Researchers at Tel Aviv University have developed spring-like fibers to help repair damaged heart tissue. Doctoral students Sharon Fleischer and Ron Feiner have fabricated fibers shaped like springs that allow engineered cardiac tissue to pump more like the real thing, the university said Monday in a release. \"Until now, when scientists have tried to engineer cardiac tissue, they\'ve used straight fibers to support the contracting cells. However, these fibers prevent the contraction of the engineered tissue,\" says Tal Dvir, who supervised the students\' work and is with the university\'s department of molecular microbiology and biotechnology. \"What we did was mimic the spring-like fibers that promote contraction and relaxation of the heart muscle. We found that by growing tissues on these fibers, we got more functional tissues.\" Cardiac tissue is engineered through cells taken from the hearts of patients or animals growing on a 3D scaffold, the university said. Over time, the cells join to form a tissue that generates its own electrical impulses and expands and contracts spontaneously. This tissue, the researchers said, then can be surgically implanted to replace damaged tissue and improve heart function in patients. Researchers said the spring-like fibers showed better mechanical properties than straight fibers, with especially improved elasticity, as the researchers theorized. \"These properties are very important, because we want to transplant the tissue into the human heart, which expands and contracts constantly,\" Fleischer said. The researchers say the processes for fabricating the fibers and assembling them into a scaffold must be refined. Most importantly, they say, the ability of the tissue to improve heart function after a heart attack needs to be tested in humans, which they say they will do in pre-clinical and then clinical trials.