Objective To construct cardiac microtissues using hiPSC-CPCs combined with fibrin gel for heart development
research and drug screening. Methods Human induced pluripotent stem cells were differentiated into cardiac progenitor cells
(hiPSCs-CPCs) by chemical differentiation method, and they were identified before being mixed in fibrin gel to construct 3D
microtissues. Cardiac microtissues were obtained when hiPSC-CPCs were differentiated into hiPSC-CMs. The morphological
changes of cardiac microtissues were observed during the culture period. The cardiac microtissues on day 15th and 30th were fro
zen sectioned and identified by immunofluorescence. The sarcomere length, Z-line width and Z-line alignment of hiPSC-CMs in
cardic microtissues were statistically analyzed. Calcium signal changes in cardiac microtissues on day 15th and 30th were detected
successfully by calcium imaging. MUSCLEMOTION ImageJ macro was used to analyze the contraction of cardiac microtissues on
day 15th and 30th
, the responses of cardiac microtissues to drugs were also detected by this software. Results hiPSC-CPCs can
be efficiently differentiated using chemical differentiation method, and cardiac microtissues with spontaneous beating could be
obtained when the microtissues were cultured to day 10th
. The cardiac microtissues could still maintain the morphology without
the occurance of dissolution after being cultured to day 30th
. Immunofluorescence results showed that cardiac microtissues ex
pressed myocardial markers cTnT and α-actinin highly. And the statistical results showed that the sarcomeres’
structure tended
to be more mature with the prolongation of culture time. Calcium imaging showed that the calcium signals of cardiac microtissues
can be detected successfully, and the prolongation of culture time may improved the consistency of calcium signal. The results of
MUSCLEMOTION ImageJ macro showed that the contraction frequency of cardiac microtissues decreased, while the contraction
amplitude increased by prolonging the culture time. The cardiac microtissues could be stimulated by isoproterenol successfully.
And the longer the incubation time, the more obvious the reaction of cardiac microtissues to isoproterenol. Conclusion Fibrin
gel combined with hiPSC-CPCs can successfully construct cardiac microtissues which is sustainable, calcium signal and con
traction easily detectable, drug response sensitive, and promising to be a useful tool for studying cardiac development and drug
screening.