Two-dimensional microarray of HepG2 spheroids using collagen/polyethylene glycol micropatterned chip.

A new cell chip technology in the form of a two-dimensional microarray of HepG2 spheroids was developed by using the microcontact printing technique. The chip consisted of several collagen spots in a triangular arrangement within a 100-mm2 area at the center of a glass plate (24 x 24 mm), which served as the cell adhesion area; the region excluding the collagen spots that was modified with polyethylene glycol (PEG) served as the non-adhesion area. HepG2 cells inoculated onto the chip gradually formed spheroids with smooth surfaces and high circularity on each collagen spot due to cell proliferation; the spheroid diameters remained constant after 10 days of culture. Such a two-dimensional microarray configuration of HepG2 spheroids could be maintained for at least 2 weeks. The spheroid diameter was directly proportional to the pitch between the collagen spots on the chip. This indicates that we can factitiously control the spheroid diameter. In addition, albumin secretion activity of HepG2 spheroids increased with the increase of spheroid diameter. This chip technology may be applicable as a cellular platform for developing two-dimensional spheroid microarrays.