They discover clues to aging and healing from a small sea creature

June 30 () –

Researchers at the US National Institutes of Health and their collaborators have discovered New insights into healing and aging by studying how a tiny sea creature regenerates a whole new body from his mouth aloneas published in the magazine ‘Cell Reports’.

The researchers sequenced the RNA of the ‘Hydractinia symbiolongicarpus’, a small tube-shaped animal that lives in the shells of hermit crabs. Just when the ‘Hydractinia‘ began to regenerate new bodies, the researchers detected a molecular signature associated with the biological process of aging, also known as senescence.

According to the study, ‘Hydractinia’ demonstrates that the fundamental biological processes of healing and aging are intertwinedwhich provides a new perspective on how aging evolved.

“Studies like this one, which explore the biology of unusual organisms, reveal both how universal many biological processes are and how much remains to be understood about their functions, relationships, and evolution. says Dr. Charles Rotimi, director of the Intramural Research Program at the National Human Genome Research Institute (NHGRI). These discoveries have great potential to provide new knowledge about human biology“.

Unraveling the evolutionary origins of fundamental biological processes, such as aging and healing, is essential to understanding human health and disease. Humans have some regenerative ability, such as healing a broken bone or even regenerating a damaged liver.

Other animals, such as salamanders and zebrafish, can replace entire limbs and replace various organs. However, animals with simple bodies, such as ‘Hydractinia’, often have the most extreme regenerative abilities.like growing a whole new body from a piece of tissue.

The regenerative role of senescence contrasts with the findings in human cells. “Most of the studies on senescence are related to chronic inflammation, cancer and age-associated diseases,” explains Andy Baxevanis, MD, NHGRI scientist and study author.

“Normally, in humans, senescent cells remain senescent, and these cells cause chronic inflammation and induce aging in adjacent cells. –Add–. From animals like Hydractinia, we can learn about how senescence can be beneficial and expand our understanding of aging and healing.”

Previously, researchers discovered that Hydractinia have a special group of stem cells for regeneration. Stem cells can change into other types of cells, so they are useful for creating new body parts.

In humans, stem cells are primarily involved in development, but highly regenerative organisms like Hydractinia use stem cells throughout their lives, storing their regenerative stem cells in the lower trunk of their bodies.

However, when researchers remove its mouth — a part away from where the stem cells reside — it grows a new body. Unlike human cells, which are locked in their fates, the adult cells of some highly regenerative organisms can revert to stem cells when the organism is injured, although this process is not well understood.

Therefore, the researchers theorized that the ‘Hydractinia’ must generate new stem cells and they looked for molecular signals that could direct this process.

When RNA sequencing pointed to senescence, the researchers scanned the Hydractinia genome for sequences similar to genes associated with human senescence. Of the three genes they identified, one was “turned on” in cells near where the animal was cut.

When the researchers deleted this gene, the animals’ ability to develop senescent cells was blocked, and without the senescent cells, the animals did not develop new stem cells and could not regenerate.

The researchers tracked senescent cells in Hydractinia to find out how this animal navigated the deleterious effects of senescence. Unexpectedly, the animals expelled the senescent cells through their mouths. Although humans can’t get rid of aging cells so easily, the functions of senescence-related genes in Hydractinia suggest how the aging process evolved.

The last time humans shared an ancestor with Hydractinia and their close relatives jellyfish and corals was more than 600 million years ago, and these animals do not age. Due to these factors, ‘Hydractinia’ can provide crucial information about our first animal ancestors. Therefore, the researchers theorize that regeneration could be the original function of senescence in the first animals.

“We still don’t know how senescent cells trigger regeneration or how widespread this process is in the animal kingdom,” says Dr. Baxevanis. “Hopefully, by studying some of our more distant animal relatives, we can begin to unlock some of the secrets of regeneration and aging, secrets that may ultimately also advance the field of regenerative medicine and the study of age-related diseases.”