Antioxidative Protective Effect of Ozone Therapy on Isolated Mitochondria from Human Sperm

Background: oxidative stress and the sperm mitochondrion

Reactive oxygen species are a normal by-product of cellular energy production, but in excess they damage lipids, proteins and DNA. In male reproductive biology this matters because sperm are unusually vulnerable to oxidative stress, and raised levels of reactive oxygen species are detectable in a sizeable minority of men investigated for infertility. The mitochondria packed into the sperm midpiece both generate the energy needed for movement and act as a trigger point for programmed cell death, so their behaviour under oxidative stress is of particular interest. Ozone/oxygen mixtures have been studied for their apparently paradoxical ability to prompt a protective antioxidant response when applied at low, controlled doses. This laboratory study set out to examine how isolated sperm mitochondria respond to such a mixture.

Study design: isolated human sperm mitochondria exposed to ozone/oxygen

This was a preclinical, in vitro experiment. Mitochondria were isolated from human sperm and studied outside the body, rather than in living men or intact sperm cells. The isolated mitochondria were exposed to an ozone/oxygen (O2/O3) mixture, and a panel of biochemical markers was measured to characterise the effect. These included the formation of reactive oxygen species, the mitochondrial membrane potential (an indicator of whether the organelle is functioning or failing), adenosine triphosphate (ATP) concentration as a measure of energy output, and markers associated with the release of cytochrome c, an early step in the apoptosis (cell-death) pathway. Comparisons were drawn across the conditions tested to gauge whether ozone/oxygen was protective or harmful.

Findings: reduced reactive oxygen species and better-preserved mitochondrial function

The authors report that exposure to the ozone/oxygen mixture was associated with lower formation of reactive oxygen species in the isolated mitochondria. Mitochondrial membrane potential was better preserved rather than collapsing, ATP concentration increased, and the markers linked to cytochrome c release and downstream apoptosis signalling were reduced. Taken together, the measurements described a protective rather than a damaging profile under the conditions tested, with the effect attributed to a controlled, low-dose exposure rather than a high oxidative challenge.

What the authors concluded

The authors concluded that low-dose ozone/oxygen exerted a protective effect on isolated human sperm mitochondria, limiting reactive oxygen species, supporting the mitochondrial respiratory chain, maintaining membrane potential and ATP, and reducing cytochrome c release and apoptosis signalling. They suggested these observations may offer insight into the role of oxidative stress in male infertility and warrant further investigation.

Limitations of this study

This is a laboratory study on mitochondria isolated from sperm and studied in a test-tube environment, not a clinical trial. It does not measure fertility, sperm motility in living men, pregnancy or any real-world reproductive outcome, and results in isolated organelles do not necessarily translate to intact sperm, to the male reproductive tract, or to whole-body treatment. The work appears to come from a single research group and was published in a smaller, open-access journal, so the findings would need independent replication before firm conclusions could be drawn. It should be read as early mechanistic evidence about how ozone/oxygen interacts with mitochondrial biology, not as evidence that ozone therapy improves human fertility. Anyone considering ozone therapy for a fertility-related concern should discuss it with a qualified clinician.