafts from donation after circulatory death (DCD) donors are increasingly accepted as an extension of the organ pool for transplantation. There is little data on the outcome of liver transplantation with DCD grafts from a pediatric donor. The objective of this study was to assess the outcome of liver transplantation with pediatric DCD grafts and to compare this with the outcome after transplantation of livers from pediatric donation after brain death (DBD) donors.

Method

All transplantations performed with a liver from a pediatric donor (≤16 years) in the Netherlands between 2002 and 2015 were included. Patient survival, graft survival, and complication rates were compared between DCD and DBD liver transplantation.

Results

In total, 74 liver transplantations with pediatric grafts were performed; twenty (27%) DCD and 54 (73%) DBD. The median donor warm ischemia time (DWIT) was 24 min (range 15–43 min). Patient survival rate at 10 years was 78% for recipients of DCD grafts and 89% for DBD grafts (p = 0.32). Graft survival rate at 10 years was 65% in recipients of DCD versus 76% in DBD grafts (p = 0.20). If donor livers in this study would have been rejected for transplantation when the DWIT ≥30 min (n = 4), the 10-year graft survival rate would have been 81% after DCD transplantation. The rate of non-anastomotic biliary strictures was 5% in DCD and 4% in DBD grafts (p = 1.00). Other complication rates were also similar between both groups.

Conclusions

Transplantation of livers from pediatric DCD donors results in good long-term outcome especially when the DWIT is kept ≤30 min. Patient and graft survival rates are not significantly different between recipients of a pediatric DCD or DBD liver. Moreover, the incidence of non-anastomotic biliary strictures after transplantation of pediatric DCD livers is remarkably low.

The bile duct in donation after cardiac death donor liver transplant

PURPOSE OF REVIEW

This review considers the biliary complications associated with liver transplantation using donation after cardiac death (DCD) donor grafts.

RECENT FINDINGS

The increasing use of DCD liver grafts with their increased incidence of biliary complications is discussed. The ethics of this greater use is briefly analysed. Recent animal and human study evidence to support the peribiliary vascular plexus' role in ischaemic cholangiopathy is reviewed. Recent advances in in-vivo and ex-vivo perfusion are explored. In particular, the latest theories regarding perfusion's peribiliary plexus preserving effects and the mechanism by which biliary regeneration may be promoted as a consequence are discussed.

SUMMARY

This article explores the need for DCD liver graft use and the associated biliary complications. The current theories regarding the cause of DCD biliary complications are reviewed, as are the current strategies to reduce them.

Pediatric organ donation and transplantation

BACKGROUND AND OBJECTIVES

There is increasing unmet need for solid organ donation. Alternative donor sources, such as donation after circulatory determination of death (DCDD), are needed. The objective of this study was to examine the impact of DCDD on trends in pediatric organ donation and transplantation.

METHODS

Data were obtained from the Organ Procurement and Transplantation Network for US organ recipients and donors from 2001 to 2010 stratified according to age, organ, and deceased donor type (DCDD or donation after neurologic determination of death). Additional data included transplant wait-list removals due to death.

RESULTS

From 2001 to 2010, pediatric organ transplant recipients increased from 1170 to 1475. Organs from DCDD donors were transplanted into children infrequently but increased from 1 to 31. Pediatric donation after neurologic determination of death decreased by 13% whereas DCDD increased by 174% (50 to 137). Recipients of pediatric grafts decreased from 3042 to 2751. Adults receiving grafts from pediatric donors decreased from 2243 to 1780; children receiving pediatric grafts increased from 799 to 971. Transplant recipients receiving pediatric DCDD grafts were few but increased annually from 50 to 128 adults and 0 to 9 children. Pediatric candidates dying waiting for an organ decreased from 262 to 110.

CONCLUSIONS

From 2001 to 2010, children received more solid organ transplants and fewer children died waiting. Organ recovery from pediatric and adult DCDD donors increased. The number of pediatric recipients of DCDD grafts remains small. Adults primarily receive the direct benefit from pediatric DCDD but other changes in organ allocation have directly benefited children.

Segmental ABO-incompatible liver graft from a donor after cardiac death in neonatal acute liver failure

Segmental liver grafts from DCD in pediatric LT have been safely used even in acute liver failure situations. Furthermore, despite the risk of antibody-mediated acute rejection, some studies have also demonstrated the safety of ABO incompatible LT in infants. The use of such grafts can be beneficial by reducing the time on the transplant waiting list but they are more susceptible to initial dysfunction and there is a lack of enthusiasm to consider their use especially for an emergency LT as a life-saving procedure. In this short article, we describe the use and successful outcome in a neonate with fulminant acute liver failure secondary to neonatal hemochromatosis who received an ABO-incompatible reduced-size DCD graft.

Current status and recent advances of liver transplantation from donation after cardiac death

The last decade saw increased organ donation activity from donors after cardiac death (DCD). This contributed to a significant proportion of transplant activity. Despite certain drawbacks, liver transplantation from DCD donors continues to supplement the donor pool on the backdrop of a severe organ shortage. Understanding the pathophysiology has provided the basis for modulation of DCD organs that has been proven to be effective outside liver transplantation but remains experimental in liver transplantation models. Research continues on how best to further increase the utility of DCD grafts. Most of the work has been carried out exploring the use of organ preservation using machine assisted perfusion. Both ex-situ and in-situ organ perfusion systems are tested in the liver transplantation setting with promising results. Additional techniques involved pharmacological manipulation of the donor, graft and the recipient. Ethical barriers and end-of-life care pathways are obstacles to widespread clinical application of some of the recent advances to practice. It is likely that some of the DCD offers are in fact probably “prematurely” offered without ideal donor management or even prior to brain death being established. The absolute benefits of DCD exist only if this form of donation supplements the existing deceased donor pool; hence, it is worthwhile revisiting organ donation process enabling us to identify counter remedial measures.