Protective effect of nafamostat mesilate on injury of porcine hepatocytes by human plasma

The Efficacy of Nafamostat Mesilate on the Performance of a Hybrid-artificial Liver using a Polyurethane foam/porcine Hepatocyte Spheroid Culture System in Human Plasma

Nafamostat mesilate (FUT) is a protease inhibitor of complement activation. The present study investigates whether FUT protects porcine hepatocytes from being injured by human plasma in a multi-capillary polyurethane foam packed-bed culture system (MC-PUF) such as the hybrid-artificial liver (PUF-HAL). Human plasmas with 1 mM of added ammonia were perfused using a small-scale PUF-HAL with porcine hepatocytes. FUT was continuously infused (10 μ g/ml, 50 μ g/ml,). The ammonia detoxification was maintained in human plasma for 24 hours and for 48 hours with FUT which suppressed the rapid increase of asparaginic acid aminotransferase (AST) and alanine aminotransferase (ALT). After 60 hours of perfusion, hepatocyte spheroids completely collapsed in the human plasma, but a small amount of hepatocyte spheroid was maintained by FUT. The effect of FUT was slightly greater at 50 μ g/ml than at 10 μ g/ml. Our results suggest that FUT has protective effects against porcine hepatocytes in human plasma, and our PUF-HAL using porcine hepatocytes can function in human plasma for about 48 hours with FUT.

Efficacy of Immunoadsorbent Devices for Maintaining Hepatic Function in Ex Vivo Direct Xenogenic Hemoperfusion

We have developed a new system for direct xenogenic hemoperfusion of a bioartificial liver support system adopting two types of immunoadsorbent devices. In this study, we compared the efficacy of each immunoadsorbent device in maintaining porcine hepatocyte function during 3 h perfusion treatment in a canine liver failure model. Suppression of humoral immunity by the immunoglobulin adsorber prevented immunogenic hepatocyte injury more effectively, and the system showed higher hepatic function when compared with suppression of cell-mediated immunity by the leukocyte adsorber. However, single use of immunoglobulin adsorber was less effective in reducing patients' systemic ammmonia levels and modulating the Fischer's ratio compared with the case of combined use of both immunoadsorbent devices. These results suggest that suppression of humoral immunity was of primary importance in preventing immunogenic hepatocyte injury, however the adsorption of leukocytes may have a synergic effect on maintaining hepatocyte function in direct xenogenic hemoperfusion.

Effects of serine protease inhibitor and prostaglandin I2 on liver transplantation from non-heart-beating rat donors

OBJECTIVES

We sought to preserve the microcirculation as a keystone in liver transplantation from a non-heart-beating donor (NHBD). The purpose of this study was to investigate the cytoprotective effects of a serine protease inhibitor, nafamostat mesilate, and prostaglandin I2 (PGI2) on livers transplanted from NHBDs.

METHODS

Male Wistar rats were used in five groups of nine rats each. In group 1, livers were retrieved from heart-beating donors (HB group); in group 2, livers were retrieved from NHBDs that had experienced agonal apnea (NHB group); in group 3, livers were retrieved in the same manner as in the NHBD group but were pretreated with nafamostat mesilate (NM), 0.2 mg/kg/h, (NM group); in group 4, livers were retrieved in the same manner as in the NHBD group but were pretreated with prostaglandin (PG) I2, 33 ng/kg/h for 30 minutes (PG group); and in group 5, livers were retrieved in the same manner as in the NHBD group but were pretreated with NM plus PG, (NM+PG group). Livers were perfused for 60 minutes with Krebs-Henseleit bicarbonate buffer after 6 hours of cold preservation, after which the perfusate and liver tissue were analyzed in one set of experiments. In another set of experiments, livers retrieved and after 1 hour of cold preservation were transplanted according to the Kamada method.

RESULTS

In the NM+PG group, the values of interleukin-1beta, tumor necrosis factor-alpha, and thromboxane B2 were significantly lower than those in the NHB group. At histologic analysis, sinusoidal endothelial cells were well preserved in the NM+PG group. The number of survivors at 7 days after liver transplantation in the 5 groups were 9, 0, 1, 1, and 3, respectively.

CONCLUSION

The serine protease inhibitor, NM, and PGI2 supported sinusoidal endothelial cells and preserved microcirculation.

Protective effects of a hibernation-inducer on hepatocyte injury induced by hypothermic preservation

BACKGROUND/PURPOSE

For hepatocyte-based cell therapy to be realistic, the method chosen for cryopreservation or hypothermic preservation is critical. The aim of the present study was to clarify whether D-Ala2-Leu5-enkephalin (DADLE), a hibernation inducer, has protective effects on hepatocytes with regard to hypothermic preservation injury.

METHODS

A suspension of rat hepatocytes was stored at 4 degrees C for 24 h with or without DADLE. Their viability was measured by the trypan blue dye exclusion method, and alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) levels in the preservation solution were measured. After 24 h of cold storage, viable hepatocytes were cultured at 37 degrees C for another 24 h. Then albumin production and lidocaine clearance were measured.

RESULTS

DADLE significantly improved the survival rate of hepatocytes. The levels of ALT and LDH in the preservation solution with DADLE were significantly lower than those in the preservation solution without DADLE. The treated viable hepatocytes maintained both albumin synthesis and lidocaine clearance.

CONCLUSIONS

DADLE appears to have protective effects on hepatocytes with regard to hypothermic preservation injury in vitro. This hibernation-inducer is useful in prolonged hypothermic preservation for hepatocyte-based therapy.

Impact of Inverse Plasma Filtration on Complement Activation in Porcine Blood

During extracorporeal circulation, activation of the complement system as a bioincompatibility reaction upon contact with artificial surfaces is well known. This may induce adverse effects for the patient as well as for the bioreactor when using a hybrid liver support system. At present, the achievable clearance rates in hybrid liver support systems are restricted by the limitations of blood flow through the capillaries of the plasma filter. In order to enhance clearance rates it is desirable to develop a high-flow plasma separation unit in which the activation of the complement system is as low as possible. Conventional plasma filters operating in normal and in inverse (blood flow around the capillaries and the capillary lumen serving as plasma compartment) modes were investigated applying an in vitro circuit (n = 4 in each group). For this purpose heparinized porcine blood was used. Complement activation was measured as generation of the soluble membrane attack complex, SC5b-9. With a normal flow mode the maximum achievable filtration rates varied from 25 to 40 mL/min, whereas the maximal filtration rates with an inverse flow mode varied from 40 to 100 mL/min. While these values were significantly higher than those with regularly operating plasma filters, there was no significant difference between normal and inverse mode in the production of SC5b-9. We conclude that the outer surface of the investigated conventional plasma filtration membranes is suitable for an inverse mode and does not lead to an excessive activation of the complement system upon dynamic blood contact. Thus, the inversion of the blood and the plasma compartments may be a possible way forward in the development of a high-flow plasma separation filter.

Xenotransplantation for liver therapy or: Can porcine hepatocytes generate physiological functions sufficient for a human patient in ALF?

Detailed knowledge about physiology, biochemistry and function is required before artificial liver devices using porcine hepatocytes may be used successfully. Improvement of cell culture conditions and tissue engineering may permit the generation of human hepatocytes as substitutes for grafts in a transplantation setting. The physiological functions of xenografts have to be compatible with those of the recipient. However, first observations indicate that most physiological interaction in widely divergent species combinations such as pig and man are considerably different. This may be crucial for the selection of a suitable organ, tissue or cell for a clinical set-up. These differences vary from organ to organ and cell to cell. Only very conservative molecules, like for example insulin or calcitonin function properly in both species, while others such as complement, albumin and erythropoietin do not fulfill their task properly or not at all.