At the base of the material is a rubbery gel known as MeTro. It’s made from tropoelastin, which is the protein that gives human tissues their elasticity.
A team working in the lab of Dr. Ali Khademhosseini made sheets of the material by taking some of the gel in its liquid state, and pressing it between a glass slide and a flat mold with a micro-patterned surface. Ultraviolet light was applied to help the gel set. Once it solidified, one side of the gel took on the pattern of the mold. The BWH scientists experimented with a variety of patterns, all of which were designed to make the material highly elastic, while retaining sufficient mechanical strength for use on the heart.