The Effect of Artificial Liver Support System on Prognosis of HBV-Derived Hepatorenal Syndrome: A Retrospective Cohort Study

Hepatorenal syndrome (HRS) could occur when patients get decompensated liver cirrhosis. Meanwhile, hepatitis B virus (HBV) infection raises the risk of mortality of the end-stage liver diseases. As the artificial liver support system (ALSS) has been applied in liver failure, whether ALSS could benefit HBV-derived HRS remains uncertain. We retrospectively enlisted eligible HRS patients and compared the baseline characteristics and prognosis between HBV-derived HRS and non-HBV-derived HRS. Furthermore, propensity score matching (PSM) and Cox regression analyses were used to assess the beneficial effect of ALSS on HBV-derived HRS. In addition, a stratified analysis was carried out according to the degree of acute kidney injury (AKI) and the number of organ failures to observe in which populations ALSS can obtain the most excellent therapeutic effect. 669 patients were diagnosed as HRS, including 298 HBV negative and 371 HBV positive. Baseline characteristics were different between patients with HBV positive and HBV negative. HBV-derived HRS has higher 28-day mortality, though without a statistical difference. After PSM, 50 patients treated with ALSS and 150 patients treated with standard medical treatment (SMT) constituted a new cohort for the following analysis. We found that ALSS could significantly benefit HRS patients (P = 0.025). Moreover, the median survival time of patients treated with ALSS was longer than those treated with SMT. INR, neutrophil percentage, and treatment with ALSS were independent predictive factors for short-term mortality in HBV-derived HRS. The stratified analysis showed that ALSS could reduce the 28-day mortality of patients with HBV-derived HRS, especially those in AKI stage 3 and with organ failure ≥ 2. Additionally, serum bilirubin was significantly lower after ALSS, and the alteration of INR and creatinine were independent predictive elements for the mortality of HBV-derived HRS. HBV-derived HRS is more severe than non-HBV-derived HRS and has a worse prognosis. ALSS could reduce the short-term mortality of patients with HBV-derived HRS, especially those in AKI stage 3 and with organ failure ≥ 2. INR and the change of creatinine and INR could predict the prognosis of HBV-derived HRS. ChiCTR2200060123.

Assessment of the Combined Effect of Plasma Exchange and Plasma Perfusion on Patients with Severe Hepatitis Awaiting Orthotopic Liver Transplantation

To determine if plasma exchange combined with plasma perfusion is a reliable and effective temporary liver support treatment for patients on the waiting list for OLT, we tested this method in 5 patients with end-stage and 3 patients with middle-stage severe hepatitis. Four patients were successfully controlled until a donor liver was available 4 to 13 days later. In contrast, the remaining 4 patients were not adequately controlled by this treatment and experienced aggravated disease progression, dying 3 to 8 days after treatment while still awaiting OLT. Of those 4 patients who received OLT, 2 patients died from multi-organ failure caused by hepatic failure, while the other 2 survived. These findings show that plasma exchange combined with plasma perfusion provides temporary support for some patients on the waiting list for OLT. The ability of patients to successfully bridge to OLT is closely associated with the degree of liver failure, complications, multi-organ failure, and the length of the waiting period for a donor liver.

Molecular adsorbent recirculating system and bioartificial devices for liver failure

Acute liver failure and acute-on-chronic liver failure remain clinical problems with unacceptable morbidity and mortality. The development of extracorporeal liver support systems that replace the detoxification, synthetic, and regulatory functions of the native liver represent a long-sought potential solution, but all the devices currently available are still far from ideal. In general, artificial (cell-free) and bioartificial liver support devices have shown their ability to decrease some circulating toxins, to ameliorate hepatic encephalopathy and other intermediate variables, and to be relatively safe. Their effects on the survival of patients with ALF or ACLF, however, have not been conclusively shown.

Liver support systems: will they ever reach prime time?

Liver support systems aim to provide temporary support of liver function while maintaining extra-hepatic function in patients with liver failure. Important advances have been achieved in the design of artificial and bio-artificial devices, but the current systems are far from meeting the ideal. Artificial devices provide detoxification through different dialysis procedures, whereas bio-artificial devices add synthetic functions by incorporating a cellular component into the system. Overall, liver support systems have consistently shown beneficial effects on the pathophysiology of liver failure, especially in acute-on-chronic liver failure. However, these beneficial effects have not been translated into an improvement of survival. Our review discusses the current evidence, paying special attention to the clinical aspects of (bio)-artificial liver support devices.

Bioartificial liver: its pros and cons

Both the large variety of liver functions for maintaining body homeostasis and the proven effectivity of whole liver transplantation in the therapy of acute liver failure (ALF), are important reasons to presume that cell-free liver support systems will not be able to adequately support the failing liver. Accordingly, bioartificial liver (BAL) systems have shown their efficacy in experimental ALF models in small and large animals, and have shown to be suitable and safe in phase 1 studies in humans with ALF. However, the optimal BAL system is still under development. Important issues are the source of the cellular component and the configuration of the BAL system with regard to cell attachment, mass transfer characteristics and oxygenation at site. The deficiency of all BAL systems to excrete bile effectively is another important topic for improvement. The great challenge for the future is to develop a well-functioning and safe human hepatic cell line which can replace the widely used porcine (xenogeneic) hepatocytes. Theoretically, a combination of a cell-free liver support system and a BAL system might be optimal for the treatment of ALF patients in the near future.

Artificial liver support system in China: a review over the last 30 years

Severe viral hepatitis with high mortality is the most common cause of liver failure in China. Treatment of severe viral hepatitis by hemoperfusion was initially adopted in the late 1970s and early 1980s. Following 10 years of development in China, a plasma exchange (PE)-centered artificial liver support system (ALSS), principally dependent on PE technology was developed. Based on the condition and symptoms of each patient, PE was given alone, or combined with hemodialysis, hemofiltration, hemodiafiltration, hemoperfusion, or plasma perfusion. In the late 1990s, training courses for ALSS were developed, and ALSS began to be carried out across China. Guidelines for artificial liver therapy were formulated and published by the Artificial Liver and Liver Failure Group of the Chinese Society of Infection. In recent years, new methods have been attempted, including small pore-size plasma separators, a molecular adsorbent-based recirculating system (MARS), and a continuous albumin purification system (CAPS). According to a retrospective analysis published in 2004, ALSS therapy significantly (P < 0.001) improved the survival rate of patients with severe hepatitis compared with patients who received only medicines (43.4%, 157/362 vs. 15.4%, 55/358 in chronic patients and 78.9%, 30/38 vs. 11.9%, 5/42 in acute and subacute patients). Furthermore, ALSS has also proved valuable as a bridge to liver transplantation in the treatment of patients with end-stage severe hepatitis in China. More recently, ALSS has been used in the treatment of drug-induced liver failure, acute fatty liver during pregnancy, and other difficult-to-treat disorders in China.

Comparison of Plasma Exchange With Different Membrane Pore Sizes in the Treatment of Severe Viral Hepatitis

Plasma exchange has become an effective mode of blood purification in patients suffering from liver failure. To assist in patient recovery, we compared two plasma separators to identify a plasma separator with suitable pore sizes to remove toxic substances effectively, and retain important plasma components. The study focused on severe viral hepatitis patients. Of 206 rounds of plasma exchange, 137 were completed with the PS-06 plasma separator (membrane pore size=0.2 microm) and 69 with the EC-4A plasma separator (membrane pore size=0.03 microm). The efficacy of different plasma separators was compared using survival rate, changes in liver biochemistry, immunoglobulin, and complement parameters. The survival rate of patients treated with PS-06 was 43.3% (13 of 30 patients). For patients treated with EC-4A, two patients were bridged to liver transplantation successfully, and 57.9% (11 of 19 patients) survived. In both groups, the levels of total bilirubin, prothrombin time, and bile acid declined significantly. Compared to PS-06, EC-4A could retain significantly larger amounts of immunoglobulin and complements. Our study revealed that plasma exchange implementation with membrane pore size 0.03 microm could remove adequate bilirubin and bile acid, a class of toxins bound to plasma protein in severe viral hepatitis patients, and reduce the loss of essential plasma macromolecules.

Clinical application of bioartificial liver support systems

OBJECTIVE

To review the present status of bioartificial liver (BAL) devices and their obtained clinical results.

BACKGROUND

Acute liver failure (ALF) is a disease with a high mortality. Standard therapy at present is liver transplantation. Liver transplantation is hampered by the increasing shortage of organ donors, resulting in high incidence of patients with ALF dying on the transplantation waiting list. Among a variety of liver assist therapies, BAL therapy is marked as the most promising solution to bridge ALF patients to liver transplantation or to liver regeneration, because several BAL systems showed significant survival improvement in animal ALF studies. Until today, clinical application of 11 different BAL systems has been reported.

METHODS

A literature review was performed using MEDLINE and additional library searches. Only BAL systems that have been used in a clinical trial were included in this review.

RESULTS

Eleven BAL systems found clinical application. Three systems were studied in a controlled trial, showing no significant survival benefits, in part due to the insufficient number of patients included. The other systems were studied in a phase I trial or during treatment of a single patient and all showed to be safe. Most BAL therapies resulted in improvement of clinical and biochemical parameters.

CONCLUSIONS

Bioartificial liver therapy for bridging patients with ALF to liver transplantation or liver regeneration is promising. Its clinical value awaits further improvement of BAL devices, replacement of hepatocytes of animal origin by human hepatocytes, and assessment in controlled clinical trials.

Large animal models of fulminant hepatic failure in artificial and bioartificial liver support research

Among the large range of organs involved in the field of tissue engineering (skin, blood vessels, cartilage, etc.) the liver has been given broad attention in the last decade. Liver support systems encompassing artificial and bioartificial systems are applied to treat patients with fulminant hepatic failure (FHF) as a bridge to orthotopic liver transplantation or to liver regeneration. To test safety, technical applicability and therapeutic effect of liver support systems, reliable animal models are needed. Due to the complexity of FHF many diverse attempts have been made to develop an adequate animal model to study liver failure, liver regeneration and liver support systems. In this paper an overview is given of the different models and their advantages and disadvantages are discussed. Suggestions are made for the most suitable large animal model to test liver support systems.

Study of severe hepatitis treated with a hybrid artificial liver support system

Artificial liver support system (ALSS) has been used to treat hepatic failure and has significantly decreased the mortality. TECA hybrid artificial liver support system (TECA-HALSS), which combines the hollow fiber bioreactor with a plasma exchange circuit, was used to assess the efficacy, safety and feasibility in treating severe hepatitis patients. The hybrid artificial liver support system (HALSS) consists of a bioreactor containing more than 5 x10(9) porcine hepatocytes and plasma exchange device. Fifteen patients with severe hepatitis were treated with this hybrid system. All patients experienced a reduction in symptoms such as fatigue, abdominal distention or ascites. After each treatment serum total bilirubin decreased markedly while prothrombin activity increased. There were ten patients whose progress of hepatocyte necrosis was stopped after HALSS treatment, and finally they recovered completely. One patient received liver transplantation after HALSS therapy and survived. No serious adverse events were noted in the fifteen patients.