During a heart attack, clots or narrowed arteries block blood flow, harming or killing cells within the tissue. The damage doesn’t end after the pain subsides. Instead, the heart’s walls thin out, the organ becomes enlarged, and scar tissue forms. If nothing is done, the patient can eventually experience heart failure. Scientists from the University of Pennsylvania have developed gels that, in animal tests, can be injected into the heart to shore up weakened areas and prevent heart failure. They developed a hydrogel that forms additional crosslinks between the polymer chains after injection. The resulting material is stiffer and lasts longer than a gel without these additional crosslinks and the gels in clinical trials. The gel is unique among hydrogels in providing mechanical support to stabilize the damaged area.