A recent surge in disruptive technologies like gene writing,[1] quantum-powered drug design,[2] and AI-driven screening[3] is rapidly transforming the drug discovery landscape. In this fast-paced, data-hungry environment, there’s more pressure than ever to maximize returns from high-throughput screening (HTS) assays and get more information from every sample.
Concentrating your high-throughput screening power
As drug discovery gets smarter, high-throughput screening assays need to work harder. Common strategies to increase the quality and power of high-throughput assays include:
- Implementing multiplexed formats to detect more analytes per well
- Leveraging advanced modalities like fluorescence polarization, FRET and TR-FRET/HTRF to improve assay quality, increase data dimensionality and enable more streamlined, homogeneous (mix-and-read) formats
- Adopting high-content, target-agnostic, cell-based screening strategies like phenotypic profiling and cell painting
- Using more disease-relevant assay systems, such as 3D cell cultures, organoids, induced pluripotent stem cells (iPSC) and donor-derived primary cells
This power comes at a price, however. The added sophistication usually calls for more development time and more expensive assay components, such as: recombinant antibodies and enzymes; advanced reporter molecules and multimodal detection systems; bespoke cell models, culture media and growth matrices.
While high-throughput screening assays generally cost in the range of $0.10 to $1.00 per well[4], this seems to be trending upwards, as screening labs adopt more complex and biologically relevant assays. By some accounts, assay costs exceeding $1.50 per compound are not uncommon in high-throughput screening campaigns.[5]
Going small has big advantages
Assay miniaturization is a smart way to reduce consumption of expensive reagents, consumables and precious samples, without compromising on information-content or data quality. At the same time, it can significantly improve throughput and turnaround times.
From SBS-standard microplates to advanced microfluidics devices and bioprinted chips, labs have access to a wide variety of options for assay miniaturization.
For the majority of high-throughput screening labs, 384 well and 1536 well microplates are still the most widely used screening formats. Ease of assay reformatting has a lot to do with this. For many biochemical assays, down-scaling to 384 and 1536 well volumes is relatively straightforward, and there are substantial gains to be made in terms of cost per well. Even for cell-based assays, where there are added challenges to handling and maintaining healthy cells in low volumes, stepping from 96 to 384 or even 1536 wells requires far less assay development, validation and infrastructure change than moving to a completely different technology like a microchip. And again, the potential benefits are well worth the effort—especially when you consider the cost of some cell lines.
Example
Take iPSC-derived cells, which can set you back more than $1,000 for a vial of 2 million viable cells. In traditional 96 well plates, a modest screen of 3,000 data points (compounds plus controls) would consume somewhere in the realm of 23 million cells. By miniaturizing down to 384 well format (8 plates), you reduce the total cell requirement to 4.6 million. That puts about $6,900 back in your pocket—not counting the additional savings you’ll see due to decreased spend on specialized culture media, growth factors and other expensive assay components.
Making assay miniaturization work for you
While 384 and 1536 well assays are now commonplace in high-throughput screening, the process of miniaturization is not always smooth sailing. A comprehensive list of potential pitfalls is beyond the scope of this article, but here are some of the biggest problem areas:
- Reformatting – Reconfiguring compound libraries for high-throughput applications can be a daunting task. Many logistical problems and opportunities for error arise when compressing large compound collections into higher density formats, performing pre-dilution steps, and making transfers between source plates and intermediate vessels or assay plates.
- Evaporation – Evaporation can lead to high well-to-well variability, assay interference and a wide range of artifacts, especially edge-well effects. It can impact on everything from reagent concentrations to cell health to signal-to-background levels. The smaller the volume, the greater the impact evaporation can have on your assay.
- Liquid handling – Breakthroughs in liquid handling and robotics have been absolutely key to making 384 and 1536 well assays feasible for high-throughput screening. Nevertheless, liquid handling automation is still one of the biggest sources of problems during miniaturization. Tip clogging, unsatisfactory retrieval of reagents (high dead volumes), poor mixing, and carryover / cross-contamination from well-to-well are just a few of the many issues that can cause delays.
- Biology – Compared to biochemical assays, cell-based systems come with an additional set of challenges due to the inherent variability, complexity and sensitivity of biological processes. Reagent waste, uneven cell distribution, monolayer damage, poor viability, phenotypic changes, and imaging artifacts are some of the risks to consider at higher well densities.
Fortunately, with anticipation and careful planning many of these risks can be mitigated or avoided altogether. In particular, choosing the right microtiter plates is one of the most important success factors in high-throughput screening assay miniaturization. To find out more about the latest tools and advances in microplate technology and how they can help you avoid problems with assay miniaturization, don’t miss our next article.
Fortunately, with anticipation and careful planning many of these risks can be mitigated or avoided altogether. In particular, choosing the right microtiter plates is one of the most important success factors in high-throughput screening assay miniaturization. To find out more about the latest tools and advances in microplate technology and how they can help you avoid problems with assay miniaturization, don’t miss our next article.
References
[1] https://www.prnewswire.com/news-releases/flagship-pioneerings-scientists-invent-a-new-category-of-genome-engineering-technology-gene-writing-301088613.html
[2] https://www.mckinsey.com/industries/life-sciences/our-insighigh throughput screening/pharmas-digital-rx-quantum-computing-in-drug-research-and-development
[3] https://www.sciencedirect.com/science/article/pii/S2472555222066692
[4] https://cancer.wisc.edu/research/resources/ddc/smsf/equipment-services/
[5] https://www.sciencedirect.com/science/article/pii/S2472555222066692