Scientists have found a way to use spinach to build working human heart muscle, potentially solving a long-standing problem in efforts to repair damaged organs.

Their study, published this month by the journal Biomaterials, offers a new way to grow a vascular system, which has been a roadblock for tissue engineering.

Scientists have already created large-scale human tissue in a lab using methods like 3D printing, but it’s been much harder to grow the small, delicate blood vessels that are vital to tissue health.

“The main limiting factor for tissue engineering … is the lack of a vascular network,” says study co-author Joshua Gershlak, a graduate student at Worcester Polytechnic Institute (WPI) in Massachusetts, in a video describing the study. “Without that