Clytia hemisphaerica medusae close epithelial wounds via sequential lamellipodia extension and actomyosin contraction without scar tissue

Malamy received transparent Clytia medusae from Houliston’s lab and recorded cell behavior at the Marine Biological Laboratory starting in 2014. Epithelial sheets close small wounds in minutes and larger ones in less than 60 minutes. No inflammation or vascular response occurs because the organism lacks an adaptive immune system. Confocal sequences show actin structures coordinating in fixed temporal order across wound sizes and shapes.

The 2023 Molecular Biology of the Cell paper establishes that both purse-string and cell-crawling mechanisms operate in the same tissue but are deployed sequentially rather than as alternatives. Actin staining and live imaging quantify the transition point when lamellipodia cease and cable contraction dominates. This sequence matches conserved epithelial behaviors reported in Drosophila and vertebrate models yet occurs without immune cell recruitment.

Transparency and absence of scarring allow direct observation of core cytoskeletal dynamics that remain obscured in mammalian assays. The same actin regulators appear in human keratinocytes, suggesting the Clytia circuit can be tested in organoid wound models. Operational translation requires mapping the molecular switches that trigger the lamellipodia-to-cable handoff.

Next steps include CRISPR perturbation of candidate actin-binding proteins in Clytia followed by quantitative wound-closure metrics in 2025–2026 experiments.