Miniaturization of a mammalian cell-based assay: Luciferase reporter gene readout in a 3 microliter 1536-well plate

The combined efforts of the fields of combinatorial chemistry and genomics have significantly increased the number of compounds and therapeutic target s available for screening. The number of compounds will reach into the mill ion range in the near future and provide vast chemical diversity for drug d iscovery. However, this reservoir of chemical diversity creates downstream hurdles for any screening effort. Properly examining this number of compoun ds increases investments dramatically, both in the number of dollars spent and amount of limited reagents depleted. Traditional HTS techniques, such a s the use of 96-well microtiter plates, have paved the way for faster proce ssing speeds, but are being rapidly overwhelmed by screening demands. Minia turization of such assays will allow for greater throughput, while concurre ntly reducing cost. To date, miniaturization efforts have been most success fully applied to bacterial and soluble protein based assays. Questions abou t the ability to deliver microquantities of mammalian cells without disrupt ion of the cell membrane and/or activation of stress responses have been ra ised. An assay has been developed in which a human T-cell screen has been a dapted to a 1536-well plate format. Through the use of a luciferase reporte r gene system, it is shown that a mammalian cell-based assay may be success fully performed in 3 mu l and potent inhibitors of the target of interest i dentified.