Technique of porcine liver procurement and orthotopic transplantation using an active porto-caval shunt

Toxoplasma gondii Infection Inhibits Histone Crotonylation to Regulate Immune Response of Porcine Alveolar Macrophages

Toxoplasma gondii (T. gondii) is an obligate intracellular parasite that can infect almost all warm-blooded animals, causing serious public health problems. Lysine crotonylation (Kcr) is a newly discovered posttranslational modification (PTM), which is first identified on histones and has been proved relevant to procreation regulation, transcription activation, and cell signaling pathway. However, the biological functions of histone crotonylation have not yet been reported in macrophages infected with T. gondii. As a result, a total of 1,286 Kcr sites distributed in 414 proteins were identified and quantified, demonstrating the existence of crotonylation in porcine alveolar macrophages. According to our results, identified histones were overall downregulated. HDAC2, a histone decrotonylase, was found to be significantly increased, which might be the executor of histone Kcr after parasite infection. In addition, T. gondii infection inhibited the crotonylation of H2B on K12, contributing on the suppression of epigenetic regulation and NF-κB activation. Nevertheless, the reduction of histone crotonylation induced by parasite infection could promote macrophage proliferation via activating PI3K/Akt signaling pathway. The present findings point to a comprehensive understanding of the biological functions of histone crotonylation in porcine alveolar macrophages, thereby providing a certain research basis for the mechanism research on the immune response of host cells against T. gondii infection.

Adenosine A2a Receptor Stimulation Attenuates Ischemia-Reperfusion Injury and Improves Survival in A Porcine Model of DCD Liver Transplantation

Orthotopic liver transplantation (OLT) using allografts from donation after circulatory death (DCD) is potentially associated with compromised clinical outcomes due to ischemia-reperfusion injury (IRI)-induced organ damage and graft-related complications. The aim of this study was to provide in vivo data on the effects of adenosine A2a receptor stimulation in a clinically relevant large animal model of DCD liver transplantation. Cardiac arrest was induced in German Landrace pigs (n = 10; 20-25 kg). After 30 min of warm ischemia, the donor liver was retrieved following a cold flush with 3 L of histidine-tryptophan-ketoglutarate-HTK solution. Animals of the treatment group (n = 5/group) received a standard dose of the selective adenosine receptor agonist CGS 21680 added to the cold flush. All grafts were stored for 4.5 h at 4 °C in HTK-solution before OLT. Hepatocellular injury, apoptosis, protein kinase A-PKA activity, graft microcirculation, liver function, and animal survival were assessed. Compared to untreated livers, adenosine A2a receptor stimulation resulted in improved tissue microcirculation (103% ± 5% vs. 38% ± 4% compared to baseline; p < 0.05), accelerated functional recovery of the graft (indocyanine green-plasma disappearance rate (ICG-PDR) of 75% ± 18% vs. 40% ± 30% after 3 h), increased PKA activity ratio (56% ± 3% vs. 32% ± 3%; p < 0.001 after 1 h), and consequently reduced tissue necrosis and apoptosis. The potent protective effects were clinically manifested in significantly improved survival in the treatment group after 72 h (100% vs. 40%; p = 0.04). The ex vivo administration of adenosine A2a receptor agonist during the back-table flush mitigates IRI-mediated tissue damage and improves functional graft recovery and survival in a large animal model of DCD liver transplantation.

Large Animal Models in Regenerative Medicine and Tissue Engineering: To Do or Not to Do

Rapid developments in Regenerative Medicine and Tissue Engineering has witnessed an increasing drive toward clinical translation of breakthrough technologies. However, the progression of promising preclinical data to achieve successful clinical market authorisation remains a bottleneck. One hurdle for progress to the clinic is the transition from small animal research to advanced preclinical studies in large animals to test safety and efficacy of products. Notwithstanding this, to draw meaningful and reliable conclusions from animal experiments it is critical that the species and disease model of choice is relevant to answer the research question as well as the clinical problem. Selecting the most appropriate animal model requires in-depth knowledge of specific species and breeds to ascertain the adequacy of the model and outcome measures that closely mirror the clinical situation. Traditional reductionist approaches in animal experiments, which often do not sufficiently reflect the studied disease, are still the norm and can result in a disconnect in outcomes observed between animal studies and clinical trials. To address these concerns a reconsideration in approach will be required. This should include a stepwise approach using in vitro and ex vivo experiments as well as in silico modeling to minimize the need for in vivo studies for screening and early development studies, followed by large animal models which more closely resemble human disease. Naturally occurring, or spontaneous diseases in large animals remain a largely untapped resource, and given the similarities in pathophysiology to humans they not only allow for studying new treatment strategies but also disease etiology and prevention. Naturally occurring disease models, particularly for longer lived large animal species, allow for studying disorders at an age when the disease is most prevalent. As these diseases are usually also a concern in the chosen veterinary species they would be beneficiaries of newly developed therapies. Improved awareness of the progress in animal models is mutually beneficial for animals, researchers, human and veterinary patients. In this overview we describe advantages and disadvantages of various animal models including domesticated and companion animals used in regenerative medicine and tissue engineering to provide an informed choice of disease-relevant animal models.

Impact of Different Clinical Perfusates During Normothermic Ex Situ Liver Perfusion on Pig Liver Transplant Outcomes in a DCD Model

Supplemental digital content is available in the text.

Background

Human albumin/dextran (HA-D), bovine-gelatin (BG), and packed red blood cells plus plasma have been used in European and North-American clinical trials of normothermic ex situ liver perfusion (NEsLP). We compared the effects of these perfusates in a porcine model during NEsLP and after transplantation.

Methods

Porcine livers were retrieved 30 minutes after circulatory death. After 5 hours of NEsLP, grafts were transplanted. Three groups (n = 6) were assessed (HA-D vs BG vs whole blood [WB]). One group of static cold storage (SCS) was evaluated for comparison with the perfusion groups. Hemodynamic variables, liver and endothelial injury, and function were assessed during NEsLP and posttransplantation.

Results

Hepatic artery flow was higher since the beginning of NEsLP in the HA-D group (HA-D, 238 ± 90 mL/min vs BG, 97 ± 33 mL/min vs WB, 148 ± 49 mL/min; P = 0.01). Hyaluronic acid was lower in the HA-D at the end of perfusion (HA-D, 16.28 ± 7.59 ng/μL vs BG, 76.05 ± 15.30 ng/μL vs WB, 114 ± 46 ng/μL; P < 0.001). After transplant, aspartate aminotransferase was decreased in the HA-D group when compared with the rest of the groups (HA-D, 444 ± 226 IU/L vs BG, 1033 ± 694 IU/L vs WB, 616 ± 444 IU/L vs SCS, 2235 ± 1878 IU/L). At 5 hours after transplant, lactate was lower in the HA-D group (HA-D, 3.88 ± 1.49 mmol/L vs BG, 7.79 ± 2.68 mmol/L vs WB, 8.16 ± 3.86 mmol/L vs SCS, 9.06 ± 3.54 mmol/L; P = 0.04). International Normalized Ratio was improved in HA-D group compared to the rest of the groups (HA-D, 1.23 ± 0.30 vs BG, 1.63 ± 0.20 vs WB, 1.50 ± 0.31 vs SCS, 1.97 ± 1.55; P = 0.03) after transplantation. In contrast, BG displayed lower aspartate aminotransferase levels during NEsLP (HA-D, 183 ± 53 IU/L vs BG, 142 ± 52 IU/L vs WB, 285 ± 74 IU/L; P = 0.01) and less cleaved-caspase-3 staining (HA-D, 2.05 ± 0.73% vs BG, 0.95 ± 1.14% vs WB, 1.74 ± 0.54% vs SCS, 7.95 ± 2.38%) compared with the other groups. On the other hand, the bile from the WB showed higher pH (HA-D, 7.54 ± 0.11 vs BG, 7.34 ± 0.37 vs WB, 7.59 ± 0.18) and lower glucose levels (HA-D, 0.38 ± 0.75 mmol/L vs BG, 1.42 ± 1.75 mmol/L vs WB, 0 ± 0 mmol/L) by the end of perfusion.

Conclusions

Overall HA-D displayed more physiologic conditions during NEsLP that were reflected in less graft injury and improved liver function and survival after transplantation. Optimization of the perfusates based on the beneficial effects found with these different solutions would potentially improve further the outcomes through the use of NEsLP in marginal grafts.

Technique for orthotopic liver transplantation in cynomolgus monkeys (Macaca fascicularis)

Purpose

Recent studies investigating new strategies to modulate the immune system have utilized animal models of liver transplantation (LT). However, the anhepatic phase (AHP) remains a crucial problem in LT. The aim of the present study is to introduce a technique for successful orthotopic LT in cynomolgus monkeys using an early-reperfusion strategy.

Methods

Orthotopicallo-LT was performed with seven donor/recipient pairs of cynomolgus monkeys.

Results

In 2 recipients, liver allografts were perfused after suprahepatic inferior vena cava (SHIVC), portal vein (PV), and infrahepatic inferior vena cava (IHIVC) anastomosis. To reduce the time of AHP in five recipients, liver allografts ware perfused after SHIVC and PV anastomosis while the IHIVC was not anastomosed. In the latter strategy, the AHP was reduced from 46 minutes to 31 minutes and a 24-hour survival rate of 80% was achieved.

Conclusion

Our results indicate that an early-reperfusion strategy can be successfully used to establish a LT model in cynomolgus monkeys with a consistently high rate of animal survival.