Vinzent N. Spetzler

Mechanism of hard-nanomaterial clearance by the liver

The liver and spleen are major biological barriers to translating nanomedicines because they sequester the majority of administered nanomaterials and prevent delivery to diseased tissue. Here we examined the blood clearance mechanism of administered hard nanomaterials in relation to blood flow dynamics, organ microarchitecture, and cellular phenotype. We found that nanomaterial velocity reduces 1000-fold as they enter and traverse the liver, leading to 7.5 times more nanomaterial interaction with hepatic cells relative to peripheral cells. In the liver, Kupffer cells (84.8%±6.4%), hepatic B cells (81.5±9.3%), and liver sinusoidal endothelial cells (64.6±13.7%) interacted with administered PEGylated quantum dots but splenic macrophages took up less (25.4±10.1%) due to differences in phenotype. The uptake patterns were similar for two other nanomaterial types and five different surface chemistries. Potential new strategies to overcome off-target nanomaterial accumulation may involve manipulating intra-organ flow dynamics and modulating cellular phenotype to alter hepatic cell interaction.

Subnormothermic ex vivo liver perfusion reduces endothelial cell and bile duct injury after donation after cardiac death pig liver transplantation

An ischemic‐type biliary stricture (ITBS) is a common feature after liver transplantation using donation after cardiac death (DCD) grafts. We compared sequential subnormothermic ex vivo liver perfusion (SNEVLP; 33°C) with cold storage (CS) for the prevention of ITBS in DCD liver grafts in pig liver transplantation (n = 5 for each group). Liver grafts were stored for 10 hours at 4°C (CS) or preserved with combined 7‐hour CS and 3‐hour SNEVLP. Parameters of hepatocyte [aspartate aminotransferase (AST), international normalized ratio (INR), factor V, and caspase 3 immunohistochemistry], endothelial cell (EC; CD31 immunohistochemistry and hyaluronic acid), and biliary injury and function [alkaline phosphatase (ALP), total bilirubin, and bile lactate dehydrogenase (LDH)] were determined. Long‐term survival (7 days) after transplantation was similar between the SNEVLP and CS groups (60% versus 40%, P = 0.13). No difference was observed between SNEVLP‐ and CS‐treated animals with respect to the peak of serum INR, factor V, or AST levels within 24 hours. CD31 staining 8 hours after transplantation demonstrated intact EC lining in SNEVLP‐treated livers (7.3 × 10−4 ± 2.6 × 10−4 cells/μm2) but not in CS‐treated livers (3.7 × 10−4 ± 1.3 × 10−4 cells/μm2, P = 0.03). Posttransplant SNEVLP animals had decreased serum ALP and serum bilirubin levels in comparison with CS animals. In addition, LDH in bile fluid was lower in SNEVLP pigs versus CS pigs (14 ± 10 versus 60 ± 18 μmol/L, P = 0.02). Bile duct histology revealed severe bile duct necrosis in 3 of 5 animals in the CS group but none in the SNEVLP group (P = 0.03). Sequential SNEVLP preservation of DCD grafts reduces bile duct and EC injury after liver transplantation. Liver Transpl 20:1296‐1305, 2014.

Solid phase microextraction fills the gap in tissue sampling protocols.

Metabolomics and biomarkers discovery are an integral part of bioanalysis. However, untargeted tissue analysis remains as the bottleneck of such studies due to the invasiveness of sample collection, as well as the laborious and time-consuming sample preparation protocols. In the current study, technology integrating in vivo sampling, sample preparation and global extraction of metabolites--solid phase microextraction was presented and evaluated during liver and lung transplantation in pig model. Sampling approaches, including selection of the probe, transportation, storage conditions and analyte coverage were discussed. The applicability of the method for metabolomics studies was demonstrated during lung transplantation experiments.

Liver transplantation in patients with end-stage liver disease requiring intensive care unit admission and intubation

Data regarding transplantation outcomes in ventilated intensive care unit (ICU)–dependent patients with end‐stage liver disease (ESLD) are conflicting. This single‐center cohort study investigated the outcomes of patients with ESLD who were intubated with mechanical support before liver transplantation (LT). The ICU plus intubation group consisted of 42 patients with decompensated cirrhosis and mechanical ventilation before transplantation. LT was considered for intubated ICU patients if the fraction of inspired oxygen was ≤40% with a positive end‐expiratory pressure ≤ 10, low pressor requirements, and the absence of an active infection. Intubated ICU patients were compared to 80 patients requiring ICU admission before transplantation without intubation and to 126 matched non–ICU‐bound patients. Patients requiring ICU care with intubation and ICU care alone had more severe postoperative complications than non–ICU‐bound patients. Intubation before transplantation was associated with more postoperative pneumonias (15% in intubated ICU transplant candidates, 5% in ICU‐bound but not intubated patients, and 3% in control group patients; P = 0.02). Parameters of reperfusion injury and renal function on postoperative day (POD) 2 and POD 7 were similar in all groups. Bilirubin levels were higher in the ICU plus intubation group at POD 2 and POD 7 after transplantation but were normalized in all groups within 3 months. The ICU plus intubation group versus the ICU‐only group and the non‐ICU group had decreased 1‐, 3‐, and 5‐year graft survival (81% versus 84% versus 92%, 76% versus 78% versus 87%, and 71% versus 77% versus 84%, respectively; P = 0.19), but statistical significance was not reached. A Glasgow coma scale score of <7 versus >7 before transplantation was associated with high postoperative mortality in ICU‐bound patients requiring intubation (38% versus 23%; P = 0.01). In conclusion, ICU admission and mechanical ventilation should not be considered contraindications for LT. With careful patient selection, acceptable long‐term outcomes can be achieved despite increased postoperative complications. Liver Transpl 21:761–767, 2015.

Low invasive in vivo tissue sampling for monitoring biomarkers and drugs during surgery.

The techniques currently used for drug, metabolite, and biomarker determination are based on sample collection, and therefore they are not suitable for repeated analysis because of the high invasiveness. Here, we present a novel method of biochemical analysis directly in organ during operation without need of a separate sample collection step: solid-phase microextraction (SPME). The approach is based on flexible microprobe coated with biocompatible extraction phase that is inserted to the tissue with no damage or disturbance of the organ. The method was evaluated during lung and liver transplantations using normothermic ex vivo liver perfusion (NEVLP) and ex vivo lung perfusion (EVLP). The study demonstrated feasibility of the method to extract wide range of endogenous compounds and drugs. Statistical analysis allowed observing metabolic changes of lung during cold ischemic time, perfusion, and reperfusion. It was also demonstrated that the level of drugs and their metabolites can be monitored over time. Based on the methylprednisolone as a selected example, the impairment of enzymatic properties of liver was detected in the injured organs but not in healthy control. This finding was supported by changes in pathways of endogenous metabolites. The SPME probe was also used for analysis of perfusion fluid using stopcock connection. The evaluation of biochemical profile of perfusates demonstrated potential of the approach for monitoring organ function during ex vivo perfusion. The simplicity of the device makes it convenient to use by medical personnel. With the microprobe, different areas of the organ or various organs can be sampled simultaneously. The technology allows assessment of organ function by biochemical profiling, determination of potential biomarkers, and drug monitoring. The use of this method for preintervention analysis could enhance the decision-making process for the best possible personalized approach, whereas post-transplantation monitoring would be used for graft assessments and fast response in case of organ failure.

Living vs. deceased donor liver transplantation provides comparable recovery of renal function in patients with hepatorenal syndrome: a matched case-control study.

Outcomes of living versus deceased donor liver transplantation in patients with chronic liver disease and hepatorenal syndrome (HRS) was compared using a matched pair study design. Thirty patients with HRS receiving a live donor liver transplantation (LDLT) and 90 HRS patients receiving a full graft deceased donor liver transplantation (DDLT) were compared. LDLT versus DDLT of patients with HRS was associated with decreased peak aspartate aminotransferase levels (339 ± 214 vs. 935 ± 1253 U/L; p = 0.0001), and similar 7‐day bilirubin (8.42 ± 7.89 vs. 6.95 ± 7.13 mg/dL; p = 0.35), and international normalized ratio levels (1.93 ± 0.62 vs. 1.78 ± 0.78; p = 0.314). LDLT vs. DDLT had a decreased intensive care unit (2 [1–39] vs. 4 [0–93] days; p = 0.004), and hospital stay (17 [4–313] vs. 26 [0–126] days; p = 0.016) and a similar incidence of overall postoperative complications (20% vs. 27%; p = 0.62). No difference was detected between LDLT and DDLT patients regarding graft survival at 1 (80% vs. 82%), at 3 (69% vs. 76%) and 5 years (65% vs. 76%) (p = 0.63), as well as patient survival at 1 (83% vs. 82%), 3 (72% vs. 77%) and 5 years (72% vs. 77%) (p = 0.93). The incidence of chronic kidney disease post‐LT (10% vs. 6%; p = 0.4) was similar between both groups. LDLT results in identical long‐term outcome when compared with DDLT in patients with HRS.

Live Donor Liver Transplantation: A Valid Alternative for Critically Ill Patients Suffering From Acute Liver Failure

We report the outcome of live donor liver transplantation (LDLT) for patients suffering from acute liver failure (ALF). From 2006 to 2013, all patients with ALF who received a LDLT (n = 7) at our institution were compared to all ALF patients receiving a deceased donor liver transplantation (DDLT = 26). Groups were comparable regarding pretransplant ICU stay (DDLT: 1 [0–7] vs. LDLT: 1 days [0–10]; p = 0.38), mechanical ventilation support (DDLT: 69% vs. LDLT: 57%; p = 0.66), inotropic drug requirement (DDLT: 27% vs. LDLT: 43%; p = 0.64) and dialysis (DDLT: 2 vs. LDLT: 0 patients; p = 1). Median evaluation time for live donors was 24 h (18–72 h). LDLT versus DDLT had similar incidence of overall postoperative complications (31% vs. 43%; p = 0.66). No difference was detected between LDLT and DDLT patients regarding 1‐ (DDLT: 92% vs. LDLT: 86%), 3‐ (DDLT: 92% vs. LDLT: 86%), and 5‐ (DDLT: 92% vs. LDLT: 86%) year graft and patient survival (p = 0.63). No severe donor complication (Dindo–Clavien ≥3 b) occurred after live liver donation. ALF is a severe disease with high mortality on liver transplant waiting lists worldwide. Therefore, LDLT is an attractive option since live donor work‐up can be expedited and liver transplantation can be performed within 24 h with excellent short‐ and long‐term outcomes.

Subnormothermic ex vivo liver perfusion is a safe alternative to cold static storage for preserving standard criteria grafts

We developed a novel technique of subnormothermic ex vivo liver perfusion (SNEVLP) for the storage of liver grafts before transplantation. To test the safety of SNEVLP for the nonextended criteria grafts (standard grafts), we compared it to a control group with minimal cold static storage (CS) time. Heart‐beating pig liver retrieval was performed. Grafts were either stored in cold unmodified University of Wisconsin solution (CS‐1), in cold University of Wisconsin solution with ex vivo perfusion additives (CS‐2), or preserved with a sequence of 3 hours CS and 3 hours SNEVLP (33°C), followed by orthotopic liver transplantation. Liver function tests and histology were investigated. Aspartate aminotransferase (AST) levels during SNEVLP remained stable (54.3 ± 12.6 U/L at 1 hour to 47.0 ± 31.9 U/L at 3 hours). Posttransplantation, SNEVLP versus CS‐1 livers had decreased AST levels (peak at day 1, 1081.9 ± 788.5 versus 1546.7 ± 509.3 U/L; P = 0.14; at day 2, 316.7 ± 188.1 versus 948.2 ± 740.9 U/L; P = 0.04) and alkaline phosphatase levels (peak at day 1, 150.4 ± 19.3 versus 203.7 ± 33.6 U/L; P = 0.003). Bilirubin levels were constantly within the physiological range in the SNEVLP group, whereas the CS‐1 group presented a large standard deviation, including pathologically increased values. Hyaluronic acid as a marker of endothelial cell (EC) function was markedly improved by SNEVLP during the early posttransplant phase (5 hours posttransplant, 1172.75 ± 598.5 versus 5540.5 ± 2755.4 ng/mL). Peak international normalized ratio was similar between SNEVLP and CS‐1 groups after transplantation. Immunohistochemistry for cleaved caspase 3 demonstrated more apoptotic sinusoidal cells in the CS‐1 group when compared to SNEVLP grafts 2 hours after reperfusion (19.4 ± 19.5 versus 133.2 ± 48.8 cells/high‐power field; P = 0.002). Adding normothermic CS‐2 had no impact on liver injury or function after transplantation when compared to CS‐1. In conclusion, SNEVLP is safe to use for standard donor grafts and is associated with improved EC and bile duct injury even in grafts with minimal CS time. Liver Transpl 22:111‐119, 2016.

Technique of Subnormothermic Ex Vivo Liver Perfusion for the Storage, Assessment, and Repair of Marginal Liver Grafts

The success of liver transplantation has resulted in a dramatic organ shortage. In most transplant regions 20-30% of patients on the waiting list for liver transplantation die without receiving an organ transplant or are delisted for disease progression. One strategy to increase the donor pool is the utilization of marginal grafts, such as fatty livers, grafts from older donors, or donation after cardiac death (DCD). The current preservation technique of cold static storage is only poorly tolerated by marginal livers resulting in significant organ damage. In addition, cold static organ storage does not allow graft assessment or repair prior to transplantation. These shortcomings of cold static preservation have triggered an interest in warm perfused organ preservation to reduce cold ischemic injury, assess liver grafts during preservation, and explore the opportunity to repair marginal livers prior to transplantation. The optimal pressure and flow conditions, perfusion temperature, composition of the perfusion solution and the need for an oxygen carrier has been controversial in the past. In spite of promising results in several animal studies, the complexity and the costs have prevented a broader clinical application so far. Recently, with enhanced technology and a better understanding of liver physiology during ex vivo perfusion the outcome of warm liver perfusion has improved and consistently good results can be achieved. This paper will provide information about liver retrieval, storage techniques, and isolated liver perfusion in pigs. We will illustrate a) the requirements to ensure sufficient oxygen supply to the organ, b) technical considerations about the perfusion machine and the perfusion solution, and c) biochemical aspects of isolated organs.

Anti‐inflammatory signaling during ex vivo liver perfusion improves the preservation of pig liver grafts before transplantation

Normothermic ex vivo liver perfusion (NEVLP) improves graft preservation by avoiding cold ischemia injury. We investigated whether the protective effects of NEVLP can be further improved by applying strategies targeted on reducing the activation of proinflammatory cytokines during perfusion. Livers retrieved under heart‐beating conditions were perfused for 4 hours. Following the preservation period, a pig liver transplantation was performed. In group 1 (n = 5), anti‐inflammatory strategies (alprostadil, n‐acetylcysteine, carbon monoxide, sevoflurane, and subnormothermic temperature [33°C]) were applied. This was compared with a perfused control group (group 2) where livers (n = 5) were perfused at 37°C without anti‐inflammatory agents, similar to the setup used in current European clinical trials, and to a control group preserved with static cold storage (group 3). During 3‐day follow‐up, markers of reperfusion injury, bile duct injury, and liver function were examined. Aspartate aminotransferase (AST) levels during perfusion were significantly lower in the study versus control group at 1 hour (52 ± 6 versus 162 ± 86 U/L; P = 0.01), 2 hours (43 ± 5 versus 191 ± 111 U/L; P = 0.008), and 3 hours (24 ± 16 versus 218 ± 121 U/L; P = 0.009). During perfusion, group 1 versus group 2 had reduced interleukin (IL) 6, tumor necrosis factor α, and galactosidase levels and increased IL10 levels. After transplantation, group 1 had lower AST peak levels compared with group 2 and group 3 (1400 ± 653 versus 2097 ± 1071 versus 1747 ± 842 U/L; P = 0.47) without reaching significance. Bilirubin levels were significantly lower in group 1 versus group 2 at day 1 (3.6 ± 1.5 versus 6.60 ± 1.5 μmol/L; P = 0.02) and 3 (2 ± 1.1 versus 9.7 ± 7.6 μmol/L; P = 0.01). A trend toward decreased hyaluronic acid, as a marker of improved endothelial cell function, was observed at 1, 3, and 5 hours after reperfusion in group 1 versus group 2. Only 1 early death occurred in each group (80% survival). In conclusion, addition of anti‐inflammatory strategies further improves warm perfused preservation. Liver Transplantation 22 1573–1583 2016 AASLD.