TY - JOUR
T1 - Expression of glutamine synthetase and carbamoylphosphate synthetase i in a bioartificial liver: markers for the development of zonation in vitro
AU - Poyck, Paul P. C.
AU - Hoekstra, Ruurdtje
AU - Vermeulen, Jacqueline L. M.
AU - van Wijk, Albert C. W. A.
AU - Chamuleau, Robert A. F. M.
AU - Hakvoort, Theodorus B. M.
AU - van Gulik, Thomas M.
AU - Lamers, Wouter H.
PY - 2008
Y1 - 2008
N2 - BACKGROUND: Mechanisms underlying hepatic zonation are not completely elucidated. In vitro test systems may provide new insights into current hypotheses. In this study, zonally expressed proteins, i.e. glutamine synthetase (GS; pericentral) and carbamoylphosphate synthetase (CPS; periportal), were tested for their expression patterns in the bioartificial liver of the Academic Medical Center (AMC-BAL). METHODS: Distribution and organization of porcine hepatocytes inside the AMC-BAL as well as GS and CPS expression were analyzed (immuno-)histochemically in time. Ten zonally expressed proteins were analyzed by RT-PCR on cell isolate and bioreactor samples. General metabolic and hepatocyte-specific functions were determined as well. RESULTS: Viable hepatocyte layers of approximately 150 microm were observed around gas capillaries, whereas inside the matrix, single cells or small aggregates were present. GS protein and mRNA levels were upregulated in time. GS protein was preferentially expressed in hepatocytes adjacent to oxygen-supplying capillaries and in previously CPS-positive hepatocytes. No shift towards a periportal or pericentral phenotype was observed from RT-PCR analysis. CONCLUSION: Induction of GS expression inside the AMC-BAL is not dependent of (low) oxygen tensions and hepatic nuclear factor 4alpha transcript levels. GS expression might be related to (1) low substrate levels and/or autocrine soluble factors, or (2) to cytoskeleton interactions, putatively associated with the beta-catenin signaling pathway
AB - BACKGROUND: Mechanisms underlying hepatic zonation are not completely elucidated. In vitro test systems may provide new insights into current hypotheses. In this study, zonally expressed proteins, i.e. glutamine synthetase (GS; pericentral) and carbamoylphosphate synthetase (CPS; periportal), were tested for their expression patterns in the bioartificial liver of the Academic Medical Center (AMC-BAL). METHODS: Distribution and organization of porcine hepatocytes inside the AMC-BAL as well as GS and CPS expression were analyzed (immuno-)histochemically in time. Ten zonally expressed proteins were analyzed by RT-PCR on cell isolate and bioreactor samples. General metabolic and hepatocyte-specific functions were determined as well. RESULTS: Viable hepatocyte layers of approximately 150 microm were observed around gas capillaries, whereas inside the matrix, single cells or small aggregates were present. GS protein and mRNA levels were upregulated in time. GS protein was preferentially expressed in hepatocytes adjacent to oxygen-supplying capillaries and in previously CPS-positive hepatocytes. No shift towards a periportal or pericentral phenotype was observed from RT-PCR analysis. CONCLUSION: Induction of GS expression inside the AMC-BAL is not dependent of (low) oxygen tensions and hepatic nuclear factor 4alpha transcript levels. GS expression might be related to (1) low substrate levels and/or autocrine soluble factors, or (2) to cytoskeleton interactions, putatively associated with the beta-catenin signaling pathway
U2 - https://doi.org/10.1159/000121609
DO - https://doi.org/10.1159/000121609
M3 - Article
C2 - 18354250
SN - 1422-6405
VL - 188
SP - 259
EP - 269
JO - Cells, tissues, organs
JF - Cells, tissues, organs
IS - 3
ER -