PHILADELPHIA — Researchers at GlaxoSmithKline have shown that high-quality compound-profiling data can be generated by using cryopreserved cells, and that these cells can be plated at various densities to generate equivalent data between 24 hours and 74 hours after plating.
Cryopreservation is “vital to getting primary cells and stem cells” into the hands of the average scientist, said John Hambor, CEO of Cognate BioServices.
Brad Justice, director of research for cell-culture automation shop Global Cell Solutions, added that he thinks automated cyto-cryopreservation will eventually be refined to where it takes less time to freeze cells, which could enhance their usefulness in screening.
Hambor and Justice participated in a panel discussion at the Seventh Annual World Pharmaceutical Congress, held here this week. An evaluation of the use of cryopreserved cells, led by Mark Wigglesworth of GlaxoSmithKline, also appeared online last week in the Journal of Biomolecular Screening.
Wigglesworth and his team used CHO cells stably expressing the recombinant human histamine H1 receptor or the recombinant human motilin GPR38 receptor, Rat 1 fibroblast cells stably expressing the human adrenergic alpha 1A receptor or the human adrenergic alpha 1B receptor, and SH-SY5Y (ATCC CRL-2266) cells stably expressing recombinant human 5-HT2 receptors.
To extend the utility and flexibility of calcium screening using Molecular Devices’ FLIPR platform, the researchers examined the use of cryopreserved cells by plating them at different densities for assays 72 hours later. This allowed plating on a Friday and assaying on a Monday.
The researchers plated the cells at 12,000; 6,000; 4,000; and 2,000 cells per well and tested them with agonist dose-response curves. Their data suggested that cryopreservation generates assays with similar variance over an extended period with six assays becoming slightly more variable and four assays becoming slightly less variable. However, the data generated within this study indicate that cryopreserved cells are no more or less variable than their continuously cultured counterparts.
“Cryopreservation is ‘vital to getting primary cells and stem cells’ into the hands of the average scientist.”
Suki Jayachandra, a senior research investigator at Bristol-Myers Squibb, who also participated in the panel discussion, posed the question — “Are some cell lines more amenable to cryopreservation?” — and said that her group has been able to overcome this challenge using baculovirus.
Cryopreserved cells are both a blessing and a curse, said Hambor. Although the cells appear capable of generating data similar in quality to that generated by continuously cultured cells, cryopreserved cells need to be authenticated “unless you ask very specifically for certain cells or a certain cell line.”
Hambor’s company, Baltimore, Md.-based Cognate BioServices, was founded in 2002, and provides a range of analytical test methods development and testing services for cell-based products. Cognate also supports biotech and pharmaceutical companies with a range of cellular technologies and services that face common challenges in development and scale-up, such as assay development.
In November 2007, Justice’s employer, Global Cell Solutions, received a $71,630 Phase I Small Business Innovation Research grant from the National Science Foundation (see CBA News, 12/17/07). At the time, the Charlottesville, Va.-based company said that that it would use the money to develop a system that can cryopreserve cells without needing to expand and culture the cells post-thaw.
Ultimately, the goal of the six-month SBIR grant, which began on Jan. 1, is to enable the cell-expansion portion of the cell culture process to be performed on the substrate, Justice told CBA News at the time. He said cells can be grown and frozen on GCS’ technology, the Global Eukaryotic Microcarrier microsphere, dubbed GEM, and customers can then purchase whole cell lots.
Researchers wanting to perform an HTS campaign could buy a validated cell lot from GCS for either a multiple timepoint study, a multi-site study, or a single study at one site where the in-house cell culture facility cannot provide enough output to keep the cell culture equipment running, said Justice.
Justice said the grant will enable GCS to explore what kind of consistency it can get from these cell lots. Specifically, he said the company hopes to demonstrate that it can freeze large numbers of cells, thaw them, and attain the consistency required to use them in studies.
The GEM microsphere, which is less than 100 µm in diameter, has a curved face, compared with the flat format of a standard T-75 flask. The curved sphere forces cells into a 3D format, similar to the way that they would be grown in vivo.
In addition, the microsphere is made of porous alginates that allow the media to move through it.
Another feature of the GEM substrate is that it is embedded with magnetic particles. The fact that the GEMs are magnetic allows GCS’ existing technology, the BioLevitator cell culture device, to pull them to the bottom, remove the media, and add new media.
Last spring, GCS and fluid measurement systems company Hamilton, located in Bonaduz, Switzerland, announced plans to co-develop and market the BioLevitator and the GEM. The companies will incorporate the GEM technology and the BioLevitator on Hamilton’s STAR platform to automate the cell culture process.