Hepatocyte spheroid culture on a polydimethylsiloxane chip having microcavities
A two-dimensional microarray technique of spherical multicellular aggregates (spheroids) using a microfabricated polydimethylsiloxane (PDMS) chip and the expression of liver-specific functions of primary rat hepatocytes on the chip were investigated. The PDMS chip, which was fabricated
by a photolithography-based technique, consisted of approximately 2500 cylindrical microcavities (approximately 1100 cavities/cm2) in a triangular arrangement of 330 μm pitch on a PDMS plate (20 × 20 mm); each cavity measured 300 μm in diameter and 100
μm in depth. Most hepatocytes on the PDMS chip gradually gathered and subsequently formed a single spheroid in each cavity until 3 days of culture. A part of the spheroid was attached to the bottom or wall surface of the microcavity, and the spheroid configuration was maintained
for at least 14 days of culture. Albumin secretion, ammonia removal and ethoxyresorufin O-dealkylase (EROD) activity, which is a cytochrome P-450-dependent reaction, of hepatocytes on the PDMS chip were higher than those of a monolayer dish or a flat PDMS dish without microcavities,
and were maintained for at least 10 days of culture. The spheroid microarray technique appears to be promising in the development of cell chips and microbioreactors.