What Is Hot and New in Basic and Translational Science in Liver Transplantation in 2023? Report of the Basic and Translational Research Committee of the International Liver Transplantation Society

The 2023 Joint Annual Congress of the International Liver Transplantation Society, European Liver and Intestine Transplant Association, and Liver Intensive Care Group of Europe were held in Rotterdam, the Netherlands, from May 3 to 6, 2023. This year, all speakers were invited to attend the Congress in person for the first time since the COVID-19 pandemic. The congress was attended by 1159 registered delegates from 54 countries representing 5 continents, with the 10 countries comprising the bulk of the delegates. Of the 647 abstracts initially submitted, 542 were eventually presented at the meeting, coming from 38 countries (mainly North America, Europe, and Asia) and 85% of them (462 abstracts) came from only 10 countries. Fifty-three (9.8%) abstracts, originated from 17 countries, were submitted under the Basic/Translational Scientific Research category, a similar percentage as in 2022. Abstracts presented at the meeting were classified as (1) ischemia and reperfusion injury, (2) machine perfusion, (3) bioengineering and liver regeneration, (4) transplant oncology, (5) novel biomarkers in liver transplantation, (6) liver immunology (rejection and tolerance), and (7) artificial intelligence and machine learning. Finally, we evaluated the number of abstracts commented in the Basic and Translational Research Committee-International Liver Transplantation Society annual reports over the past 5 y that resulted in publications in peer-reviewed journals to measure their scientific impact in the field of liver transplantation.

Pursuing living donor liver transplantation improves outcomes of patients with autoimmune liver diseases - An intention-to-treat analysis

Background Living donor liver transplantation (LDLT) offers the opportunity to decrease waitlist time and mortality for patients with AILD; autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), and primary sclerosing cholangitis (PSC). We compared the survival of patients with a potential live donor (pLDLT) on the waitlist vs. no potential live donor (pDDLT), on an intention-to-treat (ITT) basis. Methods Our retrospective cohort study investigated adults with AILD listed for liver transplant at our program between 2000 and 2021. The pLDLT group comprised recipients with a potential live donor. Otherwise, they were included in the pDDLT group. ITT survival was assessed from the time of listing. Results Of the 533 patients included, 244(43.8%) had a potential living donor. Waitlist dropout was higher for the pDDLT groups among all AILDs (pDDLT 85[29.4%] vs. pLDLT 9[3.7], p<0.001). The 1-, 3- and 5-year ITT survival rates were higher for pLDLT vs. pDDLT among all AILDs (95.7%vs.78.1%, 89.0%vs.70.1%, and 87.1%vs.65.5%, p<0.001). After adjusting for covariates, pLDLT was associated with a 38% reduction in the risk of death among the AILD cohort (HR:0.62, 95%CI:0.42-0.93[p<0.05]), and 60% among the PSC cohort (HR:0.40, 95%CI:0.22-0.74[p<0.05]). There were no differences in the 1-, 3- and 5-year post-transplant survival between LDLT and DDLT (AILD: 95.6%vs.92.1%, 89.9%vs.89.4%, and 89.1%vs. 87.1%, p=0.41). This was consistent after adjusting for covariates (HR: 0.97, 95%CI:0.56-1.68[p>0.9]). Conclusion Our study suggests that having a potential live donor could decrease the risk of death in patients with PSC on the waitlist. Importantly, the post-transplant outcomes in this population are similar between the LDLT and DDLT groups.

Should advanced donor age be a deterrent in the utilization of grafts from donation after cardiac death in deceased donor liver transplantation? The Toronto experience

BACKGROUND

Advanced donor age paired with donation after cardiac death (DCD) increases the risk of transplantation, precluding widespread use of grafts from such donors worldwide. Our aim was to analyze outcomes of liver transplantation using grafts from older DCD donors and donation after brain death (DBD) donors.

METHODS

Patients who underwent liver transplantation using grafts from deceased donors between January 2016 and December 2021 were included in the study. Short-and long-term outcomes were analyzed for 4 groups of patients: those who received DCD and DBD grafts from younger (< 50 yr) and older (≥ 50 yr) donors.

RESULTS

Of the 807 patients included in the analysis, 44.7% (n = 361) of grafts were received from older donors, with grafts for older DCD donors comprising 4.7% of the total cohort (n = 38). Patients who received grafts from older donors had a lower incidence of biliary strictures than those who received grafts from younger donors (7.9% v. 20.0% for DCD donation, p = 0.14, and 4.9% v. 6.8% for DBD donation, p = 0.34), with a significantly lower incidence of ischemic-type biliary strictures in patients who received grafts from older versus younger DCD donors (2.6% v. 18.0%, p = 0.04). There was no difference in 1- and 3-year graft survival rates among patients who received grafts from older and younger DCD donors (92.1% v. 90.8% and 80.2% v. 80.9%, respectively) and those who received grafts from older and younger DBD donors (90.1% v. 93.2% and 85.3% v. 84.4%, respectively) (p = 0.85). Pretransplantation admission to the intensive care unit (hazard ratio [HR] 9.041, p < 0.001) and nonalcoholic steatohepatitis (HR 2.197, p = 0.02) were found to significantly affect survival of grafts from older donors.

CONCLUSION

Donor age alone should not be the criterion to determine the acceptability of grafts in liver transplantation. With careful selection criteria, older DCD donors could make a valuable contribution to expanding the liver donor pool, with grafts that produce comparable results to those obtained with standard-criteria grafts.

Medical Assistance in Dying (MAiD) as a Source of Liver Grafts: Honouring the Ultimate Gift

OBJECTIVE

To report the clinical outcomes of liver transplants from donors after medical assistance in dying (MAiD) versus donors after cardiac death (DCD) and deceased brain death (DBD).

SUMMARY BACKGROUND DATA

In North America, the number of patients needing liver transplants exceeds the number of available donors. In 2016, MAiD was legalized in Canada.

METHODS

All patients undergoing deceased donor liver transplantation at Toronto General Hospital between 2016 and 2021 were included in the study. Recipient perioperative and postoperative variables and donor physiological variables were compared among 3 groups.

RESULTS

Eight hundred seven patients underwent deceased donor liver transplantation during the study period, including DBD (n=719; 89%), DCD (n=77; 9.5%), and MAiD (n=11; 1.4%). The overall incidence of biliary complications was 6.9% (n=56), the most common being strictures (n=55;6.8%), highest among the MAiD recipients [5.8% (DBD) vs. 14.2% (DCD) vs. 18.2% (MAiD); P =0.008]. There was no significant difference in 1 year (98.4% vs. 96.4% vs. 100%) and 3-year (89.3% vs. 88.7% vs. 100%) ( P =0.56) patient survival among the 3 groups. The 1- and 3- year graft survival rates were comparable (96.2% vs. 95.2% vs. 100% and 92.5% vs. 91% vs. 100%; P =0.37).

CONCLUSION

With expected physiological hemodynamic challenges among MAiD and DCD compared with DBD donors, a higher rate of biliary complications was observed in MAiD donors, with no significant difference noted in short-and long-term graft outcomes among the 3 groups. While ethical challenges persist, good initial results suggest that MAiD donors can be safely used in liver transplantation, with results comparable with other established forms of donation.

Meso-Rex bypass versus portosystemic shunt for the management of extrahepatic portal vein obstruction in children: systematic review and meta-analysis

PURPOSE

Extrahepatic portal vein obstruction (EHPVO) is a major cause of non-cirrhotic portal hypertension in children. Surgical procedures for EHPVO include portosystemic shunts (PSS) and meso-Rex bypass (MRB). We conducted a systematic review and meta-analysis to compare the effectiveness of MRB versus PSS in EHPVO patients.

METHODS

A systematic literature search was performed using four databases. Articles reporting EHPVO and comparing patients who received MRB and PSS were included in the analysis.

RESULTS

We retrieved 851 papers, of which five observational studies met the inclusion criteria. There was no difference in shunt complications, mortality, or gastrointestinal bleeding after surgery between MRB and PSS in the meta-analysis. MRB had increased shunt complications compared with PSS in the non-comparative studies. MRB had a potential advantage over PSS in long-term prognosis in one comparative study. Overall, the quality of the evidence was low.

CONCLUSIONS

Based on available data, our meta-analysis indicates that MRB does not increase shunt complications, mortality, or gastrointestinal bleeding after surgery. The present study did not reveal superiority for either MRB or PSS. The paucity of well conducted trials in this area justifies future multicenter studies and studies that examine long-term outcomes.

Diaphragmatic Hernia following Pediatric Liver Transplantation: An Underappreciated Complication Prone to Recur

INTRODUCTION

 Postoperative diaphragmatic hernia (DH) is a rare but potentially life-threatening complication following pediatric liver transplantation (LT). In the current literature, a total of 49 such hernias have been reported in 17 case series. We present eight additional cases, three of which reoccurred after surgical correction, and review the current literature with a focus on recurrence.

MATERIALS AND METHODS

 The study sample included children (<18 years of age) who underwent LT between June 2013 and June 2020 at five large transplant centers and who subsequently presented with DH. During the study period, a total of 907 LT was performed. Eight DH were recognized, and risk factors were analyzed.

RESULTS

 For the eight children with DH, the mean age at LT was 28.0 (5-132) months. All patients with a DH received left lateral segment split grafts except one, who received a full left lobe. The mean weight at time of LT was 11.8 (6.6-34) kg. Two patients had a primary abdominal muscle closure, and six had a temporary silastic mesh closure. All eight children presented with a right posterolateral DH. The small bowel was herniated in the majority of cases. Symptoms reported included nausea, vomiting, and respiratory distress. Two patients were asymptomatic, and discovery was incidental. All patients underwent prompt primary surgical repair. Three DH hernias (37.5%) recurred despite successful surgical correction.

CONCLUSION

 DH following liver transplant with technical variant grafts may be underreported and is prone to recur despite surgical correction. A better understanding of the pathophysiology and more thorough reporting may help increase awareness. Early detection and prompt surgical management are the cornerstones of a successful outcome.

Mast cells as modulators of T-cell responses

Although mast cells have long been considered the integral effector cell in allergy and atopic disease, the paradigm of mast cell function is now evolving to incorporate data showing that mast cells make innumerable contributions to both protective and pathologic immune responses. Mast cells express cell surface molecules with costimulatory or co-inhibitory activity and produce a multitude of mediators that can direct dendritic cell (DC) or T-cell differentiation and function. In addition, mast cells exhibit a widespread distribution and are in close proximity to DCs and T cells at several critical sites. While there has been amazing progress in characterizing mast cell populations in vitro, only recently has the ability to monitor their in vivo effects become a reality. In this review, we discuss the evolution of our understanding of mast cell biology with an emphasis on their established and hypothesized roles in influencing T-cell differentiation and function. The fact that T-cell and mast cell interactions exist and are a normal component of most adaptive immune responses is one of the best illustrations of the now established concept that innate and adaptive immunity are not completely independent entities.

Role of toll-like receptor 4 in the proinflammatory response to Vibrio cholerae O1 El tor strains deficient in production of cholera toxin and accessory toxins

Following intranasal inoculation, Vibrio cholerae KFV101 (DeltactxAB DeltahapA DeltahlyA DeltartxA) colonizes and stimulates tumor necrosis factor alpha and interleukin 1beta (IL-1beta) in mice, similar to what occurs with isogenic strain P4 (DeltactxAB), but is less virulent and stimulates reduced levels of IL-6, demonstrating a role for accessory toxins in pathogenesis. Morbidity is enhanced in C3H/HeJ mice, indicating that Toll-like receptor 4 is important for infection containment.

Pattern of malignancy in a place in Western India

Analysis of 4500 cases of malignancy encountered in a general hospital in Western India showed that: (1) parts of buccopharynx were the site involved in nearly 25 per cent of these cases. In women the incidence of buccopharyngeal carcinoma was less than in men but was not insignificant (nearly 5 per cent of all malignancies found in women); (2) the cervix was the next frequent site involved accounting for 22 per cent of the total and 80 per cent of the female cancer; (3) cancer of breast was not less common (5 per cent of the total and 12 per cent of the female cancer); (4) oesophageal cancer was far more common than malignant neoplastic lesions of the other parts of the gastrointestinal tract (two-thirds of all cases being found in the oesophagus); (5) carcinoma of skin was not a common lesion.High frequency of the types of cancer mentioned in the first two paragraphs is a "ommon facto" of many such reports from India. On the other hand, reported incidences of the types mentioned in the paragraphs number (3), (4) and (5) show wide variations in different parts of the country.