Discovery of Jellyfish Tentacle Regeneration: Unveiling the Remarkable Role of Stem-Like Proliferative Cells

In a groundbreaking study, Japanese scientists have unraveled the mystery behind how Cladonema jellyfish can regenerate their tentacles in just a matter of days. This revelation sheds light on the pivotal role played by unique stem-like proliferative cells in this rapid regenerative process, offering valuable insights into similar regenerative phenomena in various species.

The Cladonema jellyfish, measuring no larger than a pinkie nail, can astonishingly regrow a severed tentacle within a mere two to three days. This remarkable ability to regenerate functional tissue is not exclusive to jellyfish but extends across species, encompassing salamanders and insects. At the heart of this regenerative prowess lies the formation of a blastema, a cluster of undifferentiated cells capable of repairing damage and eventually developing into the missing appendage. While jellyfish, along with other cnidarians like corals and sea anemones, have long been known for their exceptional regenerative abilities, the mechanism behind the crucial blastema formation has remained an enigma until now.

A team of researchers based in Japan has unveiled a key revelation: stem-like proliferative cells, actively dividing and growing but not yet specialized into specific cell types, emerge at the site of injury and collaborate in the creation of the blastema. These findings, published on December 21 in the esteemed scientific journal PLOS Biology, represent a significant leap in our understanding of regenerative processes.

Notably, these stem-like proliferative cells within the blastema differ from the resident stem cells typically found within the tentacle. Yuichiro Nakajima, the corresponding author and a lecturer in the Graduate School of Pharmaceutical Sciences at the University of Tokyo, elucidates that the repair-specific proliferative cells primarily contribute to the epithelium, the thin outer layer, of the newly formed tentacle. In contrast, the resident stem cells, present in and around the tentacle, are responsible for generating all cellular lineages during the jellyfish’s normal maintenance and repair activities. The repair-specific proliferative cells make their appearance solely in response to injury, thus enabling the rapid regeneration of a fully functional tentacle within a few days. This swift regeneration is of particular significance since jellyfish rely on their tentacles for hunting and feeding.

The research findings also offer insights into the nuances of blastema formation across different animal groups. Sosuke Fujita, the first author and a postdoctoral researcher in the same laboratory as Nakajima, explains that their aim was to dissect the mechanism of blastema formation using the tentacle of the cnidarian jellyfish Cladonema as a regenerative model. Importantly, Cladonema is considered a non-bilaterian, an animal that does not undergo bilateral (left-right) development during embryonic growth. Fujita’s work may thus provide valuable evolutionary perspectives.

Comparatively, salamanders, being bilaterian animals capable of regenerating limbs, possess stem cells specialized for specific cell-type needs, akin to the repair-specific proliferative cells observed in jellyfish. Fujita posits that these repair-specific proliferative cells serve as analogs to the restricted stem cells in bilaterian salamander limbs, suggesting that blastema formation by such cells is a common feature independently acquired for the regeneration of complex organs and appendages during animal evolution.

While the cellular origins of the repair-specific proliferative cells in the blastema remain a mystery, the researchers acknowledge the limitations of current tools to investigate their source or identify other similar stem-like cells. Nakajima emphasizes the need for genetic tools that can trace specific cell lineages and manipulate Cladonema, which could ultimately yield insights into blastema formation mechanisms in regenerative animals, including jellyfish. Such knowledge may, in the long run, aid in identifying cellular and molecular components that can enhance our own regenerative capabilities.

This research was made possible through grants from various organizations, including the Japan Society for the Promotion of Science KAKENHI, Japan Science and Technology Agency, Japan Agency for Medical Research and Development, and Japan’s National Institute for Basic Biology collaborative research program.

Reference: “Distinct stem-like cell populations facilitate functional regeneration of the Cladonema medusa tentacle” by Sosuke Fujita, Mako Takahashi, Gaku Kumano, Erina Kuranaga, Masayuki Miura, and Yu-ichiro Nakajima, published on December 21, 2023, in PLOS Biology. DOI: 10.1371/journal.pbio.3002435.

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More about Jellyfish Tentacle Regeneration

• PLOS Biology: Link to the scientific journal where the research findings were published.
• Cladonema Jellyfish: Information about Cladonema jellyfish for further context.
• Stem Cells: Explanation of stem cells and their roles in regeneration.
• Regenerative Biology: Overview of regenerative processes in animals.
• Japan Society for the Promotion of Science: Information about the organization that provided funding for the research.