Abstract
We here report a newly developed spheroid microarray technique in which rat hepatocytes form almost the same diameter of spherical multicellular aggregates (spheroids) and are immobilized at high density on a spheroid microarray (SM) chip. The SM chip consisted of 2,800 cavities of 300 µm diameter in triangle arrangement within a 16 mm square on a polystyrene plate. Hepatocytes formed one spheroid in each cavity, in which the spheroid diameter can be controlled by inoculated cell densities. The spheroids stably maintained ammonia removal and albumin secretion, which are markers of detoxification and protein synthesis of liver, for at least 14 days of culture on the SM chip, compared with hepatocytes that had a spreading cellular shape and lost their functions in conventional monolayer culture on a collagen-coated surface. The activation of enzyme P-450 depending on the concentrations of 3-methylcholanthrene, a carcinogen, was detected in the spheroids on the chip by fluorescence of resorufin converted from ethoxyresorufin. Thus cell responses could be evaluated on the chip by using the fluorescent technique. These results suggest that a spheroid microarray on the chip is a promising technique for high-throughput cell-based analysis.
