Successful AAV8 gene therapy on hepatic ex situ machine perfusion for mitochondrial neurogastrointestinal encephalomyopathy.

Ex situ normothermic machine perfusion (NMP) is rapidly emerging as a novel platform for testing therapeutics in human donor livers. Recently perfusion of explanted patient livers was achieved, raising the possibility of using these diseased organs to increase the fidelity and resolution of drug testing and development. Here, we provide proof-of-principle for the feasibility of this approach in the context of gene therapy.

Modelling the potential use of pre-exposure prophylaxis to reduce nosocomial SARS-CoV-2 transmission.

The nosocomial transmission of respiratory pathogens is an ongoing healthcare challenge, with consequences for the health of vulnerable individuals. Outbreaks in hospitals can require the closure of bays or entire wards, reducing hospital capacity and having a financial impact upon healthcare providers. Here we evaluate a novel strategy of pre-exposure prophylaxis as a means to reduce the nosocomial transmission of SARS-CoV-2.

Single-Cell Transcriptomic Profiling of Cholangiocyte Organoids Derived from Bile Ducts of Primary Sclerosing Cholangitis Patients.

Background And Aims: Primary sclerosing cholangitis (PSC) is a chronic inflammatory liver disorder without effective medical treatment which is characterized by inflammation and fibrotic structures around the bile ducts. Biliary epithelial cells (cholangiocytes) are the target and potential disease drivers in PSC, yet little is known if cholangiocytes from PSC patients differ from non-PSC controls. To characterize cholangiocytes at early rather than end-stage disease, cholangiocyte organoids (COs) were derived from diseased bile ducts of PSC patients and compared to organoids generated from disease controls.

Ursodeoxycholic acid is associated with a reduction in SARS-CoV-2 infection and reduced severity of COVID-19 in patients with cirrhosis.

Background And Aims: Studies have demonstrated that reducing farnesoid X receptor activity with ursodeoxycholic acid (UDCA) downregulates angiotensin-converting enzyme in human lung, intestinal and cholangiocytes organoids in vitro, in human lungs and livers perfused ex situ, reducing internalization of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) into the host cell. This offers a potential novel target against coronavirus disease 2019 (COVID-19). The objective of our study was to compare the association between UDCA exposure and SARS-CoV-2 infection, as well as varying severities of COVID-19, in a large national cohort of participants with cirrhosis.

FXR inhibition may protect from SARS-CoV-2 infection by reducing ACE2.

Preventing SARS-CoV-2 infection by modulating viral host receptors, such as angiotensin-converting enzyme 2 (ACE2), could represent a new chemoprophylactic approach for COVID-19 that complements vaccination. However, the mechanisms that control the expression of ACE2 remain unclear. Here we show that the farnesoid X receptor (FXR) is a direct regulator of ACE2 transcription in several tissues affected by COVID-19, including the gastrointestinal and respiratory systems.

Organoids and regenerative hepatology.

The burden of liver diseases is increasing worldwide, with liver transplantation remaining the only treatment option for end-stage liver disease. Regenerative medicine holds great potential as a therapeutic alternative, aiming to repair or replace damaged liver tissue with healthy functional cells. The properties of the cells used are critical for the efficacy of this approach.

Altered TMPRSS2 usage by SARS-CoV-2 Omicron impacts infectivity and fusogenicity.

The SARS-CoV-2 Omicron BA.1 variant emerged in 2021 and has multiple mutations in its spike protein. Here we show that the spike protein of Omicron has a higher affinity for ACE2 compared with Delta, and a marked change in its antigenicity increases Omicron's evasion of therapeutic monoclonal and vaccine-elicited polyclonal neutralizing antibodies after two doses.

Cardiovascular ACE2 receptor expression in patients undergoing heart transplantation.

Aims: Membrane-bound angiotensin-converting enzyme (ACE)2 is the main cellular access point for SARS-CoV-2, but its expression and the effect of ACE inhibition have not been assessed quantitatively in patients with heart failure. The aim of this study was to characterize membrane-bound ACE2 expression in the myocardium and myocardial vasculature in patients undergoing heart transplantation and to assess the effect of pharmacological ACE inhibition.

Methods And Results: Left ventricular (LV) tissue was obtained from 36 explanted human hearts from patients undergoing heart transplantation.

Cholangiocyte organoids can repair bile ducts after transplantation in the human liver.

Organoid technology holds great promise for regenerative medicine but has not yet been applied to humans. We address this challenge using cholangiocyte organoids in the context of cholangiopathies, which represent a key reason for liver transplantation. Using single-cell RNA sequencing, we show that primary human cholangiocytes display transcriptional diversity that is lost in organoid culture.

Tissue engineering of the biliary tract and modelling of cholestatic disorders.

Our insight into the pathogenesis of cholestatic liver disease remains limited, partly owing to challenges in capturing the multitude of factors that contribute to disease pathogenesis in vitro. Tissue engineering could address this challenge by combining cells, materials and fabrication strategies into dynamic modelling platforms, recapitulating the multifaceted aetiology of cholangiopathies. Herein, we review the advantages and limitations of platforms for bioengineering the biliary tree, looking at how these can be applied to model biliary disorders, as well as exploring future directions for the field.

Isolation and propagation of primary human cholangiocyte organoids for the generation of bioengineered biliary tissue.

Pediatric liver transplantation is often required as a consequence of biliary disorders because of the lack of alternative treatments for repairing or replacing damaged bile ducts. To address the lack of availability of pediatric livers suitable for transplantation, we developed a protocol for generating bioengineered biliary tissue suitable for biliary reconstruction. Our platform allows the derivation of cholangiocyte organoids (COs) expressing key biliary markers and retaining functions of primary extra- or intrahepatic duct cholangiocytes within 2 weeks of isolation.

Use of Biliary Organoids in Cholestasis Research.

Cholangiocytes play a crucial role in the pathophysiology of cholestasis. However, research on human cholangiocytes has been restricted by challenges in long-term propagation and large-scale expansion of primary biliary epithelium. The advent of organoid technology has overcome this limitation allowing long-term culture of a variety of epithelia from multiple organs.

What gastroenterologists and hepatologists should know about organoids in 2019.

Most of the research behind new medical advances is carried out using either animal models or cancer cells, which both have their disadvantage in particular with regard to medical applications such as personalized medicine and novel therapeutic approaches. However, recent advances in stem cell biology have enabled long-term culturing of organotypic intestinal or hepatic tissues derived from tissue resident or pluripotent stem cells. These 3D structures, denoted as organoids, represent a substantial advance in structural and functional complexity over traditional in vitro cell culture models that are often non-physiological and transformed.