Jellyfish close wounds in minutes — and their repair mechanics may map to human skin

Researchers led by Jocelyn Malamy at the University of Chicago and the Marine Biological Laboratory are studying Clytia hemisphaerica, a transparent hydrozoan jellyfish, to understand wound healing. Clytia’s medusa form seals small wounds within minutes and larger ones in under an hour, without forming scar tissue — closer to scar-free embryonic healing than adult mammalian repair. Because the animals are transparent and lack an immune system that triggers inflammation, scientists can watch epithelial cells stitch tissue back together in a live animal in real time, unobscured by the complications present in mammals.

The key finding, published in Molecular Biology of the Cell, is that all epithelial wound healing in Clytia runs on two structures acting in sequence. First, lamellipodia — actin-rich, foot-like extensions — crawl across the basement membrane and drag their parent cells over the gap, a mechanism Malamy shows operates even in tiny wounds inside a single cell. Second, an actomyosin cable forms behind the advancing lamellipodia and contracts once they’ve covered the membrane, which becomes essential when debris or a torn membrane blocks the lamellipodia’s path. For wounds too large to span this way, the whole epithelial sheet lifts and migrates collectively until the leading cells meet. The work is significant because these mechanisms appear conserved across species: Malamy notes the jellyfish epithelial cells are indistinguishable from any squamous epithelium, suggesting insights could transfer to mammalian and human wound healing. Her next target is basement membrane repair, a process still poorly understood in any organism.