Simultaneous Screening of Zebrafish Larvae Cardiac and Respiratory
Functions: A Microfluidic Multi-Phenotypic Approach
Abstract
Multi-phenotypic screening of multiple zebrafish larvae plays an
important role in enhancing the quality and speed of biological assays.
Many microfluidic devices have been presented for zebrafish phenotypic
assays, but multi-organ screening of multiple larvae, from different
needed orientations, in a single device that can enable rapid and
large-sample testing is yet to be achieved. Here, we propose a
multi-phenotypic quadruple-fish microfluidic chip for simultaneous
monitoring of fin movement and heart activity of 5–7-day
postfertilization zebrafish larvae trapped in the chip. In each
experiment, fin movements of four larvae were quantified in the dorsal
view in terms of fin beat frequency (FBF). Positioning of four optical
prisms next to the traps provided the lateral views of the four larvae
and enabled heart rate (HR) monitoring. The device’s functionality in
chemical testing was validated by assessing the impacts of ethanol on
heart and fin activities. Larvae treated with 3% ethanol displayed a
significant drop of 13.2% and 35.8% in HR and FBF, respectively.
Subsequent tests with cadmium chloride highlighted the novel application
of our device for screening the effect of heavy metals on cardiac and
respiratory function at the same time. Exposure to 5 μg/L cadmium
chloride revealed a significant increase of 8.2% and 39.2% in HR and
FBF, respectively. The device can be employed to improve quantitative
multi-phenotypic screening of zebrafish larvae in response to chemical
stimuli in various chemical screening assays, in applications such as
ecotoxicology and drug discovery.