Multiple arterial thromboemboli after COVID-19. / Multiple arterielle tromboembolier etter covid-19.

BACKGROUND: We present the case of a man in his fifties who presented with bilateral lower extremity ischaemia three weeks after COVID-19 infection. The patient had known. CASE PRESENTATION: On arrival at the emergency department his left lower extremity had reduced sensation but preserved motor function. His right lower extremity had spontaneously improved on arrival. A CT angiogram showed thromboembolism in both popliteal arteries with extension down the tibiofibular trunk. An acute bilateral mechanical thromboembolectomy of the popliteal artery and tibiofibular trunk was performed. Postoperatively he was hypoxic and a CT thorax angiogram showed bilateral pulmonary embolism, a floating aortic thrombus and ground glass opacification changes typical after COVID-19 viral pneumonia. The patient was systemically anticoagulated. Echocardiography revealed an apical thrombus. There were no signs of cardiac arrhythmia. Haematological diagnostic tests were all negative. INTERPRETATION: It is presumed that a previous COVID-19 infection contributed to the systemic thrombotic events. The patient was discharged after 9 days in good health and able to walk a normal distance.

Evolution of graft morphology and function after recellularization of decellularized rat livers.

Decellularization of livers is a well-established procedure. Data on different reseeding techniques or the functional evolution and reorganization processes of repopulated grafts remains limited. A proprietary, customized bioreactor was established to repopulate decellularized rat livers (n = 21) with primary rat hepatocytes (150 × 106 cells) via the hepatic artery and to subsequently evaluate graft morphology and function during 7 days of ex vivo perfusion. Grafts were analysed at 1 h, 6 h, 12 h, 24 h, 3 days, 5 days and 7 days after recellularization (all n = 3) by immunohistological evaluation, hepatocyte-related enzyme (aspartate transaminase, alanine transaminase and lactate dehydrogenase) and albumin measurement in the perfusate. This appears to be the first available protocol for repopulation of rat livers via the hepatic artery. Within the first 24 h after repopulation, the hepatocytes seemed to migrate out of the vascular network and form clusters in the parenchymal space around the vessels. Graft function increased for the first 24 h after repopulation with a significantly higher function compared to standard two-dimensional culture after 24 h. Thereafter, graft function constantly decreased with significantly lower values after 6 days and 7 days of perfusion, although histologically viable hepatocytes were found even after this period. The data suggests that, owing to a constant loss of function, repopulated grafts should potentially be implanted as soon as cell engraftment and graft re-organization are completed. Copyright © 2016 John Wiley & Sons, Ltd.

Improved rat liver decellularization by arterial perfusion under oscillating pressure conditions.

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.

Implantation of a Tissue-Engineered Neo-Bile Duct in Domestic Pigs.

BACKGROUND: Extrahepatic bile duct injuries remain severe complications during cholecystectomies and often require reconstruction by bilioenteric anastomosis (i.e., hepaticojejunostomy), which comes with further long-term complications (e.g., recurring ascending cholangitis, secondary biliary cirrhosis). In the case of inherent extrahepatic biliary atresia or during liver transplant, artificial or engineered bile ducts could allow novel surgical strategies without the need for hepaticojejunostomy. METHODS: We present data on the implantation of in vitro-generated neo-bile ducts in 5 domestic pigs. The neo-bile ducts were engineered through decellularization of allogeneic blood vessels and recellularization with autologous cholangiocytes. On postoperative days 0, 1, 7, and 14, blood samples were taken and analyzed (aspartate aminotransferase, alanine aminotransferase, bilirubin, alkaline phosphatase, creatinine, and leukocytes). Magnetic resonance cholangiopancreatography was performed on postoperative day 14 on 1 pig. Fourteen days after implantation, the pigs were sacrificed and the bile ducts were explanted. RESULTS: All pigs survived the complete study period without severe complications. None of the pigs showed signs of biliary leakage or peritonitis. The neo-bile ducts were infiltrated by neutrophils, and neoangiogenesis was observed around and into the implanted tissue. CONCLUSION: We present a novel strategy for extrahepatic bile duct replacement by implantation of an autologous neo-bile duct generated ex vivo. Whether the presented technique allows the long-term replacement of native bile ducts must be further evaluated.

Procedure for Decellularization of Rat Livers in an Oscillating-pressure Perfusion Device.

Decellularization and recellularization of parenchymal organs may enable the generation of functional organs in vitro, and several protocols for rodent liver decellularization have already been published. We aimed to improve the decellularization process by construction of a proprietary perfusion device enabling selective perfusion via the portal vein and/or the hepatic artery. Furthermore, we sought to perform perfusion under oscillating surrounding pressure conditions to improve the homogeneity of decellularization. The homogeneity of perfusion decellularization has been an underestimated factor to date. During decellularization, areas within the organ that are poorly perfused may still contain cells, whereas the extracellular matrix (ECM) in well-perfused areas may already be affected by alkaline detergents. Oscillating pressure changes can mimic the intraabdominal pressure changes that occur during respiration to optimize microperfusion inside the liver. In the study presented here, decellularized rat liver matrices were analyzed by histological staining, DNA content analysis and corrosion casting. Perfusion via the hepatic artery showed more homogenous results than portal venous perfusion did. The application of oscillating pressure conditions improved the effectiveness of perfusion decellularization. Livers perfused via the hepatic artery and under oscillating pressure conditions showed the best results. The presented techniques for liver harvesting, cannulation and perfusion using our proprietary device enable sophisticated perfusion set-ups to improve decellularization and recellularization experiments in rat livers.

Porcine liver decellularization under oscillating pressure conditions: a technical refinement to improve the homogeneity of the decellularization process.

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.