What? I will investigate what differentiates the extracellular matrix of the heart in two different vertebrate species. The pig, like other adult mammals, form a permanent fibrotic scar after injury while salamanders fully regenerate. I will explore whether the regenerative capacity of cells from pro-fibrotic hearts can be altered by the introduction of matrix from pro-regenerative salamander hearts. Why? All biological tissues consist of cells and a fibrous material known as the extracellular matrix, which makes up the scaffolding on which cells live, grow and move. It is becoming increasingly clear, that while the role of the ECM has traditionally been viewed mainly as structural support, the matrix can in fact control the fate and behavior of cells, including their capacity for repair. How? I will characterize the extracellular matrix of the pro-fibrotic pig and pro-regenerative salamander heart. I will then investigate how heart cells alter their behavior and capacity for repair when grown on pro-fibrotic versus pro-regenerative matrix. Ultimately, to what degree does the fundamental regenerative capacity of the vertebrate heart stem from the extracellular matrix?