Open access tool and microfluidic devices for phenotypic quantification of heart function of intact fruit fly and zebrafish larvae | JoVE Visualize

Open access tool and microfluidic devices for phenotypic quantification of heart function of intact fruit fly and zebrafish larvae

Alireza Zabihihesari¹, Arezoo Khalili¹, Arthur J Hilliker²

¹Department of Mechanical Engineering, York University, Toronto, ON, Canada.

Computers in Biology and Medicine|March 28, 2021

View abstract on PubMed

Summary

Researchers developed new MATLAB software for in-vivo heart monitoring in fruit fly (Drosophila melanogaster) and zebrafish (Danio rerio) larvae using microfluidics. This automated system quantifies key heartbeat parameters in intact organisms, advancing cardiovascular research.

Area of Science:

Cardiovascular physiology
Developmental biology
Bioengineering

Background:

Conventional methods for quantifying heart activity in model organisms are complex, often requiring dissection or anesthesia.
Microfluidics enables reversible immobilization without anesthesia, but manual heart monitoring remains challenging due to organism movement and cardiac interruptions.
The larval stage of Drosophila melanogaster and Danio rerio is ideal for heart studies due to maturity, optical clarity, and myogenic hearts.

Purpose of the Study:

To develop and validate a novel MATLAB-based software for automated in-vivo quantification of heartbeat parameters in intact Drosophila melanogaster and Danio rerio larvae.
To overcome limitations of existing methods by enabling precise measurements in non-dissected, non-anesthetized organisms within microfluidic devices.
To establish a user-friendly platform for comprehensive cardiac function analysis in small model organisms.

Main Methods:

Utilized microfluidic devices for whole-organism assays and reversible immobilization of larvae.
Developed image segmentation algorithms within MATLAB software to automatically detect the heart and extract heartbeat signals.
Applied the smoothness priors approach (SPA) for noise reduction and M-mode imaging for detailed parameter quantification.

Main Results:

The software achieved over 94% accuracy in detecting heartbeats and cardiac arrests in intact Drosophila larvae.
Successfully quantified multiple cardiac parameters, including heart rate, arrhythmicity, end-diastolic/end-systolic diameters, shortening distance, fractional shortening, and shortening velocity.
Demonstrated the first in-vivo quantification of these comprehensive parameters in intact zebrafish and fruit fly larvae.

Conclusions:

The developed user-friendly software enables accurate in-vivo quantification of larval heart function in microfluidic devices for Drosophila melanogaster and Danio rerio.
This novel approach offers a significant advancement over traditional methods, allowing for detailed cardiac analysis in intact, living organisms.
The software has broad potential for application in other biological models and for high-throughput screening of drugs and genetic factors affecting heart function.