Historical and Cultural Background

Various myths tell the stories about the quest for rejuvenation. It was believed that magic or intervention of a supernatural power can bring back the youth and many mythical adventurers set out on a journey to do that, for themselves, their relatives or some authority that sent them. 

In some religions people were to be rejuvenated after death prior to placing them in heaven. 

The stories continued well into the 16th century. A famous Spanish explorer Juan Ponce de León led the expedition around the Caribbean islands and into Florida to find the Fountain of Youth. Led by the rumours, the expedition continued the search and many perished. The Fountain was nowhere to be found as locals were unaware of its exact location. 

Since the emergence of philosophy, sages and self-proclaimed wizards always made enormous efforts to find the secret of youth, both for themselves and for their noble patrons and sponsors. It was widely believed that some potions may restore the youth. 

Another commonly cited approach was attempting to transfer the essence of youth from young people to old. Some examples of this approach were sleeping with virgins or children (sometimes literally sleeping, not necessarily having sex), drinking their blood. 

The quest for rejuvenation reached its height with Alchemy. All around the Europe and also beyond alchemists were looking for the Philosopher's Stone, the mythical substance that, as it was believed, could not only turn lead into gold, but also prolong life and restore youth. Although the set goal was not achieved, Alchemy paved the way to the scientific method and so to the medical advances of today. 

Modern developments

According to modern science, there are no natural laws preventing successful rejuvenation. Aging is an accumulation of damage to macromolecules, cells, tissues and organs. If any of that damage can be repaired, the result is rejuvenation. 

There have been many experiments which have been shown to increase the maximum life span of laboratory animals, thereby achieving life extension. A few experimental methods have had limited success in partially rejuvenating laboratory animals and humans, such as replacing hormones to youthful levels. 

Most attempts at genetic repair have traditionally involved the use of a retrovirus to insert a new gene into a random position on a chromosome. But by attaching zinc fingers (which determine where transcription factors bind) to endonucleases (which break DNA strands) homologous recombination can be induced to correct and replace defective (or undesired) DNA sequences. The first applications of this technology are to isolate stem cells from the bone marrow of patients having blood disease mutations, to correct those mutations in laboratory dishes using zinc finger endonucleases and to transplant the stem cells back into the patients (SCIENCE; 310:1894-1896 (2005)). 

Regenerative medicine uses three different strategies: (1) implantation of stem cells from culture into an existing tissue structure (2) implantation of stem cells into a tissue scaffold that guides restoration or (3) induction of residual cells of a tissue structure to regenerate the necessary body part. A salamander can not only regenerate a limb, but can regenerate the lens or retina of an eye and can regenerate an intestine. For regeneration the salamander tissues form a blastema by de-differentiation of mesenchymal cells, and the blastema functions as a self-organizing system to regenerate the limb (SCIENCE; 310:1919-1923 (2005)). 

Yet another option involves cosmetic changes to the individual to create the appearance of youth. These are generally superficial and do little to make the person healthier or live longer, but the lack of depressing over their appearance may elevate their mood, and have positive side effects normally correlated with happiness. Cosmetic surgery is a large industry offering treatments such as removal of wrinkles ("face lift"), removal of extra fat (liposuction) and reshaping or augmentation of various body parts (abdomen, breasts, face). There are also, as always in history, many fake rejuvenation products that do not work.