Optimization of mass transfer for toxin removal and immunoprotection of hepatocytes in a bioartificial liver

Geir I. Nedredal, Bruce P. Amiot, Peter Nyberg, Jennifer Luebke-Wheeler, Joseph B. Lillegard, Travis J. McKenzie, Scott L. Nyberg

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

This study was designed to determine optimal operating conditions of a bioartificial liver (BAL) based on mass transfer of representative hepatotoxins and mediators of immune damage. A microprocessor-controlled BAL was used to study mass transfer between patient and cell compartments separated by a hollow fiber membrane. Membrane permeability (70, 150, or 400 kDa molecular weight cut-off - MWCO), membrane convection (high: 50 mL/ min; medium: 25 mL/min; low: 10 mL/min; diffusion: 0 mL/min), and albumin concentration in the cell compartment (0.5 or 5 g%) were considered for a total of 24 test conditions. Initially, the patient compartment contained pig plasma supplemented with ammonia (0.017 kDa), unconjugated bilirubin (0.585 kDa), conjugated bilirubin (0.760 kDa), TNF-α (17 kDa), pig albumin (67 kDa), pig IgG (147 kDa), and pig IgM (900 kDa). Mass transfer of each substance was determined by its rate of appearance in the cell compartment. Membrane fouling was assessed by dextran polymer technique. Of the three tested variables (membrane pore size, convection, and albumin concentration), membrane permeability had the greatest impact on mass transfer (P < 0.001). Mass transfer of all toxins was greatest under high convection with a 400 kDa membrane. Transfer of IgG and IgM was insignificant under all conditions. Bilirubin transfer was increased under high albumin conditions (P = 0.055). Fouling of membranes ranged from 7% (400 kDa), 24% (150 kDa) to 62% (70 kDa) during a 2-h test interval. In conclusion, optimal toxin removal was achieved under high convection with a 400-kDa membrane, a condition which should provide adequate immunoprotection of hepatocytes in the BAL.

Original languageEnglish (US)
Pages (from-to)995-1003
Number of pages9
JournalBiotechnology and Bioengineering
Volume104
Issue number5
DOIs
StatePublished - Dec 1 2009

Keywords

  • Albumin
  • Ammonia
  • Bilirubin
  • Bioartificial liver
  • Mass transfer
  • TNF-α

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology

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  • Cite this

    Nedredal, G. I., Amiot, B. P., Nyberg, P., Luebke-Wheeler, J., Lillegard, J. B., McKenzie, T. J., & Nyberg, S. L. (2009). Optimization of mass transfer for toxin removal and immunoprotection of hepatocytes in a bioartificial liver. Biotechnology and Bioengineering, 104(5), 995-1003. https://doi.org/10.1002/bit.22450