A freely swimming jellyfish replica made from silicone polymer and rat heart cells is reported this week in Nature Biotechnology. The study, which advances a quantitative and system-level approach to tissue engineering, provides new insights into the design of muscular pumps.

             Kit Parker, John Dabiri and colleagues began by scrutinizing previous work on how jellyfish swim. They defined three key features of the jellyfish stroke cycle and predicted tissue-engineering approaches that might be able to mimic them. The jellyfish ‘power’ stroke—rapid, symmetric contraction of a compressible bell by a network of electrically active cells—might be copied by electrically stimulating a sheet of rat heart muscle cells. The slow ‘recovery’ stroke might be replicated by growing the rat heart cells on an elastic material that would return to its original shape. Additional in-depth analysis of young jellyfish revealed the local and global patterns of muscle-cell activation that underlie swimming. By varying the shape and muscle architecture of their designs, the authors succeeded in creating millimeter-sized constructs that closely simulate the swimming and feeding behaviors of jellyfish. The quantitative reverse engineering strategy developed in this study may be applicable to tissue engineering in a therapeutic context.