Liver failure: basis of benefit of therapy with the molecular adsorbents recirculating system

Extracorporeal liver support and liver transplantation for acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) is defined by acute decompensation, organ failure and a high risk of short-term mortality. This condition is characterized by an overwhelming systemic inflammatory response. Despite treating the precipitating event, intensive monitoring and organ support, clinical deterioration can occur with very poor outcomes. During the last decades, several extracorporeal liver support systems have been developed to try to reduce ongoing liver injury and provide an improved environment for the liver to regenerate or as a bridging therapy until liver transplantation. Several clinical trials have been performed to evaluate the clinical efficacy of extracorporeal liver support systems, but no clear impact on survival has been proven. DIALIVE is a novel extracorporeal liver support device that has been built to specifically address the pathophysiological derangements responsible for the development of ACLF by replacing dysfunctional albumin and removing pathogen and damage-associated molecular patterns (PAMPs and DAMPs). In phase II clinical trial, DIALIVE appears to be safe, and it seems to be associated with a faster time to the resolution of ACLF compared with standard medical treatment. Even in patients with severe ACLF, liver transplantation saves lives and there is clear evidence of transplant benefit. Careful selection of patients is required to attain good results from liver transplantation, but many questions remain unanswered. In this review, we describe the current perspectives on the use of extracorporeal liver support and liver transplantation for ACLF patients.

The Effect of Molecular Adsorbent Recirculating System in Patients With Liver Failure: A Case Series of 44 Patients

BACKGROUND

Liver failure is associated with a high mortality rate, with many patients requiring transplant for definitive treatment. The Molecular Adsorbent Recirculating System (MARS) is a nonbiologic system that provides extracorporeal support. Literature on MARS therapy is mixed: outcomes support MARS therapy for patients with isolated acute liver failure, but data on patients with chronic disease is varied. Several case studies report success using MARS as a bridging treatment for patients awaiting transplant. The purpose of this case series is to present the outcomes of 44 patients who underwent MARS therapy for liver failure, 19 of whom used MARS therapy as a bridging therapy to transplant.

METHODS

This study retrospectively identified 44 patients who underwent MARS therapy for liver failure at Mayo Clinic, Jacksonville, between January 2014 and April 2021. Variables of interest included changes in laboratory markers of hepatic functioning, number and length of MARS therapy sessions, transplantation status, and mortality.

RESULTS

Following MARS therapy, there were improvements in mean serum bilirubin, ammonia, urea, creatinine, International Normalized Ratio, alanine aminotransferase, and aspartate aminotransferase levels. Twenty-seven patients (61.36%) survived the hospital stay; 17 (38.63%) died in the hospital. The majority of surviving patients (n = 19; 73.07%) received liver transplant. Six did not require transplant (22.22%). All but 1 patient who received MARS as a bridging treatment to transplant survived the follow-up period (n = 18; 94.74%).

CONCLUSIONS

Outcomes of these 44 cases suggest that MARS improves liver failure-associated laboratory parameters and may be effective therapy as a bridge to liver transplant.

Plasma Filtration Adsorption Dialysis (PFAD): A New Technology for Blood Purification

Severe sepsis is one of the most significant challenges in critical care. Despite all the developments achieved in infectious diseases and critical care, along with numerous attempts to develop treatments, the mortality rate of severe sepsis and septic shock remains unacceptably high. The pathophysiology of severe sepsis and septic shock is only partially understood. Circulating pro-inflammatory and anti-inflammatory mediators appear to participate in the complex cascade of events which leads to deranged microcirculatory function, as we know from the peak concentration hypothesis.

Therapeutic trials targeting single pro-inflammatory and anti-inflammatory mediators failed to demonstrate any benefit, suggesting that the unselective removal of different mediators may be a more appropriate approach.

In severe sepsis several blood purification techniques, such as continuous hemofiltration (CVVH), high volume hemofiltration (HVHF), pulse high volume hemofiltration (HVHF), plasma filtration, plasma adsorption, coupled plasma filtration adsorption (CPFA), have been proposed but such techniques appear to have both theorical as well as practical limitations.

Plasma Filtration Adsorption Dialysis (PFAD) is a new extracorporeal treatment which combines different principles of blood purification in a single device. The core of this technique is a new dialyzer composed by three suitable compartments that provide specific functions. The association of multiple principles permits specific removal of molecules implicated in the pathophysiology of patient's disease and re-establishment of hydro-electrolyte, acid-base equilibrium, if renal dysfunction-failure is present. The final target of PFAD is to obtain complete purification by combining principles of physics and chemistry to remove hydrophilic and hydrophobic molecules with a very wide range of weights.

A non-adhesive hybrid scaffold from gelatin and gum Arabic as packed bed matrix for hepatocyte perfusion culture

Development of liver support systems has become one of the most investigated areas for the last 50 years because of the shortage of donor organs for orthotopic liver transplantations. Bioartificial liver (BAL) device is one of the alternatives for liver failure which provides a curing method and support patients to recover from certain liver failure diseases. The biological compartment of BAL is called the bioreactor where functionally active hepatocytes are maintained to support the liver specific functions. We have developed a packed bed bioreactor with a cytocompatible, polysaccharide-protein hybrid scaffold. The scaffold prepared from gelatin and gum Arabic acts as a packed bed matrix for hepatocyte culture. Quantitative evaluation of the hepatocytes cultured using packed bed bioreactor demonstrated that cells maintained liver specific functions like albumin and urea synthesis for seven days. These results indicated that the system can be scaled up to form the biological component of a bioartificial liver.

Using albumin to improve the therapeutic properties of diabetes treatments

Achieving tight glycaemic control remains an unmet need for many patients with type 2 diabetes, despite improved treatments. To meet glycaemic targets, attempts have been made to improve existing drugs and to develop new classes of drugs. Recent advances include insulin analogues that more closely mimic physiologic insulin levels, and incretin-based therapies, which capitalize on the glucoregulatory properties of native glucagon-like peptide-1 (GLP-1). Although promising, these agents are associated with limitations, including hypoglycaemia with insulin, gastrointestinal adverse events with GLP-1 receptor agonists and frequent dosing with both classes. Albumin is an abundant natural drug carrier that has been used to improve the half-life, tolerability and efficacy of a number of bioactive agents. Here, we review the physiologic roles of albumin and how albumin technologies are being used to prolong duration of action of therapies for diabetes, including insulin and incretin-based therapies.

Management of hepatic encephalopathy

Hepatic encephalopathy (HE), the neuropsychiatric presentation of liver disease, is associated with high morbidity and mortality. Reduction of plasma ammonia remains the central therapeutic strategy, but there is a need for newer novel therapies. We discuss current evidence supporting the use of interventions for both the general management of chronic HE and that necessary for more acute and advanced disease.

Acute-on-chronic liver failure: current concepts on definition, pathogenesis, clinical manifestations and potential therapeutic interventions

In recent years, acute-on-chronic liver failure has been recognized as a specific clinical form of liver failure associated with cirrhosis. The syndrome refers to an acute deterioration of liver function and subsequently of other end organs over a period of weeks following a precipitating event in a patient with previously well- or reasonably well-compensated cirrhosis. These precipitating events include either an indirect (e.g., variceal hemorrhage, sepsis) or a direct (e.g., drug-induced) hepatotoxic factor. The short-term mortality for this condition is more than 50%. At present, considerable efforts are ongoing to better characterize the syndrome, to gain further insight into its pathophysiology and to optimize therapy. This article aims to highlight the current concepts of these various aspects.

Increase of octanoate concentrations during extracorporeal albumin dialysis treatments

Extracorporeal liver support procedures based on albumin dialysis require the use of pharmaceutical-grade human serum albumin (HSA). Those preparations contain octanoate, which is added as stabilizer during the production process. For octanoate, a direct involvement in the pathogenesis of liver failure complications as well as an indirect influence by competitive displacement effects at the albumin molecule have been described. During five Single Pass Albumin Dialysis (SPAD) and three Molecular Adsorbent Recirculating System (MARS) treatments the changes of octanoate concentrations in blood and dialysate were investigated. An octanoate increase in patient blood was observed during passage of the filter for both SPAD (585 micromol/L [338-1022 micromol/L]) (median [range]) and MARS (182 micromol/L [71-437 micromol/L]) during the first three hours of treatment. The molar ratio of octanoate/albumin at the blood outflow was significantly higher during SPAD treatments (1.73 [0.86-2.64] vs. 0.54 [0.31-1.1]; P = 0.001) during MARS. Changes of octanoate blood levels during SPAD were significantly higher than during MARS (P < 0.001). The shift of octanoate from the dialysate to the patient was persistent during SPAD (median 67.6 micromol/min), whereas during MARS a decrease over time was observed (from 25.5 to 7.5 micromol/min). During albumin dialysis procedures a transfer of octanoate into patient blood occurs. The time-course and extent are different between both albumin dialysis procedures. Given the positive clinical effects reported mainly for MARS, the clinical impact of albumin dialysis-associated transfer of octanoate during extracorporeal liver support needs to be evaluated further.

Effective bilirubin reduction by single-pass albumin dialysis in liver failure

Albumin dialysis is widely accepted as a liver-support technique for patients with liver failure. The Molecular Adsorbent Recirculating System, the widely accepted albumin dialysis technique, has limited use in developing countries because of its technical difficulties and high cost. Therefore, we assessed the efficacy of the more practical modality, the single-pass albumin dialysis (SPAD), in terms of bilirubin reduction, as a marker of albumin-bound toxins removal, as well as the patient outcomes. Twelve acute or acute-on-chronic patients with liver failure who had hyperbilirubinemia (total bilirubin > 20 mg/dL) were treated with SPAD by using 2% human serum albumin dialysate for 6 h. SPAD treatment significantly improved the levels of total bilirubin, conjugated bilirubin, urea, and creatinine (P < 0.001 for all parameters). The reduction ratios of these four parameters were 22.9 +/- 3.8%, 20.9 +/- 5%, 19.0 +/- 4.1%, and 27.7 +/- 3.2%, respectively. No significant difference was observed between serum ammonia before and after treatment. No significant changes in mean arterial pressures were noted during the maneuver, representing cardiovascular tolerability. No treatment-related complications were found. The 15-day in-hospital survival was 16.7%. However, a subgroup of the patients who had moderate severity showed 100% 15-day-survival rate (2 of 2 patients). In conclusion, SPAD is salutarily effective in reducing bilirubin in patients with liver failure. The procedure is safe and simply set up.

Acute systemic, splanchnic and renal haemodynamic changes induced by molecular adsorbent recirculating system (MARS) treatment in patients with end-stage cirrhosis

AIM

To evaluate the acute effect of treatment with the molecular adsorbent recirculating system (MARS) on splanchnic, renal and systemic haemodynamics in patients with end-stage cirrhosis.

METHODS

Twelve patients with end-stage cirrhosis, undergoing MARS treatment, were enrolled. The following haemodynamic parameters were measured by means of Doppler ultrasonography and thoracic electrical bioimpedance, before and after each session: portal velocity, renal and splenic resistance indices, cardiac output, cardiac stroke volume, heart rate, mean arterial pressure, systemic vascular resistance.

RESULTS

Median portal velocity increased significantly after treatment (23.7 vs. 20.3 cm/s, P < 0.05) while renal resistance index (0.72 vs. 0.75, P < 0.05) and splenic resistance index (0.60 vs. 0.65, P < 0.05) decreased significantly. Mean arterial pressure (83 vs. 81 mmHg, P < 0.05) and vascular resistance (899 vs. 749 dyne. s/cm5, P < 0.05) increased significantly, while cardiac output and stroke volume showed no significant changes.

CONCLUSIONS

Data emerging from this investigation suggest that MARS treatment improves significantly various haemodynamic alterations in cirrhotic patients in the short term. The observed decrease in renal vascular resistance and improvement in splenic resistance index, a parameter related to portal resistance, which leads us to hypothesize that these haemodynamic effects are probably mediated by clearance of vasoactive substances during MARS treatment.

Systemic and regional hemodynamics in pigs with acute liver failure and the effect of albumin dialysis

OBJECTIVE

Acute liver failure (ALF) is haemodynamically characterized by a hyperdynamic circulation. The aims of this study were to investigate the systemic and regional haemodynamics in ALF, to measure changes in nitric oxide metabolites (NOx) and to evaluate whether these haemodynamic disturbances could be attenuated with albumin dialysis.

MATERIAL AND METHODS

Norwegian Landrace pigs (23-30 kg) were randomly allocated to groups as controls (sham-operation, n = 8), ALF (hepatic devascularization, n = 8) and ALF + albumin dialysis (n = 8). Albumin dialysis was started 2 h after ALF induction and continued for 4 h. Systemic and regional haemodynamics were monitored. Creatinine clearance, nitrite/nitrate and catecholamines were measured. A repeated measures ANOVA was used to analyse the data.

RESULTS

In the ALF group, the cardiac index increased (PGT < 0.0001), while mean arterial pressure (PG = 0.02) and systemic vascular resistance decreased (PGT < 0.0001). Renal resistance (PG = 0.04) and hind-leg resistance (PGT = 0.003) decreased in ALF. There was no difference in jejunal blood flow between the groups. ALF pigs developed renal dysfunction with increased serum creatinine (PGT = 0.002) and decreased creatinine clearance (P = 0.02). Catecholamines were significantly higher in ALF, but NOx levels were not different. Albumin dialysis did not attenuate these haemodynamic or renal disturbances.

CONCLUSIONS

The haemodynamic disturbances during the early phase of ALF are characterized by progressive systemic vasodilatation with no associated changes in metabolites of NO. Renal vascular resistance decreased and renal dysfunction developed independently of changes in renal blood flow. After 4 h of albumin dialysis there was no attenuation of the haemodynamic or renal disturbances.

Prometheus versus molecular adsorbents recirculating system: comparison of efficiency in two different liver detoxification devices

Albumin dialysis by the molecular adsorbents recirculating system (MARS) and by fractionated plasma separation, adsorption, and dialysis (Prometheus[PROM]) represent novel nonbiological liver support systems specifically designed to remove albumin-bound substances. Preliminary evidence suggests a favorable impact of MARS on the course and outcome of liver failure. This study aimed at comparing the detoxification capacity of both devices. For this purpose, we performed a retrospective analysis on data prospectively collected in patients with acute-on-chronic liver failure treated with either the MARS (n = 9) or the PROM (n = 9) device on 2-5 consecutive days. Each treatment was performed for at least 5 h at identical blood and dialysate flows. Blood clearances were calculated during the first treatment session for urea nitrogen, creatinine, total bilirubin, and bile acids from paired arterial and venous line samples after 1, 4, and 6 h of treatment. Reduction ratios for all single-treatment sessions, and the overall treatment phase, were calculated from pretreatment and post-treatment values. For all markers but bile acids, the single-treatment as well as the overall treatment phase reduction ratios obtained with PROM were significantly higher compared with those obtained with MARS. PROM led at all time points to higher clearances for all evaluated solutes. Blood clearances of protein-bound substances declined over time with MARS, but not with PROM. In conclusion, a significant decline in the serum level of water-soluble and protein-bound toxins was achieved with both devices. PROM produces higher blood clearances for most toxins, which results in higher delivered treatment doses compared with a matching treatment with MARS.

Molecular adsorbent recirculating system (MARS) application in liver failure: clinical and hemodepurative results in 22 patients

PURPOSE

Acute liver failure (ALF) and acute on chronic liver failure (ACLF) still show a poor prognosis. MARS was used in 22 patients with ALF or ACLF to prolong patient survival for liver function recovery or as a bridge to transplantation.

DESIGN

Evaluation of depurative efficiency, biocompatibility, hemodynamics, encephalopathy (HE) and clinical outcome.

PROCEDURES

During 71 five-hour sessions we evaluated (0', 60', 120', 180', 240', 300'): bilirubin, ammonia, cholic acid (CCA), chenodeoxycholic acid (CCDCA), leukocytes, platelets, hemoglobin and mean arterial pressure (MAP). Serum creatinine, electrolytes, cardiac output, cardiac index (bioimpedence) and HE (West Haven Criteria score) were evaluated at 0' and 300'. STATISTICAL METHODS AND OUTCOME MEASURES: Student's t-test for pre- vs. end-session values was used. For bilirubin and ammonia the correlation test was made between pre- and end-session values and between pre-session values and removal rates (RRS).

MAIN FINDINGS

Survival was 90.9% at 7 days, 40.9% at 30 days. Pre- vs. end-session: bilirubin from 37.2 +/- 12.5 mg/dL to 24.9 +/- 8.9 mg/dL (p < 0.01), ammonia from 88.0 +/- 60.4 micromol/L to 43.6 +/- 32.9 micromol/L (p < 0.01), CCA from 42.8 +/- 21.0 micromol/L 18.2 +/- 9.8 micromol/L (p < 0.01), CCDCA from 26.3 +/- 6.3 micromol/L to 15.7+/-7.6 micromol/L (p<0.01). The correlation test between pre-session values of bilirubin and ammonia vs. RR S was respectively 0.32 (p = 0.01) and 0.30 (p = 0.04). Leukocytes, platelets and hemoglobin remained stable. MAP increased from 82.0 +/- 12.0 mmHg to 87.0 +/- 13.0 mmHg (p < 0.05), West Haven Criteria score decreased from 2.7 +/- 0.7 to 0.7 +/- 0.7 (p < 0.001).

CONCLUSION

MARS treatment led in all patients to an improvement of clinical, hemodynamic and neurological conditions, with significant reduction in the hepatic toxins blood level. Treatment biocompatibility and tolerance were satisfactory.

Outcome from molecular adsorbent recycling system (MARS) liver dialysis following drug-induced liver failure

RATIONALE

Fulminant liver failure from drug ingestion is associated with a high mortality, and the introduction of liver transplantation has improved the mortality significantly if done in a timely fashion. Recently, molecular adsorbent recycling system (MARS) liver dialysis has been introduced as a support for liver failure with varying results. We review our experience with drug-induced liver failure and the impact of MARS liver dialysis on the outcome, in a setting where cadaveric liver transplantation is rarely available.

RESULTS

A total of 13 patients were treated, and 40 sessions of MARS liver dialysis were conducted in the intensive care unit. The majority of cases were because of herbal medicine toxicity. Total bilirubin, conjugated bilirubin, and delta bilirubin were significantly reduced, with no change in unconjugated bilirubin. All patients satisfied the criteria for urgent liver transplantation with an average Model End Stage Liver Disease (MELD) score of 35. Only one patient received a liver transplantation from a live donor (right lobe). Overall mortality was 85%. Median time-to-death from the start of MARS was 8 days.

CONCLUSIONS

MARS liver dialysis in a setting without timely liver transplantation is associated with a poor outcome. It does, however, provide a window of time for consideration of living donors in the setting of limited cadaveric donors.

Preconditioning by extracorporeal liver support (MARS) of patients with cirrhosis and severe liver failure evaluated for living donor liver transplantation -- a pilot study

PURPOSE

The aim of this prospective study was to evaluate the effectiveness of preconditioning molecular adsorbent recirculating system (MARS) treatment on patients with acute-on-chronic liver failure (AoCLF), who were awaiting living donor liver transplantation (LDLT).

PATIENTS AND METHODS

Between January and December 2001, 10 consecutive AoCLF patients (with progressive hyperbilirubinemia (>20 mg/dl) and hepatic encephalopathy grade > or =2) were studied. MARS was used in eight of these patients who were evaluated for LDLT during 2001. Three AoCLF patients who received LDLT before clinical use of MARS were used as historical controls.

RESULTS

Because of a shortage of donors, only five out of 10 patients considered for LDLT could receive transplants. Three patients were treated with MARS for 8 h the day before receiving LDLT, and all three survived. The remaining two patients who received transplants, and who were not pretreated with MARS, died from sepsis and multi-organ failure within 2 weeks. Four of the patients who did not receive transplants because of donor shortage died despite 1 or 3 MARS treatments, however bilirubin levels and grade of encephalopathy were significantly reduced in these patients.

CONCLUSIONS

Results of this small pilot study suggest that MARS, by reducing the severity of jaundice and encephalopathy, might be effective as a bridging option in AoCLF patients awaiting LDLT.

Development of a scaled up liver device incorporating cryo-preserved pig liver micro-organs

BACKGROUND/AIMS

Currently there is no effective therapy for most patients with fulminant or end stage liver disease.

METHODS

Pig liver micro-organs (LMOs), which preserve liver micro-architecture and ensure a maximal 150-200mum distance from a source of nutrients and gases have been prepared and a method to cryo-preserve them has been developed. A new scaled-up extra-corporeal liver device termed aLIVE-H in which LMOs are exposed to liver-like hemodynamic conditions has also been developed. The purpose of this work is to test the safety and function of cryo-preserved LMOs and how the hemodynamic properties of the scaled up aLIVE device affect their function.

RESULTS

Pig LMOs in aLIVE-H, transcribe albumin and Factor V at similar levels, irrespective of their position within the bioreactor, indicating that the hemodynamic features of the aLIVE-H device allow for homogeneous plasma distribution and proper function at different locations. Cryo-preserved LMOs transcribe albumin and Factor V at levels comparable to those transcribed by a normal pig liver. Connecting the aLIVE-H bioreactor to normal pigs did not affect key blood components and biochemical parameters.

CONCLUSIONS

An extra-corporeal liver device aLIVE-H which imitates the hemodynamic and functional properties of the normal liver and incorporates cryo-preserved LMOs has been developed and characterized. aLIVE-H was found to perform key synthetic liver functions.

Clinical experience with molecular adsorbent recirculating system (MARS) in patients with drug-induced liver failure

The molecular adsorbent recirculating system (MARS) is a novel extracorporeal technique for liver support. We report the clinical results in a group of fourteen patients with drug-induced liver failure. Fourteen patients, aged 22-83 years, with acute or subacute liver failure [mean Child-Turcotte-Pugh (CTP) score 11 (range 8-15)] due to the intake of various drugs (diet pill overdose-2; Chinese traditional medicine (CTM)-4; antibiotic, paracetamol, tuberculostatic, or vasodilator abuse-8) were treated with one to seven sessions of MARS. Beneficial effects such as the improvement of encephalopathy and prothrombin activity, as well as a reduction of bilirubin and ammonia were recorded during MARS treatments. Thirteen out of fourteen patients survived the hospitalization (93%), and two of the discharged patients died during the follow-up of 6-12 months. The overall survival rate was about 79%. MARS therapy can contribute to the improved treatment of drug-induced liver failure patients.

Equipment review: the molecular adsorbents recirculating system (MARS)

The molecular adsorbents recirculating system (MARS^®) is a form of artificial liver support that has the potential to remove substantial quantities of albumin-bound toxins that have been postulated to contribute to the pathogenesis of liver cell damage, haemodynamic instability and multi-organ failure in patients with acute liver failure (ALF) and acute-on-chronic liver failure (AoCLF). These toxins include fatty acids, bile acids, tryptophan, bilirubin, aromatic amino acids and nitric oxide. Data from controlled clinical trials are limited so far. One of two studies performed on small numbers of patients with AoCLF suggest a survival benefit, but no controlled data are available in the ALF setting. Our preliminary experience with MARS therapy, instituted late in the clinical course of five patients with severely impaired liver function, including three with AoCLF precipitated by sepsis and two with liver dysfunction due to sepsis in the absence of pre-existing chronic liver disease, indicates some clinical efficacy. However, the overall survival rate (1 of 5; 20%) remained poor. More data obtained from larger cohorts of patients enrolled in randomised controlled studies will be required in both the AoCLF and ALF settings to identify categories of liver failure patients who might benefit most from MARS treatment, to ascertain the most appropriate timing of intervention and to determine the overall impact on outcome, including cost-effectiveness.