Study Suggests Biological Age Can be Reversed in Humans

Study Suggests Biological Age Can be Reversed in Humans

Scientists may have succeeded not only in slowing the sands of time, but actually reversing the aging process. In a yearlong trial, participants lost an average of 2.5 years from their biological ages.

The study participants’ biological ages were measured by studying changes in their genomes. Over time, DNA methylation increases, and the level can be detected through biochemical tests. These modifications to the genome occur throughout people’s lives and are a good indicator of age. The more marks detected on the genome, the older the person is.

The researchers were attempting to simulate the thymus gland, which plays an important role in the immune system.  The thymus is responsible for producing T-cells, which are an essential part of the immune system. Blood cells are created in the bone marrow and then migrate to the thymus where they mature into T-cells.

The thymus gland starts to deteriorate after birth at a low rate through a process called involution, but after puberty the rate of deterioration accelerates, and thymus tissue is replaced with fatty tissue. By the age of around 65, the thymus gland permanently stops producing T-cells. Without any replenishment of T-cells, people become more susceptible to infection, the body becomes less efficient at fighting cancer, and immune system disorders are more likely to develop. With more T-cells, older people would be able to fight infections more efficiently and an increased T-cell count could help improve the effectiveness of cancer treatments.

The study was focused on stimulating the thymus gland to slow involution and thus increase the number of T-cells. This was achieved by administering a growth hormone that had previously been shown to stimulate regeneration of the thymus in animal studies. Since the growth hormone was known to increase the risk of patients developing diabetes, two anti-diabetes drugs were also administered.

Following treatment, the blood cell count in patients had increased and an MRI study revealed that in 77.7% of patients, fat tissue in the thymus had been replaced with regenerated thymus tissue.

The investigation of the effect of the drugs on participants’ epigenetic clocks was secondary, and only took place after the study had ended. Four aspects of the epigenetic clock were studied and all four showed significant reversals in aging. The effects of the treatment also appear to be robust. The patients who provided a follow up blood test after 6 months still showed the positive effects of the treatment.

While the study suggests the aging process can be slowed, and biological age could be reversed to some degree, the results of the study should be treated with some caution. The study was only conducted on 9 patients (9 white males, aged 51-65 years) and there was no control group.  The researchers are now planning a much larger study on males and females of various ages and ethnicities to see if the effects are reproducible.

Further information on the study can be found in the journal Nature. DOI: 0.1038/d41586-019-02638-w

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