Mechanistics of formation and ultrastructural evaluation of hepatocyte spheroids.

Freshly harvested rat hepatocytes form spheroids on uncoated positively charged polystyrene surfaces. Time lapse microscopy revealed that cell movement and reorganization were involved in spheroid formation. Ultrastructural evaluation using scanning and transmission electron microscopy indicated polarized cellular morphology and extensive cell-cell communication within spheroids. Bile canalicular structures were observed to surround each individual hepatocyte, forming an intricate three-dimensional continuous network of channels that appeared to end as pores/holes on the surface of the spheroid. The maintenance of differentiated cellular morphology coincided with preservation of hepatocyte viability and enhanced levels of tissue specific functions in spheroids.