John M. Anastasatos, MD and Luis O. Vasconez, MD
Beverly Hills, CA

Introduction

People everywhere are increasingly becoming more interested in ways that can allow them not only to stay and look young but also to feel young. This is not a new phenomenon.  The pursuit of eternal youth has been an idea as old as mankind.

In the Greek mythology the goddess of dawn Eos asked Zeus to grant her lover Tihonos, a mere mortal, immortality. Although Zeus granted her wish, she neglected to ask that he remains eternally young. He thus grew old and decrepit…eventually praying for his own death. Fear of having to live a long life in a debilitated state is very prevalent in Western societies.

Elli Metchnikoff the 1908 Nobel Laureate for immunology claims in his book “ The prolongation of Life” that aging can be slowed by eating yogurt and removing the large intestine. Related thinking has prevailed for throughout most of the 20th century as evidenced by the multiple regimens and practices of colonics across the world.

In 1869 the renown at the time scientist Brown-Sequard transplanted young guinea pig testes into a dozen old dogs and thought that the dogs exhibited prolonged vigor. Twelve years later feeling that he was failing in vigor he transplanted into himself injections of an extract of crushed dog and pig testes. By repot he regained much of his former strength.  Soon after many other physicians across Europe were injecting people with similar extracts for reason ranging from cancer to rejuvenation.

Today the pursuit of “the fountain of youth” is as prevalent and prominent as ever. The public is increasingly trying to find out information about “anti-aging “regimes. Physicians get more frequently asked about such techniques and regimens. There is a plethora of scientific and non-scientific information available to the public via the mass media and the Internet. Plastic surgeons can have a very integral role in the addressing these questions and managing anti-aging. This also therefore creates the responsibility to be educated about the potential of the different techniques, and therapies proposed and guide the patients in the right and safe path.

There is preliminary information so far that certain anti-aging regimens may improve body function and tone as well as emotional and physical well being. Long term data is unavailable however. The initial excitement from these reports may act to mislead people. This is where the role of the plastic surgeon may be instrumental. Educating the public will allow them to actively become key members of this rapidly growing field of medicine as well as reinforce the trust of the public on their doctors. 

Aging mechanisms and theories

In order to ever be in a position to slow the aging process it is only intuitive that we must understand the process or processes of aging. Why does aging occur and through which mechanisms does it proceed?
The answer to that is not yet known. However there are some theories that increasingly are gaining more scientific foundation.

According to this theory the cells of all eucaryotic organisms have a finite life as predominantly determined by a specific number of possible cell divisions for the different cell lines of the same organism. Cells derived from different species have a Hayflick limit that is correlated with the species longevity. In addition cells derived from patients with accelerated aging syndromes such as Progeria, Werner’s syndrome and Trisomy 21 have a significantly reduced repicative capacity compared to aged – matched individuals. These findings may be indicative of the presence of a genetic mitotic clock that counts the number of cell divisions rather than chronological or metabolic age.
The molecular mechanisms that control replicative senescence are still unknown. However the onset of senescence can be delayed and in certain cases cells may escape cell –cycle control completely and become immortalized. There have been many models developed to explain this. The more credible ones point to the ability of in-vitro transformation of cells lines that allow them to escape and acquire extended life. Cells past that point succumb to death due to various chromosomal instabilities but rarely may they emerge from such crisis due to somatic mutations.

Telomeres play a very important role to the process of cell senescence and their role is increasingly recognized more as a vital one in the regulation of aging. Eukaryotic chromosome ends are capped by telomeres, which consist of repeated sequences of TTAGGG. Their known role is in maintaining chromosomal stability and in the attachment of chromosomes to the nuclear matrix during cell division. The length of telomeres varies among different chromosomes within the same cell or even among the same chromosome in different cells.

Telomerase is a ribonucleoprotein complex capable of synthesizing the telomeric repeat sequence de novo using RNA as a template. This enzymatic ability was first identified in Tetrahymena and later in other species, including yeast and humans.

The telomere hypothesis of aging suggests that telomere shortening in the absence of telomerase is the mitotic clock for replicative cells in normal somatic cells. The number of cell divisions is registered by the gradual loss of telomeric sequences. Eventually telomeres shorten to a critical length past which the particular cell lines cannot replicate any more. The presence of telomerase according to this hypothesis would be necessary for maintaining the immortal phenotype. This has been substantiated by evidence correlating telomerase expression with immortality. Simple organisms like Tetrahymena, ciliates and yeast have unlimited replicative capacity. Human cell germ lines like the testes are essentially immortal and have long and stable telomeres with increasing age. Telomerase activity has been detected in both human testes and ovaries. However no telomerase activity has been found so far in most other normal tissues.

The most credible evidence for this theory is by Bodnar et al who took telomerase negative normal human   retinal pigment epithelial cells and foreskin fibroblasts. They transfected them with vectors encoding for the human telomerase catalytic subunit. The telomerase-expressing clones had elongated telomeres, divided vigorously and had reduced staining for b-galactosidase which is a bio marker for cell senescence. Furthermore the these  cell lines  had a normal Karyotype  and  exceeded their  normal life  span  by at least  20 doublings  therefore  establishing a  causal  association between cell senescence and telomere shortening  in vitro.

The oxidative stress theory

Another major hypothesis for aging postulates that senescence associated loss of functional capacity is due to the progressive accumulation of oxidative damage. This hypothesis is based on the fact that oxygen is a potentially toxic substance and its use by aerobic organisms although vital for survival may also be hazardous for the long-term existence. There are several indications that the oxidant challenge may not be trivial to aerobic organisms. It is estimated that ~2-3% of the oxygen consumed by aerobic cells diverted to the generation of harmful oxygen radicals. In the rat, a typical cell may undergo about 100000 attacks on its DNA by oxygen radicals per day. Oxygen free radicals not only damage DNA but also RNA, proteins and other macromolecules within a certain biological system. The basic tenet of the oxidative stress hypothesis is that senescence related loss of function is due to progressive and irregular accrual of molecular oxidative damage.
It is very difficult to measure directly the generation of the amounts of oxygen radicals in biological systems. Therefore indirect measurements are made from bio markers that are products of interactions of the oxygen radicals with macromolecules. From a plethora of available studies the main point that emerges is that molecular oxidative damage during aging is ubiquitous, substantial, and like mortality rates it increases exponentially with age.
The etiology of an age-related increase in the amount of oxidative damage can be linked to three factors: (i) a progressive decline in antioxidative defenses, (ii) an increase in the generation of oxygen free radicals, and (iii) a decline in the efficiency of repair and removal of the damaged structures.
Sohal et al provides one of the most convincing pieces of experimental evidence to support this hypothesis. They looked at the effect of simultaneous over expression of Cu, Zn-superoxide dismutase and catalase which act in tandem to remove oxygen free radicals in Transgenic Drosophila melanogaster. They found that as compared with diploid controls, transgenic flies carrying three copies of each of these genes exhibited up to 1/3 extension of their average and maximum life span, a retardation in the age related accumulation of oxygen radicals, less DNA damage in response to XRAY and an attenuation of the age related increase of Mitochondria oxygen radical formation.
Therefore in vitro, the reduction of oxidative damage has been shown to prolong life in the flies.

The caloric restriction model

Three  regimes  are known to  extend  life span in animals: (i) lowered  ambient  temperature in poikilotherms  and hibernating animals, (ii) a  decrease in physical activity in poikilotherms, and  (iii) caloric  restriction. It has been demonstrated that the maximum life span of flies can be extended by ~2.5 fold by a reduction of 10 degrees Celsius or by the abolition of flying which requires a rate of oxygen consumption 50-100 fold of the non-flying state.
The caloric restriction model is one of the more interesting and exciting models to study the aging process. In 1935, McCay’s laboratory demonstrated that a reduction in the total food intake significantly increased the mean and maximum life span of laboratory rodents.Over the last six decades, numerous laboratories have successfully repeated McCay’s observations with a variety of strains of rats and mice. Recent studies demonstrate that the increases in survival are due to decreased intake of calories i.e. CR.
CR does not imply malnutrition however. Furthermore life span extension by CR has been reported in fish, spiders, flies and other non-rodent species.
The mechanism by which CR works is not yet known.  The increase in survival occurs with retardation in disease and pathology; therefore it is often argued that CR increases the survival in rodents simply by retarding disease processes rather than altering aging and senescence. While it is very difficult to separate disease from senescence, research over the past 2 decades demonstrates that CR retards the changes that occur with age in most physiological processes, and these changes generally precede any alterations observed in pathology and disease.
It was thought for a long time that reduction of body fat; growth and decrease in metabolic rate were involved. However these postulates have been disputed.   The main thing that prevails from the CR studies most of which have been performed on rodents is that CR does improve the efficiency of the energy utilization mechanisms.
Several studies in the rat suggest that therefore CR achieves improved glucose efficiency and sensitivity.

There are studies in process on non-human primates and humans as well. Waldorf et al studied eight humans for a period of six months in the biosphere-2 project. They were fed a classically restricted diet which was mostly vegetarian. They were not malnourished however. They found that these humans had a reduction in blood glucose, total leukocyte count, cholesterol and blood pressure. These are changes similar to those seen in the calorically restricted animals.

Although many of the actions of dietary restriction have been suggested to play a causal role in anti-aging it is very difficult to establish causality. There is a generic problem is aging research that relates to the fact that there are multiple interacting processes over a very long period of time. Related to this problem is the fact that non- –human primates and humans have very long life spans so it’s very difficult if not impossible to determine the affect.  We therefore use biological bio markers to assess the anti-aging action of dietary restriction in these long-lived species. The information published today is limited but these studies are just beginning.

A new genetically engineered mouse model resembling human aging was discovered recently. A new mouse mutant named Klotho presents a syndrome characterized by reduced life span, decreased activity, infertility, osteoporosis, arteriosclerosis, atrophy of the skin and muscle wasting. All these phenotypes were caused by the disruption of a single gene called Klotho.  This gene encodes a novel protein that appears to function outside of the cells and thus is very different from that involved in previously described premature-aging syndromes which function in the nucleus. The Klotho protein functions through a signaling pathway involving a circulating humoral factor(s). Despite the fact that these mice show systemic evidence of aging only limited organs produced the klotho product. When the klotho protein was administered into limited organs it rescued all of the systemic aged phenotypes! Thus the possibility is raised whether this protein functions as a humoral factor or an anti-aging hormone. This is the first laboratory animal model to study aging and is expected to bring new insights into this field.

Anti-aging and the role of hormones 

Most of the experimental evidence on the action of hormones comes from rodents. With age there is a reduction of many hormones in both the art and the humans. In the rat there is a decline in secretion of hypothalamic GnRH, GHRH, dopamine, Norepinephrine, vasopressin, pituitary LH, FSH, TRH, and GH, gonadal hormones. In elderly humans there  is  a  decline in the  secretion of  gonadal hormones, GH, somatomedins, vasopressin, but there is  an increase  of the gonadotropins due  to  a  decrease in gonadal hormone  secretion. The decline in hormone secretion with age is believed to contribute to many decreases in body functions. The best evidence or suggestion for an anti-aging effect stems from the fact that in rats hormone elevation can inhibit or reverse certain
aging changes.

Human Growth Hormone

Growth hormone (GH) is a single chain polypeptide of 191 amino acids which is produced by the somatotropic cells of the anterior pituitary gland. It promotes linear growth in children and is also an important anabolic hormone with stimulatory effects on protein synthesis and lipolysis. GH has direct and indirect effects on tissues. The indirect effects are primarily mediated by the insulin like growth factor-1 (IGF-1). Most of circulating IGF-1 is produced by the liver under the action of GH. With advancing age men and women with no clinical evidence of pituitary pathology show decrease of GH and IGF-1.   Both aging and GH deficiency states are associated with decreases in protein synthesis, body mass, bone mass, and increase in body fat. It is speculated and theorized that   the reduced levels of these hormones may account for the changes we see with aging.

In 1990 Rudman et al investigated the effects of supplementing GH to elderly men with documented decreased levels of IGF-1.  Twelve healthy men received growth hormone supplementation for a period of 6 months compared to controls that received nothing. They found that the group who took growth hormone had an 8.8 percent increase in lean body mass, a 14.4 percent decrease in adipose tissue and a 1.6 percent increase in vertebral body density .Additional studies have confirmed the effects of growth hormone on body composition in men and women. However these studies have not documented a change in muscle strength or better oxygen utilization. Taafee et al studied the response of adding GH to resistance training in a group of 18 healthy men, 65 to 82 years of age. They had only strength training regimes for the first 14 weeks followed by more strength training regimes with the addition of GH or placebo for the last 10 weeks of the study. That study showed that strength training increased muscle strength but the addition of GH did not augment or improve muscle strength.

When it comes to the effect on fat that is complex. The pulsatile release of GH is threefold less than that of normal men with lower pulse frequency during the daytime. The estimated production rate of GH in obese men is about 25% that of normal men.

Bone and mineral loss is a predictable accompaniment of aging in both men and women. Peak bone mass in women is achieved by age 35 and then bone mass falls at a rate of 0.5-1%/year until menopause. After menopause the rate of bone loss is about 2%/year for the first 5-10 years and it falls at a lower rate following that. In men peak bone mass occurs at about 35-40 and is about 25% higher than in women and it falls at a rate of 0.3%/year. The rates of bone depletion vary considerably among different individuals and some people do not become bone depleted with advancing age. Clinically evident osteoporosis depends on many factors such as nutrition, level of physical activity, peak adult mass and genetic factors.
A lot of interest has been placed upon GH as an anti-aging therapy to revert or improve bone loss. GH does improve intestinal absorption of both calcium and phosphorus by increasing the production of vitamin D. In vitro and in vivo studies in animals reveal that GH induces osteoblastic action and pro collagen formation. Studies of bone metabolism in acromegalic patients have demonstrated increased bone turn over and increased forearm bone density and decreased spinal bone density. The reason for the difference in the axial versus the appendicular skeleton is not clear. Information about bone mass in GH-deficient adults is limited to two studies. In the first report therapy with recombinant methionyl GH for 12 weeks did not change bone mineral density in the forearm but it increased lumbar bone mass in 6 patients. In another study eight patients that were treated with GH initially at a low dose of GH for 6 months followed by 6 months of treatment at a higher dose. At the end of one year biopsies from the forearm demonstrated a decrease in bone density. Biopsies from the iliac crests of 5 osteoporotic women within the group showed no apparent treatment effect.   A   2 –year randomized study compared the effects of co-administration of GH plus calcitonin versus calcitonin only to two groups of post-menopausal women. The two groups showed similar increases in total body calcium content whereas only the calcitonin plus GH group showed a decrease in the radial bone density content. In another study 14 postmenopausal osteoporotic women were treated with GH for 6 months then with calcitonin for 3 months for a total duration of 2 years. Although there was a 2.3% increase in the total body calcium content the bone mineral content did not change as shown by iliac crest biopsies.


It appears that the administration of GH   increases bone turnover in both osteoporotic and non-osteoporotic older people. It remains to be elucidated if such treatment stimulates bone formation to a greater degree of bone resorption and the mechanisms by which such occurs.

Long term administration of GH to non elderly GH deficient adults may cause side effects such as edema, hypertension, carpal tunnel syndrome, and trigger finger, arthralgias, and fluid retention. In older men short term administration of GH has caused supraphysiological increases of IGF-1, hyperinsulinemia, and impaired glucose tolerance as well as decreased sodium excretion and edema. Furthermore it is not known if the effect on GH long term can be implicated in carcinogenesis especially since cancer incidence increases with age.
An analysis of the studies reveals that side effects are related to the dose administered as that is reflected by supraphysiological levels of IGF-1. It is important to note that the current regimens of administration to elderly and non- –elderly men are nonphysiological.
In summary there is some good evidence for the short term use of GH in select groups of people with a documented deficiency. However long term effects are not known yet because most studies did not exceed 12 months.

Dehydroepiandrosterone

It is called the mother steroid because it is produced by the adrenal glands abundant amounts and can be used as a precursor for other steroid hormones including androgens and estrogens. However to this date its purpose and physiologic function is not known. It has both estrogenic and androgenic effects but no known receptors in the body. There is no evidence for a vital function since patients without functioning adrenals function without its supplementation.
Claims for its role as an anti-aging hormone stem from the mere fact that its concentration decreases with age. Morales  et al conducted a 6-month placebo controlled trial and found remarkable increase in the perceived physical and emotional well being. These patients showed improved quality of sleep, greater energy, and increased ability to handle stress in 67% of the men and 84% of the women.  IGF-1 levels increased in that study.
In another study by Yen et al lean body mass and muscle strength increased and body fat mass decreased.
It has been proposed that it may have anticancer effects however these effects have been shown on animal studies and not in humans.
Declining DHEA levels have been implicated in the age related cardiovascular disease. The best evidence comes from a study conducted by Barrett-Connor and Goodman-Gruen. Between 1972 and 1974 82 % of a geographically defined community of older adults in CA were recruited. 1029 men and 942 women were followed for 19 years. This is the only prospective based community based study of DHEAS with fatal CVD outcomes in both men and women. All patients were followed for vital status.  When the cohort was adjusted for other risk factors final analyses failed to show statistical significance.
A three-week study of the effects of 50mg DHEA given to 11 postmenopausal women showed an enhancement in insulin sensitivity and decrease in triglyceride levels.
A lot of the information on the action and effects of DHEA comes from a symposium published at The New York academy of Sciences conference where about one fourth of the participants were taking DHEA themselves.
Side effects of DHEA are anecdotal and include hirsuitism, acne, hair loss, deepening of voice in women and a report of hepatitis. Furthermore there is the theoretical risk of promoting hormonally sensitive cancers like breast cancer and prostate cancer.

Melatonin

It is synthesized by the pineal gland from tryptophan and secreted mostly at night. There is a growing body of evidence on the physiologic function of melatonin. It is lipophilic and potentially interacts with a number of intracellular targets. It acts as a calcium-calmodulin antagonist. Furthermore it acts as one of the most potent scavenger of hydroxyl free radicals and it can bind particular sites within the cell nucleus.  The significance for this is not yet known. Melatonin receptors have been identified in the suprachiasmatic nucleus of rodents but not yet humans. Thus aging which is associated with a reduction of output from the circadian clock may be mediated by melatonin.
Walter Pierpaoli believes that aging is initiated by the pineal gland siting a study in mice where their life span can be increased by 25% by the exogenous administration of melatonin.
Melatonin also acts on the immune system. Pinealectomy causes decreased reactivity in laboratory animals. These are reversed with exogenous administration of melatonin.

Side effects include contamination by an impurity, resetting the body’s circadian clock incorrectly and daytime drowsiness. The long term complications from taking melatonin are not known.
In summary there are many studies that show beneficial effects on laboratory animals and in vitro models.  There is no evidence today that melatonin has an anti-ageing action on man. There are however placebo –controlled studies that show that melatonin is helpful in sleep disorders and jet lag.

Testosterone

Despite the early pioneering work of Charles Brown-Sequard in 1889 with human rejuvenation our present knowledge of the action of testicular hormones on aging is limited.
Testosterone is believed to have a life shortening effects upon its tissues.
Castration is reported to increase the life duration of pacific salmon, lampreys, rats and human inmates in a mental institution. Cancer of the prostate a significant cause of death in elderly men has not been seen in eunuchs.
Serum testosterone concentrations decline in men as they age. This decline may contribute to decreases in libido, muscle strength, and mass that often occur in aging men. Preliminary reports suggest that androgen replacement in men restore body weight and lean body mass, increase the hematocrit and decrease the biochemical indexes of bone turnover.
Present use of this hormone is indicated for hematological disorders, hereditary angioedema, endometriosis, and hypogonadism. There is no evidence for testosterone use as an anti-aging therapy.

Adrenal catecholamins

It has long ago postulated that the stress of modern living by maintaining high levels of catecholamins are capable of producing atheroma. This stems from studies in many animals that show that CA’s even in small doses damage the arteries and thus predispose to lipid deposition on the intima. There is a very large volume of clinical, epidemiological and experimental evidence that shows that repeated exposure to stress damages not only the cardiovascular system but also the immune system, nervous system, digestive and skeletal muscle systems. It has been recently postulated that some of the injury of CA’s may be due to the fact that they release oxygen free radicals. The increased levels of circulating catecholamines in the elderly may contribute to tissue aging.

Anti-aging and the role of vitamins

People have obsessed over the past decades about potential therapeutic uses of vitamins beyond what is known about their documented action. It is thought that many acts as anti-oxidants but the most evidence regarding a beneficial use of a vitamin pertains to the vitamin E.

Vitamin E has been examined in many epidemiological studies with a clear reduction of Cerebrovascular disease (CVD) in many of them. Several lies of evidence support the administration of vitamin E above the currently recommended amounts. A high intake of this vitamin may modulate atherogenesis via a variety of mechanisms including inhibition of lipid peroxidation of the membranes, inhibit cytokine release, platelet reactivity, smooth muscle proliferation, and control of the vascular tone. Also it inhibits the interaction of the vascular endothelium with inflammatory cells. Furthermore vitamin E has been found to modulate the genes for the expression of adhesion molecules on endothelial cells, and also influences the expression of integrins on the surface of leukocytes.
The National Institute on Aging is conducting a multicenter study on vitamin E for prevention of Alzheimer’s disease and memory dysfunction.
There is good data for vitamin E supplementation. The most common problem associated with vitamin E overdose is reduced clotting which is also the effect that we want to achieve when we give people aspirin. The risk factor for overdosing vitamin E is probably acceptable even if the benefit may be small.

Although the evidence for vitamin E is growing, the information that we have about the other antioxidants is limited at best. For a long time people thought that beta-carotene (which is converted to vitamin A in the body) supplementation would decrease the risk of cancer but beta carotene when taken in pill has been found to increase lung cancer in smokers.It was also believed that beta-carotene may have been helpful in the prevention of cataracts but this also has not been proven. Furthermore several well designed studies have shown that it offers no protection against heart disease.
As for vitamin C many physicians advocate taking mega doses to enhance the immune system. This notion however is anecdotal for the most part.  Furthermore we know that mega doses are certainly not required for connective tissue healing.
Some studies have shown that people who eat diets high in vitamin C (found mainly in citrus fruits) have lower rates of cancer and heart disease. However it very unclear whether taking vitamin C supplements has similar effects.
Overdosing on vitamin C is not benign. Taking mega doses of vitamin C and then suddenly stopping predisposes someone to developing rebound scurvy. Recently an in vitro study at the University of Pennsylvania showed that vitamin C pills can act as a catalyst to help make a toxin that damages DNA- a step that may predispose to aging and cancer.
Although there are no claims for vitamin D as an anti-aging or anti-cancer nutrient there is evidence that many adults may be deficient. In a study done at the MGH, 57% of normal adult patients had vitamin D deficiency which means that they could not absorb calcium properly. Vitamin D deficiency is probably even more prevalent in older people, especially in those who are homebound in nursing homes, so supplementation is very important for their bony health.

Selenium is a mineral that is thought to help with wound healing and prevent cancer. No conclusive evidence exists though to prove such claims.

Coenzyme Q10 is an antioxidant produced by the body but also has many dietary sources, including meats and seafood’s. Claims that it slow aging and stop cancer are not proven. However there may be some promise for its usage in the management of congestive heart failure.

Conclusion and future directions

The industrialized nation’s investments in improved nutrition, medical technology, and public health have paid off handsomely, raising the average life expectancy in Europe and the United States from less than 47 years in 1890 to a ripe 75.5 in 1993. Japan has done even better, leading the world with an average life expectancy of 76.6 years for men and 83 for women. More recently the developing countries have been showing similar gains. The lengthening of the expectancy for the population is one the greatest triumphs of humanity.

Extended survival is achieved because we have the sophisticated technology to control and better manage chronic disease better. As the    population grows older the need for us to come up with strategies to make them look and feel younger will increase as well as function better. This is an emerging and unique opportunity for physicians like plastic surgeons who are involved daily with improving form and function. It will allow us  to participate further  and even guide the overall care  of our  patients  therefore  bringing us  closer  to them and their  needs. Furthermore we may have an obligation to preach caution until more scientific evidence becomes available for the effects of all these different therapies.
One thing that becomes clear through this report is that there are no panaceas for aging. Despite tempting claims there is no product that has been proven to prevent or reverse aging. In addition not only these therapies are very costly but also they may have serious side effects.

More research is needed to elucidate the complex interplay of genetic, hormonal and environmental factors that are responsible for aging. In conclusion keeping patients functional and living a quality life requires a holistic approach. I think certain key points are the following:
Physical Heath: (Good diet, exercise, no smoking, moderate use of alcohol).
Social Health: (a network of relationships and friendships).
Use of non-pharmacological approaches to the degree possible.
Having a sense of purpose in life.