Increase your output — decrease experiment costs and time What is high-throughput screening?
Lo, and Brent R. In fact, considerable effort has been invested in HD drug discovery, predominantly in academic environments but also in the biopharmaceutical industry to some certain extent. One hurdle in drug discovery for most neurodegenerative disorders is their incompletely understood, multigenic, and multifactorial etiology.
Thus, animal models of these diseases may often recapitulate only some aspects of such diseases and rarely reproduce the full pathophysiology of the human diseases [ 3 ], [ 4 ]. In contrast, HD is caused by a well-defined mutation in a single autosomal gene that has a dominant and fully penetrant phenotype.
This simplicity in the genetics of HD has allowed the creation of a variety of cells cultures and transgenic animal models for HD in which there can be greater confidence that these models do capture important aspects of human disease initiation and progression [ 5 ].
This chapter will focus on the development and implementation of high-throughput and high-content in vitro assays for the discovery of HD therapeutics. High-throughput screening HTS of small molecules allows the rapid interrogation of the effects of thousands to hundreds of thousands of small molecules in a variety of in vitro and cell-based assays, whereas high-content High throughput screening hts assays uses and formats HCS approaches may sacrifice some of these high-throughput capabilities in return for great biological and phenotypic complexity in the assay endpoints used.
Why do we need such high-throughput and high-content methods? Simply because we do not currently have sufficient knowledge of the molecular targets and pathways that may be therapeutic for HD nor do we know how to design a priori custom small molecule compounds that will be guaranteed to have the desired effect on such biological targets.
Hence rapid testing of many tens of thousands or more drug molecule candidates in HD models offers the potential for systematized serendipity, that we will encounter effective compounds in such discovery campaigns that will prove to be clinically relevant, using controllable and predictable in vitro screening processes.
Such efforts in the field have identified a number of hits that are being pursued as drug leads see Chapters 8 and 12, this volume. In the following sections we will describe different strategies and approaches in the design and implementation of HTS and HCS screens for HD, and will also discuss the development of prioritization schemes for potential drug leads identified, future screening approaches, and the use of these compounds for gaining new insights into mechanisms underlying HD.
Schematic describing the drug discovery process using HTS. HTS is a method of testing thousands of compounds rapidly in parallel for their activity in one or more biological assays. The basic components of HTS are a miniaturized biological assay, automated transfers and liquid handling steps, and automated quantitative readout of the assays.
The development of this field has been fueled by advances in robotics and engineering that allow automation of assays, as well as by miniaturization of cellular and biochemical assays.
The technology needed to detect more complex cellular phenotypes in a high-throughput format is also rapidly evolving, allowing screens that yield more biologically complex information. This can be especially useful for disease states such as HD, in which particular cellular phenotypes relating to disease are known but in which the specific disease pathways leading to these phenotypic changes are not known with certainty.
Many of these more complex screens are image based and can assay subcellular biological processes. They have depended on dramatic improvements in recent years in automated microscopy and image analysis.
This emerging field is appropriately named high-content screening because the information content in each test is increased relative to conventional in vitro assays, such as protein enzyme assays.
For any high-throughput or high-content screen, the initial and the most critical step is the choice of assay endpoints. At this stage, one seeks to choose an assay that most closely reflects the disease process and yet is amenable to miniaturization and compatible with automation.
The choice of assay can be complicated by a lack of understanding of the exact disease process to target or by the ability to generate a model that recapitulates all aspects of a complex disease. Thus, there is always a tradeoff between complexity and screenability.
This is particularly true for HD, for which a wide variety of pathological mechanisms have been proposed to be relevant for disease but none has been biologically, much less clinically, validated.
To compensate for such uncertainty, a broad range of phenotypes in different HD model assays has been brought to bear in HTS screening campaigns with the hope that consensus targets and pathways will emerge across several screening assays.
Although this leads to a multiplicity of assays and accompanying time and costs, it holds the promise of identifying leads that can affect several pathological processes important in HD pathogenesis. Not surprisingly, the choice of compounds that are to be screened can have a great impact on the quality of hits retrieved and their ultimate developmental potential as drug lead candidates.
Here we discuss compound library assembly before we move on to assay development. Chemical Compound Libraries A wide spectrum of screening compounds is available from a range of commercial vendors. These compounds range from natural products to purely synthetic compounds.
Natural products are obtained from plants, animals, or microorganisms and have been a mainstay for new drug discovery since the beginning of modern pharmaceutical development [ 8 ]. Although natural product compounds are frequently superior in terms of biological activity and chemical complexity, they have the disadvantages of higher costs, limited availability, and difficulty of chemical synthesis [ 9 ].
Purely synthetic compounds are usually made from a few simple chemical building blocks, and synthetic libraries are often assembled by altering the starting chemical structure of the building blocks and then joining them together in a large number of different combinations. Synthetic compounds have the advantage of straightforward and inexpensive resynthesis, as well as the ability of making numerous analogs for improving potency and efficacy, pharmacodynamic properties, and reducing unwanted side effects such as cellular toxicity and other offtarget actions.Numerous pharmaceutical companies have adopted assays for detecting activation of pregnane X receptor (PXR), a nuclear receptor known to regulate expression of cytochrome P (CYP) drug-metabolizing enzymes (1).
High-throughput screening (HTS) is a method for scientific experimentation especially used in drug discovery and relevant to the fields of biology and chemistry. Using robotics, data processing/control software, liquid handling devices, and sensitive detectors, high-throughput screening allows a researcher to quickly conduct millions of chemical, genetic, or pharmacological tests.
Register to the premier event for the European life sciences discovery and technology community. June Brussels. The need for more efficient and cost-effective preclinical screening of anti-cancer drugs. The design and development of all new drugs, for the most part, follow a similar trend of progression.
Directory of computer-aided Drug Design tools Click2Drug contains a comprehensive list of computer-aided drug design (CADD) software, databases and web services. Organ-on-a-Chip Assays. Emulating organ physiology by co-culturing cells in a supportive 3D matrix and using microfluidic channels to perfuse nutrients or compounds over the resulting cellular structures, is rapidly gaining popularity as a biologically relevant screening model for new drugs or toxicity.