Pancreatic Allograft Thrombosis: Suggestion for a CT grading system and management algorithm

Pancreatic allograft thrombosis (PAT) remains the leading cause of non-immunological graft failure. Herein we propose a new CT grading system of PAT to identify risk factors for allograft loss and outline a management algorithm by retrospective review of consecutive pancreatic transplants between 2009-2014. Triple-phase CT scans were graded independently by two radiologists as; Grade 0 – no thrombosis, Grade 1 – peripheral thrombosis, Grade 2 – intermediate non-occlusive thrombosis and Grade 3 – central occlusive thrombosis. Twenty-four of 103 (23.3%) recipients were diagnosed with PAT (including grade 1). Three grafts (2.9%) were lost due to portal vein thrombosis. On multivariate analysis, pancreas after SPK/PAK transplant, acute rejection and CT finding peri-pancreatic oedema and/or inflammatory change were significant risk factors of PAT. Retrospective review of CT images revealed more grade 1 and 2 thromboses than were initially reported. There was no significant difference in graft or patient survival, post-operative stay or morbidity of recipients with grade 1 or 2 thrombosis who were or were not anticoagulated. Our data suggest that therapeutic anticoagulation is not necessary for grade 1 and 2 arterial and grade 1 venous thrombosis. The proposed grading system can assist clinicians in decision making and provide standardised reporting for future studies

Protocol of a randomised controlled, open-label trial of ex vivo normothermic perfusion versus static cold storage in donation after circulatory death renal transplantation.

Introduction: Ex vivo normothermic perfusion (EVNP) is a novel technique that reconditions the kidney and restores renal function prior to transplantation. Phase I data from a series of EVNP in extended criteria donor kidneys have established the safety and feasibility of the technique in clinical practice. Methods and analysis: This is a UK-based phase II multicentre randomised controlled trial to assess the efficacy of EVNP compared with the conventional static cold storage technique in donation after circulatory death (DCD) kidney transplantation. 400 patients receiving a kidney from a DCD donor (categories III and IV, controlled) will be recruited into the study. On arrival at the transplant centre, kidneys will be randomised to receive either EVNP (n=200) or remain in static cold storage (n=200). Kidneys undergoing EVNP will be perfused with an oxygenated packed red cell solution at near body temperature for 60 min prior to transplantation. The primary outcome measure will be determined by rates of delayed graft function (DGF) defined as the need for dialysis in the first week post-transplant. Secondary outcome measures include incidences of primary non-function, the duration of DGF, functional DGF defined as <10% fall in serum creatinine for 3 consecutive days in the first week post-transplant, creatinine reduction ratio days 2 and 5, length of hospital stay, rates of biopsy-proven acute rejection, serum creatinine and estimated glomerular filtration rate at 1, 3, 6 and 12 months post-transplant and patient and allograft survival. The EVNP assessment score will be recorded and the level of fibrosis and inflammation will also be measured using tissue, blood and urine samples. Ethics and dissemination. The study has been approved by the National Health Service (NHS) Health Research Authority Research Ethics Committee. The results are expected to be published in 2020. Trial registration number: ISRCTN15821205; Pre-results.Kidney Research UK (SP/MEKC/1/2014); University of Cambridge and University Hospitals of Cambridge Foundation Trust, Cambridge CB2 OQQ

RNF43/ZNRF3 loss predisposes to hepatocellular-carcinoma by impairing liver regeneration and altering the liver lipid metabolic ground-state

RNF43/ZNRF3 negatively regulate WNT signalling. Both genes are mutated in several types of cancers, however, their contribution to liver disease is unknown. Here we describe that hepatocyte-specific loss of Rnf43/Znrf3 results in steatohepatitis and in increase in unsaturated lipids, in the absence of dietary fat supplementation. Upon injury, Rnf43/Znrf3 deletion results in defective hepatocyte regeneration and liver cancer, caused by an imbalance between differentiation/proliferation. Using hepatocyte-, hepatoblast- and ductal cell-derived organoids we demonstrate that the differentiation defects and lipid alterations are, in part, cell-autonomous. Interestingly, ZNRF3 mutant liver cancer patients present poorer prognosis, altered hepatic lipid metabolism and steatohepatitis/NASH signatures. Our results imply that RNF43/ZNRF3 predispose to liver cancer by controlling the proliferative/differentiation and lipid metabolic state of hepatocytes. Both mechanisms combined facilitate the progression towards malignancy. Our findings might aid on the management of those RNF43/ZNRF3 mutated individuals at risk of developing fatty liver and/or liver cancer

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. COs are subsequently seeded on polyglycolic acid (PGA) scaffolds or densified collagen constructs for 4 weeks to generate bioengineered tissue retaining biliary characteristics. Expertise in organoid culture and tissue engineering is desirable for optimal results. COs correspond to mature functional cholangiocytes, differentiating our method from alternative organoid systems currently available that propagate adult stem cells. Consequently, COs provide a unique platform for studies in biliary physiology and pathophysiology, and the resulting bioengineered tissue has broad applications for regenerative medicine and cholangiopathies

Somatic mutant clones colonize the human esophagus with age.

The extent to which cells in normal tissues accumulate mutations throughout life is poorly understood. Some mutant cells expand into clones that can be detected by genome sequencing. We mapped mutant clones in normal esophageal epithelium from nine donors (age range, 20 to 75 years). Somatic mutations accumulated with age and were caused mainly by intrinsic mutational processes. We found strong positive selection of clones carrying mutations in 14 cancer genes, with tens to hundreds of clones per square centimeter. In middle-aged and elderly donors, clones with cancer-associated mutations covered much of the epithelium, with NOTCH1 and TP53 mutations affecting 12 to 80% and 2 to 37% of cells, respectively. Unexpectedly, the prevalence of NOTCH1 mutations in normal esophagus was several times higher than in esophageal cancers. These findings have implications for our understanding of cancer and aging.Wellcome Trust Cancer Research U

Selection of Oncogenic Mutant Clones in Normal Human Skin Varies with Body Site

Skin cancer risk varies substantially across the body, yet how this relates to the mutations found in normal skin is unknown. Here we mapped mutant clones in skin from high- and low-risk sites. The density of mutations varied by location. The prevalence of NOTCH1 and FAT1 mutations in forearm, trunk, and leg skin was similar to that in keratinocyte cancers. Most mutations were caused by ultraviolet light, but mutational signature analysis suggested differences in DNA-repair processes between sites. Eleven mutant genes were under positive selection, with TP53 preferentially selected in the head and FAT1 in the leg. Fine-scale mapping revealed 10% of clones had copy-number alterations. Analysis of hair follicles showed mutations in the upper follicle resembled adjacent skin, but the lower follicle was sparsely mutated. Normal skin is a dense patchwork of mutant clones arising from competitive selection that varies by location. / Significance: Mapping mutant clones across the body reveals normal skin is a dense patchwork of mutant cells. The variation in cancer risk between sites substantially exceeds that in mutant clone density. More generally, mutant genes cannot be assigned as cancer drivers until their prevalence in normal tissue is known

Succinate accumulation drives ischaemia-reperfusion injury during organ transplantation.

During heart transplantation, storage in cold preservation solution is thought to protect the organ by slowing metabolism; by providing osmotic support; and by minimising ischaemia-reperfusion (IR) injury upon transplantation into the recipient1,2. Despite its widespread use our understanding of the metabolic changes prevented by cold storage and how warm ischaemia leads to damage is surprisingly poor. Here, we compare the metabolic changes during warm ischaemia (WI) and cold ischaemia (CI) in hearts from mouse, pig, and human. We identify common metabolic alterations during WI and those affected by CI, thereby elucidating mechanisms underlying the benefits of CI, and how WI causes damage. Succinate accumulation is a major feature within ischaemic hearts across species, and CI slows succinate generation, thereby reducing tissue damage upon reperfusion caused by the production of mitochondrial reactive oxygen species (ROS)3,4. Importantly, the inevitable periods of WI during organ procurement lead to the accumulation of damaging levels of succinate during transplantation, despite cooling organs as rapidly as possible. This damage is ameliorated by metabolic inhibitors that prevent succinate accumulation and oxidation. Our findings suggest how WI and CI contribute to transplant outcome and indicate new therapies for improving the quality of transplanted organs.Work in the M.P.M. laboratory was supported by the Medical Research Council UK (MC_U105663142) and by a Wellcome Trust Investigator award (110159/Z/15/Z) to M.P.M. Work in the C.F. laboratory was supported by the Medical Research Council (MRC_MC_UU_12022/6). Work in the K.S.P. laboratory was supported by the Medical Research Council UK. Work in the RCH lab laboratory was supported by a Wellcome Trust Investigator award (110158/Z/15/Z) and a PhD studentship for .L.P from the University of Glasgow. A.V.G. was supported by a PhD studentship funded by the National Institute for Health Research Blood and Transplant Research Unit (NIHR BTRU) in Organ Donation and Transplantation at the University of Cambridge in collaboration with Newcastle University and in partnership with NHS Blood and Transplant (NHSBT)

Cross-tissue immune cell analysis reveals tissue-specific adaptations and clonal architecture in humans

Despite their crucial role in health and disease, our knowledge of immune cells within human tissues remains limited. Here, we surveyed the immune compartment of 15 tissues of six deceased adult donors by single-cell RNA sequencing and paired VDJ sequencing. To systematically resolve immune cell heterogeneity across tissues, we developed CellTypist, a machine learning tool for rapid and precise cell type annotation. Using this approach, combined with detailed curation, we determined the tissue distribution of 45 finely phenotyped immune cell types and states, revealing hitherto unappreciated tissue-specific features and clonal architecture of T and B cells. In summary, our multi-tissue approach lays the foundation for identifying highly resolved immune cell types by leveraging a common reference dataset, tissue-integrated expression analysis and antigen receptor sequencing. One Sentence Summary We provide an immune cell atlas, including antigen receptor repertoire profiling, across lymphoid and non-lymphoid human tissues

The landscape of somatic mutation in normal colorectal epithelial cells.

The colorectal adenoma-carcinoma sequence has provided a paradigmatic framework for understanding the successive somatic genetic changes and consequent clonal expansions that lead to cancer1. However, our understanding of the earliest phases of colorectal neoplastic changes-which may occur in morphologically normal tissue-is comparatively limited, as for most cancer types. Here we use whole-genome sequencing to analyse hundreds of normal crypts from 42 individuals. Signatures of multiple mutational processes were revealed; some of these were ubiquitous and continuous, whereas others were only found in some individuals, in some crypts or during certain periods of life. Probable driver mutations were present in around 1% of normal colorectal crypts in middle-aged individuals, indicating that adenomas and carcinomas are rare outcomes of a pervasive process of neoplastic change across morphologically normal colorectal epithelium. Colorectal cancers exhibit substantially increased mutational burdens relative to normal cells. Sequencing normal colorectal cells provides quantitative insights into the genomic and clonal evolution of cancer

APOBEC mutagenesis is a common process in normal human small intestine

APOBEC mutational signatures SBS2 and SBS13 are common in many human cancer types. However, there is an incomplete understanding of its stimulus, when it occurs in the progression from normal to cancer cell and the APOBEC enzymes responsible. Here we whole-genome sequenced 342 microdissected normal epithelial crypts from the small intestines of 39 individuals and found that SBS2/SBS13 mutations were present in 17% of crypts, more frequent than most other normal tissues. Crypts with SBS2/SBS13 often had immediate crypt neighbors without SBS2/SBS13, suggesting that the underlying cause of SBS2/SBS13 is cell-intrinsic. APOBEC mutagenesis occurred in an episodic manner throughout the human lifespan, including in young children. APOBEC1 mRNA levels were very high in the small intestine epithelium, but low in the large intestine epithelium and other tissues. The results suggest that the high levels of SBS2/SBS13 in the small intestine are collateral damage from APOBEC1 fulfilling its physiological function of editing APOB mRNA. Whole-genome sequencing of healthy human epithelial crypts from the small intestines of 39 individuals highlights APOBEC enzymes as a common contributor to the overall mutational burden in this tissue.Peer reviewe