One approach of regenerative medicine to generate functional hepatic tissue in vitro is decellularization and recellularization, and several protocols for the decellularization of livers of different species have been published. This appears to be the first report on rat liver decellularization by perfusion under oscillating pressure conditions, intending to optimize microperfusion and minimize damage to the ECM. Four decellularization protocols were compared: perfusion via the portal vein (PV) or the hepatic artery (HA), with (+P) or without (-P) oscillating pressure conditions. All rat livers (n = 24) were perfused with 1% Triton X-100 and 1% sodium dodecyl sulphate, each for 90 min with a perfusion rate of 5 ml/min. Perfusion decellularization was observed macroscopically and the decellularized liver matrices were analysed by histology and biochemical analyses (e.g. levels of DNA, glycosaminoglycans and hepatocyte growth factor). Livers decellularized via the hepatic artery and under oscillating pressure showed a more homogeneous decellularization and less remaining DNA, compared with the livers of the other experimental groups. The novel decellularization method described is effective, quick (3 h) and gentle to the extracellular matrix and thus represents an improvement of existing methodology. Copyright © 2014 John Wiley & Sons, Ltd.

Decellularization of pancreata and repopulation of these non-immunogenic matrices with islets and endothelial cells could provide transplantable, endocrine Neo- Pancreata. In this study, rat pancreata were perfusion decellularized and repopulated with intact islets, comparing three perfusion routes (Artery, Portal Vein, Pancreatic Duct). Decellularization effectively removed all cellular components but conserved the pancreas specific extracellular matrix. Digital subtraction angiography of the matrices showed a conserved integrity of the decellularized vascular system but a contrast emersion into the parenchyma via the decellularized pancreatic duct. Islets infused via the pancreatic duct leaked from the ductular system into the peri-ductular decellularized space despite their magnitude. TUNEL staining and Glucose stimulated insulin secretion revealed that islets were viable and functional after the process. We present the first available protocol for perfusion decellularization of rat pancreata via three different perfusion routes. Furthermore, we provide first proof-of-concept for the repopulation of the decellularized rat pancreata with functional islets of Langerhans. The presented technique can serve as a bioengineering platform to generate implantable and functional endocrine Neo-Pancreata.

Decellularization and recellularization of parenchymal organs may facilitate the generation of autologous functional liver organoids by repopulation of decellularized porcine liver matrices with induced liver cells. We present an accelerated (7 h overall perfusion time) and effective protocol for human-scale liver decellularization by pressure-controlled perfusion with 1% Triton X-100 and 1% sodium dodecyl sulfate via the hepatic artery (120 mmHg) and portal vein (60 mmHg). In addition, we analyzed the effect of oscillating pressure conditions on pig liver decellularization (n=19). The proprietary perfusion device used to generate these pressure conditions mimics intra-abdominal conditions during respiration to optimize microperfusion within livers and thus optimize the homogeneity of the decellularization process. The efficiency of perfusion decellularization was analyzed by macroscopic observation, histological staining (hematoxylin and eosin [H&E], Sirius red, and alcian blue), immunohistochemical staining (collagen IV, laminin, and fibronectin), and biochemical assessment (DNA, collagen, and glycosaminoglycans) of decellularized liver matrices. The integrity of the extracellular matrix (ECM) postdecellularization was visualized by corrosion casting and three-dimensional computed tomography scanning. We found that livers perfused under oscillating pressure conditions (P(+)) showed a more homogenous course of decellularization and contained less DNA compared with livers perfused without oscillating pressure conditions (P(-)). Microscopically, livers from the (P(-)) group showed remnant cell clusters, while no cells were found in livers from the (P(+)) group. The grade of disruption of the ECM was higher in livers from the (P(-)) group, although the perfusion rates and pressure did not significantly differ. Immunohistochemical staining revealed that important matrix components were still present after decellularization. Corrosion casting showed an intact vascular (portal vein and hepatic artery) and biliary framework. In summary, the presented protocol for pig liver decellularization is quick (7 h) and effective. The application of oscillating pressure conditions improves the homogeneity of perfusion and thus the outcome of the decellularization process.

Preoperative assessment of liver function and?prediction of postoperative functional reserve are important in patients scheduled for liver resection. While determination of absolute liver function currently mostly relies on laboratory tests and clinical scores, postoperative remnant liver function is estimated volumetrically using imaging data obtained with computed tomography (CT) or magnetic resonance imaging (MRI). Accurate estimation of hepatic function is also relevant for intensive care patients, oncologic patients, and patients with diffuse liver disease. The indocyanine green (ICG) test is still the only established test for estimating true global liver function. However, more recent tools such as the LiMAx test also allow global assessment of hepatic function. These tests are limited when liver function is inhomogeneously distributed, which is the case in such conditions as unilateral cholestasis or after portal vein embolization. Imaging-based liver function tests were first developed in nuclear medicine and, compared with laboratory tests, have the advantage of displaying the spatial distribution of liver function. Nuclear medicine scans are obtained using tracers such as?99mTc galactosyl and 99mTc mebrofenin. Liver function is typically assessed using planar scintigraphy. However, three-dimensional volumetry is possible with single-photon emission computed tomography (SPECT-CT). Another technique for image-based liver function estimation is Gd-EOB-enhanced MRI. While metabolization of Gd-EOB in the body is similar to that of ICG and mebrofenin, its distribution in the liver can be displayed by MRI with higher temporal and spatial resolution. Moreover, MRI-based determination of liver function can be integrated into routine preoperative imaging. This makes MRI an ideal candidate for preoperative determination of?liver function, though the best pulse sequence and the parameter to be derived from the image information remain to be identified. Another question to be answered is how the results may be affected by renal function and the presence of hyperbilirubinemia. As more results from clinical evaluation including comparison with postoperative liver function data become available, image-based liver function tests, especially with use of Gd-EOB as the contrast medium, have the potential to add another dimension to preoperative imaging. Key Points: ??Liver function consists of a multitude of subfunctions such as biotransformation, excretion and storage. ??Global liver function tests are score-based tests such as Child-Pugh or MELD as well as the ICG- and LiMAx-test. ??Imaging-based liver function tests add spatial information. Current clinical standard is the 99mTc-Mebrofenin-scintigraphy. ??MRI-based function tests with Gd-EOB-DTPA have the potential to integrate seamlessly into clinical workup, feature a higher temporal and spatial resolution and do not rely on ionizing radiation. Citation Format: ??Geisel D, L?demann L, Hamm B et?al. Imaging-Based Liver Function Tests ? Past, Present and F...

Background: Despite the ongoing global pandemic, the impact of COVID-19 on cardiac structure and function is still not completely understood. Myocarditis is a rare but potentially serious complication of other viral infections with variable recovery, and is, in some cases, associated with long-term cardiac remodeling and functional impairment.Aim: To assess myocardial injury in patients who recently recovered from an acute SARS-CoV-2 infection with advanced cardiac magnetic resonance imaging (CMR) and endomyocardial biopsy (EMB).Methods: In total, 32 patients with persistent cardiac symptoms after a COVID-19 infection, 22 patients with acute classic myocarditis not related to COVID-19, and 16 healthy volunteers were included in this study and underwent a comprehensive baseline CMR scan. Of these, 10 patients post COVID-19 and 13 with non-COVID-19 myocarditis underwent a follow-up scan. In 10 of the post-COVID-19 and 15 of the non-COVID-19 patients with myocarditis endomyocardial biopsy (EMB) with histological, immunohistological, and molecular analysis was performed.Results: In total, 10 (31%) patients with COVID-19 showed evidence of myocardial injury, eight (25%) presented with myocardial oedema, eight (25%) exhibited global or regional systolic left ventricular (LV) dysfunction, and nine (28%) exhibited impaired right ventricular (RV) function. However, only three (9%) of COVID-19 patients fulfilled updated CMR–Lake Louise criteria (LLC) for acute myocarditis. Regarding EMB, none of the COVID-19 patients but 87% of the non-COVID-19 patients with myocarditis presented histological findings in keeping with acute or chronic inflammation. COVID-19 patients with severe disease on the WHO scale presented with reduced biventricular longitudinal function, increased RV mass, and longer native T1 times compared with those with only mild or moderate disease.Conclusions: In our cohort, CMR and EMB findings revealed that SARS-CoV-2 infection was associated with relatively mild but variable cardiac involvement. More symptomatic COVID-19 patients and those with higher clinical care demands were more likely to exhibit chronic inflammation and impaired cardiac function compared to patients with milder forms of the disease.