|
Robert Browning wrote, "Grow old with me, the best is yet to be" more than 100 years ago. At that time, it may have well been very true. Even twenty, or ten, years ago that still held true. As the dawn rises on a new millenium amazing new advances in science and technology are occurring along with a shift in public consciousness, make it possible to now control the aging process.
Over the recorded existence of man the average human life span has increased. This increase is owed to improvements in medical care, including the use of antibiotics, improvements in housing, education and sanitation. However, there appears to be a maximum, or fixed, end point. Recent research reports have indicated that the aging process itself could indeed be modified. Evidence for this comes from the isolation of "longevity genes", as well as the effect on cell longevity by modification of the ends of the chromosomes (the telomeres), elimination of treacherous free radicals, glucose cross-linking of proteins, and the effect of hormones and protective enzymes.
Human cells have a limited life span. In a test tube a normal human cell will divide about 50 times and then dies of old age. This seems to put a ceiling on the human life span. The culprits are telomeres-minute units at the end of the DNA chain. Each time a cell divides it must duplicate its DNA. This process results in the shortening of the telomeres. After about 50 such replications the telomeres are gone, and the cell loses its ability to divide.
Howard Cooke of the Medical Research Council in Edinburgh, documented the first connection between aging and telomeres. He noticed that the telomeres in reproductive cells were longer than those in shorter-lived somatic cells (the kind found in muscle, skin and nerve tissue). He suggested that ever-shortening telomeres might determine a cells life-span. In other words, he proposed that the telomere length offered a clock for telling a cell's longevity.
In a barrage of papers published over the last few years, researchers have shown that the telomerase gene can be activated in human cells, and that it does extend cell life. The initial development was a report in the August 15, 1997, issue of Science. A group headed by Nobel laureate Thomas Cech, of the University of Colorado at Boulder, and colleagues at Geron Corporation, had isolated the human gene for a catalytic protein called telomerase reverse transcriptase (hTRT).
hTRT is only present in immortal cells, whereas the gene for telomerase is pre-sent in all cells. hTRT serves to fuse the repeating sequences of DNA to the chromosomes, thereby lengthening the telomeres. Proof that introduction of the hTRT gene into mortal cells would cause them to produce active telomerase was offered in the December 1, 1997, issue of Nature Genetics by the Geron group, in a collaboration with researchers from the University of Texas Southwestern Medical Center in Dallas.
Telomerase is a rarely-expressed enzyme believed to play a key role in the regulation of cell life span, functioning as part of a molecular clock of cell aging. Its absence imparts mortality to some cells and its presence imparts replicative immortality to others.
"Reconstituting telomerase activity, especially in normal human cells, is a major milestone in telomerase biology that has widespread implications for the treatment of cancer and age-related diseases," said Jerry Shay, Ph.D., professor of cell biology at the University of Texas Southwestern Medical Center in Dallas.
"Since cell senescence contributes to age-related disorders and limits the efficacy of cell and gene therapies, the ability to extend the life span of normal cells would have broad therapeutic and commercial impact," stated Ronald Eastman, Geron's President and Chief Executive Officer.
While the effect this will have on the general public is still yet undetermined, according to Jerry Shay Ph.D., "Telomerase will allow us to take a person's own cells, manipulate and rejuvenate them, and give them back to the same patient. The rejuvenated cells could help grow new skin for burn victims and cure diseases caused by the failure of aging cells to divide, such as macular degeneration."
For the first time in history, control of the aging process lies in the hands of mankind. How we will respond to that challenge is still an open question. But one thing is certain, for the generations just being born, living to be 100 will be routine.
LifeStyle Advantage Longevity System
2401 South 24th Street
Phoenix, AZ 85034