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

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.

Normothermic Regional Perfusion in Pediatric Controlled Donation After Circulatory Death Can Lead to Optimal Organ Utilization and Posttransplant Outcomes

BACKGROUND

The benefits of normothermic regional perfusion (NRP) in posttransplant outcomes after controlled donation after the determination of death by circulatory criteria (cDCD) has been shown in different international adult experiences. However, there is no information on the use of NRP in pediatric cDCD donors.

METHODS

This is a multicenter, retrospective, observational cohort study describing the pediatric (<18 y) cDCD procedures performed in Spain, using either abdominal NRP or thoracoabdominal NRP and the outcomes of recipients of the obtained organs.

RESULTS

Thirteen pediatric cDCD donors (age range, 2-17 y) subject to abdominal NRP or thoracoabdominal NRP were included. A total of 46 grafts (24 kidneys, 11 livers, 8 lungs, 2 hearts, and 1 pancreas) were finally transplanted (3.5 grafts per donor). The mean functional warm ischemic time was 15 min (SD 6 min)' and the median duration of NRP was 87 min (interquartile range, 69-101 min). One-year noncensored for death kidney graft survival was 91.3%. The incidence of delayed graft function was 13%. One-year' noncensored-for-death liver graft survival was 90.9%. All lung and pancreas recipients had an excellent evolution. One heart recipient died due to a septic shock.

CONCLUSIONS

This is the largest experience of pediatric cDCD using NRP as graft preservation method. Although our study has several limitations, such as its retrospective nature and the small sample size, its reveals that NRP may increase the utilization of cDCD pediatric organs and offer optimal recipients' outcomes.

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.

Pediatric transplantation: An international perspective

The international practice of transplant in the pediatric population is heterogenous. Global trends in pediatric transplant activity are increasing, with diffusion of transplant activities into developing and emerging economies. There have been impacts of the COVID-19 pandemic which have in the earlier part of the pandemic caused a decrease in the number of transplants. While deceased donor programs are well established in advanced economies, emerging and developing countries rely heavily on live donor programs. Prioritization of organs for children exists in different forms throughout the world. Pediatric transplantation as a sub-specialty is young but growing around the world with a need to train surgeons and physicians in this discipline. Outreach efforts with multi-national and multi-institutional partnerships have enabled resource poor countries to establish new transplant programs for children. Further international collaboration, good quality data collection and audit, prospective research and ongoing mentorship and education are needed to further improve outcomes of all children receiving solid organ transplants.

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.

Over 30 Years of Pediatric Liver Transplantation at the Charité-Universitätsmedizin Berlin

Background: Pediatric liver transplantation (LT) is the treatment of choice for children with end-stage liver disease and in certain cases of hepatic malignancies. Due to low case numbers, a technically demanding procedure, the need for highly specialized perioperative intensive care, and immunological, as well as infectious, challenges, the highest level of interdisciplinary cooperation is required. The aim of our study was to analyze short- and long-term outcomes of pediatric LT in our center. Methods: We conducted a retrospective single-center analysis of all liver transplantations in pediatric patients (≤16 years) performed at the Department of Surgery, Charité – Universitätsmedizin Berlin between 1991 and 2021. Three historic cohorts (1991–2004, 2005–2014 and 2015–2021) were defined. Graft- and patient survival, as well as perioperative parameters were analyzed. The study was approved by the institutional ethics board. Results: Over the course of the 30-year study period, 212 pediatric LTs were performed at our center. The median patient age was 2 years (IQR 11 years). Gender was equally distributed (52% female patients). The main indications for liver transplantation were biliary atresia (34%), acute hepatic necrosis (27%) and metabolic diseases (13%). The rate of living donor LT was 25%. The median cold ischemia time for donation after brain death (DBD) LT was 9 h and 33 min (IQR 3 h and 46 min). The overall donor age was 15 years for DBD donors and 32 years for living donors. Overall, respective 1, 5, 10 and 30-year patient and graft survivals were 86%, 82%, 78% and 65%, and 78%, 74%, 69% and 55%. One-year patient survival was 85%, 84% and 93% in the first, second and third cohort, respectively (p = 0.14). The overall re-transplantation rate was 12% (n = 26), with 5 patients (2%) requiring re-transplantation within the first 30 days. Conclusion: The excellent long-term survival over 30 years showcases the effectiveness of liver transplantation in pediatric patients. Despite a decrease in DBD organ donation, patient survival improved, attributed, besides refinements in surgical technique, mainly to improved interdisciplinary collaboration and management of perioperative complications.

Protective Effects of Bone Marrow Mesenchymal Stem Cells (BMMSCS) Combined with Normothermic Machine Perfusion on Liver Grafts Donated After Circulatory Death via Reducing the Ferroptosis of Hepatocytes

BACKGROUND To improve the quality of liver grafts from extended-criteria donors donated after circulatory death (DCD), this study explored whether bone marrow mesenchymal stem cells (BMMSCs) combined with normothermic machine perfusion (NMP) have protective effects on DCD donor livers and the effects of ferroptosis in this procedure. MATERIAL AND METHODS Twenty-four male rat DCD donor livers were randomly and averagely divided into normal, static cold storage (SCS), NMP, and NMP combined with BMMSCs groups. Liver function, bile secretion, and pathological features of DCD donor livers were detected to evaluate the protective effects of NMP and BMMSCs on DCD donor livers. Hydrogen peroxide was used to induce an oxidative stress model of hepatocyte IAR-20 cells to evaluate the protective effects of BMMSCs in vitro. RESULTS Livers treated with NMP combined with BMMSCs showed better liver function, relieved histopathological damage, reduced oxidative stress injury and ferroptosis, and the mechanism of reduction was associated with downregulation of intracellular reactive oxygen species (ROS) and free Fe²⁺ levels. BMMSCs showed significant protective effects on the ultrastructure of DCD donor livers and ROS-induced injury to IAR-20 cells under electron microscopy. BMMSCs also significantly improved the expression level of microtubule-associated protein 1 light chain 3 (LC3)-II in both DCD donor livers and ROS-induced injured IAR-20 cells, including upregulating the expression of ferritin. CONCLUSIONS BMMSCs combined with NMP could reduce the level of ROS and free Fe²⁺ in oxidative stress damaged rat DCD donor livers, potentially reduce the ferroptosis in hepatocytes, and repair both morphology and function of DCD donor livers.

Is donation after circulatory determination of death feasible for pediatric patients in italy?

To determine the potential effect of a donation after cardiac death active program on the number of organ donors in a Italian Pediatric Intensive Care Unit (PICU). We conducted a retrospective study of all deaths in PICU of an academic Children Hospital between 2012 and 2020, tracing the organ donation activity. Patients were categorized as brain deaths, deaths despite maximal resuscitation, and deaths after withdrawal or limitation of life support. Patient demographics, premortem physiology, end-of-life circumstances, and functional warm ischemia time were recorded. Eligible donors after cardiac death were identified by the absence of medical contraindication and functional warm ischemia time <60 minutes. Of 124 deaths that occurred during the study period, 34 met criteria for brain death, 23 were potential donors, and 13 became actual donors. Of the remaining 90 patients that met criteria for cardiac death, 66 died despite maximal resuscitation, 24 died after withdrawal or limitation of care and between them 13 were identified as theoretically eligible DCD donors. Of these, 5 patients had a functional warm ischemia time of <1 hour and were potential candidates for DCD of 10 kidneys and 2 lungs. Even if few children could have been eligible for DCD in the study period, an active program could have been able to increase the number of potential organ donors by 20% in the last eight years at our institution. DCD deserves to be explored in Italy as a new option for children.

Normothermic Machine Perfusion Combined with Bone Marrow Mesenchymal Stem Cells Improves the Oxidative Stress Response and Mitochondrial Function in Rat Donation After Circulatory Death Livers

There is a need to improve the quality of donor liver from donation after circulatory death (DCD). The purpose of this study was to investigate the effects and mechanism of normothermic machine perfusion (NMP) combined with bone marrow mesenchymal stem cells (BMMSCs) on the oxidative stress and mitochondrial function in DCD livers. DCD livers were obtained, a rat NMP system was established, and BMMSCs were extracted and identified. The DCD livers were grouped by their preservation method: Normal, static cold storage (SCS), NMP (P), and NMP combined with BMMSCs (PB), and the preservation time was up to 8 h. An IAR20 cell oxidative stress injury model was established in vitro by simulating DCD oxidative stress injury and coculturing with BMMSCs for 6 h. Compared with SCS group, after 6 h in vitro, the PB and P groups had significantly improved liver function and liver histological damage, reduced hepatocyte apoptosis and oxidative stress, improved hepatocyte mitochondrial damage, and increased mitochondrial membrane potential. These indicators were significantly better in the PB group than in the P group. BMMSCs significantly inhibited reactive oxygen species release from the IAR20 cell oxidative stress model in vitro, ameliorated mitochondrial damage, and increased mitochondrial membrane potential level. BMMSCs also downregulated the JUN N-terminal kinase-nuclear factor kappa B (JNK-NF-κB) signaling pathway significantly in the IAR20 cell oxidative stress model and promoted AMP-activated protein kinase (AMPK) activation. We verified that NMP combined with BMMSCs also played the same role in the PB group. NMP combined with BMMSCs could improve liver quality by relieving oxidative stress injury and improving mitochondrial function in rat DCD livers. The mechanism of protective role might involve inhibiting the JNK-NF-κB pathway to reduce oxidative stress and promote AMPK activation, thereby reducing mitochondrial damage and increase mitochondrial function.

Bone marrow mesenchymal stem cells combine with normothermic machine perfusion to improve rat donor liver quality-the important role of hepatic microcirculation in donation after circulatory death

Donation after circulatory death (DCD) can expand the donor pool effectively. A gap remains in outcome between DCD livers and living donor livers, warranting improved DCD liver quality and urgent resolution. Bone marrow mesenchymal stem cells (BMMSCs) can regulate immunity, participate in the anti-inflammatory response, and secrete cytokines. We investigated the effect of BMMSCs combined with normothermic machine perfusion (NMP) on DCD liver quality, and the role of microcirculation therein. Rat thoracic aortas were clipped to obtain DCD livers, and a rat NMP system was established. The DCD livers were grouped by preservation method: normal, static cold storage (SCS), NMP (P), and BMMSCs plus NMP (BP); storage time was up to 8 h. Liver function in outflow perfusate was detected by biochemical methods; liver tissue histopathology was observed by hematoxylin–eosin staining; hepatocyte ultrastructure was observed by transmission electron microscopy; hepatocyte apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling; liver microcirculation–related indicators were detected by immunofluorescence, immunohistochemistry, Western blotting, and enzyme-linked immunosorbent assay. Compared with SCS, P and BP significantly improved liver function and liver histological damage, reduced hepatocyte apoptosis, and repaired hepatocyte mitochondrial damage after 6 h in vitro. BP also significantly inhibited intrahepatic macrophage activation and intercellular adhesion, improved endothelial damage, and significantly improved endothelin 1–nitric oxide balance and microcirculation perfusion. In conclusion, BP can improve DCD liver microcirculation and quality. The mechanism may be the improvement of improve hepatic sinusoidal endothelial injury and microcirculation perfusion by inhibiting macrophage activation and intercellular adhesion.