Advances in high-content screening (HCS) instrumentation have significantly increased throughput and improved ease of use such that the technology is moving from its traditional role in secondary screening to the earlier stages of the drug-discovery process. At the same time, the process bottleneck has shifted from screening to analytics. The challenges inherent in the technology including data capture, storage, and multivariate data analysis will be discussed at Cambridge HealthTech’s “High-Content Screening” meeting to be held later this month in San Francisco.
A handful of presenters spoke to GEN prior to the assembly. Among them was Ann Hoffman, senior principal scientist at Roche Discovery Technologies, who will discuss assay development in the “Setting up an HCA Lab” workshop at the conference. Specifically she will talk about her experiences with Columbus™, the new enterprise system software from PerkinElmer, currently being evaluated by several of Roche’s core screening labs using images and data captured on the Opera system.
“High-content screening instrumentation and software has evolved to the point that the current focus for researchers is on assay development and data analysis,” Hoffman explains. “The current challenges in the lab are how to develop robust assays to measure cellular processes in new cell types, including cardiomyocytes, primary cells, T cells, and B cells. In addition, developing new probes and sensors to follow complex cellular processes and identify key proteins in the signal transduction pathways of interest are challenges. The constant push is toward more quantitative measurements that enable a better understanding of the disease process.”
Most HCS labs today have multiple instruments, some of which are dedicated to particular assay protocols. HCS has now been pushed upstream in the drug discovery and development process to be fully integrated into most primary screens, particularly those where imaging is essential to query the antigens of interest. It has also been pushed downstream for applications such as predictive tox profiling and other forms of compound profiling.
While the progress has been measur able, it has not yet yielded new marketed drugs. Scientists are contributing to the cellular knowledge base that is improving drug candidate prioritization earlier in the drug-development process. Further, there is a growing trend toward combinatorial analysis, for example, by combining HCS with genomic protocols and tools (e.g., siRNA). Scientists have been able to gather breakthrough results that have increased the predictive value in drug discovery.
The development of predictive in vitro toxicology tools for use in high content screening, a focus at Millipore, has become a high growth area for this reagent provider. Following up on their kits for hepatotoxicity, cell cycle analysis, and DNA damage, in December, Millipore launched its next set of kits focusing on neurotoxicity. At the HCS meeting, Stella Redpath, Ph.D., group product manager, will be presenting case-study data based on the use of these recently launched kits for monitoring neurotoxicity in using HCS.
The kits provide a complete solution with reagents, antibodies, and a control set of neurotoxins, and are suitable for all high-content instrumentation on the market, according to Dr. Redpath. The kit reagents can also be used for sample detection on confocal or conventional fluorescence microscopy.
“The assay has been successfully applied to neural cell growth using human, rat, and mouse cell types with primary cells and cell lines. We also have developed co-culture conditions for the use of astrocytes in culture with neurons.”
“In addition, we’ve developed a differentiated cellular model based on PC12 rat cells that have been treated with neural growth factor for six days, as well as the co-culture assays for neurons and astrocytes. This cellular model is sensitive to neural toxins as measured by their altered profile of neural-specific biomarkers: bIII tubulin, synaptophysin, and glial fibrillary acidic protein.”
The three biomarkers are the best predictors of neurotoxicity available today, Dr. Redpath insists. Her group has found that the combined profile of these markers is informative, and they provide an earlier indication of neurotoxicity than can be seen by just looking for morphological changes in the cells including neuronal damage, astrocyte hypertrophy, gliosis, and synaptotoxicity.
“The kits may be more sensitive than traditional assays such as MTT or LDH assays, which rely on late-stage cytotoxic endpoints. Our new kits can detect neurotoxic effects at lower concentrations than these biochemical assays. Further, the profiles correlate highly with the results of morphological studies including neurite outgrowth as reported in the literature.”