Parallelized Impedance‐Based Platform for Continuous Dose‐Response Characterization of Antischistosomal Drugs

Abstract

Schistosomiasis is an acute and chronic disease caused by tropical parasitic worms of the genus Schistosoma, which parasitizes annually over 200 million people worldwide. Screening of antischistosomal compounds is hampered by the low throughput and potential subjectivity of the visual evaluation of the parasite phenotypes, which affects the current drug assays. Here, an impedance‐based platform, capable of assessing the viability of Schistosoma mansoni schistosomula exposed to drugs, is presented. This automated and parallelized platform enables unbiased and continuous measurements of dose–response relationships for more than 48 h. The platform performance is established by exposure of schistosomula to three test compounds, praziquantel, oxethazaine, and mefloquine, which are known to affect the larvae phenotypes. The system is thereafter used to investigate the response of schistosomula to methiothepine, an antipsychotic compound, which causes complex drug‐induced effects. Continuous monitoring of the parasites reveals transient behavioral phenotypes and allows for extracting temporal characteristics of dose–response curves, which are essential for selecting drugs that feature high activity and fast kinetics of action. These measurements demonstrate that impedance‐based detection provides a wealth of information for the in vitro characterization of candidate antischistosomals and, represents a promising tool for the identification of new lead compounds.

Schistosomiasis Drug Discovery in the Era of Automation and Artificial Intelligence

“…More recently (65), the system was reformulated, becoming more automated, performing at a higher throughput (32 experiments run in parallel) and allowing long-term culturing of NTS. This assay was successful in determining the EC 50 of mefloquine and oxethazaine which were of the same order of magnitude as those calculated by microscopy (65).…”

Real-time and automated monitoring of antischistosomal drug activity profiles for screening of compound libraries

“…We developed an integrated microwell plastic chip to establish reliable and automated impedance-based monitoring of schistosomula motility after exposure to compounds from large drug libraries ( Figure 1 A). The chip was fabricated using polystyrene (PS), a standard and well-characterized laboratory plastic material, to avoid absorption and/or adsorption of small hydrophobic drug molecules ( van Meer et al., 2017 ; Ravaynia et al., 2020 ). The PS chips were produced using injection molding, which allowed for high-volume and low-cost fabrication ( Figure S1 ).…”

“…The small microwell volume and dimensions (65 μL, 5 mm in height) resulted in fast and reliable sedimentation of the NTS onto the electrodes (within ∼3 min, Figure 1 B). Moreover, the geometry and physical dimensions of the electrodes and microwells were optimized to achieve high sensitivity in the volume extending to a 100-μm height above the electrodes, which is in the same range as the size of the NTS (∼50 × 100 μm 2 ), as previously described ( Ravaynia et al., 2020 ). To provide enough throughput for drug screening applications, the platform could accommodate 4 PS chips, and up to four platforms could be stacked in an incubator to simultaneously record from 16 chips, so that 128 conditions could be assessed in a single run ( Figure 1 C).…”

“…By applying a threshold of 70% relative inhibition of parasite viability (motility index upon drug exposure normalized to that of vehicle controls) ( Ravaynia et al., 2020 ) after 72 h of constant drug exposure, five hit compounds (E-D5/MMV688991, C-C5/MMV1578555, A-H2/MMV1634491, A-D8/MMV1582497, and D-A4/MMV394033) were selected for further evaluation and ranked according to their dynamics using the impedance-based screen ( Figure 4 B; for viability and phenotypic details see also Figure S8 and Table S2 and). E-D5 exhibited the fastest in vitro lethal effect on schistosomula, which occurred 3 h after drug dosage.…”

Validation of a human-serum-based in vitro growth method for drug screening on juvenile development stages of Schistosoma mansoni

“…Next, we exposed worms grown in vitro and in vivo to five additional marketed drugs with known antischistosomal activity and different mechanisms of action [ 20 ] and compared sensitivities after 21 days of development ( Table 3 ). The drugs used were auranofin [ 22 ], mefloquine [ 23 ], nicardipine [ 20 , 24 ], oxamniquine [ 25 ] and oxethazaine [ 20 , 26 ]. Oxamniquine was not lethal against worms grown either in vivo or in vitro , resulting in IC 50 values above the range of concentrations used.…”