Aging is characterized by a progressive loss of physiological integrity, resulting in impaired function and susceptibility to disease and death. This biological deterioration is considered a major risk factor for diseases such as cancer, cardiovascular disease, diabetes and Alzheimer's disease. At the cellular level, there are two key hallmarks of the aging process: shortened telomere length and cellular senescence. Repeated intermittent hyperoxia exposure using certain hyperbaric oxygen regimens can induce regenerative effects that typically occur during hypoxia.
Telomeres are tandem nucleotide repeats located at the ends of chromosomes that maintain genome stability. Telomeres shorten during replication (mitosis) due to the inherent inability to fully replicate the terminal portion of the lagging DNA strand. Telomere length (TL) is between 4 and 15 kb, gradually shortened by about 20 to 40 bases per year, and is associated with different diseases, poor physical function and thinning of the cerebral cortex. Cellular senescence is a cell cycle arrest induced by telomere shortening and other senescence-related stimuli unrelated to TL, such as non-telomeric DNA damage. The main purpose of senescence is to prevent the reproduction of damaged cells by the immune system triggering their elimination. Accumulation of senescent cells with senescence reflects increased production of these cells and/or decreased clearance of them, which in turn exacerbates damage and leads to senescence.
A growing body of research has identified several drugs that can reduce the rate of telomere shortening. Several lifestyle interventions, including endurance training, diet, and supplements targeting cellular metabolism and oxidative stress, have been reported to have relatively small effects on TL.
Hyperbaric oxygen therapy treatment utilizes 100% oxygen at ambient pressure above one atmosphere absolute (ATA) to increase the amount of oxygen dissolved in body tissues. Repeated intermittent hyperoxia exposure, using certain hyperbaric oxygen therapy treatment protocols, can induce physiological effects that typically occur during periods of hypoxia in a hyperoxic environment, the so-called hyperoxia-hypoxia paradox. Furthermore, it was recently demonstrated that hyperbaric oxygen therapy treatment can induce cognitive enhancement in healthy older adults through a mechanism involving regional changes in cerebral blood flow. At the cellular level, hyperbaric oxygen therapy treatment was demonstrated to induce the expression of hypoxia-inducible factor (HIF), vascular endothelial growth factor (VEGF), and sirtuin (SIRT), stem cell proliferation, mitochondrial biogenesis, angiogenesis, and neurogenesis. However, no studies to date have examined the effects of hyperbaric oxygen therapy on the accumulation of TL and senescent cells. The aim of this study was to assess whether hyperbaric oxygen therapy affects TL and senescence-like T cell populations in older adults. This study suggests that hyperbaric oxygen therapy may induce significant anti-aging effects, including increased telomere length and clearance of senescent cells.