Viability of developmental stages of Schistosoma mansoni quantified with xCELLigence worm real-time motility assay (xWORM).

Infection with helminth parasites causes morbidity and mortality in billions of people and livestock worldwide. Where anthelmintic drugs are available, drug resistance is a major problem in livestock parasites, and a looming threat to public health. Monitoring the efficacy of these medicines and screening for new drugs has been hindered by the lack of objective, high-throughput approaches. Several cell monitoring technologies have been adapted for parasitic worms, including video-, fluorescence-, metabolism enzyme- and impedance-based tools that minimize the screening bottleneck. Using the xCELLigence impedance-based system we previously developed a motility-viability assay that is applicable for a range of helminth parasites. Here we have improved substantially the assay by using diverse frequency settings, and have named it the xCELLigence worm real-time motility assay (xWORM). By utilizing strictly standardized mean difference analysis we compared the xWORM output measured with 10, 25 and 50 kHz frequencies to quantify the motility of schistosome adults (human blood flukes) and hatching of schistosome eggs. Furthermore, we have described a novel application of xWORM to monitor movement of schistosome cercariae, the developmental stage that is infectious to humans. For all three stages, 25 kHz was either optimal or near-optimal for monitoring and quantifying schistosome motility. These improvements in methodology sensitivity should enhance the capacity to screen small compound libraries for new drugs both for schistosomes and other helminth pathogens at large.

Electrical impedance as a novel biomarker of myotube atrophy and hypertrophy.

Measuring myotube thickness is a physiological and unbiased approach for screening therapeutic compounds that prevent skeletal muscle atrophy or induce hypertrophy. However, an accurate cell thickness estimate is often quite challenging because of the extreme heterogeneity of the myotube cellular population and therefore the lack of a regular distribution of perturbed myotubes. Here the authors present a novel method to evaluate changes in myotube thickness via measuring cellular electrical impedance. They demonstrate that both qualitative and quantitative changes in electrical impedance as a function of cellular adhesion in real time correlate well with variation in myotube thickness caused by atrophy or hypertrophy agents. Conversely, pharmacologically blocking myotube hypertrophy prevents changes in electrical impedance. Thus, impedance can be used as a reliable and sensitive biomarker for myotube atrophy or hypertrophy. Application of this technique to drug screening might be beneficial in finding novel treatments preventing muscle atrophy and other diseases associated with any morphological change in cell shape.

Screening and identification of small molecule compounds perturbing mitosis using time-dependent cellular response profiles.

Cellular processes such as cell cycle progression, mitosis, apoptosis, and cell migration are characterized by well-defined events that are modulated as a function of time. Measuring these events in the context of time and its perturbation by small molecule compounds and RNAi can provide mechanistic information about cellular pathways being affected. We have used impedance-based time-dependent cell response profiling (TCRP) to measure and characterize cellular responses to antimitotic compounds or siRNAs. Our findings indicate that small molecule perturbation of mitosis leads to unique TCRP. We have further used this unique TCRP signature to screen 119 595 compound library and identified novel antimitotic compounds based on clustering analysis of the TCRPs. Importantly, 113 of the 117 hit compounds in the TCRP antimitotic cluster were confirmed as antimitotic based on independent assays, thus establishing the robust predictive nature of this profiling approach. In addition, potent and novel agents that induce mitotic arrest either by directly interfering with tubulin polymerization or by other mechanisms were identified. The TCRP approach allows for a practical and unbiased phenotypic profiling and screening tool for small molecule and RNAi perturbation of specific cellular pathways and time resolution of the TCRP approach can serve as a complement for other existing multidimensional profiling approaches.