Figure 3
Detection of the particle displacement of the HMD and the analysis of tissue function. (a) Representative observation of microchannels loaded with particles. X indicates the axis of the particle position. The red square indicates the selected location in (b). (b) Representative pattern of particle displacement. The red dotted circles indicate the same particle at the end-diastolic (top) and end-systolic (bottom) phases during the pulsation of 3D cardiac microtissues. (c) Representative changes in the particle position in accordance with the interval and frequency of the electrical stimulation. After 500-ms interval stimulation, the HMD could capture 1 time point in 2 stimulations (2:1 block), which is equivalent to 1000-ms interval stimulation. (d) Representative relationship between the frequency of electrical stimulation (X) and the particle displacement distance in the whole beating cycle (Y). The results of the regression analysis are shown. All data are shown in Supplementary Fig. 2a. (e) Particle displacement distance and speed of the whole beating cycle at each electrical stimulation interval in HMDs constructed from the GCaMP3-253G1 (n = 7) and FFI01 s04 (n = 6) human iPSC lines, respectively. *P < 0.05. **P < 0.01. ***P < 0.001. (f) Calculation of the physiological parameters. ΔV = stroke volume, z = vertical displacement of the diaphragm, P = applied pressure, F = applied force, r = radius of the chamber, w = width of the microchannel, d = depth of the microchannel, and x = particle displacement distance. In (a) and (b), cellSens Standard (version 1.18) (https://www.olympus-lifescience.com/en/software/cellsens/) (Olympus) was used.
