First hint that body’s ‘biological age’ can be reversed
Nature said:A small clinical study in California has suggested for the first time that it might be possible to reverse the body’s epigenetic clock, which measures a person’s biological age.
For one year, nine healthy volunteers took a cocktail of three common drugs — growth hormone and two diabetes medications — and on average shed 2.5 years of their biological ages, measured by analysing marks on a person’s genomes. The participants’ immune systems also showed signs of rejuvenation.
The results were a surprise even to the trial organizers — but researchers caution that the findings are preliminary because the trial was small and did not include a control arm.
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The epigenetic clock relies on the body’s epigenome, which comprises chemical modifications, such as methyl groups, that tag DNA. The pattern of these tags changes during the course of life, and tracks a person’s biological age, which can lag behind or exceed chronological age.
Scientists construct epigenetic clocks by selecting sets of DNA-methylation sites across the genome. In the past few years, Horvath — a pioneer in epigenetic-clock research — has developed some of the most accurate ones.
The latest trial was designed mainly to test whether growth hormone could be used safely in humans to restore tissue in the thymus gland. The gland, which is in the chest between the lungs and the breastbone, is crucial for efficient immune function. White blood cells are produced in bone marrow and then mature inside the thymus, where they become specialized T cells that help the body to fight infections and cancers. But the gland starts to shrink after puberty and increasingly becomes clogged with fat.
Evidence from animal and some human studies shows that growth hormone stimulates regeneration of the thymus. But this hormone can also promote diabetes, so the trial included two widely used anti-diabetic drugs, dehydroepiandrosterone (DHEA) and metformin, in the treatment cocktail.
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