Screening
The electrical resistance is as high as in the conven- tional manual method. The addition of compound solution is accomplished through a fine quartz cap- illary inside the micropipette. The autofocusing of solution application on to the cell surface allows extremely rapid solution exchange (<10ms). Small volumes (~1µL) enable experiments with only ~10 cells per measurement for very reliable pharmaco- logical data. Ion channel screening is performed with high and stable success rates using purely phys- iological solutions without addition of Fluoride. The f11 is available with 1-6 measurement chambers. Temperature control and intracellular perfusion are available options. By moving to an industrial pro- duction environment, a single channel f11 is avail- able for less than $100,000 and the consumable pipettes cost less than $2. flyion also offers ion chan- nel screening, assay development and cell line devel- opment services (Figure 21).
Human embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) could prove to be an unlimited source of cardiomyocytes. Stem cell tech-
nology offers great potential for toxicology studies in drug discovery. Cardiomyocytes derived from pri- mate ESCs /iPSCs responded to and predicted side- effects of drugs which have been reported for QT prolongation in vivo. The Hamamatsu FDSS/uCELL (
www.sales.hamamatsu.com), equip- ped with the high speed and high sensitivity camera, enables the detection of Ca2+ and membrane poten- tial from human ESCs /iPSCs-derived cardiomy- ocytes in a 96-well plate format. The Ca2+ oscilla- tions originate from the sarcoplasmic reticulum and are dependent on the IP3 and the ryanodine recep- tor. The Ca2+ oscillations activate the Na+-Ca2+ exchanger, giving rise to subthreshold depolarisa- tions of the membrane potential and/or action potentials. Using 3uM Fluo-8AM, the FDSS/uCELL measured the stable and uniform oscillations of the cardiomyocytes, 100-200µm wide in single clamp, and demonstrated the drastic reduction of oscilla- tions by adding 10µM channel blocker (TTX) with the simultaneous dispensing head of the FDSS/uCELL. Having the correlation with the stan- dard electrophysiology assay, the cell-based assay is
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Drug Discovery World Fall 2011
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