Some varieties of hydra are immortal, in the sense that mortality rate and measures of function do not change over time. A hydra is in essence a sophisticated bundle of stem cells, somewhat analogous to an early embryo, capable of replacing any of its component parts. Are there aspects of hydra cellular biochemistry that could be introduced into more structured, sophisticated species to extend life? One view is that hydra-like strategies for longevity are incompatible with a central nervous system that retains information. Another view is that this point doesn't rule out all of the potentially interesting biochemistry in this species. Certainly, researchers have already started to move genes and other aspects of cellular biochemistry from long-lived species to short-lived species, such as from naked mole rats to mice, in order to test the bounds of the possible.
Hydra vulgaris ("Hydra") exhibits negligible senescence due to continuous self-renewal and stem cell cycling, contrasting sharply with short-lived, eutelic rotifers that exhibit rapid aging and fixed somatic cell numbers post-development. These organisms therefore represent extremes on the spectrum of invertebrate lifecycles and offer a unique opportunity to test whether patterns of gene expression associated with repressed senescence in Hydra can delay senescence in aging-prone animal models. We hypothesize that introducing Hydra-like gene expression profiles into rotifers (e.g., Brachionus manjavacas) via genetic manipulation will extend healthspan and reduce age-related mortality, providing proof-of-principle for effective manipulation of conserved anti-aging mechanisms.
While translation to humans remains highly speculative at this early stage, the rotifer-Hydra model provides a proof-of-principle framework for discovering targets potentially more relevant to mammalian aging than those from other invertebrate systems. If Brachionus manjavacas can, at least to some extent, exhibit more negligible senescence via transfer of relevant Hydra-like gene expression patterns, this would constitute the required proof-of-principle for the overall concept. It is a long leap from rotifers to geroprotective strategies for humans, but without the initial step from Hydra to rotifer, nothing else would likely be possible. Therefore, we posit that Hydra to rotifer, considered long term, is of relevance to the question of aging, senescence, and geroprotective strategies for humans.
Link: https://doi.org/10.18632/aging.206370
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