[Show abstract][Hide abstract] ABSTRACT: Introduction:
The intra-hepatic vascular anatomy in rodents, its variations and corresponding supplying and draining territories in respect to the lobar structure of the liver have not been described. We performed a detailed anatomical imaging study in rats and mice to allow for further refinement of experimental surgical approaches.
LEWIS-Rats and C57Bl/6N-Mice were subjected to ex-vivo imaging using μCT. The image data were used for semi-automated segmentation to extract the hepatic vascular tree as prerequisite for 3D visualization. The underlying vascular anatomy was reconstructed, analysed and used for determining hepatic vascular territories.
The four major liver lobes have their own lobar portal supply and hepatic drainage territories. In contrast, the paracaval liver is supplied by various small branches from right and caudate portal veins and drains directly into the vena cava. Variations in hepatic vascular anatomy were observed in terms of branching pattern and distance of branches to each other. The portal vein anatomy is more variable than the hepatic vein anatomy. Surgically relevant variations were primarily observed in portal venous supply.
For the first time the key variations of intrahepatic vascular anatomy in mice and rats and their surgical implications were described. We showed that lobar borders of the liver do not always match vascular territorial borders. These findings are of importance for the design of new surgical procedures and for understanding eventual complications following hepatic surgery.
[Show abstract][Hide abstract] ABSTRACT: Cholestasis is a common complication in liver diseases that triggers a proliferative response of the biliary tree. Bile duct ligation (BDL) is a frequently used model of cholestasis in rodents. To determine which changes occur in the 3D-architecture of the interlobular biliary duct (BD) during cholestasis, we used 3D-confocal imaging, surface reconstructions and automated image quantification covering a period up to 28 days after BDL. We show a highly reproducible sequence of interlobular duct remodeling, where cholangiocyte proliferation initially causes corrugation of the luminal duct surface, leading to an approximately 5-fold increase in surface area. This is analogous to the function of villi in the intestine or sulci in the brain, where an expansion of area is achieved within a restricted volume. The increase in surface area is further enhanced by duct branching, branch elongation and finally loop formation through self-joining, whereby an initially relatively sparse mesh surrounding the portal vein becomes 5-fold denser through elongation, corrugation and ramification. The number of connections between BD and the lobular bile canalicular network by the canals of Hering decreases proportionally to the increase in BD length, suggesting that no novel connections are established. The diameter of the interlobular BD remains constant after BDL, a response qualitatively distinct from that of large bile ducts which rather tend to enlarge their diameters. Therefore, volume enhancement is only due to net elongation of the ducts. Since curvature and tortuosity of the BD are unaltered this enlargement of the biliary tree is caused by branching and not by convolution. In conclusion, BDL causes adaptive remodeling that aims at optimizing the intraluminal surface area by corrugation and branching. This article is protected by copyright. All rights reserved.
[Show abstract][Hide abstract] ABSTRACT: The German transplantation system is in a crisis due to a lack of donor organs. Information campaigns are one of the main approaches to increase organ donation rates. Since 2012, German health insurance funds are obliged by law to inform their members about organ donation. We raised the hypothesis: The willingness to sign a donor card rises due to the subsequent increase of specific knowledge by receiving the information material of the health insurance funds.
The objective of the study was to assess the influence of information campaigns on the specific knowledge and the willingness to donate organs.
We conducted an online survey based on recruitment via Facebook groups, advertisements using the snowball effect, and on mailing lists of medical faculties in Germany. Besides the demographic data, the willingness to hold an organ donor card was investigated. Specific knowledge regarding transplantation was explored using five factual questions resulting in a specific knowledge score.
We recruited a total of 2484 participants, of which 32.7% (300/917) had received information material. Mean age was 29.9 (SD 11.0, median 26.0). There were 65.81% (1594/2422) of the participants that were female. The mean knowledge score was 3.28 of a possible 5.00 (SD 1.1, median 3.0). Holding a donor card was associated with specific knowledge (P<.001), but not with the general education level (P=.155). Receiving information material was related to holding a donor card (P<.001), but not to a relevant increase in specific knowledge (difference in mean knowledge score 3.20 to 3.48, P=.006). The specific knowledge score and the percentage of organ donor card holders showed a linear association (P<.001).
The information campaign was not associated with a relevant increase in specific knowledge, but with an increased rate in organ donor card holders. This effect is most likely related to the feeling of being informed, together with an easy access to the organ donor card.
[Show abstract][Hide abstract] ABSTRACT: Organ engineering is a new strategy to cope with the shortage of donor organs. A functional scaffold from explanted organs is prepared by removing all cellular components (decellularization) and the reseeding (repopulation) of the organ scaffold to generate a functional organ in vitro for transplantation. This technique was also applied to the liver (liver engineering).
Outline of the current state of the art and resulting approaches for future research strategies.
Systematic review according to the PRISMA guidelines: a PubMed-based literature search (search terms liver, decellularization), selection of relevant articles based on predetermined criteria for relevance (e.g. decellularization, repopulation and transplantation), extraction and critical appraisal of data and results concerning the conditions for decellularization, repopulation and transplantation.
Decellularization was successfully performed in small and large animal models. Hepatocytes as well as stem cells and hepatic cell lines were applied for repopulation and 7 publications could show the successful transplantation of acellular and repopulated organ scaffolds. The current scientific need for further studies concerning the source of donor organs, optimization of the decellularization process, the cell type for the reseeding process and the establishment of the optimal conditions for the repopulation of the scaffold is still tremendous. For successful recellularization of the liver three goals need to be achieved: (1) reseeding of the organ scaffold with a sufficient amount of parenchymal cells, (2) endothelialization of the vascular tree to ensure the supply of oxygen and nutrients to parenchymal cells and (3) an appropriate epithelialization of the biliary tree. In order to progress to clinical trials a suitable transplantation model to verify the function of the organ constructs must be established.
Liver engineering using biological cell-free organ scaffolds represents a scientific and ethical challenge. The existing results emphasize the potential of this new and promising strategy to create organs for transplantation in the future.
[Show abstract][Hide abstract] ABSTRACT: Introduction: Bile duct ligation (BDL) is commonly used to study cholestasis and periportal fibrosis. Despite extensive studies, the spatial-temporal organization of the biliary tree in BDL remains unclear. Methods: To analyze and quantify the biliary tree after BDL, C57Bl/6N mice underwent BDL or sham operation and were observed for 6 hours to 28 days (n = 6/group). At predefined time-points (6h, 1 d, 3 d, 5 d, 7 d, 14 d and 28 d), blood and liver samples were collected for analysis of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) to assess hepatic parenchymal injury and alkaline phosphatase (AP) activities as well as bilirubin for biliary damage. Liver samples were subjected to routine histology and confocal microscopy. Confocal 3D-reconstructions were performed for periportal bile ducts and their links to lobular bile canaliculi. Immunostaining was performed combining antibodies directed against DPPIV/CD26 to visualize the bile canaliculi and the apical membrane of the bile ducts, anti-keratin19 (KRT19) to stain the bile duct epithelial cells, glutamine synthetase to identify the pericentral region of the lobules, anti-donkey mouse IgG which served as an immunoglobulin binds to the sinusoidal endothelial cells thereby visualizing sinusoids. Hepatocyte nuclei were counter stained by DAPI. Results: BDL caused damage to hepatic parenchyma and biliary epithelia cells, as indicted by a significant substantial elevation of transaminases and AP, which peaked on POD28. Histopathological examination of the liver revealed that the fraction of BrdU positive bile duct cells at day 3, 5 and 7 increased in BDL livers with a peak on POD3 compared to sham-operated livers. Morphometric analysis revealed that the total number of bile duct cells per periportal field significantly increased by days 7, 14 and 28 in BDL but peaked a little later. Confocal microscopy revealed that the periportal bile ducts showed extensive branching and increased diameter in BDL mice as compared to sham operated mice. The average numbers of Hering canals occurring per unit length of the bile duct were significantly decreased at days 14 and 28 after BDL. Conclusion: Bile duct ligation leads to biliary tree damage, thus initiating a regenerative response which is culminated in a maximal hepatobiliary cell proliferation 3 days post BDL. Increased hepatobiliary cell proliferation likely manifest as a general enlargement of the biliary tree through enhanced branching and dilation of the ducts.
Full-text · Article · Jan 2015 · Zeitschrift für Gastroenterologie
[Show abstract][Hide abstract] ABSTRACT: Quantitative analysis of histologic slides is of importance for pathology and also to address surgical questions. Recently, a novel application was developed for the automated quantification of whole-slide images. The aim of this study was to test and validate the underlying image analysis algorithm with respect to user friendliness, accuracy, and transferability to different histologic scenarios. The algorithm splits the images into tiles of a predetermined size and identifies the tissue class of each tile. In the training procedure, the user specifies example tiles of the different tissue classes. In the subsequent analysis procedure, the algorithm classifies each tile into the previously specified classes. User friendliness was evaluated by recording training time and testing reproducibility of the training procedure of users with different background. Accuracy was determined with respect to single and batch analysis. Transferability was demonstrated by analyzing tissue of different organs (rat liver, kidney, small bowel, and spleen) and with different stainings (glutamine synthetase and hematoxylin-eosin). Users of different educational background could apply the program efficiently after a short introduction. When analyzing images with similar properties, accuracy of >90% was reached in single images as well as in batch mode. We demonstrated that the novel application is user friendly and very accurate. With the "training" procedure the application can be adapted to novel image characteristics simply by giving examples of relevant tissue structures. Therefore, it is suitable for the fast and efficient analysis of high numbers of fully digitalized histologic sections, potentially allowing "high-throughput" quantitative "histomic" analysis.
No preview · Article · Dec 2014 · Applied immunohistochemistry & molecular morphology: AIMM / official publication of the Society for Applied Immunohistochemistry
[Show abstract][Hide abstract] ABSTRACT: Ischemic preconditioning exerts a protective effect in hepatic ischemia/reperfusion injury. The exact mechanism of ischemic preconditioning action remains largely unknown. Recent studies suggest that autophagy plays an important role in protecting against ischemia/reperfusion injury. However, the role of autophagy in ischemic preconditioning-afforded protection and its regulatory mechanisms in liver ischemia/reperfusion injury remain poorly understood. This study was designed to determine whether ischemic preconditioning could protect against liver ischemia/reperfusion injury via heme oxygenase-1-mediated autophagy.
Full-text · Article · Dec 2014 · Critical Care Medicine
[Show abstract][Hide abstract] ABSTRACT: Liver dysfunction has been known to occur frequently in cases of sepsis. Excessive inflammation and apoptosis are pathological features of acute liver failure. Recent studies suggest that activation of glycogen synthase kinase- (GSK-) 3β is involved in inflammation and apoptosis. We aimed to investigate the protective effects of GSK-3β inhibition on polymicrobial sepsis-induced liver injury and to explore the possible mechanisms. Polymicrobial sepsis was induced by cecal ligation and puncture (CLP), and SB216763 was used to inhibit GSK-3β in C57BL/6 mice. GSK-3β was activated following CLP. Administration of SB216763 decreased mortality, ameliorated liver injury, and reduced hepatic apoptosis. The inhibition of GSK-3β also reduced leukocyte infiltration and hepatic inflammatory cytokine expression and release. Moreover, GSK-3β inhibition suppressed the transcriptional activity of nuclear factor-kappa B (NF-κB) but enhanced the transcriptional activity of cAMP response element binding protein (CREB) in the liver. In in vitro studies, GSK-3β inhibition reduced inflammatory cytokine production via modulation of NF-κB and CREB signaling pathways in lipopolysaccharide-stimulated macrophages. In conclusion, these findings suggest that GSK-3β blockade protects against CLP-induced liver via inhibition of inflammation by modulating NF-κB and CREB activity and suppression of hepatic apoptosis.
Full-text · Article · Nov 2014 · Mediators of Inflammation