In the medusa stage of the cnidarian Cladonema pacificum, an organism with exceptional regenerative capacity, aging produced progressive structural shrinkage, loss of differentiated neurons and stinging cells, accumulating DNA damage, and depletion of stem cell-associated populations. Aged animals showed delayed wound closure, defective blastema formation, and incomplete tentacle recovery, indicating that regenerative decline is not avoided even in species built for repair. The finding places limits on regeneration as a conserved feature of aging across the animal kingdom rather than a mammal-specific constraint.
Key Points
- Aged jellyfish showed delayed wound closure and defective blastema formation
- Stem cell populations, neurons and proliferative activity declined with age
- Regenerative decline appears conserved even in highly regenerative species
Longevity Analysis
Repair capacity depends less on the injury response itself than on the condition of the tissue before injury occurs. Here, the loss of proliferating stem cell populations, the attrition of neurons and specialized cells, and accumulating DNA damage preceded the failure to rebuild a tentacle — the regenerative deficit was downstream of a deteriorating baseline. For human health optimization, the implication is that interventions aimed at regeneration must address the maintenance of the stem cell pool and the burden of genomic damage long before repair is demanded, and that early markers of declining tissue turnover carry more predictive weight than post-injury recovery speed.
Original published by Wiley Aging Cell, by Ren Kanehisa, Hiroko Nakatani, Sho Takatori, Taisuke Tomita, Masayuki Miura, Yu‐ichiro Nakajima .