Dexamethasone effects on rat hepatocyte spheroid formation and function

Hepatocytes cultured on moderately adhesive surfaces or in spinner flasks spontaneously self-assemble into spherical tissue-like aggregates (spheroids). These spheroids have smooth surfaces and tissue-like polarized cell morphology, including bile canalicular-like channels, and maintain high viability and liver-specific functions for extended culture periods. Dexamethasone (DEX), a synthetic glucocorticoid, is known to elicit various responses in gene expression, and is often added to hepatocyte culture medium. The morphology and liver-specific protein production of hepatocyte spheroids were assessed under DEX concentrations ranging from 50 nM to 10 mu M. DEX altered the kinetics of spheroid formation in a concentration-dependent fashion, with increasing concentrations inhibiting aggregation and promoting aggregate disassembly on culture dishes. DEX addition to spinner cultures resulted in smaller, more irregularly shaped spheroids and a higher incidence of aggregate clumping. Albumin and urea production were also higher in DEX cultures, but this effect was not as sensitive to concentration and occurred irrespective of the state of aggregation. RTPCR was utilized to assess the mRNA levels of extracellular matrix proteins, E-cadherin, and cytochrome P-450 enzymes. Results indicated a slight increase in fibronectin and collagen III mRNA early in the cultures, possibly contributing to the changes in morphology observed.