High-content screening
At a cellular level, parallel acquisition of data on different cell properties, for example activity of signal transduction cascades and cytoskeleton integrity is the main advantage of this method in comparison to the faster but less detailed high throughput screening.
The selection of molecules based on a cellular phenotype does not require a prior knowledge of the biochemical targets that are affected by compounds.
However the identification of the biological target will make subsequent preclinical optimization and clinical development of the compound hit significantly easier.
Given the increase in the use of phenotypic/visual screening as a cell biological tool, methods are required that permit systematic biochemical target identification if these molecules are to be of broad use.
[7] High-content screening technology is mainly based on automated digital microscopy and flow cytometry, in combination with IT-systems for the analysis and storage of the data.
“High-content” or visual biology technology has two purposes, first to acquire spatially or temporally resolved information on an event and second to automatically quantify it.
Spatially resolved instruments are typically automated microscopes, and temporal resolution still requires some form of fluorescence measurement in most cases.
These include speed, a live cell chamber that includes temperature and CO2 control (some also have humidity control for longer term live cell imaging), a built in pipettor or injector for fast kinetic assays, and additional imaging modes such as confocal, bright field, phase contrast and FRET.
What all instruments share is the ability to take, store and interpret images automatically and integrate into large robotic cell/medium handling platforms.
Third-party software alternatives are often used for particularly challenging screens or where a laboratory or facility has multiple instruments and wishes to standardize to a single analysis platform.
Beyond drug discovery, chemical genetics is aimed at functionalizing the genome by identifying small molecules that acts on most of the 21,000 gene products in a cell.
In the early 1990s, the development of charge-coupled device (CCD) cameras for research created the opportunity to measure features in pictures of cells- such as how much protein is in the nucleus, how much is outside.
By analogy, if one imagines a football field and dinner plates laid across it, instead of looking at all of them, the investigator would choose a handful near the score line and had to leave the rest.
