by Dr. Weihong Wang, manager of molecular and cell biology, Lancaster Laboratories

Introduction
Characterization of a biological product, which includes the determination of physicochemical properties, biological activity, immunochemical properties, purity and impurities, is necessary to establish the safety and efficacy profile of a given product (ICH Q6B). Cell culture based potency assays are often the preferred format for determining biological activity since they measure the physiological response elicited by the product and can generate results within a relatively short period of time unlike typical animal based assays. Cell based potency assays are also often the only functional assays used for product release and stability programs. Other uses of cell based assays include qualification of internal reference standards; characterization of process intermediates, formulations, and degradation products; and support of changes in the product production process.