26 July, Washington
A new study has found that sex hormones can reverse ageing by stimulating production of an enzyme naturally found in the human organism, Telomerase, which is the closest of all known substances to a “cellular elixir of youth.”
The strategy was tested in patients with genetic diseases associated with mutations in the gene that codes for telomerase, such as aplastic anemia and pulmonary fibrosis. The authors said that the results suggest that the approach can combat the damage caused to the organism by telomerase deficiency.
“One of the processes associated with aging is progressive shortening of telomeres, DNA-protecting structures at the ends of chromosomes, like the plastic tips on shoelaces,” said Rodrigo Calado of the University of Sao Paulo. “Each time a cell divides, its telomeres get shorter. Eventually, the cell can’t replicate anymore and dies or becomes senescent. However, telomerase can keep the length of telomeres intact, even after cell division.”
In practice, he added, telomere length is a laboratory measure of a cell’s “age.” Some cells avoid aging by using telomerase to lengthen their telomeres through the addition of DNA sequences, thereby maintaining their capacity to multiply and “stay young.”
In an embryo, where tissue is still in the formative stage, telomerase is expressed by practically every cell. After this period, only cells that are constantly dividing, such as hematopoietic (blood-forming) stem cells, which can differentiate into a variety of specialized cells, continue to produce telomerase.
“Aplastic anemia is one of the diseases that can be caused by telomerase deficiency,” Calado said. “Bone marrow stem cells age prematurely and fail to produce enough red blood cells, white blood cells and platelets, making the patient dependent on blood transfusions and more susceptible to infections.”
“The study we’ve just published was designed to find out whether the effect we’d observed in the lab also occurred in humans, and the results indicate that it does,” Calado noted.
Instead of estrogen, the researchers treated the patients with androgen, he explained, because it has long been used as a drug in cases of congenital anemia and offers the advantage of stimulating an increase in the mass of hemoglobin (red blood cells), which estrogen cannot do.
Although the results of the study suggest that drugs can be used to reverse one of the biological drivers of aging, it is not yet clear whether the benefits of treatment would surpass the risks in healthy people, especially if the treatment involved the use of sex hormones.
Some groups, such as patients undergoing chemotherapy or radiotherapy, may benefit from drugs that stimulate telomerase in the future.
The study appears in New England Journal of Medicine.