Scientists in the U.S. and Portugal have developed a method for growing adult-like human heart muscle from blood-derived human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs), in just four weeks. The resulting heart muscle displayed features, including adult-like gene expression and an organized ultrastructure, which hasn’t been demonstrated using other methods for growing human heart tissue in the laboratory.

Key to the Columbia University-led team’s achievement was the use of early-stage hiPS-CMs that have only just started to contract spontaneously, and subjecting these cells to an increasingly intense conditioning regime that triggers the developing heart tissue to mature. “The common approach in our field has been that the more mature the starting cardiomyocytes, the better,” says Kacey Ronaldson-Bouchard, Ph.D., first author of the researchers’ published paper in Nature . “However, we found that very early-stage cells, which still have developmental plasticity, would respond better to the external signals we …