An automated chemical screening pipeline for drug discovery in zebrafish

Centre for Neuroregeneration, University of Edinburgh, Chancellor’s Building, 49 Little France Crescent, Edinburgh EH16 4SB

Loss of myelin, the pathological hallmark of Multiple Sclerosis (MS) results in disrupted axonal function and a host of associated debilitating symptoms resulting in long-term disability. Current treatments, primarily aimed at stopping or slowing the autoimmune attack central to relapsing-remitting MS, are effective but none have proven successful in preventing the secondary progressive neurodegenerative stage of the disease or improving remyelination. Therefore, the aim of this study was to develop a fully automated chemical screening pipeline in zebrafish to identify chemical regulators of myelination. VAST (Vertebrate Automated Screening Technology) is the first commercially available system that enables automated zebrafish handling, orientation and data acquisition. Combined with a high-speed spinning disk system an entire fish can be orientated and imaged in around 1 min, representing an increase in speed of over 10-fold compared with manual approaches. Scripts for automated analysis of oligodendrocyte cell number were written to allow fast, accurate and reproducible counts, free from experimenter error. To identify regulators of oligodendrocyte number, we screened a library of small-bioactive compounds and identified several novel hits for secondary analysis.

In summary, we have developed a fully automated zebrafish chemical screening pipeline that decreases screening time over 10-fold compared with manual approaches. Chemical screens that would previously have taken weeks to complete manually can now be reduced to a matter of days while ensuring a permanent record of all data acquired. In addition, we have shown the validity of the screening pipeline for identifying regulators of oligodendrocyte number through identifying a number of novel hits that increased oligodendrocyte number. We have since demonstrated the versatility of the system for screening different reporter lines and developmental stages using custom automated analyses.

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