Principle of MARS (Molecular Adsorbent Recirculating System)
Core Mechanism
MARS operates through albumin dialysis, using human serum albumin as a selective molecular adsorbent to remove both protein-bound toxins (like bilirubin and bile acids) and water-soluble toxins (like ammonia and uremic substances) from the patient's blood. 1, 2
The system works through a three-step detoxification process:
Patient's blood is exposed to an albumin-enriched dialysate circuit where toxic substances bound to the patient's albumin are transferred to fresh human serum albumin circulating in a closed loop 3, 4
The albumin-containing dialysate then undergoes remote detoxification through bicarbonate dialysis and a two-step adsorption process using charcoal and ion exchange resins 3, 4
The regenerated albumin is recirculated back to continue removing toxins from the patient's blood, creating a continuous cycle of detoxification 1, 2
Technical Components
MARS combines three blood purification modalities simultaneously:
- Dialysis removes water-soluble toxins like ammonia and uremic substances 1, 3
- Filtration allows for volume management and removal of middle-molecular-weight substances 3
- Adsorption captures protein-bound toxins after they transfer from patient albumin to dialysate albumin 1, 4
Physiological Rationale
The system exploits albumin's natural scavenging properties:
Human serum albumin binds pathophysiologically relevant molecules including bilirubin, bile acids, free fatty acids, and aromatic amino acids that accumulate in liver failure 1, 2
These albumin-bound toxins contribute to complications such as hepatic encephalopathy, hepatorenal syndrome, hyperdynamic hypotonic circulation, impaired hepatic protein synthesis, and intractable pruritus 3, 4
By selectively regenerating the patient's albumin, MARS increases the albumin binding capacity and removes accumulated toxins 2
Clinical Effects
MARS achieves simultaneous liver and kidney detoxification:
- Removes ammonia (reducing cerebral edema and intracranial pressure in fulminant hepatic failure) 1
- Removes bilirubin and bile acids (eliminating refractory pruritus and improving cholestasis) 5, 4
- Improves hemodynamics (both central and local circulation) 2
- Stabilizes organ functions (liver, brain, and kidney) 2, 6
Primary Clinical Role
MARS functions as a bridge to liver transplantation or native liver recovery, not as definitive therapy, by temporarily stabilizing patients with acute liver failure or acute-on-chronic liver failure while awaiting organ availability or hepatic regeneration 7, 1, 6
The system has been used in over 4,000 patients in approximately 16,000 treatment sessions, making it the most frequently used extracorporeal liver support method 3