High-throughput Screening and High-content Screening

The research and development of new drugs promotes the continuous development of the pharmaceutical industry. Drug discovery is the beginning of new drug development. With the continuous development of technology, the acquisition of target compounds has become faster and more efficient. People have established various compound libraries classified by different characteristics such as source, structure, and function. The number of compounds in the compound library ranges from a few hundred to millions. How to screen out pharmacologically active compounds from a large number of compounds is a hot spot in current research.

Drug screening is the process of evaluating the biological activity, pharmacological effects and medicinal value of substances (samples) that may be used as drugs by using appropriate methods and technologies. Drug screening is an important link connecting drugs from laboratory research to clinical application. It is an important means to realize drug discovery. It is the key to improving R&D efficiency, shortening the cycle, reducing costs, and reducing risks in the development of new drugs.

High-throughput screening (HTS) and high-content screening(HCS) ( Xia X.F., Wong S.T. stem cells, 2012, 30(9): 1800-1807)

High-throughput screening (HTS)

With the continuous development of combinatorial chemistry, conventional screening methods cannot handle the geometrically increasing number of target molecules and compounds. In this context, high-throughput screening technologies have emerged.

• Concept

High throughput screening (HTS) technology is a technical system. The system is based on experimental methods at the molecular and cellular level, using microplate format as the experimental tool carrier, which can detect a large number of samples at the same time through automated means, and support its operation with the corresponding database obtained.

• Introduction

HTS technology is mostly molecular or cellular level analytical detection methods established based on optical detection, including fluorescence detection, chemiluminescence detection, spectrophotometric detection, etc. Due to its characteristics such as trace quantity, rapidity, sensitivity and accuracy, HTS has been widely used in drug discovery. HTS models are mostly at the molecular level, and the screened targets include receptors, enzymes, ion channels, and so on. The basic model of HTS is to evaluate the biological activity of a large number of samples with a single screening model, from which samples that are active against a certain target are found. The scale of HTS is at least to screen thousands of samples daily.

• Advantages

  Compared with ordinary drug screening, HTS has obvious advantages

  • Full utilization of medicinal resources: HTS relies on a sample library with a large number of samples to realize the large-scale drug screening and utilize medicinal material resources to a large extent.
  • Small sample amount: HTS is a micro-screening system. The amount of sample is generally at the microgram level, which saves sample resources and experimental materials and reduces the screening cost of a single drug.
  • Automatic operation: HTS adopts computer-controlled automatic operation, which reduces operation errors and improves screening efficiency and accuracy of results.
  • Combination of multidisciplinary theory and technology: In the screening process, multidisciplinary theories and technologies such as molecular pharmacology, genetic science, and computer science are applied.

High-content screening (HCS)

In order to reduce the screening cost of HTS and increase the screening speed, people have adopted measures to reduce the size of screening samples, from the original screening mainly on 96-well plates to high-density microplate screening on 384-well plates or 1536-well plates. However, since the reaction volume cannot be reduced indefinitely, increasing the amount of information in each single screening and discovering more information content has become a new development direction. Therefore, high-content screening (HCS) technology, which can simultaneously collect drug action signals with different meanings on the same screening model, has emerged.

• Concept

HCS is a technology that takes cells as the detection object, records images of cells in a multi-well plate through microscopic imaging, and analyzes the activity of substances in the cells by analyzing the information in the images.

• Introduction

The HCS technology is the result of the integration of various technologies such as sample preparation, automated analysis equipment, supporting detection reagents, data processing software, and bioinformatics. The main components of the HCS system include fluorescence microscopy system, automated fluorescence image acquisition system, detection equipment, image processing and analysis software, result analysis and data management system.

HCS technology is a screening technique with diversified screening results. The HCS model is mainly established at the cellular level. HCS can simultaneously detect the influence of samples on cell morphology, growth, differentiation, migration, apoptosis, metabolic pathways and signal transduction while maintaining the integrity of cell structure and function, thereby obtaining screening results in many aspects. The targets involved include membrane receptors, intracellular components, organelles and so on.

HCS can obtain a large amount of information related to genes, proteins and other cellular components in a single experiment to determine the biological activity and potential toxicity of the compound.

HCS technology realizes the simultaneous detection of multiple targets and multiple parameters of compounds, making it possible to comprehensively evaluate the druggability of active compounds at the cellular level.

• Advantages

  Compared with HTS, HCS has obvious advantages

  • The screening volume does not need to be too small: the detection volume does not increase due to the increase in detection indicators, and the experimental operation is also simple, feasible and automated.
  • Diversified screening results: HCS has not only the final reading of sample wells, but also cell count, cell morphology analysis, cell spatial structure analysis, and cell imaging analysis.
  • Multi-indicator and multi-target interaction: HCS can obtain information on the effects of samples on multiple targets after one screening.
  • Obtaining information on a cell basis: Obtaining information on a cell basis means that researchers can obtain information from various reactions in the cell population. In the past, the microplate well was used as the unit, and the information was only derived from the average response of all cells in a microplate well.

Drug screening is a key link in the development of new drugs. The effective integration of various drug screening technologies is an effective way to better achieve the purpose of drug screening, and will provide better technical support for the development of new drugs, thereby bringing good news to human health.