Researchers are now able to use induced pluripotent stem cells (iPSC) to form a model of human adult-like cardiac muscle by introducing electric and mechanical stimulation at an early stage. Since this muscle is similar to the adult heart, it could serve as a better model for testing the effects of drugs and toxic substances than current tissue-engineered heart models. The study, performed by scientists at Columbia University, New York City, and funded by the National Institutes of Health, was published today in Nature.