Hepatic artery reconstruction using an operating microscope in pediatric liver transplantation-Is it worth the effort?

INTRODUCTION: In pediatric liver transplantation (pLT), hepatic artery thrombosis (HAT) is associated with inferior transplant outcome. Hepatic artery reconstruction (HAR) using an operating microscope (OM) is considered to reduce the incidence of HAT. METHODS: HAR using an OM was compared to a historic cohort using surgical loupes (SL) in pLT performed between 2009 and 2020. Primary endpoint was the occurrence of HAT. Secondary endpoints were 1-year patient and graft survival determined by Kaplan-Meier analysis and complications. Multivariate analysis was used to identify independent risk factors for HAT and adverse events. RESULTS: A total of 79 pLTs were performed [30 (38.0%) living donations; 49 (62.0%) postmortem donations] divided into 23 (29.1%) segment 2/3, 32 (40.5%) left lobe, 4 (5.1%) extended right lobe, and 20 (25.3%) full-size grafts. One-year patient and graft survival were both 95.2% in the OM group versus 86.2% and 77.8% in the SL group (p = .276 and p = .077). HAT rate was 0% in the OM group versus 24.1% in the SL group (p = .013). One-year patient and graft survival were 64.3% and 35.7% in patient with HAT, compared to 93.9% and 92.8% in patients with no HAT (both p < .001). Multivariate analysis revealed HAR with SL (p = .022) and deceased donor liver transplantation (DDLT) (p = .014) as independent risk factors for HAT. The occurrence of HAT was independently associated with the need for retransplantation (p < .001) and biliary leakage (p = .045). CONCLUSION: In pLT, the use of an OM is significantly associated to reduce HAT rate, biliary complications, and graft loss and outweighs the disadvantages of delayed arterial perfusion and prolonged warm ischemia time (WIT).

[COVID-19 Pandemic in Germany: The Current Situation in Thoracic Surgery]. / COVID-19-Pandemie in Deutschland: Die aktuelle Lage in der Thoraxchirurgie.

BACKGROUND: The new COVID-19 pandemic has an impact on routine thoracic surgery. Various concepts and recommendations are being pursued to protect patients and hospital staff. However, the implementation of these recommendations may depend on the existing infrastructure, local conditions and in-house procedural instructions. MATERIAL AND METHOD: Between 11th May and 26th May 2020, an anonymous online survey on the topic of COVID-19 was conducted among thoracic surgeons in Germany. The survey consisted of 16 questions on the local COVID-19 case numbers, protective measures, procedural instructions and treatment concepts. The results were summarised, descriptively analysed and discussed. RESULTS: The response rate of 42.6% (n = 66), included replies from 23 (34.8%) specialised hospitals, 18 (27.3%) maximum care hospitals and 14 (21.2%) university clinics. COVID-19-positive patients were treated in 65 (99%) clinics and 37.9% of the clinics also performed surgery on COVID-19-positive patients. Nasopharyngeal swabs were the main instrument for COVID-19 patient testing (in 95.4% of the clinics). Test results influenced decisions on treatment in 71.2% of the clinics. In 59.1% of clinics, safety equipment was supplemented with FFP2 masks and eye protection during thoracic surgeries due to the COVID-19 pandemic. DISCUSSION: Almost all thoracic surgeons reported that they had treated patients with COVID-19 and half of them also had performed surgery on COVID-19-positive patients. The applied procedural instructions as well as the effects of COVID-19 on treatment decisions and patient-doctor contact differed between the reporting clinics.

Improvement of Normothermic Ex Vivo Machine Perfusion of Rat Liver Grafts by Dialysis and Kupffer Cell Inhibition With Glycine.

Normothermic ex vivo liver machine perfusion might be a superior preservation strategy for liver grafts from extended criteria donors. However, standardized small animal models are not available for basic research on machine perfusion of liver grafts. A laboratory-scaled perfusion system was developed consisting of a custom-made perfusion chamber, a pressure-controlled roller pump, and an oxygenator. Male Wistar rat livers were perfused via the portal vein for 6 hours using oxygenated culture medium supplemented with rat erythrocytes. A separate circuit was connected via a dialysis membrane to the main circuit for plasma volume expansion. Glycine was added to the flush solution, the perfusate, and the perfusion circuit. Portal pressure and transaminase release were stable over the perfusion period. Dialysis significantly decreased the potassium concentration of the perfusate and led to significantly higher bile and total urea production. Hematoxylin-eosin staining and immunostaining for single-stranded DNA and activated caspase 3 showed less sinusoidal dilatation and tissue damage in livers treated with dialysis and glycine. Although Kupffer cells were preserved, tumor necrosis factor α messenger RNA levels were significantly decreased by both treatments. For proof of concept, the optimized perfusion protocol was tested with donation after circulatory death (DCD) grafts, resulting in significantly lower transaminase release into the perfusate and preserved liver architecture compared with baseline perfusion. In conclusion, our laboratory-scaled normothermic portovenous ex vivo liver perfusion system enables rat liver preservation for 6 hours. Both dialysis and glycine treatment were shown to be synergistic for preservation of the integrity of normal and DCD liver grafts.

Human Stem Cells Promote Liver Regeneration After Partial Hepatectomy in BALB/C Nude Mice.

BACKGROUND: Mesenchymal stem cells (MSCs) have been suggested to augment liver regeneration after surgically and pharmacologically induced liver failure. To further investigate this we processed human bone marrow-derived MSC according to good manufacturing practice (GMP) and tested those cells for their modulatory capacities of metabolic alterations and liver regeneration after partial hepatectomy in BALB/c nude mice. METHODS: Human MSCs were obtained by bone marrow aspiration of healthy donors as in a previously described GMP process. Transgenic GFP-MSCs were administered i.p. 24 h after 70% hepatectomy in BALB/c nude mice, whereas control mice received phosphate-buffered saline. Mice were sacrificed 2, 3, and 5 d after partial hepatectomy. Blood and organs were harvested and metabolic alterations as well as liver regeneration subsequently assessed by liver function tests, multianalyte profiling immunoassays, histology, and immunostaining. RESULTS: Hepatocyte and sinusoidal endothelial cell proliferation were significantly increased after partial hepatectomy in mice receiving MSC compared to control mice (Hepatocyte postoperative day 3, P < 0.01; endothelial cell postoperative day 5, P < 0.05). Hepatocyte fat accumulation correlated inversely with hepatocyte proliferation (r2 = 0.4064, P < 0.01) 2 d after partial hepatectomy, with mice receiving MSC being protected from severe fat accumulation. No GFP-positive cells could be detected in the samples. Serum levels of IL-6, HGF, and IL-10 were significantly decreased at day 3 in mice receiving MSC when compared to control mice (P < 0.05). Relative body weight loss was significantly attenuated after partial hepatectomy in mice receiving MSC (2 d and 3 d, both P < 0.001) with a trend toward a faster relative restoration of liver weight, when compared to control mice. CONCLUSIONS: Human bone marrow-derived MSC attenuate metabolic alterations and improve liver regeneration after partial hepatectomy in BALB/c nude mice. Obtained results using GMP-processed human MSC suggest functional links between fat accumulation and hepatocyte proliferation, without any evidence for cellular homing. This study using GMP-proceeded MSC has important regulatory implications for an urgently needed translation into a clinical trial.

Body Mass Index Thresholds and the Use of Bariatric Surgery in the Field of Kidney Transplantation in Germany.

BACKGROUND: Obesity in the recipient is linked to inferior transplant outcome. Consequently, access to kidney transplantation (KT) is often restricted by body mass index (BMI) thresholds. Bariatric surgery (BS) has been established as a superior treatment for obesity compared to conservative measures, but it is unclear whether it is beneficial for patients on the waiting list. METHODS: A national survey consisting of 16 questions was sent to all heads of German KT centers. Current situation of KT candidates with obesity and the status of BS were queried. RESULTS: Center response rate was 100%. Obesity in KT candidates was considered an important issue (96.1%; n = 49/51) and 68.6% (n = 35/51) of departments responded to use absolute BMI thresholds for KT waiting list access with ≥ 35 kg/m2 (45.1%; n = 23/51) as the most common threshold. BS was considered an appropriate weight loss therapy (92.2%; n = 47/51), in particular before KT (88.2%; n = 45/51). Sleeve gastrectomy was the most favored procedure (77.1%; n = 37/51). Twenty-one (41.2%) departments responded to evaluate KT candidates with obesity by default but only 11 (21.6%) had experience with ≥ n = 5 transplants after BS. Concerns against BS were malabsorption of immunosuppressive therapy (39.2%; n = 20/51), perioperative morbidity (17.6%; n = 9/51), and malnutrition (13.7%; n = 7/51). CONCLUSIONS: Obesity is potentially limiting access for KT. Despite commonly used BMI limits, only few German centers consider BS for obesity treatment in KT candidates by default. A national multicenter study is desired by nearly all heads of German transplant centers to prospectively assess the potentials, risks, and safety of BS in KT waitlisted patients.

Minimally invasive liver surgery: the Charité experience.

Minimally invasive liver surgery (MILS) was established as last abdominal surgical specialty through the 1990s. With a shift from mainly benign to malignant indications, MILS was shown to be equal to open liver surgery in terms of oncological outcomes, with benefits in intraoperative blood loss, postoperative pain, postoperative complication rates, hospital length of stay and quality of life. With colorectal liver metastases and hepatocellular carcinoma as the most common indications, most liver resection can be performed minimally invasive nowadays, including patients with liver cirrhosis. Initially perceived limitations of laparoscopic liver surgery were weakened by gaining experience, technical progress and pioneering of new resection approaches. Lately robotic liver surgery was adopted to the field of MILS to further push the limits. To simplify first resections, technical variations of the minimally invasive approach can be utilized, and difficulty scores help to select resections suitable to the level of experience. We hereby give an overview of the establishing of a minimally invasive liver surgery program at our center.

Dual versus single vessel normothermic ex vivo perfusion of rat liver grafts using metamizole for vasodilatation.

BACKGROUND: Normothermic ex vivo liver perfusion (NEVLP) is a promising strategy to increase the donor pool in liver transplantation. Small animal models are essential to further investigate questions regarding organ preservation and reconditioning by NEVLP. A dual vessel small animal NEVLP (dNEVLP) model was developed using metamizole as a vasodilator and compared to conventional portovenous single vessel NEVLP (sNEVLP). METHODS: Livers of male Wistar rats were perfused with erythrocyte-supplemented culture medium for six hours by either dNEVLP via hepatic artery and portal vein or portovenous sNEVLP. dNEVLP was performed either with or without metamizole treatment. Perfusion pressure and flow rates were constantly monitored. Transaminase levels were determined in the perfusate at the start and after three and six hours of perfusion. Bile secretion was monitored and bile LDH and GGT levels were measured hourly. Histopathological analysis was performed using liver and bile duct tissue samples after perfusion. RESULTS: Hepatic artery pressure was significantly lower in dNEVLP with metamizole administration. Compared to sNEVLP, dNEVLP with metamizole treatment showed higher bile production, lower levels of transaminases during and after perfusion as well as significantly lower necrosis in liver and bile duct tissue. Biochemical markers of bile duct injury showed the same trend. CONCLUSION: Our miniaturized dNEVLP system enables normothermic dual vessel rat liver perfusion. The administration of metamizole effectively ameliorates arterial vasospasm allowing for six hours of dNEVLP, with superior outcome compared to sNEVLP.

Development of a Rat Liver Machine Perfusion System for Normothermic and Subnormothermic Conditions.

Ex vivo liver machine perfusion (MP) is a promising alternative for preservation of liver grafts from extended criteria donors. Small animal models can be used to evaluate different perfusion conditions. We here describe the development of a miniaturized ex vivo MP system for rat liver grafts, evaluating cell-free and erythrocyte-based perfusion solutions, subnormothermic and normothermic temperatures, and dialysis. A perfusion chamber was designed after a suitable liver position was identified. Normothermic ex vivo liver perfusion (NEVLP) required supplementation of erythrocytes to reduce cell damage. Perfusion with erythrocytes led to rising potassium levels after 12 h (NEVLP, 16.2 mM, interquartile range [IQR]: 5.7 and subnormothermic ex vivo liver perfusion [SNEVLP], 12.8 mM, IQR: 3.5), which were normalized by dialysis using a laboratory dialysis membrane (NEVLP, 6.2 mM, IQR: 0.5 and SNEVLP, 5.3 mM, IQR: 0.1; p = 0.004). Livers treated with NEVLP conditions showed higher bile production (18.52 mg/h/g, IQR: 8.2) compared to livers perfused under SNEVLP conditions (0.4 mg/h/g, IQR: 1.2, p = 0.01). Reducing the perfusion volume from 100 to 50 mL allowed for higher erythrocyte concentrations, leading to significantly lower transaminases (15.75 U/L/mL, IQR: 2.29 vs. 5.97 U/L/mL, IQR: 18.07, p = 0.002). In conclusion, a well-designed perfusion system, appropriate oxygen carriers, dialysis, and miniaturization of the perfusion volume are critical features for successful miniaturized ex vivo liver MP. Impact Statement Ex vivo liver machine perfusion (MP) is an emerging preservation alternative to static cold storage. Even though clinical studies have shown benefits for extended criteria donor grafts, standardized systems for perfusion of rat liver grafts are not available, which are inevitable for large-scaled studies on liver reconditioning by ex vivo MP. We here comprehensively describe the development of an ex vivo rat liver perfusion system that can be used as modular setting in various approaches of liver MP. We describe pitfalls and techniques that might be of interest when establishing such perfusion systems for basic and translational research.

Prevalence of Steatosis Hepatis in the Eurotransplant Region: Impact on Graft Acceptance Rates.

Due to the shortage of liver allografts and the rising prevalence of fatty liver disease in the general population, steatotic liver grafts are considered for transplantation. This condition is an important risk factor for the outcome after transplantation. We here analyze the characteristics of the donor pool offered to the Charité - Universitätsmedizin Berlin from 2010 to 2016 with respect to liver allograft nonacceptance and steatosis hepatis. Of the 2653 organs offered to our center, 19.9% (n=527) were accepted for transplantation, 58.8% (n=1561) were allocated to other centers, and 21.3% (n = 565) were eventually discarded from transplantation. In parallel to an increase of the incidence of steatosis hepatis in the donor pool from 20% in 2010 to 30% in 2016, the acceptance rates for steatotic organs increased in our center from 22.3% to 51.5% in 2016 (p < 0.001), with the majority (86.9%; p > 0.001) having less than 30% macrovesicular steatosis hepatis. However, by 2016, the number of canceled transplantations due to higher grades of steatosis hepatis had significantly increased from 14.7% (n = 15) to 63.6% (42; p < 0.001). The rising prevalence of steatosis hepatis in the donor pool has led to higher acceptance rates of steatotic allografts. Nonetheless, steatosis hepatis remains a predominant phenomenon in discarded organs necessitating future concepts such as organ reconditioning to increase graft utilization.

The Predictive Value of the Maximal Liver Function Capacity Test for the Isolation of Primary Human Hepatocytes.

The need for primary human hepatocytes is constantly growing for basic research, as well as for therapeutic applications. However, the isolation outcome strongly depends on the quality of liver tissue, and we are still lacking a preoperative test that allows the prediction of the hepatocyte isolation outcome. In this study, we evaluated the "maximal liver function capacity test" (LiMAx) as predictive test for the quantitative and qualitative outcome of hepatocyte isolation. This test is already used in clinical routine to measure preoperative and to predict postoperative liver function. The patient's preoperative mean LiMAx was obtained from the patient records, and preoperative computed tomography and magnetic resonance images were used to calculate the whole liver volume to adjust the mean LiMAx. The outcome parameters of the hepatocyte isolation procedures were analyzed in correlation with the adjusted mean LiMAx. Primary human hepatocytes were isolated from partial hepatectomies (n = 64). From these 64 hepatectomies we included 48 to our study and correlated their isolation outcome parameters with volume corrected LiMAx values. From a total of 11 hepatocyte isolation procedures, metabolic parameters (albumin, urea, and aspartate aminotransferase or AST) were assessed during the hepatocyte cultivation period of 5 days. The volume adjusted mean LiMAx showed a significant positive correlation with the total cell yield (p = 0.049; r = 0.242; n = 48). The correlations of volume adjusted LiMAx values with viable cell yield and cell viability did not reach statistical significance. To create a more homogenous study group regarding tumor entities, subgroup analyses were performed. A subgroup analysis of isolations from patients with colorectal metastasis revealed a significant correlation between volume adjusted mean LiMAx and total cell yield (p = 0.012; r = 0.488; n = 21) and viable cell yield (p = 0.034; r = 0.405; n = 21), whereas a subgroup analysis of isolations of patients with carcinoma of the biliary tree showed significant correlations of volume adjusted mean LiMAx with cell viability (r = 0.387; p = 0.046; n = 20) and lacked significant correlations with total cell yield (r = -0.060; p = 0.401; n = 20) and viable cell yield (r = 0.012; p = 0.480; n = 20). The volume-adjusted mean LiMAx did not show a significant correlation with any of the metabolic parameters. In conclusion, the LiMAx test might be a useful tool to predict the quantitative outcome of hepatocyte isolation, as long as underlying liver disease is taken into consideration.

Hepatocyte Isolation After Laparoscopic Liver Resection.

Liver tissue obtained from partial hepatectomy is a common source for isolation of primary human hepatocytes. Until now, liver resections were most commonly performed by conventional open surgery. Although the laparoscopic approach is currently emerging in liver surgery, data on the outcome of hepatocyte isolation from laparoscopically resected liver tissue are not available. A total of 22 hepatocyte isolations were performed using the two-step collagenase perfusion technique from October 2015 to March 2016. Liver tissue was obtained from n = 15 open liver resections (OLRs) and n = 7 laparoscopic liver resections (LLRs). Isolation parameters (cell yield, viability, and Percoll survival) were assessed and hepatocyte function (plating efficiency, urea, albumin, and aspartate aminotransferase) was measured over a culture period of 6 days (OLR: n = 13; LLR: n = 3). Total cell yield (OLR: 36.81 ± 6.77 × 10(6) cells/g vs. LLR 16.84 ± 10.66 × 10(6) cells/g, p = 0.0318) as well as viable yield (OLR 31.70 ± 6.05 × 10(6) cells/g vs. LLR 14.70 ± 9.89 × 10(6) cells/g, p = 0.0260) was significantly higher in the OLR group. Subgroup analysis revealed that the worse outcome of isolation of laparoscopically resected liver tissue was associated with right-lateral LLRs, whereas hepatocyte isolation from left-lateral LLRs was as effective as from open surgery. Hepatocyte function did not differ between hepatocytes from openly resected versus left-lateral laparoscopically resected liver tissue. We here present the first data on hepatocyte isolation from laparoscopic liver surgery. Although the overall outcome is worse compared with open surgery, our data suggest that liver tissue from laparoscopic resection of the left lobe is an excellent source for primary human hepatocytes.