BioMarker Pharmaceuticals Develops
By Saul Kent, Director, Life Extension Foundation
There is now scientific evidence that a therapy can slow the aging process in laboratory animals. BioMarker Pharmaceuticals (www.biomarkerinc.com), a new company funded by Life Extension, has discovered that metformin, a drug used to treat diabetes, can mimic many of the changes in gene expression found in calorically-restricted mice, which live much longer, healthier lives than normally-fed mice.
Caloric restriction (CR) is the most effective method of slowing aging, preventing diseases such as atherosclerosis, diabetes and cancer, and extending maximum life span in mammals. Since the 1930s, studies in rats, mice, monkeys and other species, have demonstrated that CR can maintain life, health and youth in animals for extended periods of time.
An unprecedented medical breakthrough
The discovery that a clinically-used drug (metformin) produces genetic effects similar to those of caloric restriction, including life span extension, is an unprecedented breakthrough in medicine, with astonishing implications for us all. For thousands of years, the medical profession has strived to prevent and treat killer diseases, but has never been able to find a method of intervening in the aging process.
Advances in sanitation, nutrition and medicine have increased life expectancy to a considerable degree. In the year 1900, the average life span in the U.S. was only 47 years. By 2000, it had risen to the high 70s. This has led to increasing numbers of people reaching advanced ages, but has had no impact whatever on the maximum age reached by the oldest of the old. Today, it is still very rare for anyone to live beyond the age of 107, although increasing numbers of people reach 100. In ancient Greece, the average life span was in the early 20s, but the longest lived people still reached 100+.
In the U.S. today, the average 50-year-old woman survives to age 81. If we were to conquer the two leading causes of death-cancer and heart disease-it would only extend the woman's life span to 88, and these added years would be a time of declining health and vigor. If we were to slow aging, on the other hand, the woman would not only be less likely to die of cancer, heart disease and other killers, but would also be healthier, more vigorous and more youthful. She would live to well over 100, with the prospect of a much longer, healthier life span from later advances in the control of aging. (Fig. 1)
An authentic advance in aging control would, in just a few short years, produce more health and longevity benefits than have yet been produced in the history of the planet. It would break through the hitherto impenetrable barrier that has kept every person on Earth in chains since the beginning of time. Just as the ability to leave Earth's orbit gave us the possibility of reaching the moon, the planets, other star systems and galaxies, the ability to extend the healthy human life span would give us the possibility of living in good health well beyond the current maximum human life span.
BioMarker has taken the first revolutionary step in developing an authentic anti-aging therapy. Before going into the details of this advance, let's take a look at the ground-breaking technology used by BioMarker to progress so quickly.
Measuring the rate of aging
Diseases can be diagnosed and, in many cases, treated effectively because they afflict a subset of the population and have known causes, biomarkers, risk factors and characteristics. Influenza, pneumonia and AIDS, for example, are caused by pathogens that produce symptoms such as respiratory distress, aches and pains, and immune dysfunction. Cancer is characterized by the accelerated proliferation of aberrant cells, heart disease and stroke by atherosclerotic plaques and abnormal blood clots, and diabetes by elevated blood levels of glucose and insulin.
Aging, on the other hand, affects everyone, is characterized by the deterioration of every tissue, organ and system in the body, and occurs in a progressive manner throughout most of the life span. The consequences of aging are so widespread, pervasive and intertwined with degenerative diseases that it is very difficult to measure the rate of aging. Since many of the features of aging are also characteristic of crippling and killing diseases-of which aging is a major, underlying cause-it is difficult to separate aging from disease processes.
The one biomarker that has been used effectively as a measure of aging is maximum life span. Every species has a characteristic life span that is determined by its rate of aging. The maximum life span of mice and rats is three years, the maximum life span of chimpanzees is 50 years, while the maximum life span of human beings is 100+.
The ability of caloric restriction to extend the maximum life span of mice and rats to as long as four-to-five years is thus strong evidence that CR retards their rate of aging. Further evidence of CR's ability to slow aging and extend youth is its ability to prevent the immune dysfunctions of old age, improve DNA repair, reduce damaging free radical activity, lower glucose and insulin levels, maintain fertility at advanced ages, boost energy levels, increase protein synthesis, reduce the accumulation of damaged proteins, inhibit the inflammatory responses of aging, lower blood levels of cholesterol and triglycerides, counteract neurodegeneration and prevent the age-related decline in the health-building hormone DHEA (dehydroepiandrosterone). CR also prevents, postpones the incidence of and reduces the severity of the diseases that normally kill mice and rats, such as cancer, kidney disease and cardiovascular disease.
At advanced ages, calorically restricted animals are thinner, smaller and more youthful looking than normally-fed animals. (Fig. 2) The most striking difference between CR and normally-fed animals, however, is their activity level. Thirty-month-old normally-fed mice, which are roughly equivalent to 75-year-old humans, are sluggish, bloated, sedentary and often have malignant tumors, if they are still alive. In contrast, 30-month-old CR mice exercise vigorously, often in acrobatic fashion, and are highly inquisitive. In observing both groups of "elderly" mice, it is obvious that the CR animals are younger and healthier than normally-aging mice. At the end of this article, readers are given contact information to enable them to learn more about BioMarker Pharmaceuticals. Among the items available is a motion picture sequence showing how much more active and youthful CR mice are than normal mice, at advanced ages.
Since CR can prevent the diseases of aging, maintain health and youth in animals at advanced ages, and extend maximum life span (in mice and rats) up to the equivalent of 160 years in humans, it is now accepted by scientists as an authentic way of slowing aging in mammals. Ongoing CR studies at the National Institute on Aging (NIA) and the University of Wisconsin have shown that CR produces similar anti-aging and antidisease effects in rhesus monkeys as in rodents, although it is too early to tell if the maximum life span of CR monkeys will be extended. Preliminary data from the NIA study indicate that CR is reducing cardiovascular disease, diabetes, cancer and liver failure in rhesus monkeys.
During a stay in Biosphere II in Arizona, the eight inhabitants were unable to grow enough food for them to eat a normal diet. As a result, they experienced unintentional caloric restriction for almost two years. One of the Biosphere II crew, Dr. Roy Walford of UCLA Medical Center, made regular biochemical and physiologic measurements of the crew, which showed strikingly similar anti-aging effects to those found in mice, rats and monkeys.
The inhabitants of Okinawa consume a healthy diet that is 20% lower in calories than those in the rest of Japan. A study found that-in the 1970s in Okinawa, death rates from stroke were reduced by 41%, cancer by 31% and heart disease by 41% below the rest of Japan. The mortality rate for 60 to 64 year olds living on Okinawa was half the rate found elsewhere in Japan, and the incidence of centenarians (people living to 100+) on the island was 2 to 40 times greater than in other Japanese communities.
When George Roth and associates at the National Institute on Aging analyzed data from the Baltimore Longitudinal Study of Aging, they found that survival was greater in men who had lower body temperature, lower plasma insulin levels and higher DHEA levels than others in the study. Since CR lowers body temperature and plasma insulin levels in both rodents and monkeys and increases DHEA levels in monkeys, these findings in the healthier men in the Baltimore study suggest that a common mechanism affects these changes in both non-human and human primates. Unfortunately, information is not available on the caloric intake of the subjects in the Baltimore Longitudinal Study, but since the men were not intentionally put on a CR diet, it is likely that anti-aging therapies that have the beneficial effects of CR can be developed. This is BioMarker's goal.
A drawback of maximum life span studies
A major drawback in using maximum life span to measure the rate of aging is that life span experiments take too long. Monkeys and humans live for such long periods of time that any attempt to determine whether a therapy can extend their maximum life span takes decades. The NIA and Wisconsin CR studies in rhesus monkeys have been going on for 10 to 15 years, yet it is still too early to determine whether CR is extending mean life span in these animals, and we won't discover the effect of CR on their maximum life span for another 30 to 40 years. No one has ever attempted a study to see if maximum life span can be extended in humans because such a study would likely outlast the life span of the researchers. Even in relatively short-lived mammals such as mice and rats, a study of maximum life span can take four to five years. Moreover, these studies are not only time-consuming, but costly.
Because of the time and money needed for maximum life span studies, scientists have been searching for short-term assays (biomarkers of aging) to measure the rate of aging in humans. A true biomarker of aging would measure a fundamental biologic function that occurs in everyone throughout the life span. It would have to be a function that underlies the diseases of aging, but is not a disease process itself, and that cannot be reversed by therapies that prevent or treat diseases. For example, a sedentary man of 50 with elevated cholesterol and blood pressure has a higher than normal risk of heart attack and stroke. If the man starts to take anti-cholesterol and anti-hypertension medications and exercises regularly, he will have lower cholesterol and blood pressure readings at age 60, but still be biologically older at 60 than he was at 50.
Another requirement for a true biomarker of aging is that it has to change fast enough to be able to see significant differences over relatively short periods of time. If a function changes so slowly that it takes 10 years or more before the change is significant, it would be impractical to use it as an assay of aging.
Finally, a biomarker of aging should be relatively non-invasive, such as a blood test or skin biopsy. A heavily invasive test, such as a brain biopsy, would be costly, time-consuming and would represent an unacceptable risk for most people. Testing for biomarkers of aging will have to be done at least once a year to generate convincing scientific evidence of the anti-aging effects of therapies. The results of such tests will need to provide scientific data quickly in order to screen therapies for their ability to retard or reverse aging.
Gene expression: true biomarkers of aging
Since genes control every aspect of biologic life, including health, aging and longevity, and caloric restriction extends healthy life span, a logical approach in the search for true biomarkers of aging is to compare gene expression in normally aging animals with gene expression in CR animals. In the 1980s, a team led by Arlan Richardson (then at Illinois State University) began to explore this comparison in rats, using tools of molecular biology, such as Northern Blot analysis. They looked at gene expression in the liver cells of 18-month-old, normally-fed rats and 18-month-old CR rats and found that protein synthesis, mRNA levels and nuclear transcription were increased two- to three-fold by caloric restriction.
The problem with using these tools of molecular biology to search for biomarkers of aging, however, is that such experiments are slow, laborious and expensive. Those problems have been solved by a new technology - high density DNA microarrays (gene chips) - developed by companies such as Affymetrix in Santa Clara, California. Gene chips have enabled scientists to detect gene expression quickly in thousands of genes at a time.
Richard Weindruch and Tomas Prolla of the University of Wisconsin have used gene chips in aging research. In 1999, they used Affymetrix gene chips to measure the expression of 6,347 genes in the gastrocnemius (leg) muscles of young (5-month) and old (30-month) mice. When they compared gene expression in normally aging mice with gene expression in CR mice, they found that many of the genetic changes of aging were reversed in the CR animals. Since then Weindruch and Prolla have conducted similar experiments in the brain and heart of mice and monkeys.
BioMarker scientists made a major breakthrough by determining that 70% of the age-related changes in gene expression reversed by long-term CR (over two years) are reversed in only two to four weeks after mice are placed on a CR diet. BioMarker used Affymetrix gene chips that measure changes in 12,000 genes in these studies. This discovery established the scientific foundation for the company's proprietary technology platform.
Screening for anti-aging therapies
Comparing the expression of thousands of genes at a time makes it possible for scientists to develop genetic profiles of aging in different organs in mice, monkeys and humans, and to discover what age-related genetic changes are prevented or reversed in models of life extension such as caloric restriction. When the key genes that govern aging are identified, scientists will be able to target the genes, the proteins they produce and the biologic mechanisms they affect in order to develop new drugs and other therapies to slow aging, prevent diseases and extend healthy life span.
Gene-chip technology has enabled scientists to measure the expression of thousands of genes at a time. Weindruch and Prolla demonstrated that you can screen for anti-aging therapies over a 25-month period. BioMarker Pharmaceuticals has made major strides in demonstrating that the screening process can take place over a much shorter period and that the benefits of CR can occur at advanced ages.
The company has also found evidence for genetic mechanisms that may be involved in the prevention of cancer and a drug (metformin) that may be an authentic anti-aging therapy.
How CR affects life span late in life
Most scientists assume that the anti-aging, life span extending effects of CR involve the gradual prevention of age-associated genetic and biologic changes, and that these effects lessen with advancing age. The early studies found that, while CR could extend life span dramatically when started early in life, it shortened life span when started later in life. Then, Weindruch and Walford found that CR can extend the life span of middle-aged (one-year-old) mice if their diet is restricted gradually to allow them to adapt to reduced caloric intake.
BioMarker has found that CR can alter gene expression in male, long-lived hybrid B6C3F1 mice very rapidly in both young and old animals. Within four weeks, shortterm CR reversed 70% of the age-related changes in gene expression reversed in mice undergoing CR for two years or more. Short-term CR induced a genetic expression profile associated with health and longevity. In some cases, gene expression was elevated, in other cases reduced, when compared to the gene changes found in naturally aging mice.
Furthermore, the company has found that CR is just as effective in extending life span late in life as it is early in life. In the BioMarker study, late-life CR increased the mean and maximum life span of mice by approximately 40% (Fig. 3) and slowed the onset of malignant tumors. These findings are evidence that CR rapidly decelerates aging, even when started late in life. They also show that the rapid effects of CR on gene expression occur in the same time frame as the rapid effects of CR on longevity. This links the gene expression and longevity effects in a probable cause-and-effect relationship.
Types of genes changed by CR
BioMarker's strategy is to search for the genes most critically involved in the aging process by exploring the changes in gene expression caused by caloric restriction in various tissues (liver, heart, brain and muscle) in mice, monkeys and humans throughout their life span, and to discover what gene changes occur when CR is started at different ages, and carried on for varying periods of time. BioMarker scientists are looking for changes in key regulatory genes that trigger secondary gene changes. They are looking for changes that occur in multiple tissue types very early in the crossover from the aging gene expression profile to the anti-aging gene expression profile.
The changes in gene expression caused by caloric restriction were separated into defined functional classes for further study. These include genes involved in carbohydrate, fat and protein metabolism; signal transduction for cell growth and proliferation, cell suicide (apoptosis); and the production of insulin, growth hormone and insulin-like growth factor-1; cellular protection against oxidative free radicals and other types of stress inducers; xenobiotic metabolism involved in detoxification of chemicals; and inflammation.
Among the metabolic genes that changed with CR were genes that indicate CR enhances the breakdown and turnover of whole-body protein. These changes should drive protein renewal throughout the body. Some of the genes reduced the enzymatic capacity for lipid biosynthesis and metabolism, which may account for the decreases in serum triglyceride and cholesterol levels in CR animals.