Search

Abstract: The surfaces of lactose particles are coated with SiOx nanostructures in a plasma downstream reactor to increase the surface roughness and thus, to reduce the prevailing van der Waals forces between the substrate particles. As a consequence of the smaller interparticle friction, both the bulk density and the flowability of plasma modified powders are increased. In this study different powder fractions with mean particle sizes between 5 and 40μm are processed separately to investigate the influence of the particle size on the process. The measured bulk densities and flow factors become larger with increasing mean particle size for both untreated and plasma treated powders. The bulk density of all powder fractions is increased by 40 to 50% and all originally cohesive powders reach an easy flowing regime through the short low-temperature plasma treatment. Scanning electron microscope images are presented to appraise the particle size and distribution of the deposited spacer structures on the lactose surface. This estimation leads to the conclusion that the spacer structures have typical diameters between 15 and 60nm and cover the surface with approximately 5 to 15%. Comparative studies investigating the influence of admixed glidants on the powder flowability show that this range is desirable for a maximal reduction of attractive van der Waals forces. [Copyright &y& Elsevier]

Background: Ex situliver machine perfusion at subnormothermic/normothermic temperature isincreasingly applied in the field of transplantation to store and evaluateorgans on the machine prior transplantation. Currently, various perfusionconcepts are in clinical and preclinical applications. Over the last 6 years ina multidisciplinary team, a novel blood based perfusion technology wasdeveloped to keep a liver alive and metabolically active outside of the bodyfor at least one week., Methods: Within thismanuscript, we present and compare three scenarios (Group 1, 2 and 3) we werefacing during our research and development (R&D) process, mainly linked tothe measurement of free hemoglobin and lactate in the blood based perfusate. Apartfrom their proven value in liver viability assessment (ex situ), these twoparameters are also helpful in R&D of a long-term liver perfusion machine and moreover supportive in the biomedical engineering process., Results: Group 1 ("good" liver on the perfusion machine) represents the best liver clearance capacity for lactate and free hemoglobin wehave observed. In contrast to Group 2 ("poor" liver on the perfusion machine), that has shown the worst clearance capacity for free hemoglobin. Astonishingly,also for Group 2, lactate is cleared till the first day of perfusion andafterwards, rising lactate values are detected due to the poor quality of theliver. These two perfusate parametersclearly highlight the impact of the organ quality/viability on the perfusion process. Whereas Group 3 is a perfusion utilizing a blood loop only (without a liver)., Conclusion: Knowing the feasible ranges (upper- and lower bound) and the courseover time of free hemoglobin and lactate is helpful to evaluate the quality ofthe organ perfusion itself and the maturity of the developed perfusion device. Freehemoglobin in the perfusate is linked to the rate of hemolysis that indicates how optimizing (gentle blood handling, minimizing hemolysis) the perfusion machine actually is. Generally, a reduced lactate clearancecapacity can be an indication for technical problems linked to the blood supplyof the liver and therefore helps to monitor the perfusion experiments.Moreover, the possibility is given to compare, evaluate and optimize developed liverperfusion systems based on the given ranges for these two parameters. Otherresearch groups can compare/quantify their perfusate (blood) parameters withthe ones in this manuscript. The presented data, findings and recommendations willfinally support other researchers in developing their own perfusion machine ormodifying commercially availableperfusion devices according to their needs., (© 2022 International Center for Artificial Organ and Transplantation (ICAOT) and Wiley Periodicals LLC.)

Current organ preservation methods provide a narrow window (usually <12 hours) to assess, transport and implant donor grafts for human transplantation. Here we report the transplantation of a human liver discarded by all centers, which could be preserved for several days using ex situ normothermic machine perfusion. The transplanted liver exhibited normal function, with minimal reperfusion injury and the need for only a minimal immunosuppressive regimen. The patient rapidly recovered a normal quality of life without any signs of liver damage, such as rejection or injury to the bile ducts, according to a 1-year follow up. This inaugural clinical success opens new horizons in clinical research and promises an extended time window of up to 10 days for assessment of viability of donor organs as well as converting an urgent and highly demanding surgery into an elective procedure., (© 2022. The Author(s), under exclusive licence to Springer Nature America, Inc.)

Robust viability assessment of grafts during normothermic liver perfusion is a prerequisite for organ use. Coagulation parameters are used commonly for liver assessment in patients. However, they are not yet included in viability assessment during ex situ perfusion. In this study, we analysed coagulation parameters during one week ex situ perfusion at 34℃. Eight discarded human livers were perfused with blood-based, heparinised perfusate for one week; perfusions in a further four livers were terminated on day 4 due to massive ongoing cell death. Coagulation parameters were well below the physiologic range at perfusion start. Physiologic levels were achieved within the first two perfusion days for factor V (68.5 ± 35.5%), factor VII (83.5 ± 26.2%), fibrinogen (2.1 ± 0.4 g/L) and antithrombin (107 ± 26.5%) in the livers perfused for one week. Despite the increased production of coagulation factors, INR was detectable only at 24h of perfusion (2.1 ± 0.3) and prolonged thereafter (INR > 9). The prolongation of INR was related to the high heparin level in the perfusate (anti-FXa > 3 U/mL). Intriguingly, livers with ongoing massive cell death also disclosed synthesis of factor V and improved INR. In summary, perfused livers were able to produce coagulation factors at a physiological level ex situ. We propose that single coagulation factor analysis is more reliable for assessing the synthetic function of perfused livers as compared to INR when using a heparinised perfusate., (© 2021 International Center for Artificial Organs and Transplantation and Wiley Periodicals LLC.)

Objective: The aim of this study was to maintain long-term full function and viability of partial livers perfused ex situ for sufficient duration to enable ex situ treatment, repair, and regeneration., Background: Organ shortage remains the single most important factor limiting the success of transplantation. Autotransplantation in patients with nonresectable liver tumors is rarely feasible due to insufficient tumor-free remnant tissue. This limitation could be solved by the availability of long-term preservation of partial livers that enables functional regeneration and subsequent transplantation., Methods: Partial swine livers were perfused with autologous blood after being procured from healthy pigs following 70% in-vivo resection, leaving only the right lateral lobe. Partial human livers were recovered from patients undergoing anatomic right or left hepatectomies and perfused with a blood based perfusate together with various medical additives. Assessment of physiologic function during perfusion was based on markers of hepatocyte, cholangiocyte, vascular and immune compartments, as well as histology., Results: Following the development phase with partial swine livers, 21 partial human livers (14 right and 7 left hemi-livers) were perfused, eventually reaching the targeted perfusion duration of 1 week with the final protocol. These partial livers disclosed a stable perfusion with normal hepatic function including bile production (5-10 mL/h), lactate clearance, and maintenance of energy exhibited by normal of adenosine triphosphate (ATP) and glycogen levels, and preserved liver architecture for up to 1 week., Conclusion: This pioneering research presents the inaugural evidence for long-term machine perfusion of partial livers and provides a pathway for innovative and relevant clinical applications to increase the availability of organs and provide novel approaches in hepatic oncology., Competing Interests: Conflict of interest: E.T.H. (Swiss Federal Institute of Technology in Zurich) (M. H., M. J. S., B. B., P. RvR., D.B.) and the University of Zurich (D.E., P.D., L.B.B. and P-A. C.) own/applied for patents on liver perfusion technology (PCT/EP2019/051252, PCT/EP20 17/068506). The authors report no other conflicts of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Introduction: The use of normothermic liver machine perfusion to repair injured grafts ex situ is an emerging topic of clinical importance. However, a major concern is the possibility of microbial contamination in the absence of a fully functional immune system. Here, we report a standardized approach to maintain sterility during normothermic liver machine perfusion of porcine livers for one week., Methods: Porcine livers (n = 42) were procured and perfused with blood at 34°C following aseptic technique and standard operating procedures. The antimicrobial prophylaxis was adapted and improved in a step-wise manner taking into account the pathogens that were detected during the development phase. Piperacillin-Tazobactam was applied as a single dose initially and modified to continuous application in the final protocol. In addition, the perfusion machine was improved to recapitulate partially the host's defense system. The final protocol was tested for infection prevention during one week of perfusion., Results: During the development phase, microbial contamination occurred in 27 out of 39 (69%) livers with a mean occurrence of growth on 4 ± 1.6 perfusion days. The recovered microorganisms suggested an exogenous source of microbial contamination. The antimicrobial agents (piperacillin/tazobactam) could be maintained above the targeted minimal inhibitory concentration (8-16 mg/L) only with continuous application. In addition to continuous application of piperacillin/tazobactam, partial recapitulation of the host immune system ex situ accompanied by strict preventive measures for contact and air contamination maintained sterility during one week of perfusion., Conclusion: The work demonstrates feasibility of sterility maintenance for one week during ex situ normothermic liver perfusion., (© 2021 Wiley Periodicals LLC.)

Objective: With the growing demand for livers in the field of transplantation, interest in normothermic ex situ machine perfusion (NMP) has increased in recent years. This may open the door for novel therapeutic interventions such as repair of suboptimal grafts. For successful long-term NMP of livers, blood glucose (BG) levels need to be maintained in a close to physiological range., Methods: We present an "automated insulin delivery" (AID) system integrated into an NMP system, which automatically adjusts insulin infusion rates based on continuous BG measurements in a closed loop manner during ex situ pig and human liver perfusion. An online glucose sensor for continuous glucose monitoring was integrated and evaluated in blood. A model based and a proportional controller were implemented and compared in their ability to maintain BG within the physiological range., Results: The continuous glucose sensor is capable of measuring BG directly in human and pig blood for multiple days with an average error of 0.6 mmol/L. There was no significant difference in the performance of the two controllers in terms of their ability to keep BG in the physiological range. With the integrated AID, BG was controlled within the physiological range on average in 80% and 76% of the perfusion time for human and pig livers, respectively., Conclusion: The presented work offers a method and shows the feasibility to maintain BG in the physiological range for multiple (up to ten) days during ex situ liver perfusion with the help of an automated AID., Significance: Maintaining BG within the physiological range is required to enable long-term ex situ liver perfusion.

Background: Long-term ex situ liver perfusion may rescue injured grafts. Little is known about bile flow during long-term perfusion. We report the development of a bile stimulation protocol and motivate bile flow as a viability marker during long-term ex situ liver perfusion., Methods: Porcine and human livers were perfused with blood at close to physiologic conditions. Our perfusion protocol was established during phase 1 with porcine livers (n = 23). Taurocholic acid was applied to stimulate bile flow. The addition of piperacillin-tazobactam (tazobac) and methylprednisolone was modified from daily bolus to controlled continuous application. We adapted the protocol to human livers (n = 12) during phase 2. Taurocholic acid was replaced with medical grade ursodeoxycholic acid., Results: Phase 2: Despite administering taurocholic acid, bile flow declined from 29.3 ± 6.5 to 9.3 ± 1.4 mL/h (P < .001). Shortly after bolus of tazobac/methylprednisolone, bile flow recovered to 39.0 ± 9.7 mL/h with a decrease of solid bile components. This implied bile salt independent bile flow stimulation by tazobac/methylprednisolone. Phase 2: Ursodeoxycholic acid was shown to stimulate bile flow ex situ in human livers. Eight livers were perfused successfully for 1 week with continuous bile flow. The other 4 livers demonstrated progressive cell death, of which only 1 exhibited bile flow., Conclusion: A lack of bile flow stimulation leads to a decline in bile flow and is not necessarily a sign of deterioration in liver function. Proper administration of stimulators can induce constant bile flow during ex situ liver perfusion for up to 1 week. Medical grade ursodeoxycholic acid is a suitable replacement for nonmedical grade taurocholic acid. The presence of bile flow alone is not sufficient to assess liver viability., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Long-term perfusion of liver grafts outside of the body may enable repair of poor-quality livers that are currently declined for transplantation, mitigating the global shortage of donor livers. In current ex vivo liver perfusion protocols, hyperoxic blood (arterial blood) is commonly delivered in the portal vein (PV). We perfused porcine livers for one week and investigated the effect of and mechanisms behind hyperoxia in the PV on hepatic arterial resistance. Applying PV hyperoxia in porcine livers (n = 5, arterial PV group), we observed an increased need for vasodilator Nitroprussiat (285 ± 162 ml/week) to maintain the reference hepatic artery flow of 0.25 l/min during ex vivo perfusion. With physiologic oxygenation (venous blood) in the PV the need for vasodilator could be reduced to 41 ± 34 ml/week (p = 0.011; n = 5, venous PV group). This phenomenon has not been reported previously, owing to the fact that such experiments are not feasible practically in vivo. We investigated the mechanism of the variation in HA resistance in response to blood oxygen saturation with a focus on the release of vasoactive substances, such as Endothelin 1 (ET-1) and nitric oxide (NO), at the protein and mRNA levels. However, no difference was found between groups for ET-1 and NO release. We propose direct oxygen sensing of endothelial cells and/or increased NO break down rate with hyperoxia as possible explanations for enhanced HA resistance.

The ability to preserve metabolically active livers ex vivo for 1 week or more could allow repair of poor-quality livers that would otherwise be declined for transplantation. Current approaches for normothermic perfusion can preserve human livers for only 24 h. Here we report a liver perfusion machine that integrates multiple core physiological functions, including automated management of glucose levels and oxygenation, waste-product removal and hematocrit control. We developed the machine in a stepwise fashion using pig livers. Study of multiple ex vivo parameters and early phase reperfusion in vivo demonstrated the viability of pig livers perfused for 1 week without the need for additional blood products or perfusate exchange. We tested the approach on ten injured human livers that had been declined for transplantation by all European centers. After a 7-d perfusion, six of the human livers showed preserved function as indicated by bile production, synthesis of coagulation factors, maintained cellular energy (ATP) and intact liver structure.

The operando study of CO 2 hydrogenation is fundamental for a more rational optimisation of heterogeneous catalyst and reactor designs. To further complement the established efficiency of microreactors in reaction screening and bridge the operating and optical gaps, a micro-view-cell is presented for Raman microscopy at extreme conditions with minimum flow interference for genuine reaction analysis. Based on a flat sapphire window unit sealed in a plug flow-type enclosure holding the sample, the cell features unique 14 mm working distance and 0.36 numerical aperture and resists 400 °C and 500 bars. The use of the cell as an in situ tool for fast process monitoring and surface catalyst characterisation is demonstrated with phase behaviour and chemical analysis of the methanol synthesis over a commercial Cu/ZnO/Al 2 O 3 catalyst.