Stem cell potential – the wave of the future?

Did you know that our bodies are programmed to live to about 120 years of age?  In reality, however, most life spans are roughly around 80 years.  Successful aging is defined as “changes due solely to the aging process, uncomplicated by damage from environment, lifestyle, or disease” – meaning that our ability to live longer can be disrupted by severe illness, severe trauma, and abnormal aging.  There is increasing evidence, however, that regenerative properties of stem cells can cure many age-related complications and delay the aging process.

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Our bodies contain many specialized – or differentiated – cells that carry out specific functions.  In contrast, a stem cell is undifferentiated.   As non-specific cells without any tissue-specific structure, stem cells can easily replicate themselves to form multiple cell types that perform specific functions like heart muscle cells, blood cells, sperm cells and nerve cells, for example.  These regeneration properties make stem cells ideal for anti-aging therapy.

Research shows that stem cells can stall the progress of some of high profile diseases by isolating cells from a patient with a genetic disorder and creating induced pluripotent stem cells.  The defective gene is replaced with a functional copy.  Then, cells are differentiated into the proper cell type and put back into the patient, restoring the vitality and functionality of the organs.  This process has been used to cure mice of Sickle Cell Anemia, suggesting that it may one day work on humans.

“In many cases, no modification is needed at all, only amplification,” says Aubrey de Grey, a British biomedical gerontologist and chief science officer of a foundation dedicated to longevity research.  “In other words, the only problem is that the body is supplying too few such cells to the places they’re needed.”

Building upon technology developed for bone marrow transplants, researchers are mounting new ways to use adult stem cells.  Tissue engineers are already working on growing patches for repairing damaged heart tissue.  And animal testing focuses on the ability to grow whole hearts, livers, lungs, and kidneys.  Stem cell transplants also show promise for treating spinal cord injuries, and the cells are helping us learn about cancer.  Like stem cells, cancer cells grow rapidly and remain undifferentiated.  “Cancer is arguably the most difficult part of aging to fix, and removing the ability for cells to divide indefinitely (which stem cells are normally supposed to be able to do) may be an important part of this,” says de Grey.  If we learn how stem cell growth and differentiation are regulated, we may be able to develop new drugs for treating cancer.

De Grey, who works with an international advisory board, is making headlines with his claim that physicians might soon be able to “cure” aging altogether.  If he’s right, the first person who will live to see their 150th birthday has already been born.  “I’d say we have a 50-50 chance of bringing aging under what I’d call a decisive level of medical control within the next 25 years or so,” he said in an interview with Reuters.  “And what I mean by ‘decisive’ is the same sort of medical control that we have over most infectious diseases today.”

Skeptics call these musings pseudoscience.  “Past and anticipated advances in geriatric medicine will continue to save lives and help to manage the degenerative diseases associated with growing older, but these interventions only influence the manifestations of aging – not aging itself,” say Doctors Olshansky, Hayflick and Carnes in a position statement on human aging.  Advocates of what has become known as anti-aging medicine claim that it’s now possible to slow, stop or reverse aging through existing medical and scientific interventions.  Olshansky et. al. caution, “There are no lifestyle changes, surgical procedures, vitamins, antioxidants, hormones or techniques of genetic engineering available today that have been demonstrated to influence the processes of human aging.”  Preventive measures are an important part of geriatric care, and following medical advice on nutrition, exercise and smoking can increase your lifespan, however these changes will not affect the process of growing old.  Anti-aging claims tied to specific drugs, vitamins or esoteric hormone mixtures aren’t supported by scientific evidence nor proven to modify the underlying processes of aging.

To combat these processes, de Grey says the desired effect is simply to replace cells that the body does not automatically replace (by division and differentiation) when they die.  He maintains that aging is basically the lifelong accumulation of molecular and cellular damage throughout the body.  Through specialized treatment, physicians will one day be able to fix those problems before they can cause irreparable damage.  De Grey envisions a time when “preventative geriatrics” require patients to go to the doctor for regular maintenance-type visits – undergoing a cocktail of gene and stem cell therapies, immune stimulation, and other medical advances to periodically stop molecular and cellular damage before it stops them.

“Stem cell therapies will almost certainly not greatly postpone the ill-health (and consequent death) associated with old age by more than a few years on their own.  However, in combination with a range of other therapies, they may do far more:  indeed, I’m pretty sure that we will eventually develop a panel of regenerative interventions that allow us to postpone age-related ill-health indefinitely,” says de Grey.  “This will have all manner of consequences for humanity, but I’m quite sure that none of those consequences, even in the absolute worst case scenario, could come close to outweighing the benefits of alleviating all the suffering that is currently associated with getting old.”

Med Monthly
Sep 2011