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In Pursuit of Immortality: The science behind life extension

Since the beginning of recorded history, humans have searched for the key to immortality and eternal youth.  From the epic of Gilgamesh, recorded on clay tablets around 2000 B.C., to Ponce de Leon's famed search for the fountain of youth in the new world, the extension of life has been a recurring theme for humanity.

Cryogenics_-System-web2Today, scientists are coming closer than ever to making real medical breakthroughs that will 'cure' aging and eventually bring an end to natural death.  Pharmaceutical discoveries, and advances in the fields of nanotechnology, cloning, stem cell research and cryonics offer tantalizing glimpses at a future free from old age, and the ability to actually reverse the aging process itself - possibilities that life extension experts feel could become a reality by 2019.  Of course, along with these discoveries come ethical questions about the meaning of life in the absence of death and the fate of religion, as well as concerns about overpopulation, boredom and why anyone would really want to live forever.

If the claims of life extension proponents sound far fetched, consider the fact that the average human lifespan has doubled since 1900 and continues to increase.  Enormous medical advances occurred during the 20th century, resulting in the development of medications and technology that were once unthinkable.  Less than 100 years ago, insulin was unknown and type 1 diabetes was a fatal and mysterious disease.  Now, insulin is an inexpensive and easily obtainable drug that saves lives every day.  Other medical devices that are common today, like internal pacemakers and contact lenses, were unthinkable just 100 years ago, and the rate of medical and scientific advances continues to increase.

In humans, like all mammals, aging begins almost as soon as we reach physical maturity.  In fact, with an average lifespan of 70 years and maximum verified lifespan of 122 years, a typical person today spends the majority of their life aging.  In biological terms, aging can be defined as an accumulation of damage to macromolecules like DNA, as well as cells, tissues and organs.  The differences in life span between species are determined by genetics, differences in the ability to repair damaged DNA, as well as differences in antioxidant enzymes and free radical production.  The science of life extension seeks to exploit these differences and alter the biological pathways involved in aging, with the ultimate goal of immortality.  In this feature, we'll discuss some of the most promising approaches in life extension science.

Chemical Life Extension

resveratrol-pictureFor years it's been common knowledge that drinking red wine (in moderation) is good for your heart.  What we didn't know was why.  Then, in 1992, a chemical named resveratrol was suggested as the cause of the cardioprotective properties of wine. Unfortunately, you'd have to drink hundreds of bottles of wine each day to consume enough resveratrol to see a significant effect, so work on a pharmaceutical form of resveratrol was begun.  Researchers have since shown that resveratrol extends the lifespan of yeast1, but studies in other species have had conflicting results.  A 2008 study on mice found that while resveratrol causes changes in gene expression that are similar to those caused by dietary restriction and mice had fewer signs of old age, unfortunately they didn't live any longer than typical mice2.

In 2008, pharmaceutical giant Glaxo Smith Kline purchased Sirtris, the company which is developing a proprietary form of resveratrol, for $720 million dollars.  Their product, SRT501 is now in Phase 2 clinical trials, and could be available in as little as 6 years.  It will be years though, before we will know whether resveratrol will extend the human lifespan.

The latest discovery is a naturally occurring substance found in the soil of Easter Island, in the southeastern Pacific Ocean. Rapamycin has shown to extend the life expectancy of laboratory mice by up to 38% . Professor Randy Strong, of the University of Texas Health Science Center, said: "We believe this is the first convincing evidence that the ageing process can be slowed and lifespan can be extended by a drug therapy starting at an advanced age."

Another leading researcher Dr Arlan Richardson was quoted as saiyng "I never thought we would find an anti-ageing pill for people in my lifetime; however, rapamycin shows a great deal of promise to do just that."

Despite the recent hype, there is not yet conclusive evidence and a UK expert has warned that it can suppress immunity.

Therapeutic cloning and stem cells

To some researchers, therapeutic cloning is the most practical approach to life extension because compared to other methods, current technology for cloning is much more advanced.  We already know how to make stem cells, and are learning more constantly about how to direct them to form different types of cells.  In order to clone the cells of a patient and create a new organ or tissue, the process starts by taking a donor egg, and replacing its nucleus with the nucleus from a patient's cell, creating an embryo.  The new cell is then be stimulated to divide, and after a few days, at the blastocyst stage of development, there are stem cells available to collect.

How_stem_cells_work

These brand new stem cells have the ability to turn into any type of cell in the human body, like muscle, blood cells or nerve cells.  Scientists grow them in a culture dish, and are working to learn what chemicals or other instructions to add to tell them what type of organ or tissue to form.  Ultimately, these newly formed, specialized cells will be injected into patients to heal damaged body parts, or used to grow whole new organs.  One possible application of this process is to make bone marrow from stem cells and then inject them into the body.  The bone marrow cells would find their way into the patient's bone marrow, and the new cells could rejuvenate many parts of the body.

Scientists have already had success growing simple organs and tissue from stem cells in laboratory experiments.  This work is being accelerated by the Armed Forces Institute of Regenerative Medicine or AFIRM, which is a $250 million initiative in cooperation with researchers at Wake Forest and Rutgers that is using soldiers' own stem cells to grow skin, muscles, tendons and bone.  It will take more research, but scientists hope to be able to clone more complex organs like hearts in the future.

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