Liver Support Systems—A Review

Abstract

Liver failure is associated with a high morbidity and mortality rate and is the seventh leading cause of death worldwide. Orthotopic liver transplantation remains the definitive treatment; however, because of the limited number of available organs many patients expire while on the transplant list. Currently, there are no established means for providing liver support as a means of bridging patients to transplantation or allowing for recovery from liver injury. Analogous to the clinical situation of renal failure, there is great interest in developing liver support systems that replace the metabolic and waste removal functions of the liver. These support systems are of two general types: artificial and bioartificial livers. In this review, based on a presentation from the 57th American Society of Artificial Internal Organs Annual Meeting (Washington, D.C., June 2011), we review the current status of liver support systems.

Translational Regenerative Medicine—Hepatic Systems

“…The cells need to be isolated and immobilized on an appropriate platform that preserves cell morphology and metabolism, and oxygen and nutrients must be provided to the cells at physiological levels. A porous membrane must be used to separate cells from blood or plasma in order to avoid immune rejection, but it must also allow passage of toxins and proteins [112,113]. The bioreactors should also be capable of scale-up and flexibility in order to provide customization according to the patient's need.…”

“…Primary human hepatocytes would be the ideal source due to their biocompatibility; however, the scarcity of human livers for hepatocyte isolation, and their limited proliferative capacity in vitro, has made their use difficult in BAL devices [106,110]. Porcine hepatocytes and hepatoblastoma cell lines have been used instead, but there are concerns about xenoresponse and retroviral transmission with the use of porcine hepatocytes [111,112]. The bioreactor housing the cells is the most vital component of the BAL device, as the efficiency of these devices is directly related to cell efficacy in the performance of metabolic and synthetic functions.…”

“…To date, none of these has been approved by the US Food and Drug Administration (FDA) for clinical use. AMC-BAL is being redesigned currently to incorporate a human hepatocytecell line [112].…”

Penetrating Liver Injuries

“…The regenerated albumin dialysate is then re-circulated to repeat the process. The usual time of treatment is 6 to 8 h per day [30].…”

“…The MARS is currently the most extensively used liver support system, having been in use since 1996 [30][31][32]. The system functions on dialysis, filtration, and absorption.…”