Associate Professor Syracuse University, United States
Introduction:: The heart is one of the most critical organs in the human body and the earliest developmental organ. Developmental defect in heart development in the embryo are highly related to maternal medication. Over 5.4 million pregnant women are under hazard of medicine toxicity, though the mechanism is still unclear. Traditional developmental drug screening models are usually based on the animal model or microarray with human cells, which are different from the human biology or difficult to mimic the developmental process. Therefore, a standard human-based testing platform for developmental toxicity testing in embryonic cardiac development is urgently needed.
Materials and Methods:: Our lab has developed a human-iPSC-derived cardiac organoid platform by micropatterning the PEG film using plasma etch, which has been proven to mimic the development of cardiac tissues and sensitively respond to various developmental factors. We created the GCaMP6f-reporter cardiac organoids with 600-µm circle pattern, which was the most suitable geometrical pattern for cardiac organoid development. Cardiac differentiation was completed using CHIR and IWP4 to modulate the WNT signaling pathway. Tested drugs were added into the differentiation media with different concentrations at day 1 after mesoderm induction, until the completion of entire differentiation. Brightfield and GCaMP videos were recorded after 20-day-culture and analyzed by Matlab software.
Results, Conclusions, and Discussions:: Results: Cardiac organoids were successfully developed for drug screening purpose. Functional cardiac organoids were developed in the center of pattern (Figure 1 A), which showed stable and rhythmic beats (Figure 1 B). GCaMP signal change showed intracellular calcium transient during cardiac function, which proved functional tissues to locate in the center of pattern (Figure 1 C, D). The difference of cardiac organoid function indicates the impact of drug toxicity on cardiac development. Taking an example of one of the tested drugs, folic acid (category A drug), we found no significant difference in beating rate, but increased contraction and relaxation velocity with the increase of concentration. Calcium signal recovered faster in the higher concentration groups (Figure 1 E, F, G). For the drug 5-fluorourcil (category X drug), cardiac development was highly impacted by the drug, which was showed as no beating organoid in the culture with high concentrations. 5-fluorourcil also increased the beat rate and decreased the calcium peak time and decay time (T30, T50, T75) (Figure 1 H, I, J).
Conclusions: Although the drugs have their unique toxicity effects on cardiac development, high concentration of most drugs interfere the cardiac functions which showed as lower bearing rate and reduced contraction velocity. Compared to prescription medicine, necessary nutritional content has lower toxicity in cardiac organoids.
