Living donor liver transplantation for pediatric and adult recipients

Generation of human hepatobiliary organoids with a functional bile duct from chemically induced liver progenitor cells

BACKGROUND

Liver disease imposes a significant medical burden that persists due to a shortage of liver donors and an incomplete understanding of liver disease progression. Hepatobiliary organoids (HBOs) could provide an in vitro mini-organ model to increase the understanding of the liver and may benefit the development of regenerative medicine.

METHODS

In this study, we aimed to establish HBOs with bile duct (BD) structures and mature hepatocytes (MHs) using human chemically induced liver progenitor cells (hCLiPs). hCLiPs were induced in mature cryo-hepatocytes using a small-molecule cocktail of TGF-β inhibitor (A-83-01, A), GSK3 inhibitor (CHIR99021, C), and 10% FBS (FAC). HBOs were then formed by seeding hCLiPs into ultralow attachment plates and culturing them with a combination of small molecules of Rock-inhibitor (Y-27632) and AC (YAC).

RESULTS

These HBOs exhibited bile canaliculi of MHs connected to BD structures, mimicking bile secretion and transportation functions of the liver. The organoids showed gene expression patterns consistent with both MHs and BD structures, and functional assays confirmed their ability to transport the bile analogs of rhodamine-123 and CLF. Functional patient-specific HBOs were also successfully created from hCLiPs sourced from cirrhotic liver tissues.

CONCLUSIONS

This study demonstrated the potential of human HBOs as an efficient model for studying hepatobiliary diseases, drug discovery, and personalized medicine.

Liver Transplantation for the Nonhepatologist

Liver transplantation (LT) is a life-saving and evidence-based intervention for patients with acute liver failure and chronic end-stage liver disease. Significant progress has been made in advancing pre-LT management, transplant techniques, post-LT long-term care, and immunosuppression regimes. However, as rates of DC continue to increase, causes of liver disease and indications for LT continue to be investigated to ensure equity and further improve liver allocation models, waitlist outcomes, and post-LT outcomes for all patient populations.

Implantation of healthy matrix-embedded endothelial cells rescues dysfunctional endothelium and ischaemic tissue in liver engraftment

OBJECTIVE

Liver transplantation is limited by ischaemic injury which promotes endothelial cell and hepatocyte dysfunction and eventually organ failure. We sought to understand how endothelial state determines liver recovery after hepatectomy and engraftment.

DESIGN

Matrix-embedded endothelial cells (MEECs) with retained healthy phenotype or control acellular matrices were implanted in direct contact with the remaining median lobe of donor mice undergoing partial hepatectomy (70%), or in the interface between the remaining median lobe and an autograft or isograft from the left lobe in hepatectomised recipient mice. Hepatic vascular architecture, DNA fragmentation and apoptosis in the median lobe and grafts, serum markers of liver damage and phenotype of macrophage and lymphocyte subsets in the liver after engraftment were analysed 7 days post-op.

RESULTS

Healthy MEECs create a functional vascular splice in donor and recipient liver after 70% hepatectomy in mouse protecting these livers from ischaemic injury, hepatic congestion and inflammation. Macrophages recruited adjacent to the vascular nodes into the implants switched to an anti-inflammatory and regenerative profile M2. MEECs improved liver function and the rate of liver regeneration and prevented apoptosis in donor liver lobes, autologous grafts and syngeneic engraftment.

CONCLUSIONS

Implants with healthy endothelial cells rescue liver donor and recipient endothelium and parenchyma from ischaemic injury after major hepatectomy and engraftment. This study highlights endothelial-hepatocyte crosstalk in hepatic repair and provides a promising new approach to improve regenerative medicine outcomes and liver transplantation.

Clinical and histological outcomes following living-related liver transplantation in children

OBJECTIVES

Living-related liver transplantation (LRLT) was developed to increase the donor pool of size-matched organs for children. In the UK only one centre performed LRLT between 1993 and 2008. This study reports the clinical and histological outcomes following adult-to-paediatric LRLT at our centre.

METHODS

Forty-six LRLTs were reviewed. Recipients had a mean age, weight and PELD score of 2.4years (range 0.5-11years), 11.0kg (3.7-32.3kg) and 11.7 (-20.3 to 49.1) respectively. The incidence of post-transplant paediatric morbidity, abnormal liver function tests and histological abnormalities was reviewed.

RESULTS

Patient and graft survival rates were 97.8%, 95.1% and 95.1%, and 97.8%, 92.1% and 71.7% at 1, 5 and 10years post-transplant respectively. Three children were re-transplanted at 44, 100 and 119months post-transplant. Nine children developed neuropsychological problems, 6 experienced educational difficulties, 5 developed post-transplant lymphoproliferative disorder and 5 suffered height or weight growth<2 centile. Normal LFTs were found in 41.7%, 50%, 68% and 64.7% of children at median follow-up of 6, 13, 61 and 85months respectively. Liver histology showed hepatitis, acute rejection, non-specific changes, biliary pathology, vascular pathology and chronic rejection in 32.9%, 29.5%, 13.4%, 10.1%, 6% and 2% of biopsies respectively.

CONCLUSIONS

The prevalence of paediatric morbidity and histological abnormalities emphasize the need for specialist and long-term follow-up following LRLT in children.

T cell-derived lymphotoxin regulates liver regeneration

BACKGROUND & AIMS

The ability of the liver to regenerate hepatic mass is essential to withstanding liver injury. The process of liver regeneration is tightly regulated by distinct signaling cascades involving components of the innate immune system, cytokines, and growth factors. However, the role of the adaptive immune system in regulation of liver regeneration is not well-defined. The role of adaptive immune system in liver regeneration was investigated in lymphocyte-deficient mice and in conditional lymphotoxin-deficient mice.

METHODS

A model of liver regeneration after 70% partial hepatectomy was used, followed by examination of liver pathology, survival, DNA synthesis, and cytokine expression.

RESULTS

We found that mice deficient in T cells show a reduced capacity for liver regeneration following partial hepatectomy. Furthermore, surface lymphotoxin, provided by T cells, is critical for liver regeneration. Mice specifically deficient in T-cell lymphotoxin had increased liver damage and a reduced capacity to initiate DNA synthesis after partial hepatectomy. Transfer of splenocytes from wild-type but not lymphotoxin-deficient mice improved liver regeneration in T cell-deficient mice. We found that an agonistic antibody against the lymphotoxin beta receptor was able to facilitate liver regeneration by reducing liver injury, increasing interleukin-6 production, hepatocyte DNA synthesis, and survival of lymphocyte-deficient (Rag) mice after partial hepatectomy.

CONCLUSIONS

The adaptive immune system directly regulates liver regeneration via a T cell-derived lymphotoxin axis, and pharmacological stimulation of lymphotoxin beta receptor might represent a novel therapeutic approach to improve liver regeneration.

Biliary complications in donors for living donor liver transplantation

OBJECTIVES

With the increasing number of living donor liver transplantations, biliary complications in donors have emerged as a major postoperative problem. The aim of the present study was to characterize the features of the biliary complications that occur in donors.

METHODS

The study subjects comprised 731 consecutive patients who donated liver grafts (434 right-lobe and 297 left-lobe grafts) for transplantation at Kyoto University Hospital from July 1999 to December 2006. Donors whose biliary complications could not be cured by conservative therapy were referred for endoscopic treatment.

RESULTS

Postoperative biliary complications occurred in 55 (7.5%) donors. Initially, 48 of these 55 donors had biliary leakage and 7 had biliary stricture. Subsequently, 5 of 48 donors with leakage developed biliary stricture. The respective incidences of biliary leakage and overall biliary complications were significantly higher among donors of right-lobe grafts (9.9% and 11.1%) than among donors of left-lobe grafts (1.7% and 2.4%). Among 55 donors with biliary complications, 24 were cured by conservative therapy, and 1 was converted to surgical repair due to ileus. Endoscopic treatment was successful in 24 of 30 (80%) donors treated by endoscopic retrograde cholangiography, while the remaining 6 (20%) patients underwent surgery due to difficulties with cannulation (N = 2), excessive biliary leakage (N = 2), or complete biliary obstruction (N = 2).

CONCLUSIONS

Donors of right-lobe grafts have a significantly higher incidence of biliary complications than donors of left-lobe grafts. When conservative therapy fails, endoscopic treatment is effective for these complications, and should be attempted as the first-line therapy before surgical repair.

Living donor transplantation between twins: guidance for Donor Advocate Teams

Using a clinical case, this paper explores the ethical complexities of assessing potential living organ donors when the proposed donor-recipient pair consists of monozygotic (identical) or dizygotic (fraternal) twins. While all donor-recipient pairs can present various ethical and psychosocial challenges, the challenges of twin pairs are unique and especially complex. Donor Advocate Teams need to be aware of these unique issues and address them during their assessment process.