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New technologies drive cell identification and selection

1st April 2013


Technologies for cell biology are bringing new efficiencies to the process of biotherapeutic discovery. Genetix platforms are playing key roles in therapeutic antibody development from target discovery through to clinical diagnosis:

Applied Imaging (recently putchased by Genetix, Ariol pathology instrumentation and CytoVision software enable the genetic nature of tumours to be studied at the level of protein biomarkers. The use of multiple serial sections or multiple tissue sections on arrays is invaluable for target discovery.

For example disease tissue used in target discovery and validation laboratories can be probed with a selection of antibodies to determine which protein biomarkers are associated with a particular class of tumour. This can now be performed at high throughput on a large scale, the data stored and classified automatically (Fig. 1). The identification of protein biomarkers offers the possibility that the markers themselves maybe a potential target. The identification of such a target allows the development of a therapeutic using an antibody generating system such as synthetic phage display or a library of cell fusions. In each case the Genetix QP Display for phage screening, or the Genetix ClonePix FL for cell selection and isolation, automates the screening process for candidate protein therapeutics.

ClonePix FL screens very large numbers of cells rapidly with multiple antigens allowing the screening and isolation of only the highest value clones (Fig. 2).

The more clones that can be screened the greater the chances of finding a cell that produces a superior molecule.

ClonePix FL eliminates the need for laborious manual limiting dilution and adds a qualitative aspect that manual methods cannot. This significantly shortens timescales from weeks to days by screening a thousand cell colonies in an hour, just three days after fusion. This simplifies cell culture, turning large scale, high throughput screening from a facility based activity to a bench top process. The economies of ClonePixFL deliver a powerful return on investment.

Switching expression constructs from hybridoma to production cell lines, such as CHO, can be undertaken by the Genetix automated bacterial transfection system the QP Expression. It automatically plates out 96 transfections in 20min and picks bacterial colonies the following day.

There are two important criteria for selection of production cell lines, one is that a large number of primary transfectants must be screened for their production capacity and second the selected cell lines must be stable.

ClonePixFL automates the crucial colony selection process, isolating mammalian cell clones on the basis of the level of expression of the protein of interest and on the speed of cell growth, delivering high yielding cells that are stable, robust and suitable for next stage scale-up to biopharmaceutical manufacturing. This is done by plating production cells such as CHO or NS0 in a semi solid matrix (CloneMatrix) such that the secreted protein accumulates around the colonies.

The detection of the secreted protein is measured using an in situ fluorescent tag Fig. 3). ClonePix FL screens over a thousand colonies in around an hour, and in a typical experiment screens over 10000 colonies and selects the top 2percent.

These cells are replated for 2–3days and the stable clones selected as candidates for production of therapeutic products. In contrast conventional limiting dilution methods screen less than 1000 clones and the process takes three times longer.

As part of the quality process for cells entering production, the CytoVision system automatically finds and analyses karyotypes for genetic integrity. CytoVision reduces the time taken for the quality control procedures and provides an electronic record. For the production of biopharmaceuticals, particularly live vaccines, this can be of paramount importance. To obtain the maximum information about the therapeutic potential of a compound before entering it into a clinical trial requires the measurement of a number of parameters. These include survival and disease progression and more recently biomarker analysis.

Applied Imaging’s Ariol system combines immunohistochemistry for measuring protein levels in tissues with cytogenetics, the gold standard for the measurement of gene copy number. The loss (or gain) of particular biomarkers can then be used as a monitor for therapeutic responses and ultimately as predictors for the effectiveness of particular treatment regimes.

To obtain the maximum information about the therapeutic potential of a compound before entering it into a clinical trial requires the measurement of a number of parameters. These include survival and disease progression and more recently biomarker analysis. Applied Imaging’s Ariol system combines immunohistochemistry for measuring protein levels in tissues with FISH, the new standard for the

measurement of gene copy number (Fig. 4) The loss (or gain) of particular biomarkers can then be used as a monitor for therapeutic responses and ultimately as predictors for the effectiveness of particular treatment regimes.

Enter 22 or at www.scientistlive.com/elab

Professor Julian Burke is with Genetix Ltd, New Milton , Hampshire. www.genetix.com





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