Variables in 'Passive' Cryopreservative Methods:Standardizing Cell-Based Assays By Reducing Cryopreservation-lnduced Variability

摘要

Cells have become essential in modern medicine as therapies, vehicles for producing high-value therapeutics, and tools for high-throughput screening of pharmaceutical compounds. In the latter area, more than 50% of drug discovery screens use cell-based assays, predominantly targeting receptors and ion channels using fluorescence-based measurements, in either or both high-throughput and high-content formats (1). Alongside a cell therapy market estimated to be worth some $5.0 billion by 2015 (2), the larger cell-based screening market is estimated to be worth $14.8.0 billion by 2018 (3).Half of all screening groups express interest in using primary cells, stem cells, and early progenitor cells in their screens rather than cell lines (4). Such cells have close physiological similarities to cells found in actual tissues. That presents a range ofchallenges because such sources are known to be highly susceptible to batch-to-batch variability. A well-documented example is the use of human primary liver cells for hepatotoxicity studies (5). Hepatocytes are obtained from liver biopsies. They are dissociated and cryopreserved before being shipped to customers, where they are thawed and plated for cell-based assays. Those cells do not proliferate, so new batches are required for extensive testing regimes. Because of inherent donor-to-donor variability (e.g., age, sex, lifestyle, and ethnicity), range of cell-handling processes, differing cryopreservation techniques (6), and variations in reagents, results obtained from such screens can vary greatly. The limitedaccess to suitable tissues also contributes to making such cells very limited and valuable.