Preconditioned cell array optimized for a three-dimensional culture of hepatocytes.

Three-dimensional culture procedures have attracted attention in various fields of cell biology. A newly developed cell array assisted in the formation of hepatocyte spheroids by two innovations: 1) micropatterning by a hydrophilic polymer, and 2) the use of bovine carotid artery-derived HH cells as feeder cells. The former contributes to the standardization of the spheroid size and the latter to the maintenance of the spheroids. We created a way to provide a ready-to-use cell array by cryopreservation of an HH feeder cell cultured array. After inoculation of HH cells on the cell array, the culture medium was replaced by freezing medium containing dimethyl sulfoxide. Thereafter, the array was frozen and stored in a -80 degrees C deep freezer. At the start of the hepatocyte culture, the cryopreserved HH cell array was thawed by adding warmed (37 degrees C) culture medium. The morphology and biological activities of the cryopreserved HH cells were intact, as confirmed by phase contrast microscopy and functional staining with calcein and formazan. The rat hepatocytes formed perfect spheroids on the cryopreserved HH cell array without any differences from those on the freshly prepared HH cell array. The CYP3A drug metabolism activities of the hepatocytes were well maintained on the cryopreserved and fresh cell arrays. The present protocol greatly shortened the time and labor required to prepare a cell array for culturing hepatocytes.