High-content screening

High-content screening (HCS), also known as high-content analysis (HCA) or cellomics, is a method that is used in biological research and drug discovery to identify substances such as small molecules, peptides, or RNAi that alter the phenotype of a cell in a desired manner. Hence high content screening is a type of phenotypic screen conducted in cells. Phenotypic changes may include increases or decreases in the production of cellular products such as proteins and/or changes in the morphology (visual appearance) of the cell. High content screening includes any method used to analyze whole cells or components of cells with simultaneous readout of several parameters. Hence the name "high content screening". Unlike high-content analysis, high-content screening implies a level of throughput which is why the term "screening" differentiates HCS from HCA, which may be high in content but low in throughput.

In high content screening, cells are first incubated with the substance and after a period of time, structures and molecular components of the cells are analyzed. The most common analysis involves labeling proteins with fluorescent tags, and finally changes in cell phenotype are measured using automated image analysis. Through the use of fluorescent tags with different absorption and emission maxima, it is possible to measure several different cell components in parallel. Furthermore, the imaging is able to detect changes at a subcellular level (e.g., cytoplasm vs. nucleus vs. other organelles). Therefore a large number of data points can be collected per cell. In addition to fluorescent labeling, various label free assays have been used in high content screening.

High-content screening (HCS) in cell-based systems uses living cells as tools in biological research to elucidate the workings of normal and diseased cells. HCS is also used to discover and optimizes new drug candidates. High content screening is a combination of modern cell biology, with all its molecular tools, with automated high resolution microscopy and robotic handling. Cells are first exposed to chemicals or RNAi reagents. Changes in cell morphology are then detected using image analysis. Changes in the amounts of proteins synthesized by cells are measured using a variety of techniques such as the green fluorescent proteins fused to endogenous proteins, or by fluorescent antibodies.

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