Automated measurement of cardiomyocyte monolayer contraction using the Exeter Multiscope

Previously, we introduced a microscope design that enabled rapid, random-access well plate imaging [ eLife, 10, e56426 (2021)10.7554/eLife.56426]. Here, we implement this design in a low-cost, compact, and portable prototype (the Exeter Multiscope) and apply it to the problem of capturing the contraction of cardiomyocyte monolayers, which have been plated into nine wells within a 96-well plate. Using a transmissive rather than reflective geometry, each well is sampled using 500 × 500 pixels across a 1.4 × 1.4 mm field of view, acquired in three colours at 3.7 Hz per well. The use of multiple illumination wavelengths provides post-hoc focus selection, further increasing the level of automation. The performance of the Exeter Multiscope is benchmarked against industry standard methods using a commercial microscope with a motorised stage and demonstrates that the Multiscope can acquire data almost 40 times faster. The data from both Multiscope and the commercial systems are processed by a 'pixel variance' algorithm that uses information from the pixel value variability over time to determine the timing and amplitude of tissue contraction. This algorithm is also benchmarked against an existing algorithm that employs an absolute difference measure of tissue contraction.