Objective

Cells used in cell based assays are usually prepared fresh from a maintenance culture. However, when handled carefully and cryopreserved according to optimized protocols, the functionality of the cells can be maintained and is fully restored after thawing of the cells. These assay ready frozen cells can be used instantly and do not need to be cultivated or passaged before. We used assay ready HepG2 cells in various applications like cytotoxicity testing, phospholipidosis assay, and LDL-uptake to demonstrate that assay ready cells are equal to fresh cells from a growing culture. The viability of the cells is not decreased and they display the typical cobblestone-like morphology of HepG2 cells. Cytotoxicity of references substances and induction of phospholipidosis can be reliably assessed with assay ready HepG2 cells. Even transporter dependent assays like the uptake of Low-Density Lipoprotein (LDL) can be performed demonstrating the high functionality of the assay ready HepG2 cells. In general, this approach provides a higher flexibility, greater reliability and increase in assay reproducibility.