Intervening in Aging
While we grow older waiting for a wider acceptance of genetic theories of aging, we can at least take advantage of the knowledge that already exists. Several genes, for instance, are known to be associated with extreme longevity.11,12 If we can mimic what they do in people who have ordinary genes, we may gain some valuable time. Drug approaches have already been pursued for this purpose, and dietary supplements may also be effective in this respect, as suggested by Rose.
But there are also many common genes that change their expression with aging in counterproductive ways, and we have tools by which we might be able to prevent and reverse these detrimental changes in ordinary genes. For example, Sangamo Biosciences is developing “zinc finger” proteins that can be used for this purpose, as reported on their web site.13 If their approach is fruitful, the zinc finger proteins could be targeted to specific cells by keying them to appropriate receptors, which would allow them to enter and therefore to turn a gene on or off in particular cells. Since only a relatively small number of master genes seem to be involved in controlling the aging process, a set of these modulators could be sufficient to facilitate greater human longevity.
One of the benefits could be the correction of a form of “cellular constipation” that may underlie a surprisingly large fraction of the aging process. Normally when proteins are damaged, the human body breaks them down into amino acids and rebuilds them, but the rate of autophagy (which means, literally, “self- eating”) diminishes in cells with age, allowing damage to accumulate with time. Researcher Ana Marie Cuervo, MD, PhD, has already engineered her own specific remedies to address this problem. A paper she coauthored describes work that has successfully rejuvenated the livers of mice.14 Very possibly, a similar approach could be applied to the brain.
Another problem that might be usefully addressed is the failure of damaged cells to die as they should through a normal process called apoptosis (programmed cell death). Rather than dying, the cells linger in the body and emit signals that promote overexpression of pro-inflammatory cytokines, or they mutate into cancer cells. By detecting inappropriate gene expression in such cells, it may be possible to re-activate apoptosis and get rid of them so they can be replaced with healthy young cells.
Cell Replacement Therapies
In the longer term we have realistic expectations for aging reversal, or regeneration. The promise of regenerative medicine (as espoused by Aubrey de Grey) has been greatly boosted by the prospect of therapies developed from embryonic and adult stem cells, or induced pluripotent stem cells (iPS) developed from an individual’s adult cells. Adult stem cells are already being used to develop therapies to regenerate tissues and organs. Embryonic stem cells have even greater potential for the development of anti-aging and anti-disease therapies because they can potentially be developed into any type of differentiated adult cells, which could then be transplanted into an aging, diseased, or injured person. The potential value of using iPS cells to develop new anti-aging therapies is that these cells are developed directly from the patient’s own adult cells without the need to form an early embryo. Since they have the same genes as the treated patient, they should not be rejected by the patient’s immune system.
Scientists including Dr. Michael West, the founder of Geron and current CEO of BioTime, Inc., have proved that embryonic stem cells can be created by inserting a person’s DNA into an ovum from a woman of reproductive age and then allowing that cell to develop into a very early embryo called a blastocyst, which is basically still just a ball of cells with a hollow cavity inside. Other scientists have proved that iPS cells can be developed from adult cells by exposing them to four genetic factors. There have been studies showing that iPS cells may not be as safe or as potent as embryonic stem cells, but Dr. West and associates recently demonstrated that some iPS cells may be as safe and potent as embryonic stem cells (see the interview with Michael West in the June 2010 issue of Life Extension Magazine® ).15 Dr. West is actively pursuing the potential of partially differentiated stem cells (progenitor cells) to regenerate or replace almost any type of cellular damage. Dr. West and his colleagues are attempting to develop a therapy to rejuvenate the vascular and immune system in old mice, which is being funded by the Life Extension Foundation®. (Refer to article Research Funded by Life Extension® Could Lead to Therapies That Reverse Human Aging for details.)
Such research efforts are attempting to reverse aging and extend healthy life span essentially by turning back the clock of aging changes in gene expression in aging cells. However, we have no way of knowing which approaches will be most beneficial. “We’re still in the blind-men-and-the-elephant stage,” comments Dr. Gregory Benford, referring to the multiple approaches being used by different researchers attempting to understand and control the aging process. Benford is a physicist who helped to capitalize Genescient, a company that is developing products based on the work of Michael Rose. “For the next 5 to 10 years,” he says, “we’ll be doing nutrigenomics—supplements developed on a genetic base.” After that, there will be a better prospect for more radical interventions.
Validation for Genetic Causes of Aging
Dr. Fahy encountered recent validation of his outlook about the genetic mechanisms involved in aging at this year’s American Aging Association conference.
Russian researchers presented evidence that the presence or absence of 27 specific SNPs (genetic variations called single-nucleotide polymorphisms) largely in certain introns (silent portions of genes that may help to control gene expression) could determine whether you are likely to live to 77 or 97.
Some of us still remember the Commodore Pet, the first desktop computer, marketed in 1977, with four kilobytes of memory.16 Aside from playing very primitive video games on its tiny screen, consumers had difficulty imagining what they could use it for. Going back just a little further, a state-of-the-art computer at MIT occupied more than two rooms and its processor consisted of 18,000 vacuum tubes.17 And this was a mere 60 years ago. Today, all of us have routine access to computers that are more than a million times as powerful while being small enough to hold in the palm of the hand, and we have difficulty imagining life without computing devices.
One mission of Life Extension Foundation® is to encourage public awareness that similar huge transformations are possible in the biosciences. Now that the human genome has been sequenced, we believe that the aging process can be controlled and biological death can be postponed or even eliminated, if sufficient resources are devoted to this challenge.
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