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Receding cytochrome P450 activity in disassembling hepatocyte spheroids.
1Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455-0132, USA.
Tissue Engineering
|August 6, 1999
Summary
Hepatocyte spheroids maintain high liver function, but disassembly reduces cytochrome P450 CYP1A1/2 activity. Fetal bovine serum (FBS) also decreases this activity, even in intact spheroids.
Area of Science:
- Hepatocyte biology
- Cell culture technology
- Drug metabolism
Background:
- Primary rat hepatocytes form multicellular spheroids with enhanced viability and liver-specific functions compared to monolayer cultures.
- Spheroid structure is maintained on Primaria petri dishes or in stirred vessels.
- Spheroid integrity is compromised by transfer to collagen-coated surfaces or addition of fetal bovine serum (FBS).
Purpose of the Study:
- To investigate the impact of hepatocyte spheroid disassembly on cytochrome P450 (CYP) 1A1/2 activity.
- To determine the effect of FBS on CYP1A1/2 activity in both disassembling and intact spheroids.
Main Methods:
- Formation of primary rat hepatocyte spheroids.
- Induction of spheroid disassembly using collagen-coated surfaces or FBS.
- Measurement of ethoxyresorufin O-dealkylation to assess CYP1A1/2 activity using confocal microscopy.
- Transmission electron microscopy to evaluate smooth endoplasmic reticulum morphology.
Main Results:
- Hepatocytes reverting to monolayer during spheroid disassembly showed significantly lower CYP1A1/2 activity.
- FBS exposure decreased CYP1A1/2 activity in intact spheroids, correlating with diminished smooth endoplasmic reticulum.
- Disassembly, regardless of the cause (collagen or FBS), led to reduced CYP1A1/2 activity.
Conclusions:
- Hepatocyte spheroid disassembly results in a marked decrease in CYP1A1/2 activity.
- FBS contains a factor that suppresses CYP1A1/2 activity, independent of spheroid structural integrity.