Rejuvenation (aging)

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Rejuvenation describes the artificial reset of biological aging processes .

Rejuvenation is different from retirement . Antiaging strategies often examine the causes of aging and try to counteract these causes in order to slow down aging . Rejuvenation, however, aims to reverse aging . Rejuvenation therefore requires a different strategy, namely repairing age-related cell and tissue damage or replacing damaged tissue with new tissue. Rejuvenation can be a means of lengthening life, but most life lengthening strategies do not involve rejuvenation.

Historical and cultural background

There are numerous legends about the pursuit of rejuvenation. It was believed that magic or the intervention of some supernatural force could bring youth back to life, and many adventurers ventured on journeys to regain youth - for themselves, their relatives, or the authorities who sent them.

The founder of the Chinese Empire, Qin Shihuangdi , sent ships with young men and women to find a pearl to rejuvenate him. According to a myth, they reached and colonized Japan .

The stories continued into the sixteenth century. The famous Spanish explorer Juan Ponce de León led an expedition to the Caribbean islands and Florida , also supposedly to find the source of eternal youth . Led by legend, the expedition continued its search while many died on board. The well was never found.

Since the beginning of philosophy , wise men and self-appointed magicians have made great efforts to unravel the mystery of youth; both for themselves and for their patrons and sponsors . It was widely believed that certain potions could restore youth to youth.

Another approach often cited was to try to transfer the youth essence of young people to old ones. Examples of this approach have been sleeping (sometimes literally sleeping, not necessarily having sex) with virgins or children , bathing in their blood, or drinking it.

The pursuit of rejuvenation reached its climax with alchemy . All over Europe and beyond, alchemists searched for the Philosopher's Stone , the mythical substance which, it was believed, could not only turn lead into gold, but also prolong life and restore youthfulness. Although this goal was not achieved, alchemy paved the way for scientific methodology and thus for today's medical advances.

Serge Abrahamovitch Voronoff was a Russian-born surgeon who worked in France in the 1920s and 1930s who achieved fame for his technique of transplanting testicular tissue from monkeys into human testicles. This was one of the first medically accepted rejuvenation therapies (before it was proven wrong in the 1930s-1940s). Technology made him a lot of money even though he was already wealthy. When his work fell out of favor, he descended from a highly respected surgeon to a subject of ridicule. By the early 1930s, 500 men had already been treated with his rejuvenation technique in France, and thousands more around the world, such as in a specially set up clinic in Algeria . Notable individuals who underwent this treatment include Harold McCormick , then Chairman of the International Harvester Company , and the aging Turkish Prime Minister.

There are more and more works in fiction that deal with the possibilities of rejuvenation treatments and their effects on society. Misspent Youth and the Commonwealth Saga by Peter F. Hamilton are among the best-known examples that tell of the short- and long-term effects of an almost perfect body change from an 80-year-old to a 20-year-old with an intact mind. The Mars trilogy is about a much more imperfect rejuvenation, including problems such as long-term memory loss and sheer boredom from extremely old age. The post-mortem figures in the Revelation Space cycle often illustrate this theme with their extremely long or basically unlimited lifespans; sheer boredom drives them to undertake risky activities.

Modern developments

Biological aging manifests itself in the accumulation of damage in macromolecules , cells , tissues and organs . If this damage can be repaired, the result is rejuvenation.

Some technologies that are attempted to achieve this goal are counted as regenerative medicine , such as the stimulation of the body's own regeneration and repair processes or the young tissue engineering area. Some simple tissues and organs such as urinary bladders have already been successfully implanted in patients, but the cultivation of fully functional complex human organs such as the heart or lungs is still a long way off.

Another alternative is cosmetic changes to restore a youthful appearance. These are generally superficial and do not improve health or extend life, however an improvement in a person's appearance can lift their mood and have positive side effects. The cosmetic surgery is a big industry that treatments such as wrinkle removal ( rhytidectomy ), removal of excess fat ( liposuction ) and reshaping of various body parts ( abdomen , breasts , face ) includes.

There are also, as always in history, many supposed rejuvenation products that don't work. Often these are powders, sprays, gels and homeopathic remedies that pretend to be a "growth hormone". The real growth hormone can only be injected because the amino acid protein is too large to be absorbed by the mucous membranes and would break down in the stomach if swallowed.

The Methuselah Mouse Prize is a scientific competition award with the ultimate goal of extending people's healthy lifespans. Its aim is to accelerate the development of revolutionary new rejuvenation therapies by giving away two cash prizes: one for the research team that breaks the world record for the oldest mouse ever; and one for the team developing the most successful old age rejuvenation therapy for mice.

Strategies for Engineered Negligible Senescence (SENS)

One of the leading modern scientific exponents of rejuvenation is the biogerontologist Aubrey de Gray. He calls his project to repair the damage that we call aging “SENS” (Strategies for Engineered Negligible Senescence, in German about “Strategies to make the aging process negligible by technical means”). For each of the known damage classes, which he calls the "seven deadly sins of aging", he suggests the following strategies to combat:

  1. In the case of muscles, cell loss can be repaired (reversed) through appropriate training . Other types of tissue would require various growth factors to stimulate cell division and in some cases stem cells would be needed.
  2. Aged cells could be removed by turning the immune system against them. Or they could be destroyed by gene therapy , by introducing "suicide genes " that specifically kill aged cells.
  3. Protein crosslinking can largely be reversed by drugs that break the links. However, in order to break some of these links, the development of enzymatic methods is likely to be necessary.
  4. Extracellular waste (such as amyloid ) could be eliminated through vaccinations that induce immune cells to "eat" the waste.
  5. To remove intracellular waste, novel enzymes would have to be used, which may be obtained from soil bacteria that can break down the waste ( lipofuscin ). Enzymes naturally occurring in the human body cannot break down this substance.
  6. In the case of mitochondrial mutations, the plan is not to repair them, but to prevent damage caused by the mutations by using gene therapy to move modified copies of the mitochondrial genes into the cell nucleus . The mitochondrial DNA experiences a high degree of mutagen damage because most of the free radicals are created in the mitochondria. A copy of the mitochondrial DNA in the nucleus will be better protected from free radicals and better DNA repair will take place when damage occurs. All mitochondrial proteins would then be imported into the mitochondria.
  7. In cancer (the deadliest consequence of mutations ) the strategy is to use gene therapy to delete the genes for telomerase and to eliminate telomerase-independent mechanisms that turn normal cells into "immortal" cancer cells. To compensate for the loss of telomerase in the stem cells, we would add fresh stem cells approximately once every decade, depending on the tissue.

These seven damage classes were discovered between 1907 and 1982, and no new ones have been added since then.

In 2009, Aubrey de Gray co-founded the SENS Foundation to drive progress in the areas listed above.

Scientific journal

Rejuvenation processes in nature

A salamander can renew not only a limb , but also the lens or retina of the eye and the intestines . For renewal, the salamander tissues form a blastema through differentiation of the mesenchymal stem cells . The blastema acts as a self-organizing system to renew the limb.

See also

Web links

Individual evidence

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